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Aidlin Harari O, Dekel A, Wintraube D, Vainer Y, Mozes-Koch R, Yakir E, Malka O, Morin S, Bohbot JD. A sucrose-specific receptor in Bemisia tabaci and its putative role in phloem feeding. iScience 2023; 26:106752. [PMID: 37234092 PMCID: PMC10206433 DOI: 10.1016/j.isci.2023.106752] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 12/22/2022] [Accepted: 04/22/2023] [Indexed: 05/27/2023] Open
Abstract
In insects, specialized feeding on the phloem sap (containing mainly the sugar sucrose) has evolved only in some hemipteran lineages. This feeding behavior requires an ability to locate feeding sites buried deeply within the plant tissue. To determine the molecular mechanism involved, we hypothesized that the phloem-feeding whitefly Bemisia tabaci relies on gustatory receptor (GR)-mediated sugar sensing. We first conducted choice assays, which indicated that B. tabaci adults consistently choose diets containing higher sucrose concentrations. Next, we identified four GR genes in the B. tabaci genome. One of them, BtabGR1, displayed significant sucrose specificity when expressed in Xenopus oocytes. Silencing of BtabGR1 significantly interfered with the ability of B. tabaci adults to discriminate between non-phloem and phloem concentrations of sucrose. These findings suggest that in phloem feeders, sugar sensing by sugar receptors might allow tracking an increasing gradient of sucrose concentrations in the leaf, leading eventually to the location of the feeding site.
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Affiliation(s)
- Ofer Aidlin Harari
- Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel
| | - Amir Dekel
- Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel
| | - Dor Wintraube
- Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel
| | - Yuri Vainer
- Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel
| | - Rita Mozes-Koch
- Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel
| | - Esther Yakir
- Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel
| | - Osnat Malka
- Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel
| | - Shai Morin
- Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel
| | - Jonathan D. Bohbot
- Department of Entomology, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel
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2
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Miehe W, Czempik L, Klebl F, Lohaus G. Sugar concentrations and expression of SUTs suggest active phloem loading in tall trees of Fagus sylvatica and Quercus robur. TREE PHYSIOLOGY 2023; 43:805-816. [PMID: 36579830 DOI: 10.1093/treephys/tpac152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 12/15/2022] [Accepted: 12/23/2022] [Indexed: 05/13/2023]
Abstract
Phloem loading and sugar distribution are key steps for carbon partitioning in herbaceous and woody species. Although the phloem loading mechanisms in herbs are well studied, less is known for trees. It was shown for saplings of Fagus sylvatica L. and Quercus robur L. that the sucrose concentration in the phloem sap was higher than in the mesophyll cells, which suggests that phloem loading of sucrose involves active steps. However, the question remains whether this also applies for tall trees. To approach this question, tissue-specific sugar and starch contents of small and tall trees of F. sylvatica and Q. robur as well as the sugar concentration in the subcellular compartments of mesophyll cells were examined. Moreover, sucrose uptake transporters (SUTs) were analyzed by heterology expression in yeast and the tissue-specific expressions of SUTs were investigated. Sugar content in leaves of the canopy (11 and 26 m height) was up to 25% higher compared with that of leaves of small trees of F. sylvatica and Q. robur (2 m height). The sucrose concentration in the cytosol of mesophyll cells from tall trees was between 120 and 240 mM and about 4- to 8-fold lower than the sucrose concentration in the phloem sap of saplings. The analyzed SUT sequences of both tree species cluster into three types, similar to SUTs from other plant species. Heterologous expression in yeast confirmed that all analyzed SUTs are functional sucrose transporters. Moreover, all SUTs were expressed in leaves, bark and wood of the canopy and the expression levels in small and tall trees were similar. The results show that the phloem loading in leaves of tall trees of F. sylvatica and Q. robur probably involves active steps, because there is an uphill concentration gradient for sucrose. SUTs may be involved in phloem loading.
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Affiliation(s)
- Wiebke Miehe
- School of Mathematics and Natural Sciences, Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Wuppertal 42119, Germany
| | - Laura Czempik
- School of Mathematics and Natural Sciences, Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Wuppertal 42119, Germany
| | - Franz Klebl
- Department of Biology, Molecular Plant Physiology, University of Erlangen-Nürnberg, Erlangen 91058, Germany
| | - Gertrud Lohaus
- School of Mathematics and Natural Sciences, Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Wuppertal 42119, Germany
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3
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Sun F, Dong X, Li S, Sha H, Gao W, Bai X, Zhang L, Yang H. Genome-wide identification and expression analysis of SUT gene family members in sugar beet (Beta vulgaris L.). Gene 2023; 870:147422. [PMID: 37031883 DOI: 10.1016/j.gene.2023.147422] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/13/2023] [Accepted: 04/04/2023] [Indexed: 04/11/2023]
Abstract
Sucrose transporters (SUTs) play an important role in the transmembrane transport and distribution of sucrose, and their activity has an important impact on plant growth and crop yield. In this study, the SUT gene family was identified in the whole beet genome using bioinformatics methods, and gene characteristics, subcellular localization prediction, phylogenetic evolution, promoter cis-elements and expression patterns were systematically analyzed. A total of 9 SUT gene family members were identified from in beet genome and divided into 3 different groups (group 1, group 2, and Group 3), which were unevenly distributed on 4 chromosomes. Most SUT family members contained photoresponsive and hormone-regulated response elements. Subcellular localization prediction showed that the BvSUT genes are all located in the inner membrane, and most of the terms identified through GO enrichment analysis are classified as "membrane" related. The results of RT-qPCR showed that the expression level of the BvSUT gene was significantly higher in the tuber enlargement stage (100-140 d) than in other stages. This study is the first to analyze the BvSUT gene family in sugar beet, and it provides a theoretical basis for the functional exploration and application of SUT genes in crop improvement, especially in sugar crops.
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Affiliation(s)
- Fenglei Sun
- Research Institute of industrial Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091, China.
| | - Xinjiu Dong
- Research Institute of industrial Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091, China
| | - Sizhong Li
- Research Institute of industrial Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091, China
| | - Hong Sha
- Research Institute of industrial Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091, China
| | - Weishi Gao
- Research Institute of industrial Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091, China
| | - Xiaoshan Bai
- Research Institute of industrial Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091, China
| | - Liming Zhang
- Research Institute of industrial Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091, China
| | - Hongze Yang
- Research Institute of industrial Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091, China.
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4
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Rademacher T, Fonti P, LeMoine JM, Fonti MV, Bowles F, Chen Y, Eckes-Shephard AH, Friend AD, Richardson AD. Insights into source/sink controls on wood formation and photosynthesis from a stem chilling experiment in mature red maple. THE NEW PHYTOLOGIST 2022; 236:1296-1309. [PMID: 35927942 DOI: 10.1111/nph.18421] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 07/30/2022] [Indexed: 06/15/2023]
Abstract
Whether sources or sinks control wood growth remains debated with a paucity of evidence from mature trees in natural settings. Here, we altered carbon supply rate in stems of mature red maples (Acer rubrum) within the growing season by restricting phloem transport using stem chilling; thereby increasing carbon supply above and decreasing carbon supply below the restrictions, respectively. Chilling successfully altered nonstructural carbon (NSC) concentrations in the phloem without detectable repercussions on bulk NSC in stems and roots. Ring width responded strongly to local variations in carbon supply with up to seven-fold differences along the stem of chilled trees; however, concurrent changes in the structural carbon were inconclusive at high carbon supply due to large local variability of wood growth. Above chilling-induced bottlenecks, we also observed higher leaf NSC concentrations, reduced photosynthetic capacity, and earlier leaf coloration and fall. Our results indicate that the cambial sink is affected by carbon supply, but within-tree feedbacks can downregulate source activity, when carbon supply exceeds demand. Such feedbacks have only been hypothesized in mature trees. Consequently, these findings constitute an important advance in understanding source-sink dynamics, suggesting that mature red maples operate close to both source- and sink-limitation in the early growing season.
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Affiliation(s)
- Tim Rademacher
- Harvard Forest, Harvard University, Petersham, MA, 01366, USA
- School of Informatics, Computing and Cyber Systems and Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Institut des Sciences de la Forêt Tempérée, Université du Québec en Outaouais, Ripon, J0V 1V0, QC, Canada
| | - Patrick Fonti
- Swiss Federal Research Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, 8903, Switzerland
| | - James M LeMoine
- School of Informatics, Computing and Cyber Systems and Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Marina V Fonti
- Swiss Federal Research Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, 8903, Switzerland
- Institute of Ecology and Geography, Siberian Federal University, Krasnoyarsk, 660041, Russia
| | | | - Yizhao Chen
- Department of Geography, University of Cambridge, Cambridge, CB2 1BY, UK
| | - Annemarie H Eckes-Shephard
- Department of Geography, University of Cambridge, Cambridge, CB2 1BY, UK
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, 223 62, Sweden
| | - Andrew D Friend
- Department of Geography, University of Cambridge, Cambridge, CB2 1BY, UK
| | - Andrew D Richardson
- School of Informatics, Computing and Cyber Systems and Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
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5
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Chen W, Diao W, Liu H, Guo Q, Song Q, Guo G, Wan H, Chen Y. Molecular characterization of SUT Gene Family in Solanaceae with emphasis on expression analysis of pepper genes during development and stresses. Bioengineered 2022; 13:14780-14798. [PMID: 36260305 PMCID: PMC9586639 DOI: 10.1080/21655979.2022.2107701] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Sucrose, an essential carbohydrate, is transported from source to sink organs in the phloem and is involved in a variety of physiological and metabolic processes in plants. Sucrose transporter proteins (SUTs) may play significant parts in the phloem loading and unloading of sucrose. In our study, the SUT gene family was identified in four Solanaceae species (Capsicum annuum, Solanum lycopersicum, S. melongena, and S. tuberosum) and other 14 plant species ranged from lower and high plants. The comprehensive analysis was performed by integration of chromosomal distribution, gene structure, conserved motifs, evolutionary relationship and expression profiles during pepper growth under stresses. Chromosome mapping revealed that SUT genes in Solanaceae were distributed on chromosomes 4, 10 and 11. Gene structure analysis showed that the subgroup 1 members have the same number of introns and exons. All the SUTs had 12 transmembrane structural domains exception from CaSUT2 and SmSUT2, indicating that a structure variation might occurred among the Solanaceae SUT proteins. We also found a total of 20 conserved motifs, with over half of them shared by all SUT proteins, and the SUT proteins from the same subgroup shared common motifs. Phylogenetic analysis divided a total of 72 SUT genes in the plant species tested into three groups, and subgroup 1 might have diverged from a single common ancestor prior to the mono-dicot split. Finally, expression levels of CaSUTs were induced significantly under heat, cold, and salt treatments, indicating diverse functions of the CaSUTs to adapt to adverse environments.
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Affiliation(s)
- Wenqi Chen
- College of Horticulture, Anhui Agricultural University, Hefei, China,State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou310021, PR China
| | - Weiping Diao
- Institute of Vegetable crops, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Nanjing, 210014, China
| | - Huiqing Liu
- Quzhou Academy of Agricultural and Forestry Sciences, Quzhou, 324000, China
| | - Qinwei Guo
- Quzhou Academy of Agricultural and Forestry Sciences, Quzhou, 324000, China
| | - Qiuping Song
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou310021, PR China
| | - Guangjun Guo
- Institute of Vegetable crops, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Nanjing, 210014, China
| | - Hongjian Wan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou310021, PR China,Hongjian Wan State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou310021, PR China
| | - Yougen Chen
- College of Horticulture, Anhui Agricultural University, Hefei, China,CONTACT Yougen Chen College of Horticulture, Anhui Agricultural University, Hefei, China
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6
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Stefan T, Wu XN, Zhang Y, Fernie A, Schulze WX. Regulatory Modules of Metabolites and Protein Phosphorylation in Arabidopsis Genotypes With Altered Sucrose Allocation. FRONTIERS IN PLANT SCIENCE 2022; 13:891405. [PMID: 35665154 PMCID: PMC9161306 DOI: 10.3389/fpls.2022.891405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 04/11/2022] [Indexed: 06/15/2023]
Abstract
Multi-omics data sets are increasingly being used for the interpretation of cellular processes in response to environmental cues. Especially, the posttranslational modification of proteins by phosphorylation is an important regulatory process affecting protein activity and/or localization, which, in turn, can have effects on metabolic processes and metabolite levels. Despite this importance, relationships between protein phosphorylation status and metabolite abundance remain largely underexplored. Here, we used a phosphoproteomics-metabolomics data set collected at the end of day and night in shoots and roots of Arabidopsis to propose regulatory relationships between protein phosphorylation and accumulation or allocation of metabolites. For this purpose, we introduced a novel, robust co-expression measure suited to the structure of our data sets, and we used this measure to construct metabolite-phosphopeptide networks. These networks were compared between wild type and plants with perturbations in key processes of sugar metabolism, namely, sucrose export (sweet11/12 mutant) and starch synthesis (pgm mutant). The phosphopeptide-metabolite network turned out to be highly sensitive to perturbations in sugar metabolism. Specifically, KING1, the regulatory subunit of SnRK1, was identified as a primary candidate connecting protein phosphorylation status with metabolism. We additionally identified strong changes in the fatty acid network of the sweet11/12 mutant, potentially resulting from a combination of fatty acid signaling and metabolic overflow reactions in response to high internal sucrose concentrations. Our results further suggest novel protein-metabolite relationships as candidates for future targeted research.
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Affiliation(s)
- Thorsten Stefan
- Department of Plant Systems Biology, University of Hohenheim, Stuttgart, Germany
| | - Xu Na Wu
- College for Life Science, Yunnan University, Kunming, China
| | - Youjun Zhang
- Department of Central Metabolism, Max-Planck-Institute of Molecular Plant Physiology, Potsdam, Germany
- Center of Plant System Biology and Biotechnology, Plovdiv, Bulgaria
| | - Alisdair Fernie
- Department of Central Metabolism, Max-Planck-Institute of Molecular Plant Physiology, Potsdam, Germany
- Center of Plant System Biology and Biotechnology, Plovdiv, Bulgaria
| | - Waltraud X. Schulze
- Department of Plant Systems Biology, University of Hohenheim, Stuttgart, Germany
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Zhang G, Cui K, Li G, Pan J, Huang J, Peng S. Stem small vascular bundles have greater accumulation and translocation of non-structural carbohydrates than large vascular bundles in rice. PHYSIOLOGIA PLANTARUM 2022; 174:e13695. [PMID: 35491933 DOI: 10.1111/ppl.13695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 04/14/2022] [Accepted: 04/27/2022] [Indexed: 06/14/2023]
Abstract
Phloem unloading and loading are associated with stem non-structural carbohydrates (NSCs) accumulation and remobilization in rice (Oryza sativa L.). Four rice recombinant inbred lines (R032, R191, R046, and R146) derived from a cross between Zhenshan 97 and Minghui 63 were used to investigate the contributions of stem large and small vascular bundles (SVBs) to NSCs accumulation and translocation. Before heading, the parenchyma cells in stem cortex tissues (PCs) surrounding SVBs had higher starch density than those surrounding large vascular bundles (LVBs). Moreover, the protein levels of sucrose transporters (SUTs), cell wall invertase, sucrose synthase, and adenosine diphosphate glucose pyrophosphorylase, as well as the phloem plasmodesma densities were higher in SVBs than those in LVBs. After heading, starch density decreased more in PCs surrounding SVBs than in LVBs. Also, the protein levels of SUTs, α-amylase, sucrose phosphate synthase and sucrose synthase, the phloem plasmodesma densities in SVBs were higher than those in LVBs. The correlations of the number and total cross-sectional area of SVBs with mass and contribution to yield of transferred NSCs were higher than those of LVBs. Our results suggest that SVBs may have higher contributions to pre-anthesis stem NSCs accumulation and post-anthesis translocation than LVBs, which is potentially attributed to the high level of protein and enzyme involved in stem unloading and loading via apoplastic and symplastic pathways.
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Affiliation(s)
- Guo Zhang
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Corp Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Kehui Cui
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Corp Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Guohui Li
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Corp Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Junfeng Pan
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Corp Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jianliang Huang
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Corp Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Shaobing Peng
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Corp Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
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Gautam T, Dutta M, Jaiswal V, Zinta G, Gahlaut V, Kumar S. Emerging Roles of SWEET Sugar Transporters in Plant Development and Abiotic Stress Responses. Cells 2022; 11:cells11081303. [PMID: 35455982 PMCID: PMC9031177 DOI: 10.3390/cells11081303] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/23/2022] [Accepted: 03/25/2022] [Indexed: 02/01/2023] Open
Abstract
Sugars are the major source of energy in living organisms and play important roles in osmotic regulation, cell signaling and energy storage. SWEETs (Sugars Will Eventually be Exported Transporters) are the most recent family of sugar transporters that function as uniporters, facilitating the diffusion of sugar molecules across cell membranes. In plants, SWEETs play roles in multiple physiological processes including phloem loading, senescence, pollen nutrition, grain filling, nectar secretion, abiotic (drought, heat, cold, and salinity) and biotic stress regulation. In this review, we summarized the role of SWEET transporters in plant development and abiotic stress. The gene expression dynamics of various SWEET transporters under various abiotic stresses in different plant species are also discussed. Finally, we discuss the utilization of genome editing tools (TALENs and CRISPR/Cas9) to engineer SWEET genes that can facilitate trait improvement. Overall, recent advancements on SWEETs are highlighted, which could be used for crop trait improvement and abiotic stress tolerance.
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Affiliation(s)
- Tinku Gautam
- Department of Genetics and Plant Breeding, Chaudhary Charan Singh University, Meerut 250004, India;
| | - Madhushree Dutta
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, India; (M.D.); (V.J.); (G.Z.); (S.K.)
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Vandana Jaiswal
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, India; (M.D.); (V.J.); (G.Z.); (S.K.)
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Gaurav Zinta
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, India; (M.D.); (V.J.); (G.Z.); (S.K.)
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Vijay Gahlaut
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, India; (M.D.); (V.J.); (G.Z.); (S.K.)
- Correspondence:
| | - Sanjay Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, India; (M.D.); (V.J.); (G.Z.); (S.K.)
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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9
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Dominguez PG, Niittylä T. Mobile forms of carbon in trees: metabolism and transport. TREE PHYSIOLOGY 2022; 42:458-487. [PMID: 34542151 PMCID: PMC8919412 DOI: 10.1093/treephys/tpab123] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 07/16/2021] [Accepted: 09/12/2021] [Indexed: 05/26/2023]
Abstract
Plants constitute 80% of the biomass on earth, and almost two-thirds of this biomass is found in wood. Wood formation is a carbon (C)-demanding process and relies on C transport from photosynthetic tissues. Thus, understanding the transport process is of major interest for understanding terrestrial biomass formation. Here, we review the molecules and mechanisms used to transport and allocate C in trees. Sucrose is the major form in which C is transported in plants, and it is found in the phloem sap of all tree species investigated so far. However, in several tree species, sucrose is accompanied by other molecules, notably polyols and the raffinose family of oligosaccharides. We describe the molecules that constitute each of these transport groups, and their distribution across different tree species. Furthermore, we detail the metabolic reactions for their synthesis, the mechanisms by which trees load and unload these compounds in and out of the vascular system, and how they are radially transported in the trunk and finally catabolized during wood formation. We also address a particular C recirculation process between phloem and xylem that occurs in trees during the annual cycle of growth and dormancy. A search of possible evolutionary drivers behind the diversity of C-carrying molecules in trees reveals no consistent differences in C transport mechanisms between angiosperm and gymnosperm trees. Furthermore, the distribution of C forms across species suggests that climate-related environmental factors will not explain the diversity of C transport forms. However, the consideration of C-transport mechanisms in relation to tree-rhizosphere coevolution deserves further attention. To conclude the review, we identify possible future lines of research in this field.
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Affiliation(s)
- Pia Guadalupe Dominguez
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Hurlingham, Buenos Aires B1686IGC, Argentina
| | - Totte Niittylä
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå 90183, Sweden
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Han X, Gao C, Liang B, Cui J, Xu Q, Schulz A, Liesche J. Evidence for conifer sucrose transporters' functioning in the light-dependent adjustment of sugar allocation. TREE PHYSIOLOGY 2022; 42:488-500. [PMID: 35020944 DOI: 10.1093/treephys/tpab149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 11/16/2021] [Indexed: 06/14/2023]
Abstract
Sucrose is the central unit of carbon and energy in plants. Active intercellular transport of sucrose is mediated by sucrose transporters (SUTs), genes for which have been found in the genomes of all land plants. However, they have only been assigned functions in angiosperm species. Here, we cloned two types of SUTs from two gymnosperms, the conifers Cedrus deodara (Roxb. G. Don) and Pinus massoniana Lambert, and analyzed their sucrose transport activities. Uptake of the fluorescent sucrose-analog esculin into tobacco epidermis cells expressing the conifer SUT confirmed their transport ability. To determine their function in planta, we investigated their mRNA abundance in relation to photosynthesis and sugar levels in leaves, inner bark, wood and roots. Combined with measurements of protein abundance and immunolocalization of C. deodara SUTs, our results suggest a role for CdSUT1G and CdSUT2 in supporting phloem transport under varying environmental conditions. The implications of these findings regarding conifer physiology and SUT evolution are discussed.
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Affiliation(s)
- Xiaoyu Han
- College of Life Sciences, Northwest A&F University, Yangling 712100, China
- Biomass Energy Center for Arid and Semi-arid Lands, Northwest A&F University, Yangling 712100, China
| | - Chen Gao
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg 1870, Denmark
| | - Buyou Liang
- College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Jingxuan Cui
- College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Qiyu Xu
- College of Life Sciences, Northwest A&F University, Yangling 712100, China
- Biomass Energy Center for Arid and Semi-arid Lands, Northwest A&F University, Yangling 712100, China
| | - Alexander Schulz
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg 1870, Denmark
| | - Johannes Liesche
- College of Life Sciences, Northwest A&F University, Yangling 712100, China
- Biomass Energy Center for Arid and Semi-arid Lands, Northwest A&F University, Yangling 712100, China
- Institute for Molecular Physiology, Heinrich-Heine-University Düsseldorf, Düsseldorf 40225, Germany
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11
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Stanfield RC, Bartlett MK. Coordination Between Phloem Loading and Structure Maintains Carbon Transport Under Drought. FRONTIERS IN PLANT SCIENCE 2022; 13:787837. [PMID: 35251074 PMCID: PMC8891486 DOI: 10.3389/fpls.2022.787837] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Maintaining phloem transport under water stress is expected to be crucial to whole-plant drought tolerance, but the traits that benefit phloem function under drought are poorly understood. Nearly half of surveyed angiosperm species, including important crops, use sucrose transporter proteins to actively load sugar into the phloem. Plants can alter transporter abundance in response to stress, providing a potential mechanism for active-loading species to closely regulate phloem loading rates to avoid drought-induced reductions or failures in phloem transport. We developed an integrated xylem-phloem-stomatal model to test this hypothesis by quantifying the joint impacts of transporter kinetics, phloem anatomy, and plant water status on sucrose export to sinks. We parameterized the model with phloem hydraulic resistances and sucrose transporter kinetic parameters compiled from the literature, and simulated loading regulation by allowing loading rates to decline exponentially with phloem pressure to prevent excessive sucrose concentrations from inducing viscosity limitations. In the absence of loading regulation, where loading rates were independent of phloem pressure, most resistance values produced unrealistic phloem pressures owing to viscosity effects, even under well-watered conditions. Conversely, pressure-regulated loading helped to control viscosity buildup and improved export to sinks for both lower and higher resistant phloem pathways, while maintaining realistic phloem pressures. Regulation also allowed for rapid loading and export in wet conditions while maintaining export and viable phloem pressures during drought. Therefore, we expect feedbacks between phloem pressure and loading to be critical to carbon transport in active-loading species, especially under drought, and for transporter kinetics to be strongly coordinated with phloem architecture and plant water status. This work provides an important and underexplored physiological framework to understand the ecophysiology of phloem transport under drought and to enhance the genetic engineering of crop plants.
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Affiliation(s)
- Ryan C. Stanfield
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
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12
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Tee EE, Samwald S, Faulkner C. Quantification of Cell-to-Cell Connectivity Using Particle Bombardment. Methods Mol Biol 2022; 2457:263-272. [PMID: 35349146 DOI: 10.1007/978-1-0716-2132-5_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Plant cells are connected by cytoplasmic bridges called plasmodesmata. Plasmodesmata are lined by the plasma membrane, essentially forming tunnels that directly connect the cytoplasm of adjacent cells through which soluble molecules can move from cell to cell. This cell-to-cell mobility is underpinned by cytoplasmic advection and diffusion in a manner dependent on molecular size. This movement of molecules is regulated by the aperture of plasmodesmata. GREEN FLUORESCENT PROTEIN (GFP) is a 27 kDa soluble protein that can move passively between cells via plasmodesmata. Thus, it serves as an ideal probe to assess plasmodesmal aperture. GFP can be transgenically produced in single cells by microprojectile bombardment-mediated transformation, and its cell-to-cell mobility can be measured by live-cell imaging and counting the number of cells (or cell layers) to which it has moved. Thus, the number of cells in which GFP is visible serves as a measure of plasmodesmal aperture and functional cell-to-cell connectivity. Here we present methods for microprojectile bombardment of GFP into leaf epidermal cells and statistical analysis of resulting data.
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Affiliation(s)
- Estee E Tee
- Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK
| | - Sebastian Samwald
- Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK
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13
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Hu Z, Tang Z, Zhang Y, Niu L, Yang F, Zhang D, Hu Y. Rice SUT and SWEET Transporters. Int J Mol Sci 2021; 22:11198. [PMID: 34681858 PMCID: PMC8540626 DOI: 10.3390/ijms222011198] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 11/17/2022] Open
Abstract
Sugar transporters play important or even indispensable roles in sugar translocation among adjacent cells in the plant. They are mainly composed of sucrose-proton symporter SUT family members and SWEET family members. In rice, 5 and 21 members are identified in these transporter families, and some of their physiological functions have been characterized on the basis of gene knockout or knockdown strategies. Existing evidence shows that most SUT members play indispensable roles, while many SWEET members are seemingly not so critical in plant growth and development regarding whether their mutants display an aberrant phenotype or not. Generally, the expressions of SUT and SWEET genes focus on the leaf, stem, and grain that represent the source, transport, and sink organs where carbohydrate production, allocation, and storage take place. Rice SUT and SWEET also play roles in both biotic and abiotic stress responses in addition to plant growth and development. At present, these sugar transporter gene regulation mechanisms are largely unclear. In this review, we compare the expressional profiles of these sugar transporter genes on the basis of chip data and elaborate their research advances. Some suggestions concerning future investigation are also proposed.
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Affiliation(s)
- Zhi Hu
- College of Resources & Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; (Z.H.); (Z.T.)
| | - Zhenjia Tang
- College of Resources & Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; (Z.H.); (Z.T.)
| | - Yanming Zhang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China; (Y.Z.); (L.N.); (F.Y.)
| | - Liping Niu
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China; (Y.Z.); (L.N.); (F.Y.)
| | - Fang Yang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China; (Y.Z.); (L.N.); (F.Y.)
| | - Dechun Zhang
- Bio-Technology Research Center, China Three Gorges University, Yichang 443002, China
| | - Yibing Hu
- College of Resources & Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; (Z.H.); (Z.T.)
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Gersony JT, McClelland A, Holbrook NM. Raman spectroscopy reveals high phloem sugar content in leaves of canopy red oak trees. THE NEW PHYTOLOGIST 2021; 232:418-424. [PMID: 33991343 DOI: 10.1111/nph.17465] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
A robust understanding of phloem functioning in tall trees evades us because current methods for collecting phloem sap do not lend themselves to measuring actively photosynthesizing canopy leaves. We show that Raman spectroscopy can be used as a quantitative tool to assess sucrose concentration in leaf samples. Specifically, we found that Raman spectroscopy can predict physiologically relevant sucrose concentrations (adjusted R2 of 0.9) in frozen leaf extract spiked with sucrose. We then apply this method to estimate sieve element sucrose concentration in rapidly frozen petioles of canopy red oak (Quercus rubra) trees and found that sucrose concentrations are > 1100 mM at midday and midnight. This concentration is predicted to generate a sieve element turgor pressure high enough to generate bulk flow through the phloem, but is potentially too high to allow for sucrose diffusion from photosynthetic cells. Our findings support the Münch hypothesis for phloem transport once the carbon is in the phloem and challenge the passive-loading hypothesis for carbon movement into the phloem for red oak. This study provides the first ˜in-situ (frozen in the functioning state) source sieve element sucrose concentration characterization in any plant, opening a new avenue for investigation of phloem functioning.
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Affiliation(s)
- Jess T Gersony
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Arthur McClelland
- Center for Nanoscale Systems, Harvard University, Cambridge, MA, 02138, USA
| | - N Michele Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
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15
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Xu Q, Liesche J. Sugar export from Arabidopsis leaves: actors and regulatory strategies. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:5275-5284. [PMID: 34037757 DOI: 10.1093/jxb/erab241] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 05/22/2021] [Indexed: 06/12/2023]
Abstract
Plant acclimation and stress responses depend on the dynamic optimization of carbon balance between source and sink organs. This optimization also applies to the leaf export rate of photosynthetically produced sugars. So far, investigations into the molecular mechanisms of how the rate is controlled have focused on sugar transporters responsible for loading sucrose into the phloem sieve element-companion cell complex of leaf veins. Here, we take a broader view of the various proteins with potential direct influence on the leaf sugar export rate in the model plant Arabidopsis thaliana, helped by the cell type-specific transcriptome data that have recently become available. Furthermore, we integrate current information on the regulation of these potential target proteins. Our analysis identifies putative control points and units of transcriptionally and post-transcriptionally co-regulated genes. Most notable is the potential regulatory unit of sucrose transporters (SUC2, SWEET11, SWEET12, and SUC4) and proton pumps (AHA3 and AVP1). Our analysis can guide future research aimed at understanding the regulatory network controlling leaf sugar export by providing starting points for characterizing regulatory strategies and identifying regulatory factors that link sugar export rate to the major signaling pathways.
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Affiliation(s)
- Qiyu Xu
- College of Life Sciences, Northwest A&F University, Yangling, China
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, China
- Biomass Energy Center for Arid and Semiarid Lands, Northwest A&F University, Yangling, China
| | - Johannes Liesche
- College of Life Sciences, Northwest A&F University, Yangling, China
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, China
- Biomass Energy Center for Arid and Semiarid Lands, Northwest A&F University, Yangling, China
- Institute for Molecular Physiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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16
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Wang G, Wu Y, Ma L, Lin Y, Hu Y, Li M, Li W, Ding Y, Chen L. Phloem loading in rice leaves depends strongly on the apoplastic pathway. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:3723-3738. [PMID: 33624763 DOI: 10.1093/jxb/erab085] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 02/19/2021] [Indexed: 06/12/2023]
Abstract
Phloem loading is the first step in sucrose transport from source leaves to sink organs. The phloem loading strategy in rice remains unclear. To determine the potential phloem loading mechanism in rice, yeast invertase (INV) was overexpressed by a 35S promoter specifically in the cell wall to block sugar transmembrane loading in rice. The transgenic lines exhibited obvious phloem loading suppression characteristics accompanied by the accumulation of sucrose and starch, restricted vegetative growth and decreased grain yields. The decreased sucrose exudation rate with p-chloromercuribenzenesulfonic acid (PCMBS) treatment also indicated that rice actively transported sucrose into the phloem. OsSUT1 (SUCROSE TRANSPORTER 1) showed the highest mRNA levels of the plasma membrane-localized OsSUTs in source leaves. Cross sections of the OsSUT::GUS transgenic plants showed that the expression of OsSUT1 and OsSUT5 occurred in the phloem companion cells. Rice ossut1 mutants showed reduced growth and grain yield, supporting the hypothesis of OsSUT1 acting in phloem loading. Based on these results, we conclude that apoplastic phloem loading plays a major role in the export of sugar from rice leaves.
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Affiliation(s)
- Gaopeng Wang
- College of Agriculture, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China
| | - Yue Wu
- College of Agriculture, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China
| | - Li Ma
- College of Agriculture, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China
| | - Yan Lin
- College of Agriculture, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China
| | - Yuxiang Hu
- College of Agriculture, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China
| | - Mengzhu Li
- College of Agriculture, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China
| | - Weiwei Li
- College of Agriculture, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China
| | - Yanfeng Ding
- College of Agriculture, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China
- Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing, China
| | - Lin Chen
- College of Agriculture, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China
- Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing, China
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17
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Fei H, Yang Z, Lu Q, Wen X, Zhang Y, Zhang A, Lu C. OsSWEET14 cooperates with OsSWEET11 to contribute to grain filling in rice. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 306:110851. [PMID: 33775358 DOI: 10.1016/j.plantsci.2021.110851] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/08/2021] [Accepted: 02/11/2021] [Indexed: 06/12/2023]
Abstract
The grain-filling process is crucial for cereal crop yields, but how the caryopsis of such plants is supplied with sugars, which are produced by photosynthesis in leaves and then transported long distance, is largely unknown. In rice (Oryza sativa), various SWEET family sucrose transporters are thought to have important roles in grain filling. Here, we report that OsSWEET14 plays a crucial part in this process in rice. ossweet14 knockout mutants did not show any detectable phenotypic differences from the wild type, whereas ossweet14;ossweet11 double-knockout mutants had much more severe phenotypes than ossweet11 single-knockout mutants, including strongly reduced grain weight and yield, reduced grain-filling rate, and increased starch accumulation in the pericarp. Both OsSWEET14 and OsSWEET11 exhibited distinct spatiotemporal expression patterns between the early stage of caryopsis development and the rapid grain-filling stage. During the rapid grain-filling stage, OsSWEET14 and OsSWEET11 localized to four key sites: vascular parenchyma cells, the nucellar projection, the nucellar epidermis, and cross cells. These results demonstrate that OsSWEET14 plays an important role in grain filling, and they suggest that four major apoplasmic pathways supply sucrose to the endosperm during the rapid grain-filling stage via the sucrose effluxers SWEET14 and SWEET11.
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Affiliation(s)
- Honghong Fei
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Zhipan Yang
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Qingtao Lu
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
| | - Xiaogang Wen
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
| | - Yi Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China.
| | - Aihong Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China.
| | - Congming Lu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China.
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18
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Kaur H, Manna M, Thakur T, Gautam V, Salvi P. Imperative role of sugar signaling and transport during drought stress responses in plants. PHYSIOLOGIA PLANTARUM 2021; 171:833-848. [PMID: 33583052 DOI: 10.1111/ppl.13364] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 01/31/2021] [Accepted: 02/06/2021] [Indexed: 05/27/2023]
Abstract
Cellular sugar status is essentially maintained during normal growth conditions but is impacted negatively during various environmental perturbations. Drought presents one such unfavorable environmental cue that hampers the photosynthetic fixation of carbon into sugars and affects their transport by lowering the cellular osmotic potential. The transport of cellular sugar is facilitated by a specific set of proteins known as sugar transporters. These transporter proteins are the key determinant of influx/ efflux of various sugars and their metabolite intermediates that support the plant growth and developmental process. Abiotic stress and especially drought stress-mediated injury results in reprogramming of sugar distribution across the cellular and subcellular compartments. Here, we have reviewed the imperative role of sugar accumulation, signaling, and transport under typical and atypical stressful environments. We have discussed the physiological effects of drought on sugar accumulation and transport through different transporter proteins involved in monosaccharide and disaccharide sugar transport. Further, we have illustrated sugar-mediated signaling and regulation of sugar transporter proteins along with the overall crosstalk of this signaling with the phytohormone module of abiotic stress response under osmotic stress. Overall, the present review highlights the critical role of sugar transport, distribution and signaling in plants under drought stress conditions.
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Affiliation(s)
- Harmeet Kaur
- Plant Molecular Biology, ICAR-National Institute for Plant Biotechnology, New Delhi, India
| | - Mrinalini Manna
- Plant Molecular Biology, National Institute of Plant Genome Research, New Delhi, India
| | - Tanika Thakur
- Agriculture Biotechnology Department, National Agri-Food Biotechnology Institute, Mohali, India
| | - Vibhav Gautam
- Centre of Experimental Medicine and Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Prafull Salvi
- Agriculture Biotechnology Department, National Agri-Food Biotechnology Institute, Mohali, India
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19
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Harding SA, Frost CJ, Tsai CJ. Defoliation-induced compensatory transpiration is compromised in SUT4-RNAi Populus. PLANT DIRECT 2020; 4:e00268. [PMID: 33015535 PMCID: PMC7522500 DOI: 10.1002/pld3.268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 07/13/2020] [Accepted: 08/23/2020] [Indexed: 06/11/2023]
Abstract
The tonoplast sucrose transporter PtaSUT4 is well expressed in leaves of Populus tremula × Populus alba (INRA 717-IB4), and its inhibition by RNA-interference (RNAi) alters leaf sucrose homeostasis. Whether sucrose partitioning between the vacuole and the cytosol is modulated by PtaSUT4 for specific physiological outcomes in Populus remains unexplored. In this study, partial defoliation was used to elicit compensatory increases in photosynthesis and transpiration by the remaining leaves in greenhouse-grown poplar. Water uptake, leaf gas exchange properties, growth and nonstructural carbohydrate abundance in source and sink organs were then compared between wild-type and SUT4-RNAi lines. Partial defoliation increased maximum photosynthesis rates similarly in all lines. There was no indication that source leaf sugar levels changed differently between wild-type and RNAi plants following partial defoliation. Sink levels of hexose (glucose and fructose) and starch decreased similarly in all lines. Interestingly, plant water uptake after partial defoliation was not as well sustained in RNAi as in wild-type plants. While the compensatory increase in photosynthesis was similar between genotypes, leaf transpiration increased less robustly in RNAi than wild-type plants. SUT4-RNAi and wild-type source leaves differed constitutively in their bulk modulus of elasticity, a measure of leaf turgor, and storage water capacitance. The data demonstrate that reduced sucrose partitioning due to PtaSUT4-RNAi altered turgor control and compensatory transpiration capacity more strikingly than photosynthesis and sugar export. The results are consistent with the interpretation that SUT4 may control vacuolar turgor independently of sink carbon provisioning.
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Affiliation(s)
- Scott A Harding
- Warnell School of Forestry and Natural Resources Department of Genetics and Department of Plant Biology University of Georgia Athens GA USA
| | - Christopher J Frost
- Warnell School of Forestry and Natural Resources Department of Genetics and Department of Plant Biology University of Georgia Athens GA USA
- Present address: BIO5 Institute University of Arizona Tucson AZ 85719 USA
| | - Chung-Jui Tsai
- Warnell School of Forestry and Natural Resources Department of Genetics and Department of Plant Biology University of Georgia Athens GA USA
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20
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Bettenfeld P, Fontaine F, Trouvelot S, Fernandez O, Courty PE. Woody Plant Declines. What's Wrong with the Microbiome? TRENDS IN PLANT SCIENCE 2020; 25:381-394. [PMID: 31983620 DOI: 10.1016/j.tplants.2019.12.024] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 12/16/2019] [Accepted: 12/20/2019] [Indexed: 06/10/2023]
Abstract
Woody plant (WP) declines have multifactorial determinants as well as a biological and economic reality. The vascular system of WPs involved in the transport of carbon, nitrogen, and water from sources to sinks has a seasonal activity, which places it at a central position for mediating plant-environment interactions from nutrient cycling to community assembly and for regulating a variety of processes. To limit effects and to fight against declines, we propose: (i) to consider the WP and its associated microbiota as an holobiont and as a set of functions; (ii) to consider simultaneously, without looking at what comes first, the physiological or pathogenic disorders; and (iii) to define pragmatic strategies, including preventive and curative agronomical practices based on microbiota engineering.
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Affiliation(s)
- Pauline Bettenfeld
- Agroécologie, AgroSup Dijon, CNRS, Université de Bourgogne, INRAE, Université de Bourgogne Franche-Comté, Dijon, France; SFR Condorcet CNRS 3417, Université de Reims Champagne-Ardenne, Unité Résistance Induite et Bioprotection des Plantes EA4707, Reims, France
| | - Florence Fontaine
- SFR Condorcet CNRS 3417, Université de Reims Champagne-Ardenne, Unité Résistance Induite et Bioprotection des Plantes EA4707, Reims, France
| | - Sophie Trouvelot
- Agroécologie, AgroSup Dijon, CNRS, Université de Bourgogne, INRAE, Université de Bourgogne Franche-Comté, Dijon, France
| | - Olivier Fernandez
- SFR Condorcet CNRS 3417, Université de Reims Champagne-Ardenne, Unité Résistance Induite et Bioprotection des Plantes EA4707, Reims, France
| | - Pierre-Emmanuel Courty
- Agroécologie, AgroSup Dijon, CNRS, Université de Bourgogne, INRAE, Université de Bourgogne Franche-Comté, Dijon, France.
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21
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Multifunctionality of Forests: A White Paper on Challenges and Opportunities in China and Germany. FORESTS 2020. [DOI: 10.3390/f11030266] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Both in Germany and in China, there is strong expertise regarding the different aspects of forest management, as well as forest products management. Nevertheless, forestry in both countries is facing challenges, some of which are regional, but many of which are shared. Therefore, experts from both countries (Technical University of Munich Germany; Northwest A&F University Yangling, China; Forestry Academy of Shaanxi, China; Thünen Institut, Germany; FEDRC GIZ Forest Policy Facility (Forestry Economics Development and Research Center of the Deutsche Gesellschaft für Internationale Zusammenarbeit GmbH), Germany; and Center for Natural Forest Protection in Shaanxi, China) met to share their knowledge and deduce recommendations for future multifunctional forest management for the temperate zone. The workshop, held at the Northwest A&F University in September 2018, included presentations and intensive discussions, as well as a field tour. The results of the workshop that are summarized in this white paper are meant to provide an overview of the multi-faceted nature of the topic for interested scientists and forest practitioners, describe tools that can be used to analyze various aspects of multifunctionality and, in an exemplary fashion, highlight gathered experience from long- and short-term experiments. Included are social demands, economic goals, and scientific baselines. The topics reach from economic evaluations of forest ecosystem services over forest management practices, including afforestation, restoration, and preparations to face climate change, to wood/forest products utilization and participation of local people for poverty reduction. Overall, an optimistic picture emerges, showing that by using adapted forest management practices, which try to embrace the concept of multifunctionality, various use schemes and demands can be integrated at single sites, allowing us to achieve both environmental protection and productive forests, including societal demands, as well as aspects of tradition and national identity.
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22
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Plasmodesmata Conductivity Regulation: A Mechanistic Model. PLANTS 2019; 8:plants8120595. [PMID: 31842374 PMCID: PMC6963776 DOI: 10.3390/plants8120595] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/03/2019] [Accepted: 12/10/2019] [Indexed: 01/16/2023]
Abstract
Plant cells form a multicellular symplast via cytoplasmic bridges called plasmodesmata (Pd) and the endoplasmic reticulum (ER) that crosses almost all plant tissues. The Pd proteome is mainly represented by secreted Pd-associated proteins (PdAPs), the repertoire of which quickly adapts to environmental conditions and responds to biotic and abiotic stresses. Although the important role of Pd in stress-induced reactions is universally recognized, the mechanisms of Pd control are still not fully understood. The negative role of callose in Pd permeability has been convincingly confirmed experimentally, yet the roles of cytoskeletal elements and many PdAPs remain unclear. Here, we discuss the contribution of each protein component to Pd control. Based on known data, we offer mechanistic models of mature leaf Pd regulation in response to stressful effects.
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23
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Epron D, Dannoura M, Ishida A, Kosugi Y. Estimation of phloem carbon translocation belowground at stand level in a hinoki cypress stand. TREE PHYSIOLOGY 2019; 39:320-331. [PMID: 29474703 DOI: 10.1093/treephys/tpy016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/15/2018] [Accepted: 01/27/2018] [Indexed: 06/08/2023]
Abstract
At stand level, carbon translocation in tree stems has to match canopy photosynthesis and carbohydrate requirements to sustain growth and the physiological activities of belowground sinks. This study applied the Hagen-Poiseuille equation to the pressure-flow hypothesis to estimate phloem carbon translocation and evaluate what percentage of canopy photosynthate can be transported belowground in a hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.) stand. An anatomical study revealed that, in contrast to sieve cell density, conductive phloem thickness and sieve cell hydraulic diameter at 1.3 m in height increased with increasing tree diameter, as did the concentration of soluble sugars in the phloem sap. At tree level, hydraulic conductivity increased by two orders of magnitude from the smallest to the largest trees in the stand, resulting in a stand-level hydraulic conductance of 1.7 × 10-15 m Pa-1 s-1. The osmotic potential of the sap extracted from the inner bark was -0.75 MPa. Assuming that phloem water potential equalled foliage water potential at predawn, the turgor pressure in the phloem at 1.3 m in height was estimated at 0.22 MPa, 0.59 MPa lower than values estimated in the foliage. With this maximal turgor pressure gradient, which would be lower during day-time when foliage water potential drops, the estimated stand-level rate of carbon translocation was 2.0 gC m-2 day-1 (30% of daily gross canopy photosynthesis), at a time of the year when aboveground growth and related respiration is thought to consume a large fraction of photosynthate, at the expense of belowground activity. Despite relying on some assumptions and approximations, this approach, when coupled with measurements of canopy photosynthesis, may further be used to provide qualitative insight into the seasonal dynamics of belowground carbon allocation.
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Affiliation(s)
- Daniel Epron
- Université de Lorraine, INRA, UMR SILVA, Faculté des Sciences et Technologies, Vandœuvre-lès-Nancy, France
- Kyoto University, Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto, Japan
| | - Masako Dannoura
- Kyoto University, Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto, Japan
- Kyoto University, Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto, Japan
| | - Atsushi Ishida
- Kyoto University, Center for Ecological Research, Otsu, Shiga, Japan
| | - Yoshiko Kosugi
- Kyoto University, Laboratory of Forest Hydrology, Graduate School of Agriculture, Kyoto, Japan
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Salmon Y, Dietrich L, Sevanto S, Hölttä T, Dannoura M, Epron D. Drought impacts on tree phloem: from cell-level responses to ecological significance. TREE PHYSIOLOGY 2019; 39:173-191. [PMID: 30726983 DOI: 10.1093/treephys/tpy153] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 12/03/2018] [Accepted: 01/25/2019] [Indexed: 06/09/2023]
Abstract
On-going climate change is increasing the risk of drought stress across large areas worldwide. Such drought events decrease ecosystem productivity and have been increasingly linked to tree mortality. Understanding how trees respond to water shortage is key to predicting the future of ecosystem functions. Phloem is at the core of the tree functions, moving resources such as non-structural carbohydrates, nutrients, and defence and information molecules across the whole plant. Phloem function and ability to transport resources is tightly controlled by the balance of carbon and water fluxes within the tree. As such, drought is expected to impact phloem function by decreasing the amount of available water and new photoassimilates. Yet, the effect of drought on the phloem has received surprisingly little attention in the last decades. Here we review existing knowledge on drought impacts on phloem transport from loading and unloading processes at cellular level to possible effects on long-distance transport and consequences to ecosystems via ecophysiological feedbacks. We also point to new research frontiers that need to be explored to improve our understanding of phloem function under drought. In particular, we show how phloem transport is affected differently by increasing drought intensity, from no response to a slowdown, and explore how severe drought might actually disrupt the phloem transport enough to threaten tree survival. Because transport of resources affects other organisms interacting with the tree, we also review the ecological consequences of phloem response to drought and especially predatory, mutualistic and competitive relations. Finally, as phloem is the main path for carbon from sources to sink, we show how drought can affect biogeochemical cycles through changes in phloem transport. Overall, existing knowledge is consistent with the hypotheses that phloem response to drought matters for understanding tree and ecosystem function. However, future research on a large range of species and ecosystems is urgently needed to gain a comprehensive understanding of the question.
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Affiliation(s)
- Yann Salmon
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, Gustaf Hällströmin katu 2b, University of Helsinki, Helsinki, Finland
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, Latokartanonkaari 7, University of Helsinki, Helsinki, Finland
| | - Lars Dietrich
- Department of Environmental Sciences, University of Basel, Schönbeinstrasse 6, Basel, Switzerland
| | - Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, PO Box 1663 MA 495, Los Alamos, NM, USA
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, Latokartanonkaari 7, University of Helsinki, Helsinki, Finland
| | - Masako Dannoura
- Kyoto University, Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto, Japan
- Kyoto University, Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto, Japan
| | - Daniel Epron
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
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25
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Dobbelstein E, Fink D, Öner-Sieben S, Czempik L, Lohaus G. Seasonal changes of sucrose transporter expression and sugar partitioning in common European tree species. TREE PHYSIOLOGY 2019; 39:284-299. [PMID: 30388274 DOI: 10.1093/treephys/tpy120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 09/17/2018] [Accepted: 10/04/2018] [Indexed: 05/13/2023]
Abstract
In temperate woody species, carbon transport from source to sink tissues is a striking physiological process, particularly considering seasonal changes. The functions of different tissues can also alternate across the seasons. In this regard, phloem loading and sugar distribution are important aspects of carbon partitioning, and sucrose uptake transporters (SUTs) play a key role in these processes. Therefore, the influence of seasons and different light-dark conditions on the expression of SUTs from 3-year-old Fagus sylvatica L., Quercus robur L. and Picea abies (L.) Karst. trees were analyzed. In addition, tissue-specific sugar and starch contents under these different environmental conditions were determined. Putative SUTs were identified in the gymnosperms (Picea abies, Ginkgo biloba L.), here for the first time, and also in the angiosperms (Q. robur, F. sylvatica). The identified SUT sequences of the different tree species cluster into three types, similar to other SUTs from herbaceous and tree species. Furthermore, the sequences from angiosperm and those from gymnosperm species form distinct clusters within the three types of SUTs. In F. sylvatica, Q. robur and P. abies, the expression levels of the different SUTs during seasons showed marked variations. Because of the high expression levels of type I SUTs in bark, wood and leaves during active growing phases in spring and summer, it can be assumed that they are involved in phloem loading, sucrose retrieval and possibly in further physiological processes. The expression patterns also indicate a flexible expression in all tissues depending on physiological requirements and environmental conditions. Compared with type I SUTs, the seasonal variations of type II SUT expression were less pronounced, whereas the seasonal variations of the type III SUT expression patterns were partly reverse. In addition to the seasonal regulation, the expressions of the different SUTs were also regulated by light in a diurnal manner.
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Affiliation(s)
- Elena Dobbelstein
- Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Gaußstr. 20, Wuppertal, Germany
| | - Daniel Fink
- Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Gaußstr. 20, Wuppertal, Germany
| | - Soner Öner-Sieben
- Clinic for General Pediatrics, Neonatology and Paediatric Cardiology, University Clinic Düsseldorf, Moorenstr. 5, Düsseldorf, Germany
| | - Laura Czempik
- Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Gaußstr. 20, Wuppertal, Germany
| | - Gertrud Lohaus
- Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Gaußstr. 20, Wuppertal, Germany
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26
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Epron D, Dannoura M, Hölttä T. Introduction to the invited issue on phloem function and dysfunction. TREE PHYSIOLOGY 2019; 39:167-172. [PMID: 30785633 DOI: 10.1093/treephys/tpz007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/08/2019] [Accepted: 01/15/2019] [Indexed: 06/09/2023]
Affiliation(s)
- Daniel Epron
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Masako Dannoura
- Kyoto University, Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto, Japan
- Kyoto University, Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto, Japan
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, Latokartanonkaari 7, University of Helsinki, Helsinki, Finland
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27
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Losada JM, Holbrook NM. Scaling of phloem hydraulic resistance in stems and leaves of the understory angiosperm shrub Illicium parviflorum. AMERICAN JOURNAL OF BOTANY 2019; 106:244-259. [PMID: 30793276 DOI: 10.1002/ajb2.1241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 12/05/2018] [Indexed: 06/09/2023]
Abstract
PREMISE OF THE STUDY Recent studies in canopy-dominant trees revealed axial scaling of phloem structure. However, whether this pattern is found in woody plants of the understory, the environment of most angiosperms from the ANA grade (Amborellales-Nymphaeales-Austrobaileyales), is unknown. METHODS We used seedlings and adult plants of the understory tropical shrub Illicium parviflorum, a member of the lineage Austrobaileyales, to explore the anatomy and physiology of the phloem in their aerial parts, including changes through ontogeny. KEY RESULTS Adult plants maintain a similar proportion of phloem tissue across stem diameters, but larger conduit dimensions and number cause the hydraulic resistance of the phloem to decrease toward the base of the plant. Small sieve plate pores resulted in an overall higher sieve tube hydraulic resistance than has been reported in other woody angiosperms. Sieve elements increase in size from minor to major leaf veins, but were shorter and narrower in petioles. The low carbon assimilation rates of seedlings and mature plants contrasted with a 3-fold higher phloem sap velocity in seedlings, suggesting that phloem transport velocity is modulated through ontogeny. CONCLUSIONS The overall architecture of the phloem tissue in this understory angiosperm shrub scales in a manner consistent with taller trees that make up the forest canopy. Thus, the evolution of larger sieve plate pores in canopy-dominant trees may have played a key role in allowing woody angiosperms to extend beyond their understory origins.
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Affiliation(s)
- Juan M Losada
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138, USA
- Arnold Arboretum of Harvard University, 1300 Centre St., Boston, MA, 02130, USA
| | - N Michele Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138, USA
- Arnold Arboretum of Harvard University, 1300 Centre St., Boston, MA, 02130, USA
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28
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Fink D, Dobbelstein E, Barbian A, Lohaus G. Ratio of sugar concentrations in the phloem sap and the cytosol of mesophyll cells in different tree species as an indicator of the phloem loading mechanism. PLANTA 2018; 248:661-673. [PMID: 29882156 DOI: 10.1007/s00425-018-2933-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/01/2018] [Indexed: 05/28/2023]
Abstract
Sucrose concentration in phloem sap was several times higher than in the cytosol of mesophyll cells. The results suggest that phloem loading involves active steps in the analyzed tree species. Phloem loading in source leaves is a key step for carbon partitioning and passive symplastic loading has been proposed for several tree species. However, experimental evidence to prove the potential for sucrose diffusion from mesophyll to phloem is rare. Here, we analyzed three tree species (two angiosperms, Fagus sylvatica, Magnolia kobus, and one gymnosperm, Gnetum gnemon) to investigate the proposed phloem loading mechanism. For this purpose, the minor vein structure and the sugar concentrations in phloem sap as well as in the subcellular compartments of mesophyll cells were investigated. The analyzed tree species belong to the open type minor vein subcategory. The sucrose concentration in the cytosol of mesophyll cells ranged between 75 and 165 mM and was almost equal to the vacuolar concentration. Phloem sap could be collected from F. sylvatica and M. kobus and the concentration of sucrose in phloem sap was about five- and 11-fold higher, respectively, than in the cytosol of mesophyll cells. Sugar exudation of cut leaves was decreased by p-chloromercuribenzenesulfonic acid, an inhibitor of sucrose-proton transporter. The results suggest that phloem loading of sucrose in the analyzed tree species involves active steps, and apoplastic phloem loading seems more likely.
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Affiliation(s)
- Daniel Fink
- Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Wuppertal, Germany
| | - Elena Dobbelstein
- Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Wuppertal, Germany
| | - Andreas Barbian
- Core Facility Electron Microscopy, UKD, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Gertrud Lohaus
- Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Wuppertal, Germany.
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29
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Ainsworth EA, Lemonnier P. Phloem function: a key to understanding and manipulating plant responses to rising atmospheric [CO 2]? CURRENT OPINION IN PLANT BIOLOGY 2018; 43:50-56. [PMID: 29329037 DOI: 10.1016/j.pbi.2017.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 12/01/2017] [Accepted: 12/10/2017] [Indexed: 06/07/2023]
Abstract
Increasing atmospheric carbon dioxide concentration ([CO2]) directly stimulates photosynthesis and reduces stomatal conductance in C3 plants. Both of these physiological effects have the potential to alter phloem function at elevated [CO2]. Recent research has clearly established that photosynthetic capacity is correlated to vascular traits associated with phloem loading and water transport, but the effects of elevated [CO2] on these relationships are largely unexplored. Plants also employ different strategies for loading sucrose and other sugars into the phloem, and there is potential for species with different phloem loading strategies to respond differently to elevated [CO2]. Recent research manipulating sucrose transporters and other key enzymes with roles in phloem loading show promise for maximizing crop performance in an elevated [CO2] world.
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Affiliation(s)
- Elizabeth A Ainsworth
- USDA ARS Global Change and Photosynthesis Research Unit, 1201 W. Gregory Drive, Urbana, IL 61801, USA; Department of Plant Biology and Institute for Genomic Biology, University of Illinois at Urbana, Champaign, USA.
| | - Pauline Lemonnier
- USDA ARS Global Change and Photosynthesis Research Unit, 1201 W. Gregory Drive, Urbana, IL 61801, USA; Department of Plant Biology and Institute for Genomic Biology, University of Illinois at Urbana, Champaign, USA
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30
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Rockwell FE, Gersony JT, Holbrook NM. Where does Münch flow begin? Sucrose transport in the pre-phloem path. CURRENT OPINION IN PLANT BIOLOGY 2018; 43:101-107. [PMID: 29704829 DOI: 10.1016/j.pbi.2018.04.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 03/30/2018] [Accepted: 04/09/2018] [Indexed: 06/08/2023]
Abstract
Current conceptions of sucrose export largely neglect the effect of transpiration-induced water potential gradients within leaf mesophyll, even as the mix of convection and diffusion in the pre-phloem path remains uncertain. It is also generally held that the relative importance of convection and diffusion in the pre-phloem path is controlled by the ratio of their respective mass transfer coefficients. Here, we consider pre-phloem sucrose transport in the presence of adverse water potential gradients, finding that whether convection impedes or aids sucrose delivery to the phloem is independent of the permeability of the plasmodesmata to bulk flow, and depends only on assimilation rate, path-length, and the diffusivity. For most tissues subject to transpiration, convection through plasmodesmata pushes sugar away from the phloem.
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Affiliation(s)
- Fulton E Rockwell
- Harvard University, Department of Organismic and Evolutionary Biology, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Jessica T Gersony
- Harvard University, Department of Organismic and Evolutionary Biology, 26 Oxford Street, Cambridge, MA 02138, USA
| | - N Michele Holbrook
- Harvard University, Department of Organismic and Evolutionary Biology, 26 Oxford Street, Cambridge, MA 02138, USA.
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31
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Carvalho MR, Losada JM, Niklas KJ. Phloem networks in leaves. CURRENT OPINION IN PLANT BIOLOGY 2018; 43:29-35. [PMID: 29306742 DOI: 10.1016/j.pbi.2017.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 12/04/2017] [Accepted: 12/16/2017] [Indexed: 06/07/2023]
Abstract
The survival of all vascular plants depends on phloem and xylem, which comprise a hydraulically coupled tissue system that transports photosynthates, water, and a variety of other molecules and ions. Although xylem hydraulics has been extensively studied, until recently, comparatively little is known quantitatively about the phloem hydraulic network and how it is functionally coupled to the xylem network, particularly in photosynthetic leaves. Here, we summarize recent advances in quantifying phloem hydraulics in fully expanded mature leaves with different vascular architectures and show that (1) the size of phloem conducting cells across phylogenetically different taxa scales isometrically with respect to xylem conducting cell size, (2) cell transport areas and lengths increase along phloem transport pathways in a manner that can be used to model Münch's pressure-flow hypothesis, and (3) report observations that invalidate da Vinci's and Murray's hydraulic models as plausible constructs for understanding photosynthate transport in the leaf lamina.
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Affiliation(s)
- Mónica R Carvalho
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA; Smithsonian Tropical Research Institute, Box 0843-03092, Balboa, Ancón, Panama
| | - Juan M Losada
- Arnold Arboretum, Harvard University, 1300 Centre St., Boston, MA 02131, USA
| | - Karl J Niklas
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA.
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32
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Babst BA, Coleman GD. Seasonal nitrogen cycling in temperate trees: Transport and regulatory mechanisms are key missing links. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 270:268-277. [PMID: 29576080 DOI: 10.1016/j.plantsci.2018.02.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 02/22/2018] [Indexed: 05/08/2023]
Abstract
Nutrient accumulation, one of the major ecosystem services provided by forests, is largely due to the accumulation and retention of nutrients in trees. This review focuses on seasonal cycling of nitrogen (N), often the most limiting nutrient in terrestrial ecosystems. When leaves are shed during autumn, much of the N may be resorbed and stored in the stem over winter, and then used for new stem and leaf growth in spring. A framework exists for understanding the metabolism and transport of N in leaves and stems during winter dormancy, but many of the underlying genes remain to be identified and/or verified. Transport of N during seasonal N cycling is a particularly weak link, since the physical pathways for loading and unloading of amino N to and from the phloem are poorly understood. Short-day photoperiod followed by decreasing temperatures are the environmental cues that stimulate dormancy induction, and nutrient remobilization and storage. However, beyond the involvement of phytochrome, very little is known about the signal transduction mechanisms that link environmental cues to nutrient remobilization and storage. We propose a model whereby nutrient transport and sensing plays a major role in source-sink transitions of leaves and stems during seasonal N cycling.
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Affiliation(s)
- Benjamin A Babst
- Arkansas Forest Resources Center, Division of Agriculture, University of Arkansas System, Monticello, AR 71656, USA; School of Forestry and Natural Resources, University of Arkansas at Monticello, Monticello, AR 71656, USA.
| | - Gary D Coleman
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, USA.
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33
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Abstract
The phloem plays a central role in transporting resources and signalling molecules from fully expanded leaves to provide precursors for, and to direct development of, heterotrophic organs located throughout the plant body. We review recent advances in understanding mechanisms regulating loading and unloading of resources into, and from, the phloem network; highlight unresolved questions regarding the physiological significance of the vast array of proteins and RNAs found in phloem saps; and evaluate proposed structure/function relationships considered to account for bulk flow of sap, sustained at high rates and over long distances, through the transport phloem.
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Affiliation(s)
- Johannes Liesche
- Biomass Energy Center for Arid and Semi-arid lands, Northwest A&F University, Yangling, China
- College of Life Science, Northwest A&F University, Yangling , China
| | - John Patrick
- Department of Biological Sciences, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, Australia
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Julius BT, Leach KA, Tran TM, Mertz RA, Braun DM. Sugar Transporters in Plants: New Insights and Discoveries. PLANT & CELL PHYSIOLOGY 2017; 58:1442-1460. [PMID: 28922744 DOI: 10.1093/pcp/pcx090] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 06/19/2017] [Indexed: 05/24/2023]
Abstract
Carbohydrate partitioning is the process of carbon assimilation and distribution from source tissues, such as leaves, to sink tissues, such as stems, roots and seeds. Sucrose, the primary carbohydrate transported long distance in many plant species, is loaded into the phloem and unloaded into distal sink tissues. However, many factors, both genetic and environmental, influence sucrose metabolism and transport. Therefore, understanding the function and regulation of sugar transporters and sucrose metabolic enzymes is key to improving agriculture. In this review, we highlight recent findings that (i) address the path of phloem loading of sucrose in rice and maize leaves; (ii) discuss the phloem unloading pathways in stems and roots and the sugar transporters putatively involved; (iii) describe how heat and drought stress impact carbohydrate partitioning and phloem transport; (iv) shed light on how plant pathogens hijack sugar transporters to obtain carbohydrates for pathogen survival, and how the plant employs sugar transporters to defend against pathogens; and (v) discuss novel roles for sugar transporters in plant biology. These exciting discoveries and insights provide valuable knowledge that will ultimately help mitigate the impending societal challenges due to global climate change and a growing population by improving crop yield and enhancing renewable energy production.
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Affiliation(s)
- Benjamin T Julius
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 116 Tucker Hall, Columbia, MO 65211, USA
| | - Kristen A Leach
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 116 Tucker Hall, Columbia, MO 65211, USA
| | - Thu M Tran
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 116 Tucker Hall, Columbia, MO 65211, USA
- Plant Imaging Consortium, USA
| | - Rachel A Mertz
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 116 Tucker Hall, Columbia, MO 65211, USA
| | - David M Braun
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 116 Tucker Hall, Columbia, MO 65211, USA
- Plant Imaging Consortium, USA
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35
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Lucas WJ, Liu CM. The plant vascular system I: From resource allocation, inter-organ communication and defense, to evolution of the monocot cambium. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2017; 59:290-291. [PMID: 28328106 DOI: 10.1111/jipb.12541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Affiliation(s)
- William J Lucas
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Chun-Ming Liu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R. China
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