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Feng Y, Chen Y, Wu X, Chen J, Zhou Q, Liu B, Zhang L, Yi C. Interplay of energy metabolism and autophagy. Autophagy 2024; 20:4-14. [PMID: 37594406 PMCID: PMC10761056 DOI: 10.1080/15548627.2023.2247300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 08/19/2023] Open
Abstract
Macroautophagy/autophagy, is widely recognized for its crucial role in enabling cell survival and maintaining cellular energy homeostasis during starvation or energy stress. Its regulation is intricately linked to cellular energy status. In this review, covering yeast, mammals, and plants, we aim to provide a comprehensive overview of the understanding of the roles and mechanisms of carbon- or glucose-deprivation related autophagy, showing how cells effectively respond to such challenges for survival. Further investigation is needed to determine the specific degraded substrates by autophagy during glucose or energy deprivation and the diverse roles and mechanisms during varying durations of energy starvation.Abbreviations: ADP: adenosine diphosphate; AMP: adenosine monophosphate; AMPK: AMP-activated protein kinase; ATG: autophagy related; ATP: adenosine triphosphate; ER: endoplasmic reticulum; ESCRT: endosomal sorting complex required for transport; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GD: glucose deprivation; GFP: green fluorescent protein; GTPases: guanosine triphosphatases; HK2: hexokinase 2; K phaffii: Komagataella phaffii; LD: lipid droplet; MAP1LC3/LC3: microtubule-associated protein1 light chain 3; MAPK: mitogen-activated protein kinase; Mec1: mitosis entry checkpoint 1; MTOR: mechanistic target of rapamycin kinase; NAD (+): nicotinamide adenine dinucleotide; OGD: oxygen and glucose deprivation; PAS: phagophore assembly site; PCD: programmed cell death; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; ROS: reactive oxygen species; S. cerevisiae: Saccharomyces cerevisiae; SIRT1: sirtuin 1; Snf1: sucrose non-fermenting 1; STK11/LKB1: serine/threonine kinase 11; TFEB: transcription factor EB; TORC1: target of rapamycin complex 1; ULK1: unc-51 like kinase 1; Vps27: vacuolar protein sorting 27; Vps4: vacuolar protein sorting 4.
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Affiliation(s)
- Yuyao Feng
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, School of Life Sciences, Huzhou University, Huzhou, China
- Department of Biochemistry, and Department of Hepatobiliary and Pancreatic Surgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Department of Vascular Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Ying Chen
- Department of Biochemistry, and Department of Hepatobiliary and Pancreatic Surgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaoyong Wu
- Department of Biochemistry, and Department of Hepatobiliary and Pancreatic Surgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Junye Chen
- Department of Vascular Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Qingyan Zhou
- Department of Biochemistry, and Department of Hepatobiliary and Pancreatic Surgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Bao Liu
- Department of Vascular Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Liqin Zhang
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, School of Life Sciences, Huzhou University, Huzhou, China
| | - Cong Yi
- Department of Biochemistry, and Department of Hepatobiliary and Pancreatic Surgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Wleklik K, Stefaniak S, Nuc K, Pietrowska-Borek M, Borek S. Identification and Potential Participation of Lipases in Autophagic Body Degradation in Embryonic Axes of Lupin ( Lupinus spp.) Germinating Seeds. Int J Mol Sci 2023; 25:90. [PMID: 38203260 PMCID: PMC10779169 DOI: 10.3390/ijms25010090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 11/28/2023] [Accepted: 12/13/2023] [Indexed: 01/12/2024] Open
Abstract
Autophagy is a fundamental process for plants that plays a crucial role in maintaining cellular homeostasis and promoting survival in response to various environmental stresses. One of the lesser-known stages of plant autophagy is the degradation of autophagic bodies in vacuoles. To this day, no plant vacuolar enzyme has been confirmed to be involved in this process. On the other hand, several enzymes have been described in yeast (Saccharomyces cerevisiae), including Atg15, that possess lipolytic activity. In this preliminary study, which was conducted on isolated embryonic axes of the white lupin (Lupinus albus L.) and Andean lupin (Lupinus mutabilis Sweet), the potential involvement of plant vacuolar lipases in the degradation of autophagic bodies was investigated. We identified in transcriptomes (using next-generation sequencing (NGS)) of white and Andean lupin embryonic axes 38 lipases with predicted vacuolar localization, and for three of them, similarities in amino acid sequences with yeast Atg15 were found. A comparative transcriptome analysis of lupin isolated embryonic axes cultured in vitro under different sucrose and asparagine nutrition, evaluating the relations in the levels of the transcripts of lipase genes, was also carried out. A clear decrease in lipase gene transcript levels caused by asparagine, a key amino acid in lupin seed metabolism which retards the degradation of autophagic bodies during sugar-starvation-induced autophagy in lupin embryonic axes, was detected. Although the question of whether lipases are involved in the degradation of autophagic bodies during plant autophagy is still open, our findings strongly support such a hypothesis.
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Affiliation(s)
- Karolina Wleklik
- Department of Plant Physiology, Faculty of Biology, Adam Mickiewicz University Poznań, Uniwersytetu Poznańskiego 6, 61-614 Poznań, Poland; (K.W.); (S.S.)
| | - Szymon Stefaniak
- Department of Plant Physiology, Faculty of Biology, Adam Mickiewicz University Poznań, Uniwersytetu Poznańskiego 6, 61-614 Poznań, Poland; (K.W.); (S.S.)
| | - Katarzyna Nuc
- Department of Biochemistry and Biotechnology, Faculty of Agronomy, Horticulture and Bioengineering, Poznań University of Life Sciences, Dojazd 11, 60-632 Poznań, Poland; (K.N.); (M.P.-B.)
| | - Małgorzata Pietrowska-Borek
- Department of Biochemistry and Biotechnology, Faculty of Agronomy, Horticulture and Bioengineering, Poznań University of Life Sciences, Dojazd 11, 60-632 Poznań, Poland; (K.N.); (M.P.-B.)
| | - Sławomir Borek
- Department of Plant Physiology, Faculty of Biology, Adam Mickiewicz University Poznań, Uniwersytetu Poznańskiego 6, 61-614 Poznań, Poland; (K.W.); (S.S.)
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3
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Yang C, Li X, Zhou J, Gao C. Autophagy contributes to positive feedback regulation of SnRK1 signaling in plants. Autophagy 2023; 19:3248-3250. [PMID: 37584544 PMCID: PMC10621257 DOI: 10.1080/15548627.2023.2247741] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/03/2023] [Accepted: 08/08/2023] [Indexed: 08/17/2023] Open
Abstract
SnRK1 (SNF1-related protein kinase 1) is a plant ortholog of yeast Snf1 and mammalian adenosine monophosphate-activated protein kinase (AMPK) that acts as a positive regulator of macroautophagy/autophagy. However, whether and how the autophagy pathway modulates SnRK1 activity remains elusive. Recently, we identified a clade of plant-specific FLZ (FCS-like zinc finger) proteins as novel ATG8 (autophagy-related 8)-interacting partners in Arabidopsis thaliana. These AtFLZs, which mainly localize on the surface of mitochondria, can inhibit SnRK1 signaling by repressing the T-loop phosphorylation of its catalytic α subunits, thereby negatively regulating carbon starvation-induced autophagy and plant tolerance to energy deprivation. Upon energy starvation, autophagy is activated to mediate the degradation of these AtFLZs, thus relieving their repression of SnRK1. More importantly, the ATG8-FLZ-SnRK1 regulatory axis appears to be functionally conserved during seed plant evolution. These findings highlight the positive role of autophagy in SnRK1 signaling activation under energy-limiting conditions in plants.Abbreviations: ADS, AIMs docking site; AIM, ATG8-interacting motif; AMPK, adenosine monophosphate-activated protein kinase; ATG, autophagy-related; ESCRT, endosomal sorting complexes required for transport; FLZ, FCS-like zinc finger protein; FREE1, FYVE DOMAIN PROTEIN REQUIRED FOR ENDOSOMAL SORTING 1; RAPTOR, REGULATORY-ASSOCIATED PROTEIN OF TOR; Snf1, SUCROSE NON-FERMENTING 1; SnRK1, SNF1-related kinase 1; TOR, TARGET OF RAPAMYCIN.
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Affiliation(s)
- Chao Yang
- Guangdong Provincial Key Laboratory of Applied Botany & Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Xibao Li
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Jun Zhou
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Caiji Gao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou, China
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Barros JAS, Cavalcanti JHF, Pimentel KG, Magen S, Soroka Y, Weiss S, Medeiros DB, Nunes-Nesi A, Fernie AR, Avin-Wittenberg T, Araújo WL. The interplay between autophagy and chloroplast vesiculation pathways under dark-induced senescence. Plant Cell Environ 2023; 46:3721-3736. [PMID: 37615309 DOI: 10.1111/pce.14701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 07/14/2023] [Accepted: 08/15/2023] [Indexed: 08/25/2023]
Abstract
In cellular circumstances where carbohydrates are scarce, plants can use alternative substrates for cellular energetic maintenance. In plants, the main protein reserve is present in the chloroplast, which contains most of the total leaf proteins and represents a rich source of nitrogen and amino acids. Autophagy plays a key role in chloroplast breakdown, a well-recognised symptom of both natural and stress-induced plant senescence. Remarkably, an autophagic-independent route of chloroplast degradation associated with chloroplast vesiculation (CV) gene was previously demonstrated. During extended darkness, CV is highly induced in the absence of autophagy, contributing to the early senescence phenotype of atg mutants. To further investigate the role of CV under dark-induced senescence conditions, mutants with low expression of CV (amircv) and double mutants amircv1xatg5 were characterised. Following darkness treatment, no aberrant phenotypes were observed in amircv single mutants; however, amircv1xatg5 double mutants displayed early senescence and altered dismantling of chloroplast and membrane structures under these conditions. Metabolic characterisation revealed that the functional lack of both CV and autophagy leads to higher impairment of amino acid release and differential organic acid accumulation during starvation conditions. The data obtained are discussed in the context of the role of CV and autophagy, both in terms of cellular metabolism and the regulation of chloroplast degradation.
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Affiliation(s)
- Jessica A S Barros
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - João Henrique F Cavalcanti
- Instituto de Educação, Agricultura e Ambiente, Universidade Federal do Amazonas, Humaitá, Amazonas, Brazil
| | - Karla G Pimentel
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Sahar Magen
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Yoram Soroka
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Shahar Weiss
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - David B Medeiros
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Adriano Nunes-Nesi
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Tamar Avin-Wittenberg
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Wagner L Araújo
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
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Yang C, Li X, Yang L, Chen S, Liao J, Li K, Zhou J, Shen W, Zhuang X, Bai M, Bassham DC, Gao C. A positive feedback regulation of SnRK1 signaling by autophagy in plants. Mol Plant 2023; 16:1192-1211. [PMID: 37408307 DOI: 10.1016/j.molp.2023.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 06/02/2023] [Accepted: 07/01/2023] [Indexed: 07/07/2023]
Abstract
SnRK1, an evolutionarily conserved heterotrimeric kinase complex that acts as a key metabolic sensor in maintaining energy homeostasis in plants, is an important upstream activator of autophagy that serves as a cellular degradation mechanism for the healthy growth of plants. However, whether and how the autophagy pathway is involved in regulating SnRK1 activity remains unknown. In this study, we identified a clade of plant-specific and mitochondria-localized FCS-like zinc finger (FLZ) proteins as currently unknown ATG8-interacting partners that actively inhibit SnRK1 signaling by repressing the T-loop phosphorylation of the catalytic α subunits of SnRK1, thereby negatively modulating autophagy and plant tolerance to energy deprivation caused by long-term carbon starvation. Interestingly, these AtFLZs are transcriptionally repressed by low-energy stress, and AtFLZ proteins undergo a selective autophagy-dependent pathway to be delivered to the vacuole for degradation, thereby constituting a positive feedback regulation to relieve their repression of SnRK1 signaling. Bioinformatic analyses show that the ATG8-FLZ-SnRK1 regulatory axis first appears in gymnosperms and seems to be highly conserved during the evolution of seed plants. Consistent with this, depletion of ATG8-interacting ZmFLZ14 confers enhanced tolerance, whereas overexpression of ZmFLZ14 leads to reduced tolerance to energy deprivation in maize. Collectively, our study reveals a previously unknown mechanism by which autophagy contributes to the positive feedback regulation of SnRK1 signaling, thereby enabling plants to better adapt to stressful environments.
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Affiliation(s)
- Chao Yang
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou 510631, China; Guangdong Provincial Key Laboratory of Applied Botany & Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Xibao Li
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Lianming Yang
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Shunquan Chen
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Jun Liao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Kailin Li
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Jun Zhou
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Wenjin Shen
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Xiaohong Zhuang
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Mingyi Bai
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA
| | - Caiji Gao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Ministry of Education & Guangdong Provincial Key Laboratory of Laser Life Science, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
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Ding J, McDowell N, Fang Y, Ward N, Kirwan ML, Regier P, Megonigal P, Zhang P, Zhang H, Wang W, Li W, Pennington SC, Wilson SJ, Stearns A, Bailey V. Modeling the mechanisms of conifer mortality under seawater exposure. New Phytol 2023. [PMID: 37376720 DOI: 10.1111/nph.19076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023]
Abstract
Relative sea level rise (SLR) increasingly impacts coastal ecosystems through the formation of ghost forests. To predict the future of coastal ecosystems under SLR and changing climate, it is important to understand the physiological mechanisms underlying coastal tree mortality and to integrate this knowledge into dynamic vegetation models. We incorporate the physiological effect of salinity and hypoxia in a dynamic vegetation model in the Earth system land model, and used the model to investigate the mechanisms of mortality of conifer forests on the west and east coast sites of USA, where trees experience different form of sea water exposure. Simulations suggest similar physiological mechanisms can result in different mortality patterns. At the east coast site that experienced severe increases in seawater exposure, trees loose photosynthetic capacity and roots rapidly, and both storage carbon and hydraulic conductance decrease significantly within a year. Over time, further consumption of storage carbon that leads to carbon starvation dominates mortality. At the west coast site that gradually exposed to seawater through SLR, hydraulic failure dominates mortality because root loss impacts on conductance are greater than the degree of storage carbon depletion. Measurements and modeling focused on understanding the physiological mechanisms of mortality is critical to reducing predictive uncertainty.
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Affiliation(s)
- Junyan Ding
- Biological Sciences Division, Pacific Northwest National Lab, PO Box 999, Richland, WA, 99352, USA
| | - Nate McDowell
- Biological Sciences Division, Pacific Northwest National Lab, PO Box 999, Richland, WA, 99352, USA
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA, 99164-4236, USA
| | - Yilin Fang
- Earth Systems Science Division, Pacific Northwest National Lab, Richland, WA, 99352, USA
| | - Nicholas Ward
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA, 98382, USA
| | - Matthew L Kirwan
- Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA, 23062, USA
| | - Peter Regier
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA, 98382, USA
| | - Patrick Megonigal
- Smithsonian Environmental Research Center, Edgewater, MD, 21037, USA
| | - Peipei Zhang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China
| | - Hongxia Zhang
- Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Wenzhi Wang
- The Key Laboratory of Mountain Environment Evolution and Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China
| | - Weibin Li
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
| | - Stephanie C Pennington
- Joint Global Change Research Institute, Pacific Northwest National Laboratory, College Park, MD, 20740, USA
| | | | - Alice Stearns
- Smithsonian Environmental Research Center, Edgewater, MD, 21037, USA
| | - Vanessa Bailey
- Biological Sciences Division, Pacific Northwest National Lab, PO Box 999, Richland, WA, 99352, USA
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Liu Q, Peng C, Schneider R, Cyr D, McDowell NG, Kneeshaw D. Drought-induced increase in tree mortality and corresponding decrease in the carbon sink capacity of Canada's boreal forests from 1970 to 2020. Glob Chang Biol 2023; 29:2274-2285. [PMID: 36704817 DOI: 10.1111/gcb.16599] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 01/03/2023] [Indexed: 05/28/2023]
Abstract
Canada's boreal forests, which occupy approximately 30% of boreal forests worldwide, play an important role in the global carbon budget. However, there is little quantitative information available regarding the spatiotemporal changes in the drought-induced tree mortality of Canada's boreal forests overall and their associated impacts on biomass carbon dynamics. Here, we develop spatiotemporally explicit estimates of drought-induced tree mortality and corresponding biomass carbon sink capacity changes in Canada's boreal forests from 1970 to 2020. We show that the average annual tree mortality rate is approximately 2.7%. Approximately 43% of Canada's boreal forests have experienced significantly increasing tree mortality trends (71% of which are located in the western region of the country), and these trends have accelerated since 2002. This increase in tree mortality has resulted in significant biomass carbon losses at an approximate rate of 1.51 ± 0.29 MgC ha-1 year-1 (95% confidence interval) with an approximate total loss of 0.46 ± 0.09 PgC year-1 (95% confidence interval). Under the drought condition increases predicted for this century, the capacity of Canada's boreal forests to act as a carbon sink will be further reduced, potentially leading to a significant positive climate feedback effect.
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Affiliation(s)
- Qiuyu Liu
- Department of Biology Sciences, Institute of Environment Sciences, University of Quebec at Montreal, Montreal, Quebec, Canada
- Centre for Forest Research, University of Quebec at Montreal, Montreal, Quebec, Canada
| | - Changhui Peng
- Department of Biology Sciences, Institute of Environment Sciences, University of Quebec at Montreal, Montreal, Quebec, Canada
- Centre for Forest Research, University of Quebec at Montreal, Montreal, Quebec, Canada
| | | | - Dominic Cyr
- Science and Technology Branch, Environment and Climate Change Canada, Gatineau, Quebec, Canada
| | - Nate G McDowell
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Lab, Richland, Washington, USA
- School of Biological Sciences, Washington State University, Pullman, Washington, USA
| | - Daniel Kneeshaw
- Centre for Forest Research, University of Quebec at Montreal, Montreal, Quebec, Canada
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Jurado-Flores A, Gotor C, Romero LC. Proteome Dynamics of Persulfidation in Leaf Tissue under Light/Dark Conditions and Carbon Deprivation. Antioxidants (Basel) 2023; 12:antiox12040789. [PMID: 37107163 PMCID: PMC10135009 DOI: 10.3390/antiox12040789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/09/2023] [Accepted: 03/21/2023] [Indexed: 04/29/2023] Open
Abstract
Hydrogen sulfide (H2S) acts as a signaling molecule in plants, bacteria, and mammals, regulating various physiological and pathological processes. The molecular mechanism by which hydrogen sulfide exerts its action involves the posttranslational modification of cysteine residues to form a persulfidated thiol motif. This research aimed to study the regulation of protein persulfidation. We used a label-free quantitative approach to measure the protein persulfidation profile in leaves under different growth conditions such as light regimen and carbon deprivation. The proteomic analysis identified a total of 4599 differentially persulfidated proteins, of which 1115 were differentially persulfidated between light and dark conditions. The 544 proteins that were more persulfidated in the dark were analyzed, and showed significant enrichment in functions and pathways related to protein folding and processing in the endoplasmic reticulum. Under light conditions, the persulfidation profile changed, and the number of differentially persulfidated proteins increased up to 913, with the proteasome and ubiquitin-dependent and ubiquitin-independent catabolic processes being the most-affected biological processes. Under carbon starvation conditions, a cluster of 1405 proteins was affected by a reduction in their persulfidation, being involved in metabolic processes that provide primary metabolites to essential energy pathways and including enzymes involved in sulfur assimilation and sulfide production.
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Affiliation(s)
- Ana Jurado-Flores
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092 Sevilla, Spain
| | - Cecilia Gotor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092 Sevilla, Spain
| | - Luis C Romero
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092 Sevilla, Spain
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Gao Y, Øverlie Arntzen M, Kjos M, Bakken LR, Frostegård Å. Denitrification by Bradyrhizobia under Feast and Famine and the Role of the bc1 Complex in Securing Electrons for N(2)O Reduction. Appl Environ Microbiol 2023; 89:e0174522. [PMID: 36662572 DOI: 10.1128/aem.01745-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Rhizobia living as microsymbionts inside nodules have stable access to carbon substrates, but also must survive as free-living bacteria in soil where they are starved for carbon and energy most of the time. Many rhizobia can denitrify, thus switch to anaerobic respiration under low O2 tension using N-oxides as electron acceptors. The cellular machinery regulating this transition is relatively well known from studies under optimal laboratory conditions, while little is known about this regulation in starved organisms. It is, for example, not known if the strong preference for N2O- over NO3- reduction in bradyrhizobia is retained under carbon limitation. Here, we show that starved cultures of a Bradyrhizobium strain with respiration rates 1 to 18% of well-fed cultures reduced all available N2O before touching provided NO3-. These organisms, which carry out complete denitrification, have the periplasmic nitrate reductase NapA but lack the membrane-bound nitrate reductase NarG. Proteomics showed similar levels of NapA and NosZ (N2O reductase), excluding that the lack of NO3- reduction was due to low NapA abundance. Instead, this points to a metabolic-level phenomenon where the bc1 complex, which channels electrons to NosZ via cytochromes, is a much stronger competitor for electrons from the quinol pool than the NapC enzyme, which provides electrons to NapA via NapB. The results contrast the general notion that NosZ activity diminishes under carbon limitation and suggest that bradyrhizobia carrying NosZ can act as strong sinks for N2O under natural conditions, implying that this criterion should be considered in the development of biofertilizers. IMPORTANCE Legume cropped farmlands account for substantial N2O emissions globally. Legumes are commonly inoculated with N2-fixing bacteria, rhizobia, to improve crop yields. Rhizobia belonging to Bradyrhizobium, the microsymbionts of several economically important legumes, are generally capable of denitrification but many lack genes encoding N2O reductase and will be N2O sources. Bradyrhizobia with complete denitrification will instead act as sinks since N2O-reduction efficiently competes for electrons over nitrate reduction in these organisms. This phenomenon has only been demonstrated under optimal conditions and it is not known how carbon substrate limitation, which is the common situation in most soils, affects the denitrification phenotype. Here, we demonstrate that bradyrhizobia retain their strong preference for N2O under carbon starvation. The findings add basic knowledge about mechanisms controlling denitrification and support the potential for developing novel methods for greenhouse gas mitigation based on legume inoculants with the dual capacity to optimize N2 fixation and minimize N2O emission.
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10
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Li X, Liao J, Bai H, Bei J, Li K, Luo M, Shen W, Yang C, Gao C. Arabidopsis flowering integrator SOC1 transcriptionally regulates autophagy in response to long-term carbon starvation. J Exp Bot 2022; 73:6589-6599. [PMID: 35852462 DOI: 10.1093/jxb/erac298] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/02/2022] [Indexed: 06/15/2023]
Abstract
Autophagy is a highly conserved, self-digestion process that is essential for plant adaptations to various environmental stresses. Although the core components of autophagy in plants have been well established, the molecular basis for its transcriptional regulation remains to be fully characterized. In this study, we demonstrate that SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), a MADS-box family transcription factor that determines flowering transition in Arabidopsis, functions as a transcriptional repressor of autophagy. EMSAs, ChIP-qPCR assays, and dual-luciferase receptor assays showed that SOC1 can bind to the promoters of ATG4b, ATG7, and ATG18c via the conserved CArG box. qRT-PCR analysis showed that the three ATG genes ATG4b, ATG7, and ATG18c were up-regulated in the soc1-2 mutant. In line with this, the mutant also displayed enhanced autophagy activity, as revealed by increased autophagosome formation and elevated autophagic flux compared with the wild type. More importantly, SOC1 negatively affected the tolerance of plants to long-term carbon starvation, and this process requires a functional autophagy pathway. Finally, we found that SOC1 was repressed upon carbon starvation at both the transcriptional and protein levels. Overall, our study not only uncovers an important transcriptional mechanism that contributes to the regulation of plant autophagy in response to nutrient starvation, but also highlights novel cellular functions of the flowering integrator SOC1.
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Affiliation(s)
- Xibao Li
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Jun Liao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Haiyan Bai
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Jieying Bei
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Kailin Li
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Ming Luo
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Wenjin Shen
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Chao Yang
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Caiji Gao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
- MOE & Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
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11
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Yang MK, Zhu XJ, Chen CM, Guo X, Xu SX, Xu YR, Du SX, Xiao S, Mueller-Roeber B, Huang W, Chen L. The plant circadian clock regulates autophagy rhythm through transcription factor LUX ARRHYTHMO. J Integr Plant Biol 2022; 64:2135-2149. [PMID: 35962716 DOI: 10.1111/jipb.13343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Accepted: 08/10/2022] [Indexed: 06/15/2023]
Abstract
Autophagy is an evolutionarily conserved degradation pathway in eukaryotes; it plays a critical role in nutritional stress tolerance. The circadian clock is an endogenous timekeeping system that generates biological rhythms to adapt to daily changes in the environment. Accumulating evidence indicates that the circadian clock and autophagy are intimately interwoven in animals. However, the role of the circadian clock in regulating autophagy has been poorly elucidated in plants. Here, we show that autophagy exhibits a robust circadian rhythm in both light/dark cycle (LD) and in constant light (LL) in Arabidopsis. However, autophagy rhythm showed a different pattern with a phase-advance shift and a lower amplitude in LL compared to LD. Moreover, mutation of the transcription factor LUX ARRHYTHMO (LUX) removed autophagy rhythm in LL and led to an enhanced amplitude in LD. LUX represses expression of the core autophagy genes ATG2, ATG8a, and ATG11 by directly binding to their promoters. Phenotypic analysis revealed that LUX is responsible for improved resistance of plants to carbon starvation, which is dependent on moderate autophagy activity. Comprehensive transcriptomic analysis revealed that the autophagy rhythm is ubiquitous in plants. Taken together, our findings demonstrate that the LUX-mediated circadian clock regulates plant autophagy rhythms.
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Affiliation(s)
- Ming-Kang Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, South China Agricultural University, Guangzhou, 510642, China
| | - Xiao-Jie Zhu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Chu-Min Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Xu Guo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Shu-Xuan Xu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Ya-Rou Xu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Shen-Xiu Du
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Shi Xiao
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Bernd Mueller-Roeber
- Department of Molecular Biology, Institute of Biochemistry and Biology, University of Potsdam, 14476, Potsdam-Golm, Germany
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam-Golm, Germany
| | - Wei Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, South China Agricultural University, Guangzhou, 510642, China
| | - Liang Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, South China Agricultural University, Guangzhou, 510642, China
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12
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McDowell NG, Ball M, Bond‐Lamberty B, Kirwan ML, Krauss KW, Megonigal JP, Mencuccini M, Ward ND, Weintraub MN, Bailey V. Processes and mechanisms of coastal woody-plant mortality. Glob Chang Biol 2022; 28:5881-5900. [PMID: 35689431 PMCID: PMC9544010 DOI: 10.1111/gcb.16297] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 05/24/2022] [Indexed: 05/26/2023]
Abstract
Observations of woody plant mortality in coastal ecosystems are globally widespread, but the overarching processes and underlying mechanisms are poorly understood. This knowledge deficiency, combined with rapidly changing water levels, storm surges, atmospheric CO2 , and vapor pressure deficit, creates large predictive uncertainty regarding how coastal ecosystems will respond to global change. Here, we synthesize the literature on the mechanisms that underlie coastal woody-plant mortality, with the goal of producing a testable hypothesis framework. The key emergent mechanisms underlying mortality include hypoxic, osmotic, and ionic-driven reductions in whole-plant hydraulic conductance and photosynthesis that ultimately drive the coupled processes of hydraulic failure and carbon starvation. The relative importance of these processes in driving mortality, their order of progression, and their degree of coupling depends on the characteristics of the anomalous water exposure, on topographic effects, and on taxa-specific variation in traits and trait acclimation. Greater inundation exposure could accelerate mortality globally; however, the interaction of changing inundation exposure with elevated CO2 , drought, and rising vapor pressure deficit could influence mortality likelihood. Models of coastal forests that incorporate the frequency and duration of inundation, the role of climatic drivers, and the processes of hydraulic failure and carbon starvation can yield improved estimates of inundation-induced woody-plant mortality.
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Affiliation(s)
- Nate G. McDowell
- Atmospheric Sciences and Global Change DivisionPacific Northwest National LabRichlandWashingtonUSA
- School of Biological SciencesWashington State UniversityPullmanWashingtonUSA
| | - Marilyn Ball
- Plant Science Division, Research School of BiologyThe Australian National UniversityActonAustralian Capital TerritoryAustralia
| | - Ben Bond‐Lamberty
- Joint Global Change Research Institute, Pacific Northwest National LaboratoryCollege ParkMarylandUSA
| | - Matthew L. Kirwan
- Virginia Institute of Marine Science, William & MaryGloucester PointVirginiaUSA
| | - Ken W. Krauss
- U.S. Geological Survey, Wetland and Aquatic Research CenterLafayetteLouisianaUSA
| | | | - Maurizio Mencuccini
- ICREA, Passeig Lluís Companys 23BarcelonaSpain
- CREAFCampus UAB, BellaterraBarcelonaSpain
| | - Nicholas D. Ward
- Marine and Coastal Research LaboratoryPacific Northwest National LaboratorySequimWashingtonUSA
- School of OceanographyUniversity of WashingtonSeattleWashingtonUSA
| | - Michael N. Weintraub
- Department of Environmental SciencesUniversity of ToledoToledoOhioUSA
- Biological Sciences DivisionPacific Northwest National LaboratoryWashingtonUSA
| | - Vanessa Bailey
- Biological Sciences DivisionPacific Northwest National LaboratoryWashingtonUSA
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13
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Chen Z, Li S, Wan X, Liu S. Strategies of tree species to adapt to drought from leaf stomatal regulation and stem embolism resistance to root properties. Front Plant Sci 2022; 13:926535. [PMID: 36237513 PMCID: PMC9552884 DOI: 10.3389/fpls.2022.926535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Considerable evidences highlight the occurrence of increasing widespread tree mortality as a result of global climate change-associated droughts. However, knowledge about the mechanisms underlying divergent strategies of various tree species to adapt to drought has remained remarkably insufficient. Leaf stomatal regulation and embolism resistance of stem xylem serves as two important strategies for tree species to prevent hydraulic failure and carbon starvation, as comprising interconnected physiological mechanisms underlying drought-induced tree mortality. Hence, the physiological and anatomical determinants of leaf stomatal regulation and stems xylem embolism resistance are evaluated and discussed. In addition, root properties related to drought tolerance are also reviewed. Species with greater investment in leaves and stems tend to maintain stomatal opening and resist stem embolism under drought conditions. The coordination between stomatal regulation and stem embolism resistance are summarized and discussed. Previous studies showed that hydraulic safety margin (HSM, the difference between minimum water potential and that causing xylem dysfunction) is a significant predictor of tree species mortality under drought conditions. Compared with HSM, stomatal safety margin (the difference between water potential at stomatal closure and that causing xylem dysfunction) more directly merge stomatal regulation strategies with xylem hydraulic strategies, illustrating a comprehensive framework to characterize plant response to drought. A combination of plant traits reflecting species' response and adaptation to drought should be established in the future, and we propose four specific urgent issues as future research priorities.
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Affiliation(s)
- Zhicheng Chen
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
| | - Shan Li
- Department of Environmental Science and Ecology, School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi’an, China
| | - Xianchong Wan
- Institute of Ecological Conservation and Restoration, Chinese Academy of Forestry, Beijing, China
| | - Shirong Liu
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
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14
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Li W, McDowell NG, Zhang H, Wang W, Mackay DS, Leff R, Zhang P, Ward ND, Norwood M, Yabusaki S, Myers-Pigg AN, Pennington SC, Pivovaroff AL, Waichler S, Xu C, Bond-Lamberty B, Bailey VL. The influence of increasing atmospheric CO 2 , temperature, and vapor pressure deficit on seawater-induced tree mortality. New Phytol 2022; 235:1767-1779. [PMID: 35644021 DOI: 10.1111/nph.18275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
Increasing seawater exposure is killing coastal trees globally, with expectations of accelerating mortality with rising sea levels. However, the impact of concomitant changes in atmospheric CO2 concentration, temperature, and vapor pressure deficit (VPD) on seawater-induced tree mortality is uncertain. We examined the mechanisms of seawater-induced mortality under varying climate scenarios using a photosynthetic gain and hydraulic cost optimization model validated against observations in a mature stand of Sitka spruce (Picea sitchensis) trees in the Pacific Northwest, USA, that were dying from recent seawater exposure. The simulations matched well with observations of photosynthesis, transpiration, nonstructural carbohydrates concentrations, leaf water potential, the percentage loss of xylem conductivity, and stand-level mortality rates. The simulations suggest that seawater-induced mortality could decrease by c. 16.7% with increasing atmospheric CO2 levels due to reduced risk of carbon starvation. Conversely, rising VPD could increase mortality by c. 5.6% because of increasing risk of hydraulic failure. Across all scenarios, seawater-induced mortality was driven by hydraulic failure in the first 2 yr after seawater exposure began, with carbon starvation becoming more important in subsequent years. Changing CO2 and climate appear unlikely to have a significant impact on coastal tree mortality under rising sea levels.
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Affiliation(s)
- Weibin Li
- State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
- Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Nate G McDowell
- Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
- School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
| | - Hongxia Zhang
- Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
- Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Wenzhi Wang
- Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
- The Key Laboratory of Mountain Environment Evolution and Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China
| | - D Scott Mackay
- Department of Geography and Department of Environment & Sustainability, University at Buffalo, Buffalo, NY, 14261, USA
| | - Riley Leff
- Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Peipei Zhang
- Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
- CAS Key Laboratory of Mountain Ecological Restoration, Bioresource Utilization & Ecological Restoration, Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China
| | - Nicholas D Ward
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA, 98382, USA
- School of Oceanography, University of Washington, Seattle, WA, 98105, USA
| | - Matt Norwood
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA, 98382, USA
| | - Steve Yabusaki
- Earth Systems Science, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Allison N Myers-Pigg
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA, 98382, USA
- Department of Environmental Sciences, University of Toledo, Toledo, OH, 43606, USA
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Stephanie C Pennington
- Pacific Northwest National Laboratory, Joint Global Change Research Institute, College Park, MD, 20740, USA
| | - Alexandria L Pivovaroff
- Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Scott Waichler
- Earth Systems Science, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Chonggang Xu
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Ben Bond-Lamberty
- Pacific Northwest National Laboratory, Joint Global Change Research Institute, College Park, MD, 20740, USA
| | - Vanessa L Bailey
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
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15
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Gomez‐Gallego M, Galiano L, Martínez‐Vilalta J, Stenlid J, Capador‐Barreto HD, Elfstrand M, Camarero JJ, Oliva J. Interaction of drought- and pathogen-induced mortality in Norway spruce and Scots pine. Plant Cell Environ 2022; 45:2292-2305. [PMID: 35598958 PMCID: PMC9546048 DOI: 10.1111/pce.14360] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 05/11/2022] [Accepted: 05/14/2022] [Indexed: 06/15/2023]
Abstract
Pathogenic diseases frequently occur in drought-stressed trees. However, their contribution to the process of drought-induced mortality is poorly understood. We combined drought and stem inoculation treatments to study the physiological processes leading to drought-induced mortality in Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) saplings infected with Heterobasidion annosum s.s. We analysed the saplings' water status, gas exchange, nonstructural carbohydrates (NSCs) and defence responses, and how they related to mortality. Saplings were followed for two growing seasons, including an artificially induced 3-month dormancy period. The combined drought and pathogen treatment significantly increased spruce mortality; however, no interaction between these stressors was observed in pine, although individually each stressor caused mortality. Our results suggest that pathogen infection decreased carbon reserves in spruce, reducing the capacity of saplings to cope with drought, resulting in increased mortality rates. Defoliation, relative water content and the starch concentration of needles were predictors of mortality in both species under drought and pathogen infection. Infection and drought stress create conflicting needs for carbon to compartmentalize the pathogen and to avoid turgor loss, respectively. Heterobasidion annosum reduces the functional sapwood area and shifts NSC allocation patterns, reducing the capacity of trees to cope with drought.
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Affiliation(s)
- Mireia Gomez‐Gallego
- Department of Forest Mycology and Plant PathologySwedish University of Agricultural SciencesUppsalaSweden
- Université de Lorraine, INRAE, IAMNancyFrance
| | - Lucia Galiano
- CREAF, Bellaterra (Cerdanyola del Vallès)CataloniaSpain
- Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès)CataloniaSpain
| | - Jordi Martínez‐Vilalta
- CREAF, Bellaterra (Cerdanyola del Vallès)CataloniaSpain
- Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès)CataloniaSpain
| | - Jan Stenlid
- Department of Forest Mycology and Plant PathologySwedish University of Agricultural SciencesUppsalaSweden
| | - Hernán D. Capador‐Barreto
- Department of Forest Mycology and Plant PathologySwedish University of Agricultural SciencesUppsalaSweden
| | - Malin Elfstrand
- Department of Forest Mycology and Plant PathologySwedish University of Agricultural SciencesUppsalaSweden
| | | | - Jonàs Oliva
- Department of Crop and Forest SciencesUniversity of LleidaLleidaSpain
- Joint Research Unit CTFC‐AGROTECNIOLleidaSpain
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16
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Zhai PF, Guan JX, He P, Liu HY, Man L, Jiang Y, Ma CC. [Changes of non-structural carbohydrates and nitrogen contents of needles and twigs in Pinus sylvestris var. mongolica plantations along an aridity gradient]. Ying Yong Sheng Tai Xue Bao 2022; 33:1518-1524. [PMID: 35729128 DOI: 10.13287/j.1001-9332.202206.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
With six Pinus sylvestris var. mongolica plantations (Huinan, Xifeng, Fujia, Zhanggutai, Naiman and Wulanaodu) along an aridity gradient in the Horqin sandy land, we examined the changes in non-structural carbohydrates (NSCs) and nitrogen (N) contents of current and one-year-old needles and twigs, to explore the carbon supply and demand status as well as the nutrient accumulation strategies of P. sylvestris var. mongolica under drought. The results showed that the contents of NSCs and soluble sugars in needles and twigs of P. sylvestris var. mongolica plantations significantly decreased with increasing aridity. From the most humid site (Huinan) to the most aridity site (Wulanaodu), the soluble sugar contents in current and one-year old needles of P. sylvestris var. mongolica decreased from 12.8% and 12.5% to 9.0% and 9.5%, respectively. The soluble sugar contents in current-year old twigs decreased from 15.6% to 9.2%. With increasing aridity, the starch contents in needles and twigs remained relatively stable, soluble sugars/starch ratio in current and one-year old needles decreased, the N contents in current and one-year old twigs significantly increased. The P. sylvestris var. mongolica plantations in the Horqin sandy land consumed soluble sugar storage under drought, resulting in a risk of mortality from 'carbon starvation'. P. sylvestris var. mongolica tended to maintain stable starch storage and accumulate N in twigs to cope with long-term drought stress.
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Affiliation(s)
- Pei-Feng Zhai
- College of Life Sciences, Tianjin Normal University, Tianjin 300387, China
| | - Jia-Xin Guan
- College of Life Sciences, Tianjin Normal University, Tianjin 300387, China
| | - Peng He
- College of Life Sciences, Tianjin Normal University, Tianjin 300387, China
| | - He-Yong Liu
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Liang Man
- College of Life Sciences, Tianjin Normal University, Tianjin 300387, China
| | - Yong Jiang
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Cheng-Cang Ma
- College of Life Sciences, Tianjin Normal University, Tianjin 300387, China
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17
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Hajek P, Link RM, Nock CA, Bauhus J, Gebauer T, Gessler A, Kovach K, Messier C, Paquette A, Saurer M, Scherer-Lorenzen M, Rose L, Schuldt B. Mutually inclusive mechanisms of drought-induced tree mortality. Glob Chang Biol 2022; 28:3365-3378. [PMID: 35246895 DOI: 10.1111/gcb.16146] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/16/2021] [Indexed: 06/14/2023]
Abstract
Unprecedented tree dieback across Central Europe caused by recent global change-type drought events highlights the need for a better mechanistic understanding of drought-induced tree mortality. Although numerous physiological risk factors have been identified, the importance of two principal mechanisms, hydraulic failure and carbon starvation, is still debated. It further remains largely unresolved how the local neighborhood composition affects individual mortality risk. We studied 9435 young trees of 12 temperate species planted in a diversity experiment in 2013 to assess how hydraulic traits, carbon dynamics, pest infestation, tree height and neighborhood competition influence individual mortality risk. Following the most extreme global change-type drought since record in 2018, one third of these trees died. Across species, hydraulic safety margins (HSMs) were negatively and a shift towards a higher sugar fraction in the non-structural carbohydrate (NSC) pool positively associated with mortality risk. Moreover, trees infested by bark beetles had a higher mortality risk, and taller trees a lower mortality risk. Most neighborhood interactions were beneficial, although neighborhood effects were highly species-specific. Species that suffered more from drought, especially Larix spp. and Betula spp., tended to increase the survival probability of their neighbors and vice versa. While severe tissue dehydration marks the final stage of drought-induced tree mortality, we show that hydraulic failure is interrelated with a series of other, mutually inclusive processes. These include shifts in NSC pools driven by osmotic adjustment and/or starch depletion as well as pest infestation and are modulated by the size and species identity of a tree and its neighbors. A more holistic view that accounts for multiple causes of drought-induced tree mortality is required to improve predictions of trends in global forest dynamics and to identify mutually beneficial species combinations.
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Affiliation(s)
- Peter Hajek
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Roman M Link
- Chair of Ecophysiology and Vegetation Ecology, University of Würzburg, Julius-von-Sachs-Institute of Biological Sciences, Würzburg, Germany
| | - Charles A Nock
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Jürgen Bauhus
- Chair of Silviculture, University of Freiburg, Freiburg, Germany
| | - Tobias Gebauer
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Arthur Gessler
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
- ETH Zurich, Institute of Terrestrial Ecosystems, Zurich, Switzerland
| | - Kyle Kovach
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Christian Messier
- Center for Forest Research, Université du Québec à Montréal, Montréal, Quebec, Canada
- University of Quebec in Outaouais (UQO), Institut des Sciences de la Forêt Tempérée (ISFORT), Gatineau, Quebec, Canada
| | - Alain Paquette
- Center for Forest Research, Université du Québec à Montréal, Montréal, Quebec, Canada
| | - Matthias Saurer
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
| | | | - Laura Rose
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Bernhard Schuldt
- Chair of Ecophysiology and Vegetation Ecology, University of Würzburg, Julius-von-Sachs-Institute of Biological Sciences, Würzburg, Germany
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18
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Hajek P, Link RM, Nock CA, Bauhus J, Gebauer T, Gessler A, Kovach K, Messier C, Paquette A, Saurer M, Scherer-Lorenzen M, Rose L, Schuldt B. Mutually inclusive mechanisms of drought-induced tree mortality. Glob Chang Biol 2022; 28:3365-3378. [PMID: 35246895 DOI: 10.1101/2020.12.17.423038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/16/2021] [Indexed: 05/22/2023]
Abstract
Unprecedented tree dieback across Central Europe caused by recent global change-type drought events highlights the need for a better mechanistic understanding of drought-induced tree mortality. Although numerous physiological risk factors have been identified, the importance of two principal mechanisms, hydraulic failure and carbon starvation, is still debated. It further remains largely unresolved how the local neighborhood composition affects individual mortality risk. We studied 9435 young trees of 12 temperate species planted in a diversity experiment in 2013 to assess how hydraulic traits, carbon dynamics, pest infestation, tree height and neighborhood competition influence individual mortality risk. Following the most extreme global change-type drought since record in 2018, one third of these trees died. Across species, hydraulic safety margins (HSMs) were negatively and a shift towards a higher sugar fraction in the non-structural carbohydrate (NSC) pool positively associated with mortality risk. Moreover, trees infested by bark beetles had a higher mortality risk, and taller trees a lower mortality risk. Most neighborhood interactions were beneficial, although neighborhood effects were highly species-specific. Species that suffered more from drought, especially Larix spp. and Betula spp., tended to increase the survival probability of their neighbors and vice versa. While severe tissue dehydration marks the final stage of drought-induced tree mortality, we show that hydraulic failure is interrelated with a series of other, mutually inclusive processes. These include shifts in NSC pools driven by osmotic adjustment and/or starch depletion as well as pest infestation and are modulated by the size and species identity of a tree and its neighbors. A more holistic view that accounts for multiple causes of drought-induced tree mortality is required to improve predictions of trends in global forest dynamics and to identify mutually beneficial species combinations.
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Affiliation(s)
- Peter Hajek
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Roman M Link
- Chair of Ecophysiology and Vegetation Ecology, University of Würzburg, Julius-von-Sachs-Institute of Biological Sciences, Würzburg, Germany
| | - Charles A Nock
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Jürgen Bauhus
- Chair of Silviculture, University of Freiburg, Freiburg, Germany
| | - Tobias Gebauer
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Arthur Gessler
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
- ETH Zurich, Institute of Terrestrial Ecosystems, Zurich, Switzerland
| | - Kyle Kovach
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Christian Messier
- Center for Forest Research, Université du Québec à Montréal, Montréal, Quebec, Canada
- University of Quebec in Outaouais (UQO), Institut des Sciences de la Forêt Tempérée (ISFORT), Gatineau, Quebec, Canada
| | - Alain Paquette
- Center for Forest Research, Université du Québec à Montréal, Montréal, Quebec, Canada
| | - Matthias Saurer
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
| | | | - Laura Rose
- Geobotany, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Bernhard Schuldt
- Chair of Ecophysiology and Vegetation Ecology, University of Würzburg, Julius-von-Sachs-Institute of Biological Sciences, Würzburg, Germany
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19
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Shen JX, Zhang YJ, Maenpuen P, Zhang SB, Zhang L, Yang L, Tao LB, Yan PY, Zhang ZM, Li SQ, Yuan X, Kongjarat W, Kaewkamol S, Tinprabat P, Chen YJ. Response of four evergreen savanna shrubs to an incidence of extreme drought: high embolism resistance, branch shedding and maintenance of nonstructural carbohydrates. Tree Physiol 2022; 42:740-753. [PMID: 35020937 DOI: 10.1093/treephys/tpab150] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 10/20/2021] [Indexed: 06/14/2023]
Abstract
Extreme drought events are becoming frequent globally, resulting in widespread plant mortality and forest dieback. Although savanna vegetation cover ~20% of the earth's land area, their responses to extreme drought have been less studied than that of forests. Herein, we quantified branch dieback, individual mortality and the associated physiological responses of four evergreen shrubs (Tarenna depauperate Hutch., Maytenus esquirolii (H. Lév.) C.Y. Cheng, Murraya exotica L., Jasminum nudiflorum Lindl.) in a savanna ecosystem in Southwest China to an incidence of extreme drought during 2019 and 2020. We found that 80-100% of the individuals of these species exhibited branch dieback, whereas individual mortality was only found in T. depauperate (4.5%). All species showed high resistance to stem embolism (P50, water potential at 50% loss of hydraulic conductivity ranged from -5.62 to -8.6 MPa), whereas the stem minimum water potentials reached -7.6 to ca -10.0 MPa during the drought. The low water potential caused high native embolism levels (percentage loss of hydraulic conductivity (PLC) 23-65%) in terminal branches, and the remaining stems maintained 15-35% PLC at the end of the drought. Large within-individual variations in stem vulnerability to embolism were detected, and shedding of vulnerable branches could be a mechanism for shrubs to reduce water and carbon consumption. Overall, the content of total nonstructural carbohydrates (NSC) and their components in the stem were generally comparable to or higher than those in the rainy season in three of the four species. Because the leaves were turgor-less for most time during the drought, high NSC levels during the drought could be due to recycling of NSC from dead branches or translocation from roots. Our results suggest high tolerance of savanna shrub species to extreme drought, which could be facilitated by high embolism resistance in some stems and shedding of vulnerable branches to maintain individual water and carbon balance.
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Affiliation(s)
- Jing-Xian Shen
- Institute of Ecology and Geobotany, School of Ecology and Environmental Sciences, Yunnan University, Kunming, Yunnan 650091, China
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- Yuanjiang Savanna Ecosystem Research Station, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yuanjiang, Yunnan 6663300, China
| | - Yong-Jiang Zhang
- School of Biology and Ecology, University of Maine, Orono, ME 04469, USA
| | - Phisamai Maenpuen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Shu-Bin Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China
| | - Lan Zhang
- School of Geography and Ecotoursim, Southwest Forestry University, Panlong District, Kunming, Yunnan 650224, China
| | - Lin Yang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
| | - Lian-Bin Tao
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
| | - Peng-Yun Yan
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
| | - Zhi-Ming Zhang
- Institute of Ecology and Geobotany, School of Ecology and Environmental Sciences, Yunnan University, Kunming, Yunnan 650091, China
| | - Shu-Qiong Li
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Xia Yuan
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Wanwalee Kongjarat
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Sasiwimol Kaewkamol
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Pimnara Tinprabat
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Ya-Jun Chen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- Yuanjiang Savanna Ecosystem Research Station, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yuanjiang, Yunnan 6663300, China
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China
- Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Yunnan 666303, China
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20
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Tsuji C, Dannoura M, Desalme D, Angeli N, Takanashi S, Kominami Y, Epron D. Drought affects the fate of non-structural carbohydrates in hinoki cypress. Tree Physiol 2022; 42:784-796. [PMID: 34635913 DOI: 10.1093/treephys/tpab135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 10/01/2021] [Indexed: 06/13/2023]
Abstract
Tree species that close stomata early in response to drought are likely to suffer from an imbalance between limited carbohydrate supply due to reduced photosynthesis and metabolic demand. Our objective was to clarify the dynamic responses of non-structural carbohydrates to drought in a water-saving species, the hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.). To this end, we pulse-labeled young trees with 13CO2 10 days after the beginning of the drought treatment. Trees were harvested 7 days later, early during drought progression, and 86 days later when they had suffered from a long and severe drought. The labeled carbon (C) was traced in phloem extract, in the organic matter and starch of all the organs, and in the soluble sugars (sucrose, glucose and fructose) of the most metabolically active organs (foliage, green branches and fine roots). No drought-related changes in labeled C partitioning between belowground and aboveground organs were observed. The C allocation between non-structural carbohydrates was altered early during drought progression: starch concentration was lower by half in the photosynthetic organs, while the concentration of almost all soluble sugars tended to increase. The preferential allocation of labeled C to glucose and fructose reflected an increased demand for soluble sugars for osmotic adjustment. After 3 months of a lethal drought, the concentrations of soluble sugars and starch were admittedly lower in drought-stressed trees than in the controls, but the pool of non-structural carbohydrates was far from completely depleted. However, the allocation to storage had been impaired by drought; photosynthesis and the sugar translocation rate had also been reduced by drought. Failure to maintain cell turgor through osmoregulation and to refill embolized xylem due to the depletion in soluble sugars in the roots could have resulted in tree mortality in hinoki cypress, though the total pool of carbohydrate was not completely depleted.
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Affiliation(s)
- Chiaki Tsuji
- Graduate School of Environmental Studies, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masako Dannoura
- Graduate School of Environmental Studies, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Dorine Desalme
- Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 34 cours Léopold, Nancy F-54000, France
| | - Nicolas Angeli
- Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 34 cours Léopold, Nancy F-54000, France
| | - Satoru Takanashi
- Forestry and Forest Products Research Institute, Kansai Research Centre, 68 Nagaikyutaroh, Momoyama, Fushimi, Kyoto 612-0855, Japan
| | - Yuji Kominami
- Forestry and Forest Products Research Institute, 1 Matsunosato, Ibaraki, Tsukuba 305-8687, Japan
| | - Daniel Epron
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
- Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 34 cours Léopold, Nancy F-54000, France
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21
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Wang K, Cai S, Xing Q, Qi Z, Fotopoulos V, Yu J, Zhou J. Melatonin delays dark-induced leaf senescence by inducing miR171b expression in tomato. J Pineal Res 2022; 72:e12792. [PMID: 35174545 DOI: 10.1111/jpi.12792] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 01/29/2022] [Accepted: 02/11/2022] [Indexed: 11/29/2022]
Abstract
Melatonin functions in multiple aspects of plant growth, development, and stress response. Nonetheless, the mechanism of melatonin in plant carbon metabolism remains largely unknown. In this study, we investigated the influence of melatonin on the degradation of starch in tomato leaves. Results showed that exogenous melatonin attenuated carbon starvation-induced chlorophyll degradation and leaf senescence. In addition, melatonin delayed leaf starch degradation and inhibited the transcription of starch-degrading enzymes after sunset. Interestingly, melatonin-alleviated symptoms of leaf senescence and starch degradation were compromised when the first key gene for starch degradation, α-glucan water dikinase (GWD), was overexpressed. Furthermore, exogenous melatonin significantly upregulated the transcript levels of several microRNAs, including miR171b. Crucially, the GWD gene was identified as a target of miR171b, and the overexpression of miR171b ameliorated the carbon starvation-induced degradation of chlorophyll and starch, and inhibited the expression of the GWD gene. Taken together, these results demonstrate that melatonin promotes plant tolerance against carbon starvation by upregulating the expression of miR171b, which can directly inhibit GWD expression in tomato leaves.
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Affiliation(s)
- Kaixin Wang
- Department of Horticulture, Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zijingang Campus, Zhejiang University, Hangzhou, People's Republic of China
| | - Shuyu Cai
- Department of Horticulture, Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zijingang Campus, Zhejiang University, Hangzhou, People's Republic of China
| | - Qufan Xing
- Department of Horticulture, Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zijingang Campus, Zhejiang University, Hangzhou, People's Republic of China
| | - Zhenyu Qi
- Agricultural Experiment Station, Zhejiang University, Hangzhou, People's Republic of China
| | - Vasileios Fotopoulos
- Department of Agricultural Sciences Biotechnology and Food Science, Cyprus University of Technology, Lemesos, Cyprus
| | - Jingquan Yu
- Department of Horticulture, Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zijingang Campus, Zhejiang University, Hangzhou, People's Republic of China
- Key Laboratory of Horticultural Plants Growth, Development and Quality Improvement, Ministry of Agriculture and Rural Affairs, Hangzhou, People's Republic of China
| | - Jie Zhou
- Department of Horticulture, Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zijingang Campus, Zhejiang University, Hangzhou, People's Republic of China
- Key Laboratory of Horticultural Plants Growth, Development and Quality Improvement, Ministry of Agriculture and Rural Affairs, Hangzhou, People's Republic of China
- Shandong (Linyi) Institute of Modern Agriculture, Zhejiang University, Linyi, People's Republic of China
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22
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Griebel A, Peters JMR, Metzen D, Maier C, Barton CVM, Speckman HN, Boer MM, Nolan RH, Choat B, Pendall E. Tapping into the physiological responses to mistletoe infection during heat and drought stress. Tree Physiol 2022; 42:523-536. [PMID: 34612494 DOI: 10.1093/treephys/tpab113] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/09/2021] [Indexed: 06/13/2023]
Abstract
Mistletoes are important co-contributors to tree mortality globally, particularly during droughts. In Australia, mistletoe distributions are expanding in temperate woodlands, while their hosts have experienced unprecedented heat and drought stress in recent years. We investigated whether the excessive water use of mistletoes increased the probability of xylem emboli in a mature woodland during the recent record drought that was compounded by multiple heatwaves. We continuously recorded transpiration ($T_{SLA}$) of infected and uninfected branches from two eucalypt species over two summers, monitored stem and leaf water potentials ($\Psi $) and used hydraulic vulnerability curves to estimate percent loss in conductivity (PLC) for each species. Variations in weather (vapor pressure deficit, photosynthetically active radiation, soil water content), host species and % mistletoe foliage explained 78% of hourly $T_{SLA}$. While mistletoe acted as an uncontrollable sink for water in the host even during typical summer days, daily $T_{SLA}$ increased up to 4-fold in infected branches on hot days, highlighting the previously overlooked importance of temperature stress in amplifying water loss in mistletoes. The increased water use of mistletoes resulted in significantly decreased host $\Psi _{\rm{leaf}}$ and $\Psi _{\rm{trunk}}$. It further translated to an estimated increase of up to 11% PLC for infected hosts, confirming greater hydraulic dysfunction of infected trees that place them at higher risk of hydraulic failure. However, uninfected branches of Eucalyptus fibrosa F.Muell. had much tighter controls on water loss than uninfected branches of Eucalyptus moluccana Roxb., which shifted the risk of hydraulic failure towards an increased risk of carbon starvation for E. fibrosa. The contrasting mechanistic responses to heat and drought stress between both co-occurring species demonstrates the complexity of host-parasite interactions and highlights the challenge in predicting species-specific responses to biotic agents in a warmer and drier climate.
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Affiliation(s)
- Anne Griebel
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2571, Australia
| | - Jennifer M R Peters
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2571, Australia
- Climate Change Science Institute & Environmental Science Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831, USA
| | - Daniel Metzen
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2571, Australia
| | - Chelsea Maier
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2571, Australia
| | - Craig V M Barton
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2571, Australia
| | - Heather N Speckman
- Department of Botany, University of Wyoming, 1000 E. Univ. Ave, Laramie, WY 82071, USA
| | - Matthias M Boer
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2571, Australia
| | - Rachael H Nolan
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2571, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2571, Australia
| | - Elise Pendall
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2571, Australia
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23
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Nakamura T, Ishida A, Kawai K, Minagi K, Saiki S, Yazaki K, Yoshimura J. Tree hazards compounded by successive climate extremes after masting in a small endemic tree, Distylium lepidotum, on subtropical islands in Japan. Glob Chang Biol 2021; 27:5094-5108. [PMID: 34170598 PMCID: PMC8518126 DOI: 10.1111/gcb.15764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 06/19/2021] [Indexed: 06/13/2023]
Abstract
Ongoing global warming increases the frequency and severity of tropical typhoons and prolonged drought, leading to forest degradation. Simultaneous and/or successive masting events and climatic extremes may thus occur frequently in the near future. If these climatic extremes occur immediately after mass seed reproduction, their effects on individual trees are expected to be very severe because mass reproduction decreases carbohydrate reserves. While the effects of either a single climate extreme or masting alone on tree resilience/growth have received past research attention, understanding the cumulative effects of such multiple events remains challenging and is crucial for predicting future forest changes. Here, we report tree hazards compound by two successive climate extremes, a tropical typhoon and prolonged drought, after mass reproduction in an endemic tree species (Distylium lepidotum Nakai) on oceanic islands. Across individual trees, the starch stored within the sapwood of branchlets significantly decreased with reproductive efforts (fruit mass/shoot mass ratio). Typhoon damage significantly decreased not only the total leaf area of apical shoots but also the maximum photosynthetic rates. During the 5-month period after the typhoon, the mortality of large branchlets (8-10-mm diameter) increased with decreasing stored starch when the typhoon hit. During the prolonged summer drought in the next year, the recovery of total leaf area, stored starch, and hydraulic conductivity was negatively correlated with the stored starch at the typhoon. These data indicate that the level of stored starch within branchlets is the driving factor determining tree regrowth or dieback, and the restoration of carbohydrates after mass reproduction is synergistically delayed by such climate extremes. Stored carbohydrates are the major cumulative factor affecting individual tree resilience, resulting in their historical effects. Because of highly variable carbohydrate levels among individual trees, the resultant impacts of such successive events on forest dieback will be fundamentally different among trees.
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Affiliation(s)
- Tomomi Nakamura
- Center for Ecological ResearchKyoto UniversityOtsuShigaJapan
| | - Atsushi Ishida
- Center for Ecological ResearchKyoto UniversityOtsuShigaJapan
| | - Kiyosada Kawai
- Center for Ecological ResearchKyoto UniversityOtsuShigaJapan
- Japan International Research Center for Agricultural SciencesTsukubaIbarakiJapan
| | - Kanji Minagi
- Center for Ecological ResearchKyoto UniversityOtsuShigaJapan
| | - Shin‐Taro Saiki
- Forestry and Forest Products Research InstituteTsukubaIbarakiJapan
| | - Kenichi Yazaki
- Hokkaido Research Center, Forestry and Forest Products Research InstituteSapporoHokkaidoJapan
| | - Jin Yoshimura
- Institute of Tropical MedicineNagasaki UniversityNagasakiNagasakiJapan
- Faculty of ScienceTokyo Metropolitan UniversityHachiojiTokyoJapan
- The University MuseumThe University of TokyoBunkyoTokyoJapan
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24
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Huang J, Hammerbacher A, Gershenzon J, van Dam NM, Sala A, McDowell NG, Chowdhury S, Gleixner G, Trumbore S, Hartmann H. Storage of carbon reserves in spruce trees is prioritized over growth in the face of carbon limitation. Proc Natl Acad Sci U S A 2021; 118:e2023297118. [PMID: 34389667 DOI: 10.1073/pnas.2023297118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Climate change is expected to pose a global threat to forest health by intensifying extreme events like drought and insect attacks. Carbon allocation is a fundamental process that determines the adaptive responses of long-lived late-maturing organisms like trees to such stresses. However, our mechanistic understanding of how trees coordinate and set allocation priorities among different sinks (e.g., growth and storage) under severe source limitation remains limited. Using flux measurements, isotopic tracing, targeted metabolomics, and transcriptomics, we investigated how limitation of source supply influences sink activity, particularly growth and carbon storage, and their relative regulation in Norway spruce (Picea abies) clones. During photosynthetic deprivation, absolute rates of respiration, growth, and allocation to storage all decline. When trees approach neutral carbon balance, i.e., daytime net carbon gain equals nighttime carbon loss, genes encoding major enzymes of metabolic pathways remain relatively unaffected. However, under negative carbon balance, photosynthesis and growth are down-regulated while sucrose and starch biosynthesis pathways are up-regulated, indicating that trees prioritize carbon allocation to storage over growth. Moreover, trees under negative carbon balance actively increase the turnover rate of starch, lipids, and amino acids, most likely to support respiration and mitigate stress. Our study provides molecular evidence that trees faced with severe photosynthetic limitation strategically regulate storage allocation and consumption at the expense of growth. Understanding such allocation strategies is crucial for predicting how trees may respond to extreme events involving steep declines in photosynthesis, like severe drought, or defoliation by heat waves, late frost, or insect attack.
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25
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Martínez-Lüscher J, Kurtural SK. Same Season and Carry-Over Effects of Source-Sink Adjustments on Grapevine Yields and Non-structural Carbohydrates. Front Plant Sci 2021; 12:695319. [PMID: 34381481 PMCID: PMC8350779 DOI: 10.3389/fpls.2021.695319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 05/25/2021] [Indexed: 06/02/2023]
Abstract
The grapevine (Vitis vinifera L.) is managed to balance the ratio of leaf area (source) to fruit mass (sink). Over cropping in the grapevine may reveal itself as spontaneous fruit abortion, delayed ripening, or as alternate bearing. The aim of this work was to study the same season and carry-over effects of manipulating source to sink ratios on grapevine phenology, leaf gas exchange, yield components, berry soluble solids accumulation, and reserve carbohydrate and soluble sugar concentration in roots. Cabernet Sauvignon grapevines were subjected to defoliation (33, 66, and 100% of the leaves retained) and fruit removal treatments (33, 66, and 100% of clusters retained) arranged in a factorial design. Results from two seasons of source-sink manipulations were substantially different. In both seasons defoliation treatments affected season-long net carbon assimilation (A N ) and stomatal conductance (g s ) where the less leaves were retained, the greater the A N and g s , and fruit removal had no impact on leaf gas exchange. In the first season, leaf area to fruit mass was hardly related to berry soluble solids and in the second season they were strongly correlated, suggesting a degree of acclimation. Defoliation treatments had great impacts on berry size, berries per cluster, and total soluble solids in both years. Fruit removal treatments only had effects on berry mass and berries per cluster in the first season, and only on berry soluble solids in the second. The predominant effect of defoliation (carbon starvation) cascaded onto reducing root starch content, root mass and delaying of veraison and leaf senescence, as well as harvest which was delayed up to 9 weeks with 33% of the leaves retained. In a third season, where grapevines grew without treatments, defoliation treatments had resultant carryover effects, including reduced leaf area, number of berries per cluster, clusters per vine, and yield, but not on leaf gas exchange dependent on previous seasons' severity of defoliation. Balancing source-to-sink ratio is crucial to obtain an adequate speed of ripening. However, this was the culmination of a more complex whole-plant regulation where the number of leaves (source strength) outweighed the effects of fruits (sink strength).
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Tomasella M, Casolo V, Natale S, Petruzzellis F, Kofler W, Beikircher B, Mayr S, Nardini A. Shade-induced reduction of stem nonstructural carbohydrates increases xylem vulnerability to embolism and impedes hydraulic recovery in Populus nigra. New Phytol 2021; 231:108-121. [PMID: 33811346 PMCID: PMC9290559 DOI: 10.1111/nph.17384] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 03/28/2021] [Indexed: 05/08/2023]
Abstract
Nonstructural carbohydrates (NSCs) have been suggested to affect xylem transport under fluctuating water availability, but conclusive evidence is still lacking. We tested the effect of shade-induced NSC depletion on xylem vulnerability to embolism and hydraulic recovery on Populus nigra saplings. Vulnerability was assessed in light-exposed (L) and shaded (S) plants with the hydraulic method, and in vivo with the optical method and X-ray micro-computed tomography. Plants were stressed to 80% loss of hydraulic conductance (PLC) and re-irrigated to check for possible recovery. We measured PLC, bark and wood NSC content, as well as xylem sap pH, surface tension (γsap ) and sugar concentration, before, during and after drought. Shading induced depletion of stem NSC (mainly starch) reserves. All methods converged in indicating higher xylem vulnerability in S than in L plants. This difference was not explained by xylem vessel and pit anatomy or by γsap . Shading impeded sap acidification and sugar accumulation during drought in S plants and prevented hydraulic recovery, which was observed in L plants. Our results highlight the importance of stem NSCs to sustain xylem hydraulic functioning during drought and suggest that light and/or adequate stem NSC thresholds are required to trigger xylem sap chemical changes involved in embolism recovery.
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Affiliation(s)
- Martina Tomasella
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
| | - Valentino Casolo
- Dipartimento di Scienze AgroalimentariAmbientali e AnimaliUniversità di UdineVia delle Scienze 91Udine33100Italy
| | - Sara Natale
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
| | - Francesco Petruzzellis
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
| | - Werner Kofler
- Department of BotanyUniversity of InnsbruckSternwartestraße 15Innsbruck6020Austria
| | - Barbara Beikircher
- Department of BotanyUniversity of InnsbruckSternwartestraße 15Innsbruck6020Austria
| | - Stefan Mayr
- Department of BotanyUniversity of InnsbruckSternwartestraße 15Innsbruck6020Austria
| | - Andrea Nardini
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
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Peltier DMP, Guo J, Nguyen P, Bangs M, Gear L, Wilson M, Jefferys S, Samuels-Crow K, Yocom LL, Liu Y, Fell MK, Auty D, Schwalm C, Anderegg WRL, Koch GW, Litvak ME, Ogle K. Temporal controls on crown nonstructural carbohydrates in southwestern US tree species. Tree Physiol 2021; 41:388-402. [PMID: 33147630 DOI: 10.1093/treephys/tpaa149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/29/2020] [Indexed: 06/11/2023]
Abstract
In trees, large uncertainties remain in how nonstructural carbohydrates (NSCs) respond to variation in water availability in natural, intact ecosystems. Variation in NSC pools reflects temporal fluctuations in supply and demand, as well as physiological coordination across tree organs in ways that differ across species and NSC fractions (e.g., soluble sugars vs starch). Using landscape-scale crown (leaves and twigs) NSC concentration measurements in three foundation tree species (Populus tremuloides, Pinus edulis, Juniperus osteosperma), we evaluated in situ, seasonal variation in NSC responses to moisture stress on three timescales: short-term (via predawn water potential), seasonal (via leaf δ13C) and annual (via current year's ring width index). Crown NSC responses to moisture stress appeared to depend on hydraulic strategy, where J. osteosperma appears to regulate osmotic potentials (via higher sugar concentrations), P. edulis NSC responses suggest respiratory depletion and P. tremuloides responses were consistent with direct sink limitations. We also show that overly simplistic models can mask seasonal and tissue variation in NSC responses, as well as strong interactions among moisture stress at different timescales. In general, our results suggest large seasonal variation in crown NSC concentrations reflecting the multiple cofunctions of NSCs in plant tissues, including storage, growth and osmotic regulation of hydraulically vulnerable leaves. We emphasize that crown NSC pool size cannot be viewed as a simple physiological metric of stress; in situ NSC dynamics are complex, varying temporally, across species, among NSC fractions and among tissue types.
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Affiliation(s)
- Drew M P Peltier
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Jessica Guo
- Geology and Geophysics, University of Utah, Salt Lake City, UT 84112, USA
| | - Phiyen Nguyen
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Michael Bangs
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Linnea Gear
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Michelle Wilson
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Stacy Jefferys
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Kimberly Samuels-Crow
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Larissa L Yocom
- Department of Wildland Resources and the Ecology Center, Utah State University, Logan, UT 84322, USA
| | - Yao Liu
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Michael K Fell
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - David Auty
- School of Forestry, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Christopher Schwalm
- Woods Hole Research Center, Falmouth, MA 02540, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - William R L Anderegg
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - George W Koch
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Marcy E Litvak
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Kiona Ogle
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
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28
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Sapes G, Demaree P, Lekberg Y, Sala A. Plant carbohydrate depletion impairs water relations and spreads via ectomycorrhizal networks. New Phytol 2021; 229:3172-3183. [PMID: 33280134 DOI: 10.1111/nph.17134] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 11/24/2020] [Indexed: 06/12/2023]
Abstract
Under prolonged drought and reduced photosynthesis, plants consume stored nonstructural carbohydrates (NSCs). Stored NSC depletion may impair the regulation of plant water balance, but the underlying mechanisms are poorly understood, and whether such mechanisms are independent of plant water deficit is not known. If so, carbon costs of fungal symbionts could indirectly influence plant drought tolerance through stored NSC depletion. We connected well-watered Pinus ponderosa seedling pairs via ectomycorrhizal (EM) networks where one seedling was shaded (D) and the other kept illuminated (LD) and compared responses to seedling pairs in full light (L). We measured plant NSCs, osmotic and water potential, and transfer of 13 CO2 through EM to explore mechanisms linking stored NSCs to plant water balance regulation and identify potential tradeoffs between plant water retention and EM fungi under carbon-limiting conditions. NSCs decreased from L to LD to D seedlings. Even without drought, NSC depletion impaired osmoregulation and turgor maintenance, both of which are critical for drought tolerance. Importantly, EM networks propagated NSC depletion and its negative effects on water retention from carbon stressed to nonstressed hosts. We demonstrate that NSC storage depletion influences turgor maintenance independently of plant water deficit and reveal carbon allocation tradeoffs between supporting fungal symbionts and retaining water.
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Affiliation(s)
- Gerard Sapes
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, 55108, USA
| | - Patrick Demaree
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Ylva Lekberg
- MPG Ranch, Missoula, MT, 59801, USA
- W.A. Franke College of Forestry & Conservation, University of Montana, Missoula, MT, 59812, USA
| | - Anna Sala
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
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29
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Yoshida H, Tanaka C. An arabinose-induced enhancement of asexual reproduction and concomitant changes in metabolic state in the filamentous fungus Bipolaris maydis. Microbiology (Reading) 2021; 167. [PMID: 33555250 DOI: 10.1099/mic.0.001009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
l-Arabinose, a major constituent pentose of plant cell-wall polysaccharides, has been suggested to be a less preferred carbon source for fungi but to be a potential signalling molecule that can cause distinct genome-wide transcriptional changes in fungal cells. Here, we explore the possibility that this unique pentose influences the morphological characteristics of the phytopathogenic fungus Bipolaris maydis strain HITO7711. When grown on plate media under different sugar conditions, the mycelial dry weight of cultures on l-arabinose was as low as that with no sugar, suggesting that l-arabinose does not substantially contribute to vegetative growth. However, the intensity of conidiation on l-arabinose was comparable to or even higher than that on d-glucose and on d-xylose, in contrast to the poor conidiation under the no-sugar condition. To explore the physiological basis of the passive growth and active conidiation on l-arabinose, we next investigated cellular responses of the fungus to these sugar conditions. Transcriptional analysis of genes related to carbohydrate metabolism showed that l-arabinose stimulates carbohydrate utilization through the hexose monophosphate shunt (HMP shunt), a catabolic pathway parallel to glycolysis and which participates in the generation of the reducing agent NADPH (the reduced form of nicotinamide adenine dinucleotide phosphate). Then, the HMP shunt was impaired by disrupting the related gene BmZwf1, which encodes glucose-6-phosphate dehydrogenase in this fungus. The resulting mutants on l-arabinose showed remarkably decreased conidiation, but a conversely increased mycelial dry weight compared with the wild-type. Our study demonstrates that l-arabinose acts to enhance resource allocation to asexual reproduction in B. maydis HITO7711 at the cost of vegetative growth, and suggests that this is mediated by the concomitant stimulation of the HMP shunt.
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Affiliation(s)
- Hiroshi Yoshida
- Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Chihiro Tanaka
- Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
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30
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Wang W, English NB, Grossiord C, Gessler A, Das AJ, Stephenson NL, Baisan CH, Allen CD, McDowell NG. Mortality predispositions of conifers across western USA. New Phytol 2021; 229:831-844. [PMID: 32918833 DOI: 10.1111/nph.16864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 08/03/2020] [Indexed: 06/11/2023]
Abstract
Conifer mortality rates are increasing in western North America, but the physiological mechanisms underlying this trend are not well understood. We examined tree-ring-based radial growth along with stable carbon (C) and oxygen (O) isotope composition (δ13 C and δ18 O, respectively) of dying and surviving conifers at eight old-growth forest sites across a strong moisture gradient in the western USA to retrospectively investigate mortality predispositions. Compared with surviving trees, lower growth of dying trees was detected at least one decade before mortality at seven of the eight sites. Intrinsic water-use efficiency increased over time in both dying and surviving trees, with a weaker increase in dying trees at five of the eight sites. C starvation was a strong correlate of conifer mortality based on a conceptual model incorporating growth, δ13 C, and δ18 O. However, this approach does not capture processes that occur in the final months of survival. Ultimately, C starvation may lead to increased mortality vulnerability, but hydraulic failure or biotic attack may dominate the process during the end stages of mortality in these conifers.
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Affiliation(s)
- Wenzhi Wang
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
- The Key Laboratory of Mountain Environment Evolution and Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu,, 610041, China
| | - Nathan B English
- School of Health, Medical and Applied Science, Central Queensland University, Townsville, QLD, 4810, Australia
| | - Charlotte Grossiord
- Functional Plant Ecology, Community Ecology Unit, Swiss Federal Institute for Forest, Snow and Landscape WSL, Lausanne,, CH-1015, Switzerland
- Plant Ecology Research Laboratory PERL, School of Architecture, Civil and Environmental Engineering, EPFL, Lausanne,, CH-1015, Switzerland
| | - Arthur Gessler
- Functional Plant Ecology, Community Ecology Unit, Swiss Federal Institute for Forest, Snow and Landscape WSL, Lausanne,, CH-1015, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zurich, Universitaetsstrasse 16, Zurich, 8092, Switzerland
| | - Adrian J Das
- Western Ecological Research Center, US Geological Survey, Three Rivers, CA, 93271, USA
| | - Nathan L Stephenson
- Western Ecological Research Center, US Geological Survey, Three Rivers, CA, 93271, USA
| | | | - Craig D Allen
- Fort Collins Science Center, New Mexico Landscapes Field Station, US Geological Survey, Los Alamos, NM,, 87544, USA
| | - Nate G McDowell
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
- School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
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31
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Teper-Bamnolker P, Danieli R, Peled-Zehavi H, Belausov E, Abu-Abied M, Avin-Wittenberg T, Sadot E, Eshel D. Vacuolar processing enzyme translocates to the vacuole through the autophagy pathway to induce programmed cell death. Autophagy 2020; 17:3109-3123. [PMID: 33249982 DOI: 10.1080/15548627.2020.1856492] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022] Open
Abstract
The caspase-like vacuolar processing enzyme (VPE) is a key factor in programmed cell death (PCD) associated with plant stress responses. Growth medium lacking a carbon source and dark conditions caused punctate labeling of 35S::VPE1-GFP (StVPE1-GFP) in potato leaves. Under conditions of carbon starvation, VPE activity and PCD symptoms strongly increased in BY-2 cells, but to a much lesser extent in VPE-RNAi BY-2 cells. During extended exposure to carbon starvation, VPE expression and activity levels peaked, with a gradual increase in BY-2 cell death. Histological analysis of StVPE1-GFP in BY-2 cells showed that carbon starvation induces its translocation from the endoplasmic reticulum to the central vacuole through tonoplast engulfment. Exposure of BY-2 culture to the macroautophagy/autophagy inhibitor concanamycin A led to, along with an accumulation of autophagic bodies, accumulation of StVPE1-GFP in the cell vacuole. This accumulation did not occur in the presence of 3-methyladenine, an inhibitor of early-stage autophagy. BY-2 cells constitutively expressing RFP-StATG8IL, an autophagosome marker, showed colocalization with the StVPE1-GFP protein in the cytoplasm and vacuole. RNAi silencing of the core autophagy component ATG4 in BY-2 cells reduced VPE activity and cell death. These results are the first to suggest that VPE translocates to the cell vacuole through the autophagy pathway, leading to PCD.Abbreviations: ATG: autophagy related; CLP: caspase-like protease; HR: hypersensitive response; PCD: programmed cell death; St: Solanum tuberosum; VPE: vacuolar processing enzyme.
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Affiliation(s)
| | - Raz Danieli
- Department of Postharvest Science, The Volcani Center, ARO, Rishon LeZion, Israel.,Institute of Plant Sciences and Genetics in Agriculture, the Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot Israel
| | - Hadas Peled-Zehavi
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot Israel
| | - Eduard Belausov
- Department of Ornamental Horticulture, The Volcani Center, ARO, Rishon LeZion, Israel
| | - Mohamad Abu-Abied
- Department of Ornamental Horticulture, The Volcani Center, ARO, Rishon LeZion, Israel
| | - Tamar Avin-Wittenberg
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Einat Sadot
- Department of Ornamental Horticulture, The Volcani Center, ARO, Rishon LeZion, Israel
| | - Dani Eshel
- Department of Postharvest Science, The Volcani Center, ARO, Rishon LeZion, Israel
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Acheampong AK, Shanks C, Cheng CY, Schaller GE, Dagdas Y, Kieber JJ. EXO70D isoforms mediate selective autophagic degradation of type-A ARR proteins to regulate cytokinin sensitivity. Proc Natl Acad Sci U S A 2020; 117:27034-27043. [PMID: 33051300 PMCID: PMC7604425 DOI: 10.1073/pnas.2013161117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The phytohormone cytokinin influences many aspects of plant growth and development, several of which also involve the cellular process of autophagy, including leaf senescence, nutrient remobilization, and developmental transitions. The Arabidopsis type-A response regulators (type-A ARR) are negative regulators of cytokinin signaling that are transcriptionally induced in response to cytokinin. Here, we describe a mechanistic link between cytokinin signaling and autophagy, demonstrating that plants modulate cytokinin sensitivity through autophagic regulation of type-A ARR proteins. Type-A ARR proteins were degraded by autophagy in an AUTOPHAGY-RELATED (ATG)5-dependent manner, and this degradation is promoted by phosphorylation on a conserved aspartate in the receiver domain of the type-A ARRs. EXO70D family members interacted with type-A ARR proteins, likely in a phosphorylation-dependent manner, and recruited them to autophagosomes via interaction of the EXO70D AIM with the core autophagy protein, ATG8. Consistently, loss-of-function exo70D1,2,3 mutants exhibited compromised targeting of type-A ARRs to autophagic vesicles, have elevated levels of type-A ARR proteins, and are hyposensitive to cytokinin. Disruption of both type-A ARRs and EXO70D1,2,3 compromised survival in carbon-deficient conditions, suggesting interaction between autophagy and cytokinin responsiveness in response to stress. These results indicate that the EXO70D proteins act as selective autophagy receptors to target type-A ARR cargos for autophagic degradation, demonstrating modulation of cytokinin signaling by selective autophagy.
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Affiliation(s)
| | - Carly Shanks
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Chia-Yi Cheng
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - G Eric Schaller
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755
| | - Yasin Dagdas
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Joseph J Kieber
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599;
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Abstract
Bacteria have a remarkable ability to sense environmental changes, swiftly regulating their transcriptional and posttranscriptional machinery as a response. Under conditions that cause growth to slow or stop, bacteria typically stabilize their transcriptomes in what has been shown to be a conserved stress response. In recent years, diverse studies have elucidated many of the mechanisms underlying mRNA degradation, yet an understanding of the regulation of mRNA degradation under stress conditions remains elusive. In this review we discuss the diverse mechanisms that have been shown to affect mRNA stability in bacteria. While many of these mechanisms are transcript-specific, they provide insight into possible mechanisms of global mRNA stabilization. To that end, we have compiled information on how mRNA fate is affected by RNA secondary structures; interaction with ribosomes, RNA binding proteins, and small RNAs; RNA base modifications; the chemical nature of 5' ends; activity and concentration of RNases and other degradation proteins; mRNA and RNase localization; and the stringent response. We also provide an analysis of reported relationships between mRNA abundance and mRNA stability, and discuss the importance of stress-associated mRNA stabilization as a potential target for therapeutic development.
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Affiliation(s)
- Diego A Vargas-Blanco
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, United States
| | - Scarlet S Shell
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, United States.,Program in Bioinformatics and Computational Biology, Worcester Polytechnic Institute, Worcester, MA, United States
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Komaitis F, Kalliampakou K, Botou M, Nikolaidis M, Kalloniati C, Skliros D, Du B, Rennenberg H, Amoutzias GD, Frillingos S, Flemetakis E. Molecular and physiological characterization of the monosaccharide transporters gene family in Medicago truncatula. J Exp Bot 2020; 71:3110-3125. [PMID: 32016431 DOI: 10.1093/jxb/eraa055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
Monosaccharide transporters (MSTs) represent key components of the carbon transport and partitioning mechanisms in plants, mediating the cell-to-cell and long-distance distribution of a wide variety of monosaccharides. In this study, we performed a thorough structural, molecular, and physiological characterization of the monosaccharide transporter gene family in the model legume Medicago truncatula. The complete set of MST family members was identified with a novel bioinformatic approach. Prolonged darkness was used as a test condition to identify the relevant transcriptomic and metabolic responses combining MST transcript profiling and metabolomic analysis. Our results suggest that MSTs play a pivotal role in the efficient partitioning and utilization of sugars, and possibly in the mechanisms of carbon remobilization in nodules upon photosynthate-limiting conditions, as nodules are forced to acquire a new role as a source of both C and N.
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Affiliation(s)
- Fotios Komaitis
- Laboratory of Molecular Biology, Department of Biotechnology, Agricultural University of Athens, Athens, Greece
| | - Katerina Kalliampakou
- Laboratory of Molecular Biology, Department of Biotechnology, Agricultural University of Athens, Athens, Greece
| | - Maria Botou
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Ioannina, Greece
| | - Marios Nikolaidis
- Bioinformatics Laboratory, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Chrysanthi Kalloniati
- Laboratory of Molecular Biology, Department of Biotechnology, Agricultural University of Athens, Athens, Greece
| | - Dimitrios Skliros
- Laboratory of Molecular Biology, Department of Biotechnology, Agricultural University of Athens, Athens, Greece
| | - Baoguo Du
- Institute of Forest Sciences, Faculty of Environment and Natural Resources, Albert Ludwig University of Freiburg, Freiburg, Germany
| | - Heinz Rennenberg
- Institute of Forest Sciences, Faculty of Environment and Natural Resources, Albert Ludwig University of Freiburg, Freiburg, Germany
- College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Grigoris D Amoutzias
- Bioinformatics Laboratory, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Stathis Frillingos
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Ioannina, Greece
| | - Emmanouil Flemetakis
- Laboratory of Molecular Biology, Department of Biotechnology, Agricultural University of Athens, Athens, Greece
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35
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Morin M, Enjalbert B, Ropers D, Girbal L, Cocaign-Bousquet M. Genomewide Stabilization of mRNA during a "Feast-to-Famine" Growth Transition in Escherichia coli. mSphere 2020; 5:e00276-20. [PMID: 32434841 DOI: 10.1128/mSphere.00276-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability to rapidly respond to changing nutrients is crucial for E. coli to survive in many environments, including the gut. Reorganization of gene expression is the first step used by bacteria to adjust their metabolism accordingly. It involves fine-tuning of both transcription (transcriptional regulation) and mRNA stability (posttranscriptional regulation). While the forms of transcriptional regulation have been extensively studied, the role of mRNA stability during a metabolic switch is poorly understood. Investigating E. coli genomewide transcriptome and mRNA stability during metabolic transitions representative of the carbon source fluctuations in many environments, we have documented the role of mRNA stability in the response to nutrient changes. mRNAs are globally stabilized during carbon depletion. For a few genes, this leads directly to expression upregulation. As these genes are regulators of stress responses and metabolism, our work sheds new light on the likely importance of posttranscriptional regulations in response to environmental stress. Bacteria have to continuously adjust to nutrient fluctuations from favorable to less-favorable conditions and in response to carbon starvation. The glucose-acetate transition followed by carbon starvation is representative of such carbon fluctuations observed in Escherichia coli in many environments. Regulation of gene expression through fine-tuning of mRNA pools constitutes one of the regulation levels required for such a metabolic adaptation. It results from both mRNA transcription and degradation controls. However, the contribution of transcript stability regulation in gene expression is poorly characterized. Using combined transcriptome and mRNA decay analyses, we investigated (i) how transcript stability changes in E. coli during the glucose-acetate-starvation transition and (ii) if these changes contribute to gene expression changes. Our work highlights that transcript stability increases with carbon depletion. Most of the stabilization occurs at the glucose-acetate transition when glucose is exhausted, and then stabilized mRNAs remain stable during acetate consumption and carbon starvation. Meanwhile, expression of most genes is downregulated and we observed three times less gene expression upregulation. Using control analysis theory on 375 genes, we show that most of gene expression regulation is driven by changes in transcription. Although mRNA stabilization is not the controlling phenomenon, it contributes to the emphasis or attenuation of transcriptional regulation. Moreover, upregulation of 18 genes (33% of our studied upregulated set) is governed mainly by transcript stabilization. Because these genes are associated with responses to nutrient changes and stress, this underscores a potentially important role of posttranscriptional regulation in bacterial responses to nutrient starvation. IMPORTANCE The ability to rapidly respond to changing nutrients is crucial for E. coli to survive in many environments, including the gut. Reorganization of gene expression is the first step used by bacteria to adjust their metabolism accordingly. It involves fine-tuning of both transcription (transcriptional regulation) and mRNA stability (posttranscriptional regulation). While the forms of transcriptional regulation have been extensively studied, the role of mRNA stability during a metabolic switch is poorly understood. Investigating E. coli genomewide transcriptome and mRNA stability during metabolic transitions representative of the carbon source fluctuations in many environments, we have documented the role of mRNA stability in the response to nutrient changes. mRNAs are globally stabilized during carbon depletion. For a few genes, this leads directly to expression upregulation. As these genes are regulators of stress responses and metabolism, our work sheds new light on the likely importance of posttranscriptional regulations in response to environmental stress.
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Giannopoulos A, Nikolopoulos D, Bresta P, Samantas A, Reppa C, Karaboiki K, Dotsika E, Fasseas C, Liakopoulos G, Karabourniotis G. Cystoliths of Parietaria judaica can serve as an internal source of CO2 for photosynthetic assimilation when stomata are closed. J Exp Bot 2019; 70:5753-5763. [PMID: 31270538 DOI: 10.1093/jxb/erz316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/25/2019] [Indexed: 06/09/2023]
Abstract
The recently reported 'alarm photosynthesis' acts as a biochemical process that assimilates CO2 derived from the decomposition of calcium oxalate crystals. This study examined whether CaCO3 cystoliths could also serve as CO2 pools, fulfilling a similar role. Shoots of Parietaria judaica were subjected to carbon starvation, abscisic acid (ABA), or bicarbonate treatments, and the volume of cystoliths and the photochemical parameters of photosystem II (PSII) were determined. The size of cystoliths was reduced under carbon starvation or ABA treatments, whereas it was restored by xylem-provided bicarbonate. Under carbon starvation, ABA, or bicarbonate treatments, the photochemical efficiency of PSII was higher, while non-photochemical quenching, representing the safe dissipation of excess PSII energy due to lack of electron sinks, was lower in treated samples compared with controls. This observation suggests the involvement of ABA or other carbon starvation cues in the release of subsidiary CO2 for photosynthesis, inevitably from an internal source, which could be the cystoliths. Carbon remobilized from cystoliths can be photosynthetically assimilated, thus acting as a safety valve under stress. Together with alarm photosynthesis, these results show a tight link between leaf carbon deposits and photosynthesis.
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Affiliation(s)
- Andreas Giannopoulos
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Dimosthenis Nikolopoulos
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Panagiota Bresta
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Aris Samantas
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Chrysavgi Reppa
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Kalliopi Karaboiki
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Elissavet Dotsika
- Stable Isotope Unit, Institute of Material Science, National Centre for Scientific Research 'Demokritos', Athens, Greece
| | - Constantinos Fasseas
- Laboratory of Electron Microscopy, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Georgios Liakopoulos
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - George Karabourniotis
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
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Chen Z, Liu S, Lu H, Wan X. Interaction of stomatal behaviour and vulnerability to xylem cavitation determines the drought response of three temperate tree species. AoB Plants 2019; 11:plz058. [PMID: 31649812 PMCID: PMC6802943 DOI: 10.1093/aobpla/plz058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
How the mortality and growth of tree species vary with the iso-anisohydric continuum and xylem vulnerability is still being debated. We conducted a precipitation reduction experiment to create a mild drought condition in a forest in the Baotianman Mountains, China, a sub-humid region. Three main sub-canopy tree species in this region were examined. After rainfall reduction, Lindera obtusiloba showed severe dieback, but two other co-occurring species did not show dieback. The water potential at stomatal closure of Dendrobenthamia japonica, L. obtusiloba and Sorbus alnifolia was -1.70, -2.54 and -3.41 MPa, respectively, whereas the water potential at 88 % loss in hydraulic conductivity of the three species was -2.31, -2.11 and -7.01 MPa, respectively. Taken together, near-anisohydric L. obtusiloba with vulnerable xylem was highly susceptible to drought dieback. Anisohydric S. alnifolia had the most negative minimum water potential, and its xylem was the most resistant to cavitation. Isohydric D. japonica conserved water by rapidly closing its stomata. Ultimately, the hydraulic safety margin (HSM) of L. obtusiloba was the smallest among the three species, especially in precipitation-reduced plots. In terms of the stomatal safety margin (SSM), L. obtusiloba was negative, while S. alnifolia and D. japonica were positive. Of the two species without dieback, rainfall reduction decreased growth of D. japonica, but did not influence growth of S. Alnifolia; meanwhile, rainfall reduction led to a decrease of non-structural carbohydrates (NSCs) in D. japonica, but an increase in S. alnifolia. It is concluded that HSM as well as SSM allow interpreting the sensitivity of the three sub-canopy species to drought. The drought-induced dieback of L. obtusiloba is determined by the interaction of stomatal behaviour and xylem vulnerability, and the species could be sensitive to climate change-caused drought although still in sub-humid areas. The isohydric/anisohydric degree is associated with NSCs status and growth of plants.
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Affiliation(s)
- Zhicheng Chen
- Institute of New Forestry Technology, Chinese Academy of Forestry, Beijing, China
| | - Shirong Liu
- Key Laboratory of Forest Ecology and Environment of State Forestry Administration, Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing, China
| | - Haibo Lu
- Key Laboratory of Forest Ecology and Environment of State Forestry Administration, Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing, China
| | - Xianchong Wan
- Institute of New Forestry Technology, Chinese Academy of Forestry, Beijing, China
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Shen C, Ji RX, Yu X, Bai XQ, Chang Y, Liu C. [Changes of non-structural carbohydrates in Caryopteris mongolica seedlings during the process of drought-induced mortality]. Ying Yong Sheng Tai Xue Bao 2019; 30:2541-2548. [PMID: 31418176 DOI: 10.13287/j.1001-9332.201908.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The changes and distribution of non-structural carbohydrate (NSC, including soluble sugar and starch) content in different organs of one-year-old Caryopteris mongolica seedlings were investigated under suitable water condition (CK), slow-dying drought stress, and fast-dying drought stress. There was no significant difference in soluble sugar content of all organs between slow-dying drought stress and CK. With the extended duration of drought, the soluble sugar content in stem increased firstly and then decreased, while starch and NSC contents decreased. The soluble sugar content in coarse roots decreased, while starch and NSC contents increased. The soluble sugar content in leaves increased, while starch and NSC contents of leaves decreased. The NSC content of leaves, stems, coarse roots and fine roots were 6.2%, 7.8%, 8.3% and 7.4% at the death time (80 days), respectively. Under fast-dying drought stress, soluble sugar content in all organs was higher than that in CK, while starch and NSC contents were lower than that in CK. With the increasing time, soluble sugar content of roots decreased, while starch and NSC contents increased. The soluble sugar, starch and NSC contents in stems increased. The soluble sugar content of leaves increased, while starch and NSC contents decreased. The NSC content of leaves, stems, coarse roots and fine roots were 5.9%, 6.6%, 8.9% and 7.7% at lethal time (30 days), respectively. Under different drought stress, non-structural carbohydrates among different organs of C. mongolica seedlings showed different dynamics. Under slow-dying drought stress, NSC gave priority to allocate energy for maintaining physiological metabolism of organs. Under fast-dying drought stress, NSC mainly maintained plant metabolism in the form of soluble sugar, regulated osmotic potential, promoted water absorption, and coped with drastic drought stress.
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Affiliation(s)
- Chao Shen
- National Engineering Laboratory of Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China
| | - Ruo Xuan Ji
- National Engineering Laboratory of Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China
| | - Xiao Yu
- National Engineering Laboratory of Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China
| | - Xue Qia Bai
- National Engineering Laboratory of Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China
| | - Yuan Chang
- National Engineering Laboratory of Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China
| | - Chao Liu
- National Engineering Laboratory of Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China
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MacAllister S, Mencuccini M, Sommer U, Engel J, Hudson A, Salmon Y, Dexter KG. Drought-induced mortality in Scots pine: opening the metabolic black box. Tree Physiol 2019; 39:1358-1370. [PMID: 31038161 DOI: 10.1093/treephys/tpz049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 04/11/2019] [Accepted: 04/15/2019] [Indexed: 06/09/2023]
Abstract
Forests are sensitive to droughts, which increase the mortality rate of tree species. Various processes have been proposed to underlie drought-induced tree mortality, including hydraulic failure, carbon starvation and increased susceptibility to natural enemies. To give insights into these processes, we assessed the metabolic effects of a mortality-inducing drought on seedlings of Pinus sylvestris L. (Scots Pine), a widespread and important Eurasian species. We found divergence over time in the foliar metabolic composition of droughted vs well-watered seedlings, with the former showing increased abundance of aromatic amino acids and decreases in secondary metabolism associated with defence. We observed no significant differences amongst provenances in these effects: seedlings from drought-prone areas showed the same foliar metabolic changes under drought as seedlings from moist environments, although morphological effects of drought varied by provenance. Overall, our results demonstrate how severe drought prior to death may target particular primary and secondary metabolic pathways, weakening defences against natural enemies and contributing to the risk of drought-induced mortality in P. sylvestris.
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Affiliation(s)
| | | | - Ulf Sommer
- NBAF-Birmingham, School of Biosciences, University of Birmingham, UK
| | - Jasper Engel
- NBAF-Birmingham, School of Biosciences, University of Birmingham, UK
| | - Andrew Hudson
- School of Biological Sciences, University of Edinburgh, UK
| | | | - Kyle G Dexter
- School of GeoSciences, University of Edinburgh, UK
- Royal Botanic Garden Edinburgh, UK
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Sapes G, Roskilly B, Dobrowski S, Maneta M, Anderegg WRL, Martinez-Vilalta J, Sala A. Plant water content integrates hydraulics and carbon depletion to predict drought-induced seedling mortality. Tree Physiol 2019; 39:1300-1312. [PMID: 31135927 DOI: 10.1093/treephys/tpz062] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/29/2019] [Accepted: 05/13/2019] [Indexed: 05/25/2023]
Abstract
Widespread drought-induced forest mortality (DIM) is expected to increase with climate change and drought, and is expected to have major impacts on carbon and water cycles. For large-scale assessment and management, it is critical to identify variables that integrate the physiological mechanisms of DIM and signal risk of DIM. We tested whether plant water content, a variable that can be remotely sensed at large scales, is a useful indicator of DIM risk at the population level. We subjected Pinus ponderosa Douglas ex C. Lawson seedlings to experimental drought using a point of no return experimental design. Periodically during the drought, independent sets of seedlings were sampled to measure physiological state (volumetric water content (VWC), percent loss of conductivity (PLC) and non-structural carbohydrates) and to estimate population-level probability of mortality through re-watering. We show that plant VWC is a good predictor of population-level DIM risk and exhibits a threshold-type response that distinguishes plants at no risk from those at increasing risk of mortality. We also show that plant VWC integrates the mechanisms involved in individual tree death: hydraulic failure (PLC), carbon depletion across organs and their interaction. Our results are promising for landscape-level monitoring of DIM risk.
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Affiliation(s)
- Gerard Sapes
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Beth Roskilly
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Solomon Dobrowski
- Department of Forest Management, University of Montana, Missoula, MT 59812, USA
| | - Marco Maneta
- Department of Geosciences, University of Montana, Missoula, MT 59812, USA
| | - William R L Anderegg
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84103, USA
| | - Jordi Martinez-Vilalta
- Centre de Recerca Ecològica i Aplicacions Forestals (CREAF) Cerdanyola del Vallès 08193 Barcelona, Spain
- Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193 Barcelona, Spain
| | - Anna Sala
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
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Wiley E, King CM, Landhäusser SM. Identifying the relevant carbohydrate storage pools available for remobilization in aspen roots. Tree Physiol 2019; 39:1109-1120. [PMID: 31094427 DOI: 10.1093/treephys/tpz051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 02/27/2019] [Accepted: 04/23/2019] [Indexed: 05/17/2023]
Abstract
Nonstructural carbohydrate (NSC) remobilization remains poorly understood in trees. In particular, it remains unclear (i) which tissues (e.g., living bark or xylem) and compounds (sugars or starch) in woody plants are the main sources of remobilized carbon, (ii) to what extent these NSC pools can be depleted and (iii) whether initial NSC mass or concentration is a better predictor of regrowth potential following disturbance. To address these questions, we collected root segments from a large mature trembling aspen stand; we then allowed them to resprout (sucker) in the dark and remobilize NSC until all sprouts had died. We found that initial starch mass, not concentration, was the best predictor of subsequent sprout mass. In total, more NSC mass (~4×) was remobilized from the living inner bark than the xylem of the roots. After resprouting, root starch was generally depleted to <0.6% w/w in both tissues. In contrast, a large portion of sugars appear unavailable for remobilization: sugar concentrations were only reduced to 12% w/w in the bark and 2% in the xylem. These findings suggest that in order to test whether plant processes like resprouting are limited by storage we need to (i) measure storage in the living bark, not just the xylem, (ii) consider storage pool size-not just concentration-and (iii) carefully determine which compounds are actually components of the storage pool.
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Affiliation(s)
- Erin Wiley
- Department of Renewable Resources, University of Alberta, Edmonton, Canada
| | - Carolyn M King
- Department of Renewable Resources, University of Alberta, Edmonton, Canada
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Vargas-Blanco DA, Zhou Y, Zamalloa LG, Antonelli T, Shell SS. mRNA Degradation Rates Are Coupled to Metabolic Status in Mycobacterium smegmatis. mBio 2019; 10:e00957-19. [PMID: 31266866 DOI: 10.1128/mBio.00957-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The logistics of tuberculosis therapy are difficult, requiring multiple drugs for many months. Mycobacterium tuberculosis survives in part by entering nongrowing states in which it is metabolically less active and thus less susceptible to antibiotics. Basic knowledge on how M. tuberculosis survives during these low-metabolism states is incomplete, and we hypothesize that optimized energy resource management is important. Here, we report that slowed mRNA turnover is a common feature of mycobacteria under energy stress but is not dependent on the mechanisms that have generally been postulated in the literature. Finally, we found that mRNA stability and growth status can be decoupled by a drug that causes growth arrest but increases metabolic activity, indicating that mRNA stability responds to metabolic status rather than to growth rate per se. Our findings suggest a need to reorient studies of global mRNA stabilization to identify novel mechanisms that are presumably responsible. The success of Mycobacterium tuberculosis as a human pathogen is due in part to its ability to survive stress conditions, such as hypoxia or nutrient deprivation, by entering nongrowing states. In these low-metabolism states, M. tuberculosis can tolerate antibiotics and develop genetically encoded antibiotic resistance, making its metabolic adaptation to stress crucial for survival. Numerous bacteria, including M. tuberculosis, have been shown to reduce their rates of mRNA degradation under growth limitation and stress. While the existence of this response appears to be conserved across species, the underlying bacterial mRNA stabilization mechanisms remain unknown. To better understand the biology of nongrowing mycobacteria, we sought to identify the mechanistic basis of mRNA stabilization in the nonpathogenic model Mycobacterium smegmatis. We found that mRNA half-life was responsive to energy stress, with carbon starvation and hypoxia causing global mRNA stabilization. This global stabilization was rapidly reversed when hypoxia-adapted cultures were reexposed to oxygen, even in the absence of new transcription. The stringent response and RNase levels did not explain mRNA stabilization, nor did transcript abundance. This led us to hypothesize that metabolic changes during growth cessation impact the activities of degradation proteins, increasing mRNA stability. Indeed, bedaquiline and isoniazid, two drugs with opposing effects on cellular energy status, had opposite effects on mRNA half-lives in growth-arrested cells. Taken together, our results indicate that mRNA stability in mycobacteria is not directly regulated by growth status but rather is dependent on the status of energy metabolism.
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Michelot-Antalik A, Granda E, Fresneau C, Damesin C. Evidence of a seasonal trade-off between growth and starch storage in declining beeches: assessment through stem radial increment, non-structural carbohydrates and intra-ring δ13C. Tree Physiol 2019; 39:831-844. [PMID: 30824921 DOI: 10.1093/treephys/tpz008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 01/08/2019] [Indexed: 06/09/2023]
Abstract
Forest decline is reported in recent decades all over the world. However, developing a clear vision of the associated tree dysfunctioning is still a challenge for plant physiologists. In this study, our aim was to examine the seasonal carbon adjustments of beech trees in the case of a long-term drought-induced decline. We compared healthy and declining trees in terms of stem radial growth, phloem sugar content and δ13C, together with xylem carbohydrates and intra-ring δ13C patterns. The radial growth of declining trees was clearly reduced by lower growth rates and shorter growing season length (44 days compared with healthy trees). The soluble sugar content was higher in the xylem of declining trees compared with the healthy ones, but similar in the phloem except at the end of their growth. Declining trees increased their levels of xylem starch content from budburst until the date of maximal growth rate. These reserve dynamics revealed an early trade-off between radial growth and starch storage that might be the result of an active or passive process. For declining trees, the slight decrease of intra-ring cellulose δ13C pattern during the early growing season was attributed to the synthesis of 13C enriched starch. For healthy trees, δ13C patterns were characterized by a progressive 13C increase along the ring, attributed to increased water-use efficiency (WUE) in response to decreased water availability. Individual variations of the crown area were negatively correlated to the intra-ring δ13C amplitude, which was ascribed to variations in canopy WUE and resource competition for healthy trees and partly to variations in the amount of reserves accumulated during spring for declining ones. Our study highlights the carbon physiological adjustment of declining trees towards reducing spring growth while storing starch, which can be reflected in the individual intra-ring cellulose δ13C patterns.
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Affiliation(s)
- Alice Michelot-Antalik
- Université de Lorraine, Inra, LAE, Nancy, France
- Laboratoire Ecologie Systématique et Evolution, UMR 8079, Université Paris-Sud, CNRS, AgroParisTech, Orsay, France
| | - Elena Granda
- Laboratoire Ecologie Systématique et Evolution, UMR 8079, Université Paris-Sud, CNRS, AgroParisTech, Orsay, France
- Department of Crop and Forest Sciences - AGROTECNIO Center, Universitat de Lleida, Lleida, Spain
| | - Chantal Fresneau
- Laboratoire Ecologie Systématique et Evolution, UMR 8079, Université Paris-Sud, CNRS, AgroParisTech, Orsay, France
| | - Claire Damesin
- Laboratoire Ecologie Systématique et Evolution, UMR 8079, Université Paris-Sud, CNRS, AgroParisTech, Orsay, France
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Wang K, Shen C, Cao P, Song LN, Yu GQ. [Changes of non-structural carbohydrates of Pinus sylvestris var. mongolica seedlings in the process of drought-induced mortality]. Ying Yong Sheng Tai Xue Bao 2018; 29:3513-3520. [PMID: 30460797 DOI: 10.13287/j.1001-9332.201811.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
To understand the distribution of non-structural carbohydrates (NSC) and adaptive mechanism in the process of drought-induced mortality, two-year-old Pinus sylvestris var. mongolica seedlings were grown under continuous natural drought condition. Needle water potential and the contents of soluble sugar, starch and total NSC in different organs (current-year-old needles, one-year-old needles, stems, coarse roots and fine roots) of the seedlings were measured when soil water content decreased to 60%, 40%, 30%, 20% and 15% of the soil field water capacity (SFC). The results showed that when the soil water content decreased from 40% SFC to 15% SFC, there was no significant change in needle water potential at predawn and midday. When soil water content decreased from 60% SFC to 30% SFC, the contents of soluble sugar, starch, total NSC and the ratio of soluble sugar and starch first decreased and then increased in all organs. When soil water content dropped from 30% SFC to 20% SFC, the soluble sugar, starch and total NSC contents decreased in the current-year-old needles, one-year-old needles, stems and fine roots. The soluble sugar content increased, but the starch and total NSC contents decreased in the coarse roots. When soil water content decreased from 20% SFC to 15% SFC, the contents of soluble sugar, starch and total NSC decreased in the current-year-old needles, one-year-old needles and stems, and the soluble sugar and total NSC contents decreased, but the starch content increased in the coarse roots, the soluble sugar content decreased, but the starch and total NSC contents increased in fine roots. The results indicated that NSC content in different organs of P. sylvestris var. mongolica seedlings varied in their adaptation to different degrees of drought. The contents of soluble sugar and total NSC in seedlings decreased under less than 30% of the soil field water capacity, with the starch being accumulated in the coarse roots and fine roots. The seedlings might be died due to carbon depletion.
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Affiliation(s)
- Kai Wang
- College of Environmental Sciences and Engineering, Liaoning Technical University, Fuxin 123000, Liaoning, China
| | - Chao Shen
- College of Environmental Sciences and Engineering, Liaoning Technical University, Fuxin 123000, Liaoning, China
| | - Peng Cao
- Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China
| | - Li Ning Song
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Guo Qing Yu
- Liaoning Institute of Sandyland Improvement and Utilization, Fuxin 123000, Liaoning, China
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Guo Q, Yoshida Y, Major IT, Wang K, Sugimoto K, Kapali G, Havko NE, Benning C, Howe GA. JAZ repressors of metabolic defense promote growth and reproductive fitness in Arabidopsis. Proc Natl Acad Sci U S A 2018; 115:E10768-77. [PMID: 30348775 DOI: 10.1073/pnas.1811828115] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The plant hormone jasmonate promotes resistance to plant-eating organisms, ranging from pathogenic microbes to mammals. Jasmonate reprograms metabolism to fuel the production of diverse defense compounds and simultaneously inhibits plant growth. Understanding how growth is influenced across a range of defense levels remains unclear, but has important implications for optimizing crop productivity. Using a genetic approach to “tune” the jasmonate response, we assessed the physiological consequences of discrete levels of defense throughout the plant life cycle. Overactivation of jasmonate response led to carbon starvation, near loss of seed production and, under extreme conditions, lethality. Our findings explain the emergence of diverse strategies to keep jasmonate responses at bay and provide new insights into metabolic processes that underlie growth–defense trade-offs. Plant immune responses mediated by the hormone jasmonoyl-l-isoleucine (JA-Ile) are metabolically costly and often linked to reduced growth. Although it is known that JA-Ile activates defense responses by triggering the degradation of JASMONATE ZIM DOMAIN (JAZ) transcriptional repressor proteins, expansion of the JAZ gene family in vascular plants has hampered efforts to understand how this hormone impacts growth and other physiological tasks over the course of ontogeny. Here, we combined mutations within the 13-member Arabidopsis JAZ gene family to investigate the effects of chronic JAZ deficiency on growth, defense, and reproductive output. A higher-order mutant (jaz decuple, jazD) defective in 10 JAZ genes (JAZ1–7, -9, -10, and -13) exhibited robust resistance to insect herbivores and fungal pathogens, which was accompanied by slow vegetative growth and poor reproductive performance. Metabolic phenotypes of jazD discerned from global transcript and protein profiling were indicative of elevated carbon partitioning to amino acid-, protein-, and endoplasmic reticulum body-based defenses controlled by the JA-Ile and ethylene branches of immunity. Resource allocation to a strong defense sink in jazD leaves was associated with increased respiration and hallmarks of carbon starvation but no overt changes in photosynthetic rate. Depletion of the remaining JAZ repressors in jazD further exaggerated growth stunting, nearly abolished seed production and, under extreme conditions, caused spreading necrotic lesions and tissue death. Our results demonstrate that JAZ proteins promote growth and reproductive success at least in part by preventing catastrophic metabolic effects of an unrestrained immune response.
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Abstract
Autophagic degradation of proteasomes (termed proteaphagy) is a conserved mechanism by which cells eliminate excess or damaged particles. This clearance is induced rapidly when organisms are starved for nitrogen and, because proteasomes are highly abundant, their breakdown likely makes an important contribution to the amino acid pools necessary for survival. By contrast, our recent studies found that proteasomes are not degraded in response to carbon starvation, even though bulk macroautophagy is similarly activated. Instead, carbon starvation induces sequestration of proteasomes into membrane-less cytoplasmic condensates previously termed proteasome storage granules (PSGs), which protect proteasomes from autophagic degradation. Preserving proteasomes in PSGs enhances the ability of yeast cells to recover from a variety of stresses, implying that rapid remobilization of stored proteasomes when conditions improve is advantageous to cell fitness. Consequently, the choice of whether to save or degrade proteasomes can profoundly impact cell survival.
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Affiliation(s)
- Richard S Marshall
- a Department of Biology , Washington University in St. Louis , St. Louis , MO , USA
| | - Richard D Vierstra
- a Department of Biology , Washington University in St. Louis , St. Louis , MO , USA
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Wei JS, Li ZS, Feng XY, Zhang Y, Chen WL, Wu X, Jiao L, Wang XC. [Ecological and physiological mechanisms of growth decline of Robinia pseudoacacia plantations in the Loess Plateau of China: A review.]. Ying Yong Sheng Tai Xue Bao 2018; 29:2433-2444. [PMID: 30039683 DOI: 10.13287/j.1001-9332.201807.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Robinia pseudoacacia has been widely planted in the Loess Plateau of China for soil and water conservation. The growth decline of R. pseudoacacia plantations has become a recently emerging challenge for the revegetation program and sustainable forest management in this region. As to the scientific definition, identified criteria and quantitative indices have not yet been comprehensively quantified, our current understanding of the ecological and physiological mechanisms for growth decline of R. pseudoacacia plantations is limited. The knowledge could enrich the basic theories of vegetation restoration and benefit the sustainable development of the afforestation project in the Loess Plateau. Through the comprehensive compilation of literatures on forest decline and tree mortality in the Loess Plateau and other regions across the world, this review summarized the mechanisms and recent research progress on growth decline for R. pseudoacacia plantations in the Loess Plateau, primarily demonstrated from ecological (e.g., climatic change, soil desiccation, the imbalance of community structure and the misconduct of forest management) and physiological (e.g., hydraulic failure, carbon starvation, genetic and molecular regulation) perspectives. Finally, we highlighted the research gap with regard to growth decline of R. pseudoacacia plantations in the Loess Plateau.
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Affiliation(s)
- Jing Shu Wei
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Zong Shan Li
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Xiao Yu Feng
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Yuan Zhang
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Liang Chen
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Xing Wu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Lei Jiao
- Shaanxi Normal University, Xi'an 710119, China
| | - Xiao Chun Wang
- Center for Ecological Research, Northeast Forestry University, Harbin 150040, China
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48
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Schofield WB, Zimmermann-Kogadeeva M, Zimmermann M, Barry NA, Goodman AL. The Stringent Response Determines the Ability of a Commensal Bacterium to Survive Starvation and to Persist in the Gut. Cell Host Microbe 2018; 24:120-132.e6. [PMID: 30008292 PMCID: PMC6086485 DOI: 10.1016/j.chom.2018.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/21/2018] [Accepted: 06/05/2018] [Indexed: 01/16/2023]
Abstract
In the mammalian gut, bacteria compete for resources to maintain their populations, but the factors determining their success are poorly understood. We report that the human gut bacterium Bacteroides thetaiotaomicron relies on the stringent response, an intracellular signaling pathway that allocates resources away from growth, to survive carbon starvation and persist in the gut. Genome-scale transcriptomics, 13C-labeling, and metabolomics analyses reveal that B. thetaiotaomicron uses the alarmone (p)ppGpp to repress multiple biosynthetic pathways and upregulate tricarboxylic acid (TCA) cycle genes in these conditions. During carbon starvation, (p)ppGpp triggers accumulation of the metabolite alpha-ketoglutarate, which itself acts as a metabolic regulator; alpha-ketoglutarate supplementation restores viability to a (p)ppGpp-deficient strain. These studies uncover how commensal bacteria adapt to the gut by modulating central metabolism and reveal that halting rather than accelerating growth can be a determining factor for membership in the gut microbiome.
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Affiliation(s)
- Whitman B Schofield
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Maria Zimmermann-Kogadeeva
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Michael Zimmermann
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Natasha A Barry
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Andrew L Goodman
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA.
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Gessler A, Cailleret M, Joseph J, Schönbeck L, Schaub M, Lehmann M, Treydte K, Rigling A, Timofeeva G, Saurer M. Drought induced tree mortality - a tree-ring isotope based conceptual model to assess mechanisms and predispositions. New Phytol 2018; 219:485-490. [PMID: 29626352 DOI: 10.1111/nph.15154] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Affiliation(s)
- Arthur Gessler
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
| | - Maxime Cailleret
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
| | - Jobin Joseph
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
| | - Leonie Schönbeck
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
| | - Marcus Schaub
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
| | - Marco Lehmann
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
| | - Kerstin Treydte
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
| | - Andreas Rigling
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
| | - Galina Timofeeva
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
| | - Matthias Saurer
- Swiss Federal Research Institute WSL, Zuercherstr. 111, Birmensdorf, 8903, Switzerland
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50
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Weber R, Schwendener A, Schmid S, Lambert S, Wiley E, Landhäusser SM, Hartmann H, Hoch G. Living on next to nothing: tree seedlings can survive weeks with very low carbohydrate concentrations. New Phytol 2018; 218:107-118. [PMID: 29424009 DOI: 10.1111/nph.14987] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 12/07/2017] [Indexed: 06/08/2023]
Abstract
The usage of nonstructural carbohydrates (NSCs) to indicate carbon (C) limitation in trees requires knowledge of the minimum tissue NSC concentrations at lethal C starvation, and the NSC dynamics during and after severe C limitation. We completely darkened and subsequently released seedlings of two deciduous and two evergreen temperate tree species for varying periods. NSCs were measured in all major organs, allowing assessment of whole-seedling NSC balances. NSCs decreased fast in darkness, but seedlings survived species-specific whole-seedling starch concentrations as low as 0.4-0.8% per dry matter (DM), and sugar (sucrose, glucose and fructose) concentrations as low as 0.5-2.0% DM. After re-illumination, the refilling of NSC pools began within 3 wk, while the resumption of growth was delayed or restricted. All seedlings had died after 12 wk of darkness, and starch and sugar concentrations in most tissues were lower than 1% DM. We conclude that under the applied conditions, tree seedlings can survive several weeks with very low NSC reserves probably also using alternative C sources like lipids, proteins or hemicelluloses; lethal C starvation cannot be assumed, if NSC concentrations are higher than the minimum concentrations found in surviving seedlings; and NSC reformation after re-illumination occurs preferentially over growth.
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Affiliation(s)
- Raphael Weber
- Department of Environmental Sciences - Botany, University of Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland
| | - Andrea Schwendener
- Department of Environmental Sciences - Botany, University of Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland
| | - Sandra Schmid
- Department of Environmental Sciences - Botany, University of Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland
| | - Savoyane Lambert
- Max-Planck Institute for Biogeochemistry, Hans Knöll Strasse 10, Jena, 07745, Germany
| | - Erin Wiley
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada
| | - Simon M Landhäusser
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada
| | - Henrik Hartmann
- Max-Planck Institute for Biogeochemistry, Hans Knöll Strasse 10, Jena, 07745, Germany
| | - Günter Hoch
- Department of Environmental Sciences - Botany, University of Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland
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