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Xu J, Zhao X, Zhong Y, Qu T, Sun B, Zhang H, Hou C, Zhang Z, Tang X, Wang Y. Acclimation of intertidal macroalgae Ulva prolifera to UVB radiation: the important role of alternative oxidase. BMC PLANT BIOLOGY 2024; 24:143. [PMID: 38413873 PMCID: PMC10900725 DOI: 10.1186/s12870-024-04762-w] [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: 04/11/2023] [Accepted: 01/23/2024] [Indexed: 02/29/2024]
Abstract
BACKGROUND Solar radiation is primarily composed of ultraviolet radiation (UVR, 200 - 400 nm) and photosynthetically active radiation (PAR, 400 - 700 nm). Ultraviolet-B (UVB) radiation accounts for only a small proportion of sunlight, and it is the primary cause of plant photodamage. The use of chlorofluorocarbons (CFCs) as refrigerants caused serious ozone depletion in the 1980s, and this had led to an increase in UVB. Although CFC emissions have significantly decreased in recent years, UVB radiation still remains at a high intensity. UVB radiation increase is an important factor that influences plant physiological processes. Ulva prolifera, a type of macroalga found in the intertidal zone, is intermittently exposed to UVB. Alternative oxidase (AOX) plays an important role in plants under stresses. This research examines the changes in AOX activity and the relationships among AOX, photosynthesis, and reactive oxygen species (ROS) homeostasis in U. prolifera under changes in UVB and photosynthetically active radiation (PAR). RESULTS UVB was the main component of solar radiation impacting the typical intertidal green macroalgae U. prolifera. AOX was found to be important during the process of photosynthesis optimization of U. prolifera due to a synergistic effect with non-photochemical quenching (NPQ) under UVB radiation. AOX and glycolate oxidase (GO) worked together to achieve NADPH homeostasis to achieve photosynthesis optimization under changes in PAR + UVB. The synergism of AOX with superoxide dismutase (SOD) and catalase (CAT) was important during the process of ROS homeostasis under PAR + UVB. CONCLUSIONS AOX plays an important role in the process of photosynthesis optimization and ROS homeostasis in U. prolifera under UVB radiation. This study provides further insights into the response of intertidal macroalgae to solar light changes.
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Grants
- No. LSKJ202203605 Laoshan Laboratory
- Nos. 41906120, 42176204, 41976132, and 41706121 National Natural Science Foundation of China
- Nos. 41906120, 42176204, 41976132, and 41706121 National Natural Science Foundation of China
- Nos. 41906120, 42176204, 41976132, and 41706121 National Natural Science Foundation of China
- Nos. 41906120, 42176204, 41976132, and 41706121 National Natural Science Foundation of China
- Nos. U1806213 and U1606404 NSFC-Shandong Joint Fund
- Nos. U1806213 and U1606404 NSFC-Shandong Joint Fund
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Affiliation(s)
- Jinhui Xu
- College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, China
| | - Xinyu Zhao
- Laoshan Laboratory, 1 Wenhai Road, Qingdao, 266237, China.
| | - Yi Zhong
- College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, China
| | - Tongfei Qu
- College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, China
| | - Baixue Sun
- College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, China
| | - Huanxin Zhang
- College of Geography and Environment, Shandong Normal University, 1 Daxue Road, Jinan, 250000, China
| | - Chengzong Hou
- College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, China
| | - Zhipeng Zhang
- Tianjin Research Institute for Water Transport Engineering, Ministry of Transport, Tianjin, 300456, China
| | - Xuexi Tang
- College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, China
- Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, 1 Wenhai Road, Qingdao, 266237, China
| | - Ying Wang
- College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, China.
- Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, 1 Wenhai Road, Qingdao, 266237, China.
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Liu Y, Zhang L, Meng S, Zhang H, Wang S, Xu C, Liu Y, Xu T, He Y, Cui Y, Tan C, Li T, Qi M. Galactinol Regulates JA Biosynthesis to Enhance Tomato Cold Tolerance. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:2547-2559. [PMID: 38286812 DOI: 10.1021/acs.jafc.3c08710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
Low temperatures can inhibit plant growth and development and reduce fruit yield. This study demonstrated that the expression of AnGolS1 from Ammopiptanthus nanus (A. nanus) encoding a galactinol synthase enhanced tomato cold tolerance. In AnGolS1-overexpressing plants, the jasmonic acid (JA) biosynthesis substrates 13-hydroperoxylinolenicacid and 12,13-epoxylinolenicacid were significantly accumulated, and the expression levels of the ethylene response factor (SlERF4-7) and serine protease inhibitor (SlSPI5) were increased. We speculated that there may be correlations among galactinol, ethylene signaling, the protease inhibitor, protease, and JA levels. The expression levels of SlERF4-7 and SlSPI5 as well as the JA content were significantly increased under exogenous galactinol treatment. Additionally, the expression of SlSPI5 was reduced in SlERF4-7-silenced plants, and SlERF4-7 was confirmed to bind to the dehydration-responsive element (DRE) of the SlSPI5 promoter. These results suggest that SlSPI5 is a target gene of the SlERF4-7 transcription factor. In addition, SlSPI5 interacted with cysteine protease (SlCPase), while SlCPase interacted with lipoxygenase (SlLOX5) and allene oxide synthase (SlAOS2). When SlCPase was silenced, JA levels increased and plant cold tolerance was enhanced. Therefore, galactinol regulates JA biosynthesis to enhance tomato cold tolerance through the SlERF4-7-SlSPI5-SlCPase-SlLOX5/SlAOS2 model. Overall, our study provides new perspectives on the role of galactinol in the JA regulatory network in plant adaptation to low-temperature stress.
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Affiliation(s)
- YuDong Liu
- College of Agriculture, Shihezi University, Shihezi 832003, China
- Key Laboratory of Special Fruits and Vegetables Cultivation Physiology and Germplasm Resources Utilization Xinjiang of Production and Construction Crops, Shihezi University, Shihezi 832003, China
| | - Li Zhang
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang 110161, China
- Key Laboratory of Agricultural Biotechnology of Liaoning Province, Shenyang Agricultural University, Shenyang 110161, China
| | - SiDa Meng
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Key Laboratory of Protected Horticulture, Ministry of Education, Key Laboratory of Horticultural Equipment, Ministry of Agriculture and Rural Affairs, Shenyang Agricultural University, Shenyang 110161, China
| | - HuiDong Zhang
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Key Laboratory of Protected Horticulture, Ministry of Education, Key Laboratory of Horticultural Equipment, Ministry of Agriculture and Rural Affairs, Shenyang Agricultural University, Shenyang 110161, China
| | - Shuo Wang
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Key Laboratory of Protected Horticulture, Ministry of Education, Key Laboratory of Horticultural Equipment, Ministry of Agriculture and Rural Affairs, Shenyang Agricultural University, Shenyang 110161, China
| | - ChuanQiang Xu
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Key Laboratory of Protected Horticulture, Ministry of Education, Key Laboratory of Horticultural Equipment, Ministry of Agriculture and Rural Affairs, Shenyang Agricultural University, Shenyang 110161, China
| | - YuFeng Liu
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Key Laboratory of Protected Horticulture, Ministry of Education, Key Laboratory of Horticultural Equipment, Ministry of Agriculture and Rural Affairs, Shenyang Agricultural University, Shenyang 110161, China
| | - Tao Xu
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Key Laboratory of Protected Horticulture, Ministry of Education, Key Laboratory of Horticultural Equipment, Ministry of Agriculture and Rural Affairs, Shenyang Agricultural University, Shenyang 110161, China
| | - Yi He
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Shenyang Agricultural University, Shenyang 110161, China
| | - YiQing Cui
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Shenyang Agricultural University, Shenyang 110161, China
| | - ChangHua Tan
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Shenyang Agricultural University, Shenyang 110161, China
| | - TianLai Li
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Key Laboratory of Protected Horticulture, Ministry of Education, Key Laboratory of Horticultural Equipment, Ministry of Agriculture and Rural Affairs, Shenyang Agricultural University, Shenyang 110161, China
| | - MingFang Qi
- College of Horticulture, Shenyang Agricultural University, Shenyang 110161, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), Key Laboratory of Protected Horticulture, Ministry of Education, Key Laboratory of Horticultural Equipment, Ministry of Agriculture and Rural Affairs, Shenyang Agricultural University, Shenyang 110161, China
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Garmash EV. Suppression of mitochondrial alternative oxidase can result in upregulation of the ROS scavenging network: some possible mechanisms underlying the compensation effect. PLANT BIOLOGY (STUTTGART, GERMANY) 2023; 25:43-53. [PMID: 36245276 DOI: 10.1111/plb.13477] [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: 08/05/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Mitochondrial alternative oxidase is an important protein involved in maintaining cellular metabolic and energy balance, especially under stress conditions. AOX genes knockout is aimed at revealing the functions of AOX genes. Under unfavourable conditions, AOX-suppressed plants (mainly based on Arabidopsis AOX1a-knockout lines) usually experience strong oxidative stress. However, a compensation effect, which consists of the absence of AOX1a leading to an increase in defence response mechanisms, concomitant with a decrease in ROS content, has also been demonstrated. This review briefly describes the possible mechanisms underlying the compensation effect upon the suppression of AOX1a. Information about mitochondrial retrograde regulation of AOX is given. The importance of ROS and mitochondrial membrane potential in triggering the signal transmission from mitochondria in the absence of AOX or disturbance of mitochondrial electron transport chain functions is indicated. The few available data on the response of the cell to the absence of AOX at the level of changes in the hormonal balance and the reactions of chloroplasts are presented. The decrease in the relative amount of reduced ascorbate at stable ROS levels as a result of compensation in AOX1a-suppressed plants is proposed as a sign of stress development. Obtaining direct evidence on the mechanisms and signalling pathways involved in AOX modulation in the genome should facilitate a deeper understanding of the role of AOX in the integration of cellular signalling pathways.
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Affiliation(s)
- E V Garmash
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
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Chadee A, Mohammad M, Vanlerberghe GC. Evidence that mitochondrial alternative oxidase respiration supports carbon balance in source leaves of Nicotiana tabacum. JOURNAL OF PLANT PHYSIOLOGY 2022; 279:153840. [PMID: 36265227 DOI: 10.1016/j.jplph.2022.153840] [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: 08/15/2022] [Revised: 10/07/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Alternative oxidase (AOX) represents a non-energy conserving pathway within the mitochondrial electron transport chain. One potential physiological role of AOX could be to manage leaf carbohydrate amounts by supporting respiratory carbon oxidation reactions. In this study, several approaches tested the hypothesis that AOX1a gene expression in Nicotiana tabacum leaf is enhanced in conditions expected to promote an increased leaf carbohydrate status. These approaches included supplying leaves with exogenous carbohydrates, comparing plants grown at different atmospheric CO2 concentrations, comparing sink leaves with source leaves, comparing plants with different ratios of source to sink activity, and examining gene expression over the diel cycle. In each case, the pattern of AOX1a gene expression was compared with that of other genes known to respond to carbohydrates and/or other factors related to source:sink activity. These included GPT1 and GPT3 (that encode chloroplast glucose 6-phosphate/phosphate translocators), SPS (that encodes sucrose phosphate synthase), SUT1 (that encodes a sucrose/H+ symporter involved in phloem loading) and UCP1 (that encodes a mitochondrial uncoupling protein). The AOX1a transcript amount was higher following the leaf sink-to-source transition, and in plants with higher source relative to sink activity due to increasing plant age. Further, these effects were amplified in plants grown at elevated CO2 to stimulate source activity, particularly at end-of-day time periods. The AOX1a transcript amount was also higher following treatment of leaves with carbohydrate, in particular sucrose. Overall, the results provide evidence that, while source leaf sucrose accumulation may signal for a down-regulation of sucrose synthesis and transport, it also signals for means to manage the excess cytosolic carbohydrate pools. This includes increased AOX respiration to support carbon oxidation pathways even if energy charge is high, in combination perhaps with some return flux of carbohydrate from cytosol to stroma through the GPT3 translocator. As discussed, these activities could contribute to maintaining plant source:sink balance, as well as photosynthetic and phloem loading capacity.
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Affiliation(s)
- Avesh Chadee
- Department of Biological Sciences, And Department of Cell and Systems Biology, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C1A4, Canada
| | - Masoom Mohammad
- Department of Biological Sciences, And Department of Cell and Systems Biology, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C1A4, Canada
| | - Greg C Vanlerberghe
- Department of Biological Sciences, And Department of Cell and Systems Biology, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C1A4, Canada.
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Sweetman C, Waterman CD, Wong DC, Day DA, Jenkins CL, Soole KL. Altering the balance between AOX1A and NDB2 expression affects a common set of transcripts in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2022; 13:876843. [PMID: 36466234 PMCID: PMC9716356 DOI: 10.3389/fpls.2022.876843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 10/24/2022] [Indexed: 06/17/2023]
Abstract
Stress-responsive components of the mitochondrial alternative electron transport pathway have the capacity to improve tolerance of plants to abiotic stress, particularly the alternative oxidase AOX1A but also external NAD(P)H dehydrogenases such as NDB2, in Arabidopsis. NDB2 and AOX1A can cooperate to entirely circumvent the classical electron transport chain in Arabidopsis mitochondria. Overexpression of AOX1A or NDB2 alone can have slightly negative impacts on plant growth under optimal conditions, while simultaneous overexpression of NDB2 and AOX1A can reverse these phenotypic effects. We have taken a global transcriptomic approach to better understand the molecular shifts that occur due to overexpression of AOX1A alone and with concomitant overexpression of NDB2. Of the transcripts that were significantly up- or down- regulated in the AOX1A overexpression line compared to wild type (410 and 408, respectively), the majority (372 and 337, respectively) reverted to wild type levels in the dual overexpression line. Several mechanisms for the AOX1A overexpression phenotype are proposed based on the functional classification of these 709 genes, which can be used to guide future experiments. Only 28 genes were uniquely up- or down-regulated when NDB2 was overexpressed in the AOX1A overexpression line. On the other hand, many unique genes were deregulated in the NDB2 knockout line. Furthermore, several changes in transcript abundance seen in the NDB2 knockout line were consistent with changes in the AOX1A overexpression line. The results suggest that an imbalance in AOX1A:NDB2 protein levels caused by under- or over-expression of either component, triggers a common set of transcriptional responses that may be important in mitochondrial redox regulation. The most significant changes were transcripts associated with photosynthesis, secondary metabolism and oxidative stress responses.
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Affiliation(s)
- Crystal Sweetman
- College of Science & Engineering, Flinders University, Bedford Park, SA, Australia
| | | | - Darren C.J. Wong
- College of Science, Australian National University, Canberra, ACT, Australia
| | - David A. Day
- College of Science & Engineering, Flinders University, Bedford Park, SA, Australia
| | - Colin L.D. Jenkins
- College of Science & Engineering, Flinders University, Bedford Park, SA, Australia
| | - Kathleen L. Soole
- College of Science & Engineering, Flinders University, Bedford Park, SA, Australia
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Zafari S, Vanlerberghe GC, Igamberdiev AU. The Role of Alternative Oxidase in the Interplay between Nitric Oxide, Reactive Oxygen Species, and Ethylene in Tobacco ( Nicotiana tabacum L.) Plants Incubated under Normoxic and Hypoxic Conditions. Int J Mol Sci 2022; 23:7153. [PMID: 35806157 PMCID: PMC9266549 DOI: 10.3390/ijms23137153] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 06/24/2022] [Indexed: 02/05/2023] Open
Abstract
The transgenic tobacco (Nicotiana tabacum L.) plants with the modified levels of alternative oxidase (AOX) were used to evaluate the physiological roles of AOX in regulating nitro-oxidative stress and metabolic changes after exposing plants to hypoxia for 6 h. Under normoxia, AOX expression resulted in the decrease of nitric oxide (NO) levels and of the rate of protein S-nitrosylation, while under hypoxia, AOX overexpressors exhibited higher NO and S-nitrosylation levels than knockdowns. AOX expression was essential in avoiding hypoxia-induced superoxide and H2O2 levels, and this was achieved via higher activities of catalase and glutathione reductase and the reduced expression of respiratory burst oxidase homolog (Rboh) in overexpressors as compared to knockdowns. The AOX overexpressing lines accumulated less pyruvate and exhibited the increased transcript and activity levels of pyruvate decarboxylase and alcohol dehydrogenase under hypoxia. This suggests that AOX contributes to the energy state of hypoxic tissues by stimulating the increase of pyruvate flow into fermentation pathways. Ethylene biosynthesis genes encoding 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, ACC oxidase, and ethylene-responsive factors (ERFs) were induced during hypoxia and correlated with AOX and NO levels. We conclude that AOX controls the interaction of NO, reactive oxygen species, and ethylene, triggering a coordinated downstream defensive response against hypoxia.
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Affiliation(s)
- Somaieh Zafari
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Greg C. Vanlerberghe
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada;
- Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
| | - Abir U. Igamberdiev
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
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Inoue T, Akaji Y, Noguchi K. Distinct responses of growth and respiration to growth temperatures in two mangrove species. ANNALS OF BOTANY 2022; 129:15-28. [PMID: 34508635 PMCID: PMC8752395 DOI: 10.1093/aob/mcab117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/09/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND AND AIMS Mangrove plants are mostly found in tropical and sub-tropical tidal flats, and their limited distribution may be related to their responses to growth temperatures. However, the mechanisms underlying these responses have not been clarified. Here, we measured the dependencies of the growth parameters and respiration rates of leaves and roots on growth temperatures in typical mangrove species. METHODS We grew two typical species of Indo-Pacific mangroves, Bruguiera gymnorrhiza and Rhizophora stylosa, at four different temperatures (15, 20, 25 and 30 °C) by irrigating with fresh water containing nutrients, and we measured growth parameters, chemical composition, and leaf and root O2 respiration rates. We then estimated the construction costs of leaves and roots and the respiration rates required for maintenance and growth. KEY RESULTS The relative growth rates of both species increased with growth temperature due to changes in physiological parameters such as net assimilation rate and respiration rate rather than to changes in structural parameters such as leaf area ratio. Both species required a threshold temperature for growth (12.2 °C in B. gymnorrhiza and 18.1 °C in R. stylosa). At the low growth temperature, root nitrogen uptake rate was lower in R. stylosa than in B. gymnorrhiza, leading to a slower growth rate in R. stylosa. This indicates that R. stylosa is more sensitive than B. gymnorrhiza to low temperature. CONCLUSIONS Our results suggest that the mangrove species require a certain warm temperature to ensure respiration rates sufficient for maintenance and growth, particularly in roots. The underground temperature probably limits their growth under the low-temperature condition. The lower sensitivity of B. gymnorrhiza to low temperature shows its potential to adapt to a wider habitat temperature range than R. stylosa. These growth and respiratory features may explain the distribution patterns of the two mangrove species.
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Affiliation(s)
| | - Yasuaki Akaji
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, Japan
| | - Ko Noguchi
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi Hachioji, Tokyo, Japan
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Qiao X, Ruan M, Yu T, Cui C, Chen C, Zhu Y, Li F, Wang S, Na X, Wang X, Bi Y. UCP1 and AOX1a contribute to regulation of carbon and nitrogen metabolism and yield in Arabidopsis under low nitrogen stress. Cell Mol Life Sci 2022; 79:69. [PMID: 34974624 PMCID: PMC11072780 DOI: 10.1007/s00018-021-04036-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 11/08/2021] [Accepted: 11/11/2021] [Indexed: 12/19/2022]
Abstract
Nitrogen (N) availability is a critical factor for plant development and crop yield, and it closely correlates to carbon (C) metabolism. Uncoupling protein (UCP) and alternative oxidase (AOX) exhibit a strong correlation with N and C metabolism. Here, we investigated the functions of UCP1 and AOX1a using their mutants and complementation lines in Arabidopsis adaptation to low N. Low N markedly increased AOX1a and UCP1 expression, alternative pathway capacity and UCP activity. Eight-day-old aox1a/ucp1 seedlings were more sensitive to low N than Col-0 and single mutants, exhibiting lower primary root length and higher anthocyanin accumulation. The net photosynthetic rate, electron transport rate, PSII actual photochemical efficiency, stomatal conductance and carboxylation efficiency were markedly decreased in ucp1 and aox1a/ucp1 compared to those in Col-0 and aox1a under low N stress; comparatively, chlorophyll content and non-photochemical quenching coefficient were the lowest and highest in aox1a/ucp1, respectively. Nitrate acquisition rate was accelerated in aox1a/ucp1, but its transport activity was decreased, which resulted in low nitrate content and nitrate reductase activity under low N condition. The C/N ratio in seeds, but not in leaves, is higher in aox1a/ucp1 than that in Col-0, aox1a and ucp1 under low N condition. RNA-seq analysis revealed that many genes involved in photosynthesis and C/N metabolism were markedly down-regulated in aox1a/ucp1 under low N stress. These results highlight the key roles of UCP1 and AOX1a in modulating photosynthetic capacity, C/N assimilation and distribution under low N stress.
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Affiliation(s)
- Xinyan Qiao
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China
| | - Mengjiao Ruan
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China
| | - Tao Yu
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China
| | - Chaiyan Cui
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China
| | - Cuiyun Chen
- Shapotou Desert Research and Experiment Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, Gansu, People's Republic of China
| | - Yuanzhi Zhu
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China
| | - Fanglin Li
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China
| | - Shengwang Wang
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China
| | - Xiaofan Na
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China
| | - Xiaomin Wang
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China.
| | - Yurong Bi
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, People's Republic of China.
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Inoue T, Yamada Y, Noguchi K. Growth temperature affects O 2 consumption rates and plasticity of respiratory flux to support shoot growth at various growth temperatures. PLANT, CELL & ENVIRONMENT 2022; 45:133-146. [PMID: 34719799 DOI: 10.1111/pce.14217] [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: 06/30/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 06/13/2023]
Abstract
The temperature dependence of respiration rates and their acclimation to growth temperature vary among species/ecotypes, but the details remain unclear. Here, we compared the temperature dependence of shoot O2 consumption rates among Arabidopsis thaliana ecotypes to clarify how the temperature dependence and their acclimation to temperature differ among ecotypes, and how these differences relate to shoot growth. We examined growth analysis, temperature dependence of O2 consumption rates, and protein amounts of the respiratory chain components in shoots of twelve ecotypes of A. thaliana grown at three different temperatures. The temperature dependence of the O2 consumption rates were fitted to the modified Arrhenius model. The dynamic response of activation energy to measurement temperature was different among growth temperatures, suggesting that the plasticity of respiratory flux to temperatures differs among growth temperatures. The similar values of activation energy at growth temperature among ecotypes suggest that a similar process may determine the O2 consumption rates at the growth temperature in any ecotype. These results suggest that the growth temperature affects not only the absolute rate of O2 consumption but also the plasticity of respiratory flux in response to temperature, supporting the acclimation of shoot growth to various temperatures.
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Affiliation(s)
- Tomomi Inoue
- National Institute for Environmental Studies, Ibaraki, Japan
| | - Yusuke Yamada
- School of Life Science, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Ko Noguchi
- School of Life Science, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
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Tussipkan D, Manabayeva SA. Employing CRISPR/Cas Technology for the Improvement of Potato and Other Tuber Crops. FRONTIERS IN PLANT SCIENCE 2021; 12:747476. [PMID: 34764969 PMCID: PMC8576567 DOI: 10.3389/fpls.2021.747476] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 10/04/2021] [Indexed: 05/07/2023]
Abstract
New breeding technologies have not only revolutionized biological science, but have also been employed to generate transgene-free products. Genome editing is a powerful technology that has been used to modify genomes of several important crops. This review describes the basic mechanisms, advantages and disadvantages of genome editing systems, such as ZFNs, TALENs, and CRISPR/Cas. Secondly, we summarize in detail all studies of the CRISPR/Cas system applied to potato and other tuber crops, such as sweet potato, cassava, yam, and carrot. Genes associated with self-incompatibility, abiotic-biotic resistance, nutrient-antinutrient content, and post-harvest factors targeted utilizing the CRISPR/Cas system are analyzed in this review. We hope that this review provides fundamental information that will be useful for future breeding of tuber crops to develop novel cultivars.
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Affiliation(s)
| | - Shuga A. Manabayeva
- Plant Genetic Engineering Laboratory, National Center for Biotechnology, Nur-Sultan, Kazakhstan
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11
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Garmash EV, Belykh ES, Velegzhaninov IO. The gene expression profiles of mitochondrial respiratory components in Arabidopsis plants with differing amounts of ALTERNATIVE OXIDASE1a under high intensity light. PLANT SIGNALING & BEHAVIOR 2021; 16:1864962. [PMID: 33369529 PMCID: PMC7889022 DOI: 10.1080/15592324.2020.1864962] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We compared the expression of mitochondrial alternative oxidase (AOX) and other non-phosphorylating respiratory components (NPhPs) in wild type and AOX1a transgenic Arabidopsis thaliana following short-term transfer of plants to higher irradiance conditions to gain more insight into the mechanisms of AOX functioning under light. The AOX1a overexpressing line (XX-2) showed the highest amount of AOX1a transcripts and AOX1A synthesis during the entire experiment, and many NPhPs genes were down-regulated after 6-8 h under the higher light conditions. Antisense AS-12 plants displayed a compensatory effect, typically after 8 h of exposure to higher irradiance, by up-regulating their expression of the majority of genes encoding AOX and other respiratory components. In addition, AS-12 plants displayed 'overcompensation effects' prior to their transfer to high light conditions, i.e., they showed a higher expression level of certain genes. As a result, the ROS content in AS-12, as in XX-2, was consistently lower than in the wild type. All NPhPs genes share, in common with AOX1a, light- and stress-related cis-acting regulatory elements (CAREs) in their promoters. However, the expression of respiratory genes does not always depend on the level of AOX1a expression. This suggests the presence of multiple combinations of signaling pathways in gene induction. Based on our results, we outline possible directions for future research.
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Affiliation(s)
- Elena V. Garmash
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
- CONTACT Elena V. Garmash Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
| | - Elena S. Belykh
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
| | - Ilya O. Velegzhaninov
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
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12
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Ding C, Chen C, Su N, Lyu W, Yang J, Hu Z, Zhang M. Identification and characterization of a natural SNP variant in ALTERNATIVE OXIDASE gene associated with cold stress tolerance in watermelon. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 304:110735. [PMID: 33568287 DOI: 10.1016/j.plantsci.2020.110735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/23/2020] [Accepted: 10/24/2020] [Indexed: 06/12/2023]
Abstract
Alternative oxidase (AOX) is a mitochondrial enzyme encoded by a small nuclear gene family, which contains the two subfamilies, AOX1 and AOX2. In the present study on watermelon (Citrullus lanatus), only one ClAOX gene, belonging to AOX2 subfamily but having a similar gene structure to AtAOX1a, was found in the watermelon genome. The expression analysis suggested that ClAOX had the constitutive expression feature of AOX2 subfamily, but was cold inducible, which is normally considered an AOX1 subfamily feature. Moreover, one single nucleotide polymorphism (SNP) in ClAOX sequence, which led to the change from Lys (N) to Asn (K) in the 96th amino acids, was found among watermelon subspecies. Ectopic expression of two ClAOX alleles in the Arabidopsis aox1a knock-out mutant indicated that ClAOXK-expressing plants had stronger cold tolerance than aox1a mutant and ClAOXN-expressing plants. Our findings suggested watermelon genome contained a single ClAOX that possessed the expression features of both AOX1 and AOX2 subfamilies. A naturally existing SNP in ClAOX differentiated the cold tolerance of transgenic Arabidopsis plants, impling a possibility this gene might be a functional marker for stress-tolerance breeding.
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Affiliation(s)
- Changqing Ding
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, PR China
| | - Cuiting Chen
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, PR China
| | - Nan Su
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, PR China
| | - Wenhui Lyu
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, PR China
| | - Jinghua Yang
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, PR China; Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Ministry of Agriculture, Hangzhou 310058, PR China
| | - Zhongyuan Hu
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, PR China; Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Ministry of Agriculture, Hangzhou 310058, PR China.
| | - Mingfang Zhang
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, PR China; Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Ministry of Agriculture, Hangzhou 310058, PR China
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13
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Garmash EV. Role of mitochondrial alternative oxidase in the regulation of cellular homeostasis during development of photosynthetic function in greening leaves. PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23:221-228. [PMID: 33190385 DOI: 10.1111/plb.13217] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 11/08/2020] [Indexed: 05/27/2023]
Abstract
Here, recent publications on the role of mitochondrial non-phosphorylating pathways (NPhPs) in the electron transport chain during the de-etiolation of wheat leaves are reviewed. Among NPhPs, the alternative oxidase (AOX) pathway is the most effective pathway in maintaining cellular redox and energy balance, especially under stress conditions, including light stress. AOX is considered to dissipate excess reductants produced in the chloroplasts, and thereby prevent photooxidation. However, when etiolated wheat plants were exposed to a physiologically relevant light level, AOX was rapidly induced and increased, although the etioplasts did not produce excess reductants and have their own strong photoprotective mechanisms. The present study provides further insights into the role of AOX in greening cells and highlights the importance of AOX in the integration of cellular signalling pathways.
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Affiliation(s)
- E V Garmash
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, 167982, Russian Federation
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14
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Inoue T, Noguchi K. Theoretical analysis of a temperature-dependent model of respiratory O 2 consumption using the kinetics of the cytochrome and alternative pathways. THE NEW PHYTOLOGIST 2021; 229:1810-1821. [PMID: 32984969 PMCID: PMC7821261 DOI: 10.1111/nph.16964] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/14/2020] [Indexed: 06/11/2023]
Abstract
Temperature dependence of plant respiratory O2 -consumption has been empirically described by the Arrhenius equation. The slope of the Arrhenius plot (which is proportional to activation energy) sometimes deviates from a constant value. We conducted kinetic model simulations of mitochondrial electron flow dynamics to clarify factors affecting the shape of the Arrhenius plot. We constructed a kinetic model of respiration in which competitive O2 -consumption by the cytochrome pathway (CP) and the alternative pathway (AP) were considered, and we used this model to describe the temperature dependence of respiratory O2 -consumption of Arabidopsis. The model indicated that the electron partitioning and activation energy differences between CP and AP were reflected in the slope and magnitude of the dependent variables of the Arrhenius plot. When the electron partitioning and activation energies of CP and AP were constant with temperature change, our model suggested that the Arrhenius plot would be almost linear. When the electron partitioning or activation energy of CP, or both, rapidly changed with temperature, the Arrhenius plot deviated from linearity, as reported in previous experimental studies. Our simulation analysis quantitatively linked the kinetic model parameters with physiological mechanisms underlying the instantaneous temperature dependence of plant respiration rate.
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Affiliation(s)
- Tomomi Inoue
- National Institute for Environmental Studies16‐2 Onogawa TsukubaIbaraki305‐8506Japan
| | - Ko Noguchi
- Department of Life ScienceTokyo University of Pharmacy and Life Sciences1432‐1 Horinouchi HachiojiTokyo192‐0392Japan
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15
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Chadee A, Vanlerberghe GC. Distinctive mitochondrial and chloroplast components contributing to the maintenance of carbon balance during plant growth at elevated CO 2. PLANT SIGNALING & BEHAVIOR 2020; 15:1795395. [PMID: 32705929 PMCID: PMC8550537 DOI: 10.1080/15592324.2020.1795395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Plant carbon balance depends upon the difference between photosynthetic carbon gain and respiratory carbon loss. In C3 plants, growth at an elevated atmospheric concentration of CO2 (ECO2) stimulates photosynthesis and raises the leaf carbohydrate status, but how respiration responds is less understood. In this study, growth of Nicotiana tabacum at ECO2 increased the protein amount of the non-energy conserving mitochondrial alternative oxidase (AOX). Growth at ECO2 increased AOX1a transcript amount, and the transcript amount of a putative sugar-responsive gene encoding a chloroplast glucose-6-phosphate/phosphate translocator (GPT3). We suggest that the elevated amounts of AOX and GPT3 represent distinctive mitochondrial and chloroplast mechanisms to manage an excessive cytosolic pool of sugar phosphates. AOX respiration could consume cytosolic sugar phosphates, without this activity being restricted by rates of ATP turnover. GPT3 could allow accumulating cytosolic glucose-6-phosphate to return to the chloroplast. This could feed starch synthesis or a glucose-6-phosphate shunt in the Calvin cycle. AOX and GPT3 activities could buffer against Pi depletions that might otherwise disrupt mitochondrial and chloroplast electron transport chain activities. AOX and GPT3 activities could also buffer against a down-regulation of photosynthetic capacity by preventing a persistent imbalance between photosynthetic carbon gain and the activity of carbon utilizing sinks.
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Affiliation(s)
- Avesh Chadee
- Department of Biological Sciences and Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, Canada
| | - Greg C. Vanlerberghe
- Department of Biological Sciences and Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, Canada
- CONTACT Greg C. Vanlerberghe Department of Biological Sciences and Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ONM1C1A4, Canada
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16
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Li YT, Liu MJ, Li Y, Liu P, Zhao SJ, Gao HY, Zhang ZS. Photoprotection by mitochondrial alternative pathway is enhanced at heat but disabled at chilling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 104:403-415. [PMID: 32683757 DOI: 10.1111/tpj.14931] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 07/01/2020] [Accepted: 07/06/2020] [Indexed: 05/02/2023]
Abstract
The mitochondrial alternative pathway (AP) represents an important photoprotective mechanism for the chloroplast, but the temperature sensitivity of its photoprotective role is unknown. In this study, using the aox1a Arabidopsis mutant, the photoprotective role of the AP was verified under various temperatures, and the mechanism underlying the temperature sensitivity of the AP's photoprotective role was clarified. It was observed that the photoprotective role of the AP increased with rising temperature but was absent at low temperature. The photoprotective role of the AP was severely reduced under non-photorespiratory conditions. Disturbance of the AP inhibited the conversion of glycine to serine in mitochondria, which may restrain upstream photorespiratory metabolism and aggravate photoinhibition. With rising temperatures, photorespiration accelerated and the restraint of photorespiration caused by disturbance of the AP also increased, determining the temperature sensitivity of the AP's photoprotective role. We also verified that not only the AP but also the cytochrome pathway in mitochondria contributes to photoprotection by maintaining photorespiration.
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Affiliation(s)
- Yu-Ting Li
- State Key Lab of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong Province, China
- College of Agronomy, Shandong Agricultural University, Tai'an, Shandong Province, China
| | - Mei-Jun Liu
- Key laboratory of Grassland Resources and Ecology of Xinjiang, College of Grassland and Environment Science, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China
| | - Ying Li
- State Key Lab of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong Province, China
| | - Peng Liu
- College of Agronomy, Shandong Agricultural University, Tai'an, Shandong Province, China
| | - Shi-Jie Zhao
- State Key Lab of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong Province, China
| | - Hui-Yuan Gao
- State Key Lab of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong Province, China
| | - Zi-Shan Zhang
- State Key Lab of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong Province, China
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17
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Weaver RJ, Carrion G, Nix R, Maeda GP, Rabinowitz S, Iverson ENK, Thueson K, Havird JC. High mitochondrial mutation rates in Silene are associated with nuclear-mediated changes in mitochondrial physiology. Biol Lett 2020; 16:20200450. [PMID: 32933406 DOI: 10.1098/rsbl.2020.0450] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mitochondrial (mt) respiration depends on proteins encoded both by the mitochondrial and nuclear genomes. Variation in mt-DNA mutation rates exists across eukaryotes, although the functional consequences of elevated mt mutation rates in some lineages remain underexplored. In the angiosperm genus Silene, closely related, ecologically similar species have either 'fast' or 'slow' mt-DNA mutation rates. Here, we investigated the functional consequences of elevated mt-DNA mutation rates on mt respiration profiles of Silene mitochondria. Overall levels of respiration were similar among Species. Fast species had lower respiration efficiency than slow species and relied up to 48% more on nuclear-encoded respiratory enzymes alternative oxidase (AOX) and accessory dehydrogenases (DHex), which participate in stress responses in plants. However, not all fast species showed these trends. Respiratory profiles of some enzymes were correlated, most notably AOX and DHex. We conclude that subtle differences in mt physiology among Silene lineages with dramatically different mt mutation rates may underly similar phenotypes at higher levels of biological organization, betraying the consequences of mt mutations.
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Affiliation(s)
- Ryan J Weaver
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Gina Carrion
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Rachel Nix
- Hankamer School of Business, Baylor University, Waco, TX 76798, USA
| | - Gerald P Maeda
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Samantha Rabinowitz
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Erik N K Iverson
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Kiley Thueson
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Justin C Havird
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
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18
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Liu J, Wang X, Yang L, Nan W, Ruan M, Bi Y. Involvement of active MKK9-MAPK3/MAPK6 in increasing respiration in salt-treated Arabidopsis callus. PROTOPLASMA 2020; 257:965-977. [PMID: 32008084 DOI: 10.1007/s00709-020-01483-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 01/20/2020] [Indexed: 06/10/2023]
Abstract
Mitogen-activated protein kinase kinase 9 (MKK9) is an upstream activator of mitogen-activated protein kinase 3 (MAPK3) and MAPK6 in planta. To investigate MKK9 roles in mitochondrial respiration in Arabidopsis, MKK9DD, the active allele with mutations of Thr-201 and Ser-205 to Asp, and MKK9KR, the allele lacking MKK9 activity with a mutation of Lys-76 to Arg, were used. Results showed that the total respiratory rate (Vt), alternative pathway capacity (Valt) and cytochrome pathway capacity (Vcyt) increased under 0-100 mM NaCl treatments but decreased under 150-300 mM NaCl treatments in Col-0 callus. However, the activation of MKK9 by dexamethasone (DEX) increased Vt, Valt and Vcyt under 200 mM NaCl treatment; moreover, Valt showed more increase than Vcyt. The activation of MKK9 in MKK9DD callus sharply increased AOX protein expression under normal and NaCl conditions, but the increase was not observed in MKK9KR callus. Further results indicated that MAPK3 and MAPK6 were involved in the MKK9-induced increase of AOX protein levels. qRT-PCR results showed that MKK9-MAPK3/MAPK6 was involved in the NaCl-induced AOX1b and AOX1d expression, but only MKK9-MAPK3 was necessary for AOX2 expression; in addition, MAPK3 regulated the AOX1a transcription in an MKK9-independent manner. MKK9 positively regulated SOD and CAT activities by affecting MAPK3 and MAPK6 and negatively regulated APX and POD activities by affecting MAPK3. Moreover, MKK9 functions as a positive factor in H2O2 accumulation under salt stress. The regulation of ethylene on alternative respiration was also associated with MKK9 under salt stress. Taken together, the MKK9-MAPK3/MAPK6 pathway plays a pivotal role in increasing alternative respiration in the salt-treated Arabidopsis callus.
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Affiliation(s)
- Jie Liu
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China
- Key Laboratory of Plant Physiology and Developmental Regulation, Guizhou Normal University, Guiyang, 550025, Guizhou, People's Republic of China
| | - Xiaomin Wang
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China.
| | - Lei Yang
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China
| | - Wenbin Nan
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China
| | - Mengjiao Ruan
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China
| | - Yurong Bi
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China.
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19
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Vanlerberghe GC, Dahal K, Alber NA, Chadee A. Photosynthesis, respiration and growth: A carbon and energy balancing act for alternative oxidase. Mitochondrion 2020; 52:197-211. [PMID: 32278748 DOI: 10.1016/j.mito.2020.04.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/28/2020] [Accepted: 04/06/2020] [Indexed: 12/26/2022]
Abstract
This review summarizes knowledge of alternative oxidase, a mitochondrial electron transport chain component that lowers the ATP yield of plant respiration. Analysis of mutant and transgenic plants has established that alternative oxidase activity supports leaf photosynthesis. The interaction of alternative oxidase respiration with chloroplast metabolism is important under conditions that challenge energy and/or carbon balance in the photosynthetic cell. Under such conditions, alternative oxidase provides an extra-chloroplastic means to optimize the status of chloroplast energy pools (ATP, NADPH) and to manage cellular carbohydrate pools in response to changing rates of carbon fixation and carbon demand for growth and maintenance. Transcriptional and post-translational mechanisms ensure that alternative oxidase can respond effectively when carbon and energy balance are being challenged. This function appears particularly significant under abiotic stress conditions such as water deficit, high salinity, or temperature extremes. Under such conditions, alternative oxidase respiration positively affects growth and stress tolerance, despite it lowering the energy yield and carbon use efficiency of respiration. In part, this beneficial effect relates to the ability of alternative oxidase respiration to prevent excessive reactive oxygen species generation in both mitochondria and chloroplasts. Recent evidence suggests that alternative oxidase respiration is an interesting target for crop improvement.
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Affiliation(s)
- Greg C Vanlerberghe
- Department of Biological Sciences, and Department of Cell and Systems Biology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C1A4, Canada.
| | - Keshav Dahal
- Fredericton Research and Development Centre, Agriculture and Agri-Food Canada, 850 Lincoln Road, P.O. Box 20280, Fredericton, New Brunswick E3B4Z7, Canada
| | - Nicole A Alber
- Department of Biological Sciences, and Department of Cell and Systems Biology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C1A4, Canada
| | - Avesh Chadee
- Department of Biological Sciences, and Department of Cell and Systems Biology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C1A4, Canada
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20
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Podgórska A, Mazur R, Ostaszewska-Bugajska M, Kryzheuskaya K, Dziewit K, Borysiuk K, Wdowiak A, Burian M, Rasmusson AG, Szal B. Efficient Photosynthetic Functioning of Arabidopsis thaliana Through Electron Dissipation in Chloroplasts and Electron Export to Mitochondria Under Ammonium Nutrition. FRONTIERS IN PLANT SCIENCE 2020; 11:103. [PMID: 32174931 PMCID: PMC7054346 DOI: 10.3389/fpls.2020.00103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/23/2020] [Indexed: 05/20/2023]
Abstract
An improvement in photosynthetic rate promotes the growth of crop plants. The sink-regulation of photosynthesis is crucial in optimizing nitrogen fixation and integrating it with carbon balance. Studies on these processes are essential in understanding growth inhibition in plants with ammonium ( NH 4 + ) syndrome. Hence, we sought to investigate the effects of using nitrogen sources with different states of reduction (during assimilation of NO 3 - versus NH 4 + ) on the photosynthetic performance of Arabidopsis thaliana. Our results demonstrated that photosynthetic functioning during long-term NH 4 + nutrition was not disturbed and that no indication of photoinhibition of PSII was detected, revealing the robustness of the photosynthetic apparatus during stressful conditions. Based on our findings, we propose multiple strategies to sustain photosynthetic activity during limited reductant utilization for NH 4 + assimilation. One mechanism to prevent chloroplast electron transport chain overreduction during NH 4 + nutrition is for cyclic electron flow together with plastid terminal oxidase activity. Moreover, redox state in chloroplasts was optimized by a dedicated type II NAD(P)H dehydrogenase. In order to reduce the amount of energy that reaches the photosynthetic reaction centers and to facilitate photosynthetic protection during NH 4 + nutrition, non-photochemical quenching (NPQ) and ample xanthophyll cycle pigments efficiently dissipate excess excitation. Additionally, high redox load may be dissipated in other metabolic reactions outside of chloroplasts due to the direct export of nucleotides through the malate/oxaloacetate valve. Mitochondrial alternative pathways can downstream support the overreduction of chloroplasts. This mechanism correlated with the improved growth of A. thaliana with the overexpression of the alternative oxidase 1a (AOX1a) during NH 4 + nutrition. Most remarkably, our findings demonstrated the capacity of chloroplasts to tolerate NH 4 + syndrome instead of providing redox poise to the cells.
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Affiliation(s)
- Anna Podgórska
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Radosław Mazur
- Institute of Biochemistry, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Monika Ostaszewska-Bugajska
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Katsiaryna Kryzheuskaya
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Kacper Dziewit
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Klaudia Borysiuk
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Agata Wdowiak
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Maria Burian
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | | | - Bożena Szal
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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21
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Weaver RJ. Hypothesized Evolutionary Consequences of the Alternative Oxidase (AOX) in Animal Mitochondria. Integr Comp Biol 2020; 59:994-1004. [PMID: 30912813 DOI: 10.1093/icb/icz015] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The environment in which eukaryotes first evolved was drastically different from what they experience today, and one of the key limiting factors was the availability of oxygen for mitochondrial respiration. During the transition to a fully oxygenated Earth, other compounds such as sulfide posed a considerable constraint on using mitochondrial aerobic respiration for energy production. The ancestors of animals, and those that first evolved from the simpler eukaryotes have mitochondrial respiratory components that are absent from later-evolving animals. Specifically, mitochondria of most basal metazoans have a sulfide-resistant alternative oxidase (AOX), which provides a secondary oxidative pathway to the classical cytochrome pathway. In this essay, I argue that because of its resistance to sulfide, AOX respiration was critical to the evolution of animals by enabling oxidative metabolism under otherwise inhibitory conditions. I hypothesize that AOX allowed for metabolic flexibility during the stochastic oxygen environment of early Earth which shaped the evolution of basal metazoans. I briefly describe the known functions of AOX, with a particular focus on the decreased production of reactive oxygen species (ROS) during stress conditions. Then, I propose three evolutionary consequences of AOX-mediated protection from ROS observed in basal metazoans: 1) adaptation to stressful environments, 2) the persistence of facultative sexual reproduction, and 3) decreased mitochondrial DNA mutation rates. Recognizing the diversity of mitochondrial respiratory systems present in animals may help resolve the mechanisms involved in major evolutionary processes such as adaptation and speciation.
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Affiliation(s)
- Ryan J Weaver
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn, AL 36849, USA
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22
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Yamada S, Ozaki H, Noguchi K. The Mitochondrial Respiratory Chain Maintains the Photosynthetic Electron Flow in Arabidopsis thaliana Leaves under High-Light Stress. PLANT & CELL PHYSIOLOGY 2020; 61:283-295. [PMID: 31603217 DOI: 10.1093/pcp/pcz193] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 10/07/2019] [Indexed: 05/02/2023]
Abstract
The plant respiratory chain includes the ATP-coupling cytochrome pathway (CP) and ATP-uncoupling alternative oxidase (AOX). Under high-light (HL) conditions, plants experience photoinhibition, leading to a damaged photosystem II (PSII). The respiratory chain is considered to affect PSII maintenance and photosynthetic electron transport under HL conditions. However, the underlying details remain unclear. In this study, we investigated the respiratory chain functions related to PSII maintenance and photosynthetic electron transport in plants exposed to HL stress. We measured the HL-induced decrease in the maximum quantum yield of PSII in the leaves of wild-type and AOX1a-knockout (aox1a) Arabidopsis thaliana plants in which CP was partially inhibited by a complex-III inhibitor. We also calculated PSII photodamage and repair rate constants. Both rate constants changed when CP was partially inhibited in aox1a plants, suggesting that the respiratory chain is related to both processes. Before HL stress, photosynthetic linear electron flow (LEF) decreased when CP was partially inhibited. After HL stress, aox1a in the presence of the CP inhibitor showed significantly decreased rates of LEF. The electron flow downstream from PSII and on the donor side of photosystem I may have been suppressed. The function of respiratory chain is required to maintain the optimal LEF as well as PSII maintenance especially under the HL stress.
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Affiliation(s)
- Shoya Yamada
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392 Japan
| | - Hiroshi Ozaki
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392 Japan
| | - Ko Noguchi
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392 Japan
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Garmash EV, Velegzhaninov IO, Ermolina KV, Rybak AV, Malyshev RV. Altered levels of AOX1a expression result in changes in metabolic pathways in Arabidopsis thaliana plants acclimated to low dose rates of ultraviolet B radiation. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2020; 291:110332. [PMID: 31928662 DOI: 10.1016/j.plantsci.2019.110332] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 10/28/2019] [Accepted: 11/02/2019] [Indexed: 05/27/2023]
Abstract
UV-B is a damaging component of solar radiation that inevitably reaches the Earth's surface. Plants have developed response mechanisms to adapt to UVB exposure. The alternative oxidase (AOX) catalyzes the ATP-uncoupling cyanide-resistant alternative pathway (AP) in plant mitochondria and is thought to be an important part of the cellular defense network under stress conditions. This study aimed to unravel the poorly understood functional significance of AOX1a induction in Arabidopsis thaliana leaves exposed to ecologically relevant doses of UVB radiation, by comparing wild-type (WT) plants with plants with modified expression of the AOX1a gene, either downregulated by antisense (AS-12) or overexpressed (XX-2). UVB exposure resulted in a phenotypic difference between lines. AOX1a overexpression resulted in the highest induction of AOX1A synthesis and MnSOD activity, and the lowest ROS level without pronounced changes in the phenotype relative to other genotypes. In AS-12 plants, expression of the majority of the genes encoding AOX was detected, other non-phosphorylating pathway components and antioxidant enzymes increased along with anthocyanin accumulation in leaves, and the ROS content was lower than in the WT. In addition to the expected AOX1 protein size (34 kDa), an AOX1 30 kDa band appeared under UVB exposure in all genotypes. However, in AS-12, the alterations in the transcript level and in the abundance of AOX1 protein isoforms induced by UVB could not fully functionally compensate for the lack of AOX1A. This was confirmed by the observed low AP capacity and increased levels of the oxidized form of ascorbate. These results highlight the importance of AOX in plant response to UVB for the control of a balanced metabolism, and indicate that AOX1a plays a key role in the regulation of the stress response.
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Affiliation(s)
- Elena V Garmash
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia.
| | - Ilya O Velegzhaninov
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
| | - Ksenia V Ermolina
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
| | - Anna V Rybak
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
| | - Ruslan V Malyshev
- Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
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24
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Clemente-Moreno MJ, Omranian N, Sáez P, Figueroa CM, Del-Saz N, Elso M, Poblete L, Orf I, Cuadros-Inostroza A, Cavieres L, Bravo L, Fernie A, Ribas-Carbó M, Flexas J, Nikoloski Z, Brotman Y, Gago J. Cytochrome respiration pathway and sulphur metabolism sustain stress tolerance to low temperature in the Antarctic species Colobanthus quitensis. THE NEW PHYTOLOGIST 2020; 225:754-768. [PMID: 31489634 DOI: 10.1111/nph.16167] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 08/22/2019] [Indexed: 05/28/2023]
Abstract
Understanding the strategies employed by plant species that live in extreme environments offers the possibility to discover stress tolerance mechanisms. We studied the physiological, antioxidant and metabolic responses to three temperature conditions (4, 15, and 23°C) of Colobanthus quitensis (CQ), one of the only two native vascular species in Antarctica. We also employed Dianthus chinensis (DC), to assess the effects of the treatments in a non-Antarctic species from the same family. Using fused LASSO modelling, we associated physiological and biochemical antioxidant responses with primary metabolism. This approach allowed us to highlight the metabolic pathways driving the response specific to CQ. Low temperature imposed dramatic reductions in photosynthesis (up to 88%) but not in respiration (sustaining rates of 3.0-4.2 μmol CO2 m-2 s-1 ) in CQ, and no change in the physiological stress parameters was found. Its notable antioxidant capacity and mitochondrial cytochrome respiratory activity (20 and two times higher than DC, respectively), which ensure ATP production even at low temperature, was significantly associated with sulphur-containing metabolites and polyamines. Our findings potentially open new biotechnological opportunities regarding the role of antioxidant compounds and respiratory mechanisms associated with sulphur metabolism in stress tolerance strategies to low temperature.
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Affiliation(s)
- María José Clemente-Moreno
- Research Group on Plant Biology under Mediterranean Conditions, Instituto de Agroecología y Economía del Agua (INAGEA), Universitat de les Illes Balears (UIB), cta. Valldemossa km 7,5, 07122, Palma de Mallorca, Spain
| | - Nooshin Omranian
- Systems Biology and Mathematical Modeling Group, Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476, Potsdam-Golm, Germany
- Bioinformatics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Patricia Sáez
- Laboratorio Cultivo de Tejidos Vegetales, Centro de Biotecnología, Departamento de Silvicultura, Facultad de Ciencias Forestales, Universidad de Concepción, 4030000, Concepción, Chile
| | - Carlos María Figueroa
- Instituto de Agrobiotecnología del Litoral, UNL, CONICET, FBCB, 3000, Santa Fe, Argentina
| | - Néstor Del-Saz
- Laboratorio de Fisiología Vegetal, Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, 4030000, Concepción, Chile
| | - Mhartyn Elso
- Laboratorio Cultivo de Tejidos Vegetales, Centro de Biotecnología, Departamento de Silvicultura, Facultad de Ciencias Forestales, Universidad de Concepción, 4030000, Concepción, Chile
| | - Leticia Poblete
- Laboratorio Cultivo de Tejidos Vegetales, Centro de Biotecnología, Departamento de Silvicultura, Facultad de Ciencias Forestales, Universidad de Concepción, 4030000, Concepción, Chile
| | - Isabel Orf
- Department of Life Sciences, Ben Gurion University of the Negev, 8410501, Beer Sheva, Israel
| | | | - Lohengrin Cavieres
- ECOBIOSIS, Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, 4030000, Concepción, Chile
| | - León Bravo
- Laboratorio de Fisiología y Biología Molecular Vegetal, Departamento de Cs. Agronómicas y Recursos Naturales, Facultad de Ciencias Agropecuarias y Forestales, Instituto de Agroindustria, Universidad de La Frontera, Temuco, Chile
- Center of Plant, Soil Interaction and Natural Resources Biotechnology, Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, 4811230, Temuco, Chile
| | - Alisdair Fernie
- Central Metabolism Group, Molecular Physiology Department, Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476, Golm, Germany
| | - Miquel Ribas-Carbó
- Research Group on Plant Biology under Mediterranean Conditions, Instituto de Agroecología y Economía del Agua (INAGEA), Universitat de les Illes Balears (UIB), cta. Valldemossa km 7,5, 07122, Palma de Mallorca, Spain
| | - Jaume Flexas
- Research Group on Plant Biology under Mediterranean Conditions, Instituto de Agroecología y Economía del Agua (INAGEA), Universitat de les Illes Balears (UIB), cta. Valldemossa km 7,5, 07122, Palma de Mallorca, Spain
| | - Zoran Nikoloski
- Systems Biology and Mathematical Modeling Group, Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476, Potsdam-Golm, Germany
- Bioinformatics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
- Center of Plant System Biology and Biotechnology (CPSBB), 4000, Plovdiv, Bulgaria
| | - Yariv Brotman
- Department of Life Sciences, Ben Gurion University of the Negev, 8410501, Beer Sheva, Israel
| | - Jorge Gago
- Research Group on Plant Biology under Mediterranean Conditions, Instituto de Agroecología y Economía del Agua (INAGEA), Universitat de les Illes Balears (UIB), cta. Valldemossa km 7,5, 07122, Palma de Mallorca, Spain
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Alternative Pathway is Involved in Nitric Oxide-Enhanced Tolerance to Cadmium Stress in Barley Roots. PLANTS 2019; 8:plants8120557. [PMID: 31795459 PMCID: PMC6963264 DOI: 10.3390/plants8120557] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/13/2019] [Accepted: 11/25/2019] [Indexed: 12/27/2022]
Abstract
Alternative pathway (AP) has been widely accepted to be involved in enhancing tolerance to various environmental stresses. In this study, the role of AP in response to cadmium (Cd) stress in two barley varieties, highland barley (Kunlun14) and barley (Ganpi6), was investigated. Results showed that the malondialdehyde (MDA) content and electrolyte leakage (EL) level under Cd stress increased in two barley varieties. The expressions of alternative oxidase (AOX) genes (mainly AOX1a), AP capacity (Valt), and AOX protein amount were clearly induced more in Kunlun14 under Cd stress, and these parameters were further enhanced by applying sodium nitroprussid (SNP, a NO donor). Moreover, H2O2 and O2− contents were raised in the Cd-treated roots of two barley varieties, but they were markedly relieved by exogenous SNP. However, this mitigating effect was aggravated by salicylhydroxamic acid (SHAM, an AOX inhibitor), suggesting that AP contributes to NO-enhanced Cd stress tolerance. Further study demonstrated that the effect of SHAM application on reactive oxygen species (ROS)-related scavenging enzymes and antioxidants was minimal. These observations showed that AP exerts an indispensable function in NO-enhanced Cd stress tolerance in two barley varieties. AP was mainly responsible for regulating the ROS accumulation to maintain the homeostasis of redox state.
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26
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Havird JC, Noe GR, Link L, Torres A, Logan DC, Sloan DB, Chicco AJ. Do angiosperms with highly divergent mitochondrial genomes have altered mitochondrial function? Mitochondrion 2019; 49:1-11. [PMID: 31229574 PMCID: PMC6885534 DOI: 10.1016/j.mito.2019.06.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 06/07/2019] [Accepted: 06/17/2019] [Indexed: 02/06/2023]
Abstract
Angiosperm mitochondrial (mt) genes are generally slow-evolving, but multiple lineages have undergone dramatic accelerations in rates of nucleotide substitution and extreme changes in mt genome structure. While molecular evolution in these lineages has been investigated, very little is known about their mt function. Some studies have suggested altered respiration in individual taxa, although there are several reasons why mt variation might be neutral in others. Here, we develop a new protocol to characterize respiration in isolated plant mitochondria and apply it to species of Silene with mt genomes that are rapidly evolving, highly fragmented, and exceptionally large (~11 Mbp). This protocol, complemented with traditional measures of plant fitness, cytochrome c oxidase activity assays, and fluorescence microscopy, was also used to characterize inter- and intraspecific variation in mt function. Contributions of the individual "classic" OXPHOS complexes, the alternative oxidase, and external NADH dehydrogenases to overall mt respiratory flux were found to be similar to previously studied angiosperms with more typical mt genomes. Some differences in mt function could be explained by inter- and intraspecific variation. This study suggests that Silene species with peculiar mt genomes still show relatively normal mt respiration. This may be due to strong purifying selection on mt variants, coevolutionary responses in the nucleus, or a combination of both. Future experiments should explore such questions using a comparative framework and investigating other lineages with unusual mitogenomes.
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Affiliation(s)
- Justin C Havird
- Department of Biology, Colorado State University, Fort Collins, CO, USA; Department of Integrative Biology, The University of Texas, Austin, TX, USA.
| | - Gregory R Noe
- Department of Biology, Colorado State University, Fort Collins, CO, USA
| | - Luke Link
- Department of Biology, Colorado State University, Fort Collins, CO, USA
| | - Amber Torres
- Department of Biology, Colorado State University, Fort Collins, CO, USA.
| | - David C Logan
- IRHS, INRA, Université d'Angers, AGROCAMPUS-Ouest, SFR 4207 QUASAV, 49071 Beaucouzé cedex, France
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO, USA.
| | - Adam J Chicco
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, USA.
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27
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Mitochondrial AOX Supports Redox Balance of Photosynthetic Electron Transport, Primary Metabolite Balance, and Growth in Arabidopsis thaliana under High Light. Int J Mol Sci 2019; 20:ijms20123067. [PMID: 31234590 PMCID: PMC6628045 DOI: 10.3390/ijms20123067] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 06/03/2019] [Accepted: 06/20/2019] [Indexed: 12/31/2022] Open
Abstract
When leaves receive excess light energy, excess reductants accumulate in chloroplasts. It is suggested that some of the reductants are oxidized by the mitochondrial respiratory chain. Alternative oxidase (AOX), a non-energy conserving terminal oxidase, was upregulated in the photosynthetic mutant of Arabidopsis thaliana, pgr5, which accumulated reductants in chloroplast stroma. AOX is suggested to have an important role in dissipating reductants under high light (HL) conditions, but its physiological importance and underlying mechanisms are not yet known. Here, we compared wild-type (WT), pgr5, and a double mutant of AOX1a-knockout plant (aox1a) and pgr5 (aox1a/pgr5) grown under high- and low-light conditions, and conducted physiological analyses. The net assimilation rate (NAR) was lower in aox1a/pgr5 than that in the other genotypes at the early growth stage, while the leaf area ratio was higher in aox1a/pgr5. We assessed detailed mechanisms in relation to NAR. In aox1a/pgr5, photosystem II parameters decreased under HL, whereas respiratory O2 uptake rates increased. Some intermediates in the tricarboxylic acid (TCA) cycle and Calvin cycle decreased in aox1a/pgr5, whereas γ-aminobutyric acid (GABA) and N-rich amino acids increased in aox1a/pgr5. Under HL, AOX may have an important role in dissipating excess reductants to prevent the reduction of photosynthetic electron transport and imbalance in primary metabolite levels.
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O'Leary BM, Asao S, Millar AH, Atkin OK. Core principles which explain variation in respiration across biological scales. THE NEW PHYTOLOGIST 2019; 222:670-686. [PMID: 30394553 DOI: 10.1111/nph.15576] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 10/18/2018] [Indexed: 05/02/2023]
Abstract
Contents Summary 670 I. Introduction 671 II. Principle 1 - Plant respiration performs three distinct functions 673 III. Principle 2 - Metabolic pathway flexibility underlies plant respiratory performance 676 IV. Principle 3 - Supply and demand interact over time to set plant respiration rate 677 V. Principle 4 - Plant respiratory acclimation involves adjustments in enzyme capacities 679 VI. Principle 5 - Respiration is a complex trait that helps to define, and is impacted by, plant lifestyle strategies 680 VII. Future directions 680 Acknowledgements 682 References 682 SUMMARY: Respiration is a core biological process that has important implications for the biochemistry, physiology, and ecology of plants. The study of plant respiration is thus conducted from several different perspectives by a range of scientific disciplines with dissimilar objectives, such as metabolic engineering, crop breeding, and climate-change modelling. One aspect in common among the different objectives is a need to understand and quantify the variation in respiration across scales of biological organization. The central tenet of this review is that different perspectives on respiration can complement each other when connected. To better accommodate interdisciplinary thinking, we identify distinct mechanisms which encompass the variation in respiratory rates and functions across biological scales. The relevance of these mechanisms towards variation in plant respiration are explained in the context of five core principles: (1) respiration performs three distinct functions; (2) metabolic pathway flexibility underlies respiratory performance; (3) supply and demand interact over time to set respiration rates; (4) acclimation involves adjustments in enzyme capacities; and (5) respiration is a complex trait that helps to define, and is impacted by, plant lifestyle strategies. We argue that each perspective on respiration rests on these principles to varying degrees and that broader appreciation of how respiratory variation occurs can unite research across scales.
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Affiliation(s)
- Brendan M O'Leary
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia
| | - Shinichi Asao
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia
| | - A Harvey Millar
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia
| | - Owen K Atkin
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia
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Kerbler SM, Taylor NL, Millar AH. Cold sensitivity of mitochondrial ATP synthase restricts oxidative phosphorylation in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2019; 221:1776-1788. [PMID: 30281799 DOI: 10.1111/nph.15509] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 09/20/2018] [Indexed: 05/03/2023]
Abstract
The combined action of the electron transport chain (ETC) and ATP synthase is essential in determining energy efficiency in plants, and so is important for cellular biosynthesis, growth and development. Owing to the sessile nature of plants, mitochondria must operate over a wide temperature range in the environment, necessitating a broad temperature tolerance of their biochemical reactions. We investigated the temperature response of mitochondrial respiratory processes in isolated mitochondria and intact plants of Arabidopsis thaliana and considered the effect of instantaneous responses to temperature and acclimation responses to low temperatures. We show that at 4°C the plant mitochondrial ATP synthase is differentially inhibited compared with other elements of the respiratory pathway, leading to decreased ADP : oxygen ratios and a limitation to the rate of ATP synthesis. This effect persists in vivo and cannot be overcome by cold-temperature acclimation of plants. This mechanism adds a new element to the respiratory acclimation model and provides a direct means of temperature perception by plant mitochondria. This also provides an alternative explanation for non-phosphorylating ETC bypass mechanisms, like the alternative oxidase to maintain respiratory rates, albeit at lower ATP synthesis efficiency, in response to the sensitivity of ATP synthase to the prevailing temperature.
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Affiliation(s)
- Sandra M Kerbler
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Nicolas L Taylor
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
- The Institute of Agriculture, The University of Western Australia, Crawley, WA, 6009, Australia
| | - A Harvey Millar
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
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30
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Sunil B, Saini D, Bapatla RB, Aswani V, Raghavendra AS. Photorespiration is complemented by cyclic electron flow and the alternative oxidase pathway to optimize photosynthesis and protect against abiotic stress. PHOTOSYNTHESIS RESEARCH 2019; 139:67-79. [PMID: 30187303 DOI: 10.1007/s11120-018-0577-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 08/24/2018] [Indexed: 05/02/2023]
Abstract
Optimization of photosynthetic performance and protection against abiotic stress are essential to sustain plant growth. Photorespiratory metabolism can help plants to adapt to abiotic stress. The beneficial role of photorespiration under abiotic stress is further strengthened by cyclic electron flow (CEF) and alternative oxidase (AOX) pathways. We have attempted to critically assess the literature on the responses of these three phenomena-photorespiration, CEF and AOX, to different stress situations. We emphasize that photorespiration is the key player to protect photosynthesis and upregulates CEF as well as AOX. Then these three processes work in coordination to protect the plants against photoinhibition and maintain an optimal redox state in the cell, while providing ATP for metabolism and protein repair. H2O2 generated during photorespiratory metabolism seems to be an important signal to upregulate CEF or AOX. Further experiments are necessary to identify the signals originating from CEF or AOX to modulate photorespiration. The mutants deficient in CEF or AOX or both could be useful in this regard. The mutual interactions between CEF and AOX, so as to keep their complementarity, are also to be examined further.
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Affiliation(s)
- Bobba Sunil
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Deepak Saini
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Ramesh B Bapatla
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Vetcha Aswani
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Agepati S Raghavendra
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.
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Moretti-Almeida G, Thomazella DPT, Pereira GAG, Monteiro G. Heterologous expression of an alternative oxidase from Moniliophthora perniciosa in Saccharomyces cerevisiae: Antioxidant function and in vivo platform for the study of new drugs against witches' broom disease. Fungal Genet Biol 2019; 126:50-55. [PMID: 30794952 DOI: 10.1016/j.fgb.2019.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 01/22/2019] [Accepted: 02/17/2019] [Indexed: 11/24/2022]
Abstract
The fungus Moniliophthora perniciosa is the causal agent of witches' broom disease (WBD), one of the most devastating diseases of cacao, the chocolate tree. Many strategies to control WBD have been tested so far, including the use of agrochemicals such as the strobilurins. Strobilurins are fungicides of the QoI family, and they are used in the control of a wide array of fungal diseases in many different crops, including cereals, field crops, fruits, tree nuts, and vegetables. These drugs act by specifically inhibiting fungal respiration at the Qo site of complex III, which is a component of the main mitochondrial respiratory chain. However, M. perniciosa is resistant to this family of chemicals. It has been postulated that this resistant phenotype is, at least in part, a result of the strong ability of this fungus to counteract the oxidative stress generated by the impairment of the main mitochondrial respiratory chain, through the activation of an alternative oxidase (Mp-AOX). To test this hypothesis, we expressed functional mitochondria-localized Mp-AOX in the model yeast Saccharomyces cerevisiae. We demonstrated that heterologous expression of Mp-AOX strongly inhibits hydrogen peroxide production by mitochondria. It also diminishes the total cell amount of oxidized glutathione (GSSG), resulting in a fifty-fold higher GSH/GSSG ratio in cells expressing Mp-AOX than in wild type cells. In addition, Mp-AOX activity decreases yeast growth rate and leads to low biomass production. Therefore, we propose the use of this heterologous expression system to direct the development of new inhibitors of fungal AOX by comparing the differences in optical density of Mp-AOX-expressing cells in the presence and absence of potential AOX inhibitors. Together, our results confirm the antioxidant role of Mp-AOX and provide an in vivo platform to be used in the screening of new fungicides based on Mp-AOX inhibition.
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Affiliation(s)
- G Moretti-Almeida
- Laboratório de Biologia Molecular e Biotecnologia Industrial de Microrganismos, Departamento de Tecnologia Bioquímico-Farmacêutica, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil
| | - D P T Thomazella
- Laboratório de Genômica e Expressão, Departamento de Genética, Evolução e Bioagentes, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP 13083-970, Brazil; Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - G A G Pereira
- Laboratório de Genômica e Expressão, Departamento de Genética, Evolução e Bioagentes, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP 13083-970, Brazil
| | - G Monteiro
- Laboratório de Biologia Molecular e Biotecnologia Industrial de Microrganismos, Departamento de Tecnologia Bioquímico-Farmacêutica, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil.
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32
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Wang M, Gu Z, Wang R, Guo J, Ling N, Firbank LG, Guo S. Plant Primary Metabolism Regulated by Nitrogen Contributes to Plant-Pathogen Interactions. PLANT & CELL PHYSIOLOGY 2019; 60:329-342. [PMID: 30388252 DOI: 10.1093/pcp/pcy211] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 10/27/2018] [Indexed: 06/08/2023]
Abstract
Nitrogen contributes to plant defense responses by the regulation of plant primary metabolism during plant-pathogen interactions. Based on biochemical, physiological, bioinformatic and transcriptome approaches, we investigated how different nitrogen forms (ammonium vs. nitrate) regulate the physiological response of cucumber (Cucumis sativus) to Fusarium oxysporum f. sp. cucumerinum (FOC) infection. The metabolic profile revealed that nitrate-grown plants accumulated more organic acids, while ammonium-grown plants accumulated more amino acids; FOC infection significantly increased levels of both amino acids and organic acids in the roots of ammonium-grown plants. Transcriptome analysis showed that genes related to carbon metabolism were mostly up-regulated in plants grown with nitrate, whereas in ammonium-grown plants the up-regulated genes were mostly those that were related to primary nitrogen metabolism. Root FOC colonization and disease incidence were positively correlated with levels of root amino acids and negatively correlated with levels of root organic acids. In conclusion, organic acid metabolism and expression of related genes increased under nitrate, whereas ammonium increased the level of amino acids and expression of related genes; these altered levels of organic acids and amino acids resulted in different tolerances to FOC infection depending on the nitrogen forms supplied.
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Affiliation(s)
- Min Wang
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Zechen Gu
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Ruirui Wang
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Junjie Guo
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Ning Ling
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | | | - Shiwei Guo
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
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Podgórska A, Burian M, Rychter AM, Rasmusson AG, Szal B. Short-term ammonium supply induces cellular defence to prevent oxidative stress in Arabidopsis leaves. PHYSIOLOGIA PLANTARUM 2017; 160:65-83. [PMID: 28008622 DOI: 10.1111/ppl.12538] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/01/2016] [Accepted: 12/13/2016] [Indexed: 05/21/2023]
Abstract
Plants can assimilate nitrogen from soil pools of both ammonium and nitrate, and the relative levels of these two nitrogen sources are highly variable in soil. Long-term ammonium nutrition is known to cause damage to Arabidopsis that has been linked to mitochondrial oxidative stress. Using hydroponic cultures, we analysed the consequences of rapid shifts between nitrate and ammonium nutrition. This did not induce growth retardation, showing that Arabidopsis can compensate for the changes in redox metabolism associated with the variations in nitrogen redox status. During the first 3 h of ammonium treatment, we observed distinct transient shifts in reactive oxygen species (ROS), low-mass antioxidants, ROS-scavenging enzymes, and mitochondrial alternative electron transport pathways, indicating rapid but temporally separated changes in chloroplastic, mitochondrial and cytosolic ROS metabolism. The fast induction of antioxidant defences significantly lowered intracellular H2 O2 levels, and thus protected Arabidopsis leaves from oxidative stress. On the other hand elevated extracellular ROS production in response to ammonium supply may be involved in signalling. The response pattern displays an intricate plasticity of Arabidopsis redox metabolism to minimise stress in responses to nutrient changes.
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Affiliation(s)
- Anna Podgórska
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, 02-096, Poland
| | - Maria Burian
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, 02-096, Poland
| | - Anna M Rychter
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, 02-096, Poland
| | | | - Bożena Szal
- Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, 02-096, Poland
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Tang Y, Sun X, Wen T, Liu M, Yang M, Chen X. Implications of terminal oxidase function in regulation of salicylic acid on soybean seedling photosynthetic performance under water stress. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2017; 112:19-28. [PMID: 28024235 DOI: 10.1016/j.plaphy.2016.11.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 11/22/2016] [Accepted: 11/22/2016] [Indexed: 05/27/2023]
Abstract
The aim of this study is to investigate whether exogenous application of salicylic acid (SA) could modulate the photosynthetic capacity of soybean seedlings in water stress tolerance, and to clarify the potential functions of terminal oxidase (plastid terminal oxidase (PTOX) and alternative oxidase (AOX)) in SA' s regulation on photosynthesis. The effects of SA and water stress on gas exchange, pigment contents, chlorophyll fluorescence, enzymes (guaiacol peroxidase (POD; EC 1.11.1.7), superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11) and NADP-malate dehydrogenase (NADP-MDH; EC1.1.1.82)) activity and transcript levels of PTOX, AOX1, AOX2a, AOX2b were examined in a hydroponic cultivation system. Results indicate that water stress significantly decreased the photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), pigment contents (Chla + b, Chla/b, Car), maximum quantum yield of PSⅡphotochemistry (Fv/Fm), efficiency of excitation capture of open PSⅡcenter (Fv'/Fm'), quantum efficiency of PSⅡphotochemistry (ΦPSⅡ), photochemical quenching (qP), and increased malondialdehyde (MDA) content and the activity of all the enzymes. SA pretreatment led to significant decreases in Ci and MDA content, and increases in Pn, Gs, E, pigment contents, Fv/Fm, Fv'/Fm', ΦPSⅡ, qP, and the activity of all the enzymes. SA treatment and water stress alone significantly up-regulated the expression of PTOX, AOX1 and AOX2b. SA pretreatment further increased the transcript levels of PTOX and AOX2b of soybean seedling under water stress. These results indicate that SA application alleviates the water stress-induced decrease in photosynthesis may mainly through maintaining a lower reactive oxygen species (ROS) level, a greater PSⅡefficiency, and an enhanced alternative respiration and chlororespiration. PTOX and AOX may play important roles in SA-mediated resistance to water stress.
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Affiliation(s)
- Yanping Tang
- College of Agronomy, Sichuan Agricultural University, No.211, Huimin Road, Gongping Town, Wenjiang District, Chengdu, 611130, Sichuan, China; Agrotechnical Extension Station, Agricultural Bureau of Dazhou City, No.52, Heye Street, Tongchuan District, Dazhou, 635000, Sichuan, China.
| | - Xin Sun
- College of Agronomy, Sichuan Agricultural University, No.211, Huimin Road, Gongping Town, Wenjiang District, Chengdu, 611130, Sichuan, China.
| | - Tao Wen
- College of Agronomy, Sichuan Agricultural University, No.211, Huimin Road, Gongping Town, Wenjiang District, Chengdu, 611130, Sichuan, China.
| | - Mingjie Liu
- College of Agronomy, Sichuan Agricultural University, No.211, Huimin Road, Gongping Town, Wenjiang District, Chengdu, 611130, Sichuan, China
| | - Mingyan Yang
- College of Agronomy, Sichuan Agricultural University, No.211, Huimin Road, Gongping Town, Wenjiang District, Chengdu, 611130, Sichuan, China
| | - Xuefei Chen
- College of Agronomy, Sichuan Agricultural University, No.211, Huimin Road, Gongping Town, Wenjiang District, Chengdu, 611130, Sichuan, China
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Zhang ZS, Liu MJ, Scheibe R, Selinski J, Zhang LT, Yang C, Meng XL, Gao HY. Contribution of the Alternative Respiratory Pathway to PSII Photoprotection in C3 and C4 Plants. MOLECULAR PLANT 2017; 10:131-142. [PMID: 27746301 DOI: 10.1016/j.molp.2016.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 09/29/2016] [Accepted: 10/05/2016] [Indexed: 05/02/2023]
Abstract
The mechanism by which the mitochondrial alternative oxidase (AOX) pathway contributes to photosystem II (PSII) photoprotection is in dispute. It was generally thought that the AOX pathway protects photosystems by dissipating excess reducing equivalents exported from chloroplasts through the malate/oxaloacetate (Mal/OAA) shuttle and thus preventing the over-reduction of chloroplasts. In this study, using the aox1a Arabidopsis mutant and nine other C3 and C4 plant species, we revealed an additional action model of the AOX pathway in PSII photoprotection. Although the AOX pathway contributes to PSII photoprotection in C3 leaves treated with high light, this contribution was observed to disappear when photorespiration was suppressed. Disruption or inhibition of the AOX pathway significantly decreased the photorespiration in C3 leaves. Moreover, the AOX pathway did not respond to high light and contributed little to PSII photoprotection in C4 leaves possessing a highly active Mal/OAA shuttle but with little photorespiration. These results demonstrate that the AOX pathway contributes to PSII photoprotection in C3 plants by maintaining photorespiration to detoxify glycolate and via the indirect export of excess reducing equivalents from chloroplasts by the Mal/OAA shuttle. This new action model explains why the AOX pathway does not contribute to PSII photoprotection in C4 plants.
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Affiliation(s)
- Zi-Shan Zhang
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an 271018, China; College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China; College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an 271018, China
| | - Mei-Jun Liu
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an 271018, China; College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - Renate Scheibe
- Department of Plant Physiology, FB5, University of Osnabrueck, 49069 Osnabrueck, Germany
| | - Jennifer Selinski
- Department of Plant Physiology, FB5, University of Osnabrueck, 49069 Osnabrueck, Germany
| | - Li-Tao Zhang
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an 271018, China; College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China; National and Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China
| | - Cheng Yang
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an 271018, China; College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China; Wheat Research Institute, Henan Academy of Agricultural Sciences, Zhengzhou, Henan 450002, China
| | - Xiang-Long Meng
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an 271018, China; College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - Hui-Yuan Gao
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an 271018, China; College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China.
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Dahal K, Vanlerberghe GC. Alternative oxidase respiration maintains both mitochondrial and chloroplast function during drought. THE NEW PHYTOLOGIST 2017; 213:560-571. [PMID: 27579773 DOI: 10.1111/nph.14169] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 07/29/2016] [Indexed: 05/19/2023]
Abstract
The mitochondrial electron transport chain (ETC) terminates at cytochrome (cyt) oxidase or alternative oxidase (AOX). In Nicotiana tabacum leaves, mitochondrial respiration in the light (RL ) declined with increasing drought severity but then increased under extreme drought, despite a steep decline in maximal cyt oxidase activity. This increased RL was absent in AOX knockdown lines, while AOX overexpression lines showed enhanced RL relative to the wild-type (WT). Cyt oxidase activity under extreme drought was higher in overexpressors and lower in knockdowns, compared with the WT, providing evidence that AOX acted to maintain cyt pathway function. The rate of RL was a strong determinant of the reduction state of the photosynthetic ETC during drought. As such, the maximal quantum yield of photosystem II was compromised in knockdowns, compared with the WT, during extreme drought. By contrast, overexpressors maintained their instantaneous leaf water-use efficiency equally as high during extreme drought as when they were well watered. In both mitochondria and chloroplasts, protein carbonyl accumulation during extreme drought was strongly increased in knockdowns, and decreased in overexpressors, relative to WT. Hence the ability of AOX to maintain critical mitochondrial and chloroplast functions during extreme drought is likely due, at least in part, to its ability to reduce oxidative damage.
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Affiliation(s)
- Keshav Dahal
- Department of Biological Sciences and Department of Cell and Systems Biology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C1A4, Canada
| | - Greg C Vanlerberghe
- Department of Biological Sciences and Department of Cell and Systems Biology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C1A4, Canada
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Dahal K, Martyn GD, Alber NA, Vanlerberghe GC. Coordinated regulation of photosynthetic and respiratory components is necessary to maintain chloroplast energy balance in varied growth conditions. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:657-671. [PMID: 28011719 PMCID: PMC5441918 DOI: 10.1093/jxb/erw469] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Mitochondria have a non-energy-conserving alternative oxidase (AOX) proposed to support photosynthesis, perhaps by promoting energy balance under varying growth conditions. To investigate this, wild-type (WT) Nicotiana tabacum were compared with AOX knockdown and overexpression lines. In addition, the amount of AOX protein in WT plants was compared with that of chloroplast light-harvesting complex II (LHCB2), whose amount is known to respond to chloroplast energy status. With increased growth irradiance, WT leaves maintained higher rates of respiration in the light (RL), but no differences in RL or photosynthesis were seen between the WT and transgenic lines, suggesting that, under non-stress conditions, AOX was not critical for leaf metabolism, regardless of growth irradiance. However, under drought, the AOX amount became an important determinant of RL, which in turn was an important determinant of chloroplast energy balance (measured as photosystem II excitation pressure, EP), and photosynthetic performance. In the WT, the AOX amount increased and the LHCB2 amount decreased with increased growth irradiance or drought severity. These changes in protein amounts correlated strongly, in opposing ways, with growth EP. This suggests that a signal deriving from the photosynthetic electron transport chain status coordinately controls the amounts of AOX and LHCB2, which then both contribute to maintaining chloroplast energy balance, particularly under stress conditions.
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Affiliation(s)
- Keshav Dahal
- Department of Biological Sciences and Department of Cell and Systems Biology, University of Toronto Scarborough, Military Trail, Toronto,
ON, Canada
| | - Greg D Martyn
- Department of Biological Sciences and Department of Cell and Systems Biology, University of Toronto Scarborough, Military Trail, Toronto,
ON, Canada
| | - Nicole A Alber
- Department of Biological Sciences and Department of Cell and Systems Biology, University of Toronto Scarborough, Military Trail, Toronto,
ON, Canada
| | - Greg C Vanlerberghe
- Department of Biological Sciences and Department of Cell and Systems Biology, University of Toronto Scarborough, Military Trail, Toronto,
ON, Canada
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Watanabe CKA, Yamori W, Takahashi S, Terashima I, Noguchi K. Mitochondrial Alternative Pathway-Associated Photoprotection of Photosystem II is Related to the Photorespiratory Pathway. PLANT & CELL PHYSIOLOGY 2016; 57:1426-1431. [PMID: 26903530 DOI: 10.1093/pcp/pcw036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 02/10/2016] [Indexed: 05/21/2023]
Abstract
Respiratory electron transport has two ubiquinol-oxidizing pathways, the cytochrome pathway (CP) and the alternative pathway (AP). The AP, which is catalyzed by the alternative oxidase (AOX), is energetically wasteful but may alleviate PSII photoinhibition under light conditions excessive for photosynthesis. However, its mechanism remains unknown. We used Arabidopsis aox1a mutants lacking AOX activity and studied the mutation's effects on photoinhibition by measuring the decrease in the maximum quantum yield of PSII (Fv/Fm) after high light exposure. Since the CP compensates for the lack of AOX, we monitored the extent of photoinhibition under conditions where CP activity is partially inhibited by antimycin A. When leaves were exposed to high light at 350 µmol m-2 s-1, the decline in Fv/Fm was significantly faster in the aox1a mutants than in the wild type. However, under conditions where photorespiration was suppressed by high CO2 or low O2 levels, the decline in Fv/Fm was suppressed in the aox1a mutants, but not in the wild type, making the difference between the wild type and mutants small. Our results demonstrate that the lack of the AP causes an acceleration of PSII photoinhibition in relation to the photorespiratory pathway, suggesting that the AP can support the activity of the photorespiratory pathway under high light conditions.
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Affiliation(s)
- Chihiro K A Watanabe
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Wataru Yamori
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
- Center for Environment, Health and Field Sciences, Chiba University, Kashiwa, Chiba, 277-0882 Japan
| | - Shunichi Takahashi
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, 2601 Australia
- Division of Environmental Photobiology, National Institute for Basic Biology, Okazaki, 444-8585 Japan
| | - Ichiro Terashima
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Ko Noguchi
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392 Japan
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Vanlerberghe GC, Martyn GD, Dahal K. Alternative oxidase: a respiratory electron transport chain pathway essential for maintaining photosynthetic performance during drought stress. PHYSIOLOGIA PLANTARUM 2016; 157:322-37. [PMID: 27080742 DOI: 10.1111/ppl.12451] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 03/11/2016] [Indexed: 05/19/2023]
Abstract
Photosynthesis and respiration are the hubs of energy metabolism in plants. Drought strongly perturbs photosynthesis as a result of both diffusive limitations resulting from stomatal closure, and in some cases biochemical limitations that are associated with a reduced abundance of key photosynthetic components. The effects of drought on respiration, particularly respiration in the light (RL ), are less understood. The plant mitochondrial electron transport chain includes a non-energy conserving terminal oxidase called alternative oxidase (AOX). Several studies have shown that drought increases AOX transcript, protein and maximum capacity. Here we review recent studies comparing wild-type (WT) tobacco to transgenic lines with altered AOX protein amount. Specifically during drought, RL was compromised in AOX knockdown plants and enhanced in AOX overexpression plants, compared with WT. Significantly, these differences in RL were accompanied by dramatic differences in photosynthetic performance. Knockdown of AOX increased the susceptibility of photosynthesis to drought-induced biochemical limitations, while overexpression of AOX delayed the development of such biochemical limitations, compared with WT. Overall, the results indicate that AOX is essential to maintaining RL during drought, and that this non-energy conserving respiration maintains photosynthesis during drought by promoting energy balance in the chloroplast. This review also outlines several areas for future research, including the possibility that enhancement of non-energy conserving respiratory electron sinks may be a useful biotechnological approach to increase plant performance during stress.
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Affiliation(s)
- Greg C Vanlerberghe
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
- Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - Greg D Martyn
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
- Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - Keshav Dahal
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
- Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
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Jian W, Zhang DW, Zhu F, Wang SX, Pu XJ, Deng XG, Luo SS, Lin HH. Alternative oxidase pathway is involved in the exogenous SNP-elevated tolerance of Medicago truncatula to salt stress. JOURNAL OF PLANT PHYSIOLOGY 2016; 193:79-87. [PMID: 26962709 DOI: 10.1016/j.jplph.2016.01.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 12/06/2015] [Accepted: 01/22/2016] [Indexed: 05/04/2023]
Abstract
Exogenous application of sodium nitroprusside (SNP) would enhance the tolerance of plants to stress conditions. Some evidences suggested that nitric oxide (NO) could induce the expression of alternative oxidase (AOX). In this study, Medicago truncatula (Medicago) was chosen to study the role of AOX in the SNP-elevated resistance to salt stress. Our results showed that the expression of AOX genes (especially AOX1 and AOX2b1) and cyanide-resistant respiration rate (Valt) could be significantly induced by salt stress. Exogenous application of SNP could further enhance the expression of AOX genes and Valt. Exogenous application of SNP could alleviate the oxidative damage and photosynthetic damage caused by salt stress. However, the stress resistance was significantly decreased in the plants which were pretreated with n-propyl gallate (nPG). More importantly, the damage in nPG-pretreated plants could not be alleviated by application of SNP. Further study showed that effects of nPG on the activities of antioxidant enzymes were minor. These results showed that AOX pathway played an important role in the SNP-elevated resistance of Medicago to salt stress. AOX could contribute to regulating the accumulation of reactive oxygen (ROS) and protect of photosystem, and we proposed that all these were depend on the ability of maintaining the homeostasis of redox state.
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Affiliation(s)
- Wei Jian
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu 610064, China
| | - Da-wei Zhang
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu 610064, China
| | - Feng Zhu
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu 610064, China
| | - Shuo-xun Wang
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu 610064, China
| | - Xiao-jun Pu
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu 610064, China
| | - Xing-guang Deng
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu 610064, China
| | - Shi-shuai Luo
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu 610064, China
| | - Hong-hui Lin
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu 610064, China.
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Wang F, Wang X, Zhao C, Wang J, Li P, Dou Y, Bi Y. Alternative pathway is involved in the tolerance of highland barley to the low-nitrogen stress by maintaining the cellular redox homeostasis. PLANT CELL REPORTS 2016; 35:317-328. [PMID: 26518429 DOI: 10.1007/s00299-015-1886-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 08/02/2015] [Accepted: 10/15/2015] [Indexed: 06/05/2023]
Abstract
Alternative pathway (AP) is involved in the tolerance of highland barley seedlings to the low-nitrogen stress by dissipating excessive reducing equivalents generated by photosynthesis and maintaining the cellular redox homeostasis. Low nitrogen (N) is a major limiting factor for plant growth and crop productivity. In this study, we investigated the roles of the alternative pathway (AP) in the tolerance of two barley seedlings, highland barley (Kunlun12) and barley (Ganpi6), to low-N stress. The results showed that the chlorophyll content and the fresh weight decreased more in Ganpi6 than those in Kunlun12 under low-N stress, suggesting that Kunlun12 has higher tolerance to low-N stress than Ganpi6. AP capacity was markedly induced by low-N stress; and it was higher in Kunlun12 than in Ganpi6. Comparatively, the cytochrome pathway capacity was not affected under all conditions. Western-blot analysis showed that the protein level of the alternative oxidase (AOX) increased under low-N stress in Kunlun12 but not in Ganpi6. Under low-N stress, the NAD(P)H content and the NAD(P)H to NAD(P)(+)+NAD(P)H ratio in Ganpi6 increased more than those in Kunlun12. Furthermore, photosynthetic parameters (Fv/Fm, qP, ETR and Yield) decreased markedly and qN increased, indicating photoinhibition occurred in both barley seedlings, especially in Ganpi6. When AP was inhibited by salicylhydroxamic acid (SHAM), the NAD(P)H content and the NAD(P)H to NAD(P)(+)+NAD(P)H ratio dramatically increased under all conditions, resulting in the marked accumulation of H(2)O(2) and malondialdehyde in leaves of both barley seedlings. Meanwhile, the malate-oxaloacetate shuttle activity and the photosynthetic efficiency were further inhibited. Taken together, AP is involved in the tolerance of highland barley seedlings to low-N stress by dissipating excess reducing equivalents and maintaining the cellular redox homeostasis.
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Affiliation(s)
- Feng Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, People's Republic of China
| | - Xiaomin Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, People's Republic of China
| | - Chengzhou Zhao
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, People's Republic of China
| | - Jianfeng Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, People's Republic of China
| | - Ping Li
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, People's Republic of China
| | - Yanqin Dou
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, People's Republic of China
| | - Yurong Bi
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, People's Republic of China.
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Velada I, Cardoso HG, Ragonezi C, Nogales A, Ferreira A, Valadas V, Arnholdt-Schmitt B. Alternative Oxidase Gene Family in Hypericum perforatum L.: Characterization and Expression at the Post-germinative Phase. FRONTIERS IN PLANT SCIENCE 2016; 7:1043. [PMID: 27563303 PMCID: PMC4980395 DOI: 10.3389/fpls.2016.01043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 07/04/2016] [Indexed: 05/05/2023]
Abstract
Alternative oxidase (AOX) protein is located in the inner mitochondrial membrane and is encoded in the nuclear genome being involved in plant response upon a diversity of environmental stresses and also in normal plant growth and development. Here we report the characterization of the AOX gene family of Hypericum perforatum L. Two AOX genes were identified, both with a structure of four exons (HpAOX1, acc. KU674355 and HpAOX2, acc. KU674356). High variability was found at the N-terminal region of the protein coincident with the high variability identified at the mitochondrial transit peptide. In silico analysis of regulatory elements located at intronic regions identified putative sequences coding for miRNA precursors and trace elements of a transposon. Simple sequence repeats were also identified. Additionally, the mRNA levels for the HpAOX1 and HpAOX2, along with the ones for the HpGAPA (glyceraldehyde-3-phosphate dehydrogenase A subunit) and the HpCAT1 (catalase 1), were evaluated during the post-germinative development. Gene expression analysis was performed by RT-qPCR with accurate data normalization, pointing out HpHYP1 (chamba phenolic oxidative coupling protein 1) and HpH2A (histone 2A) as the most suitable reference genes (RGs) according to GeNorm algorithm. The HpAOX2 transcript demonstrated larger stability during the process with a slight down-regulation in its expression. Contrarily, HpAOX1 and HpGAPA (the corresponding protein is homolog to the chloroplast isoform involved in the photosynthetic carbon assimilation in other plant species) transcripts showed a marked increase, with a similar expression pattern between them, during the post-germinative development. On the other hand, the HpCAT1 (the corresponding protein is homolog to the major H2O2-scavenging enzyme in other plant species) transcripts showed an opposite behavior with a down-regulation during the process. In summary, our findings, although preliminary, highlight the importance to investigate in more detail the participation of AOX genes during the post-germinative development in H. perforatum, in order to explore their functional role in optimizing photosynthesis and in the control of reactive oxygen species (ROS) levels during the process.
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Affiliation(s)
- Isabel Velada
- ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Laboratório de Biologia Molecular, Universidade de ÉvoraPólo da Mitra, Évora, Portugal
| | - Hélia G. Cardoso
- ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Laboratório de Biologia Molecular, Universidade de ÉvoraPólo da Mitra, Évora, Portugal
- *Correspondence: Hélia G. Cardoso
| | - Carla Ragonezi
- ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Laboratório de Biologia Molecular, Universidade de ÉvoraPólo da Mitra, Évora, Portugal
| | - Amaia Nogales
- Linking Landscape, Environment, Agriculture and Food, Instituto Superior de Agronomia-Universidade de LisboaLisboa, Portugal
| | - Alexandre Ferreira
- ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Laboratório de Biologia Molecular, Universidade de ÉvoraPólo da Mitra, Évora, Portugal
| | - Vera Valadas
- ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Laboratório de Biologia Molecular, Universidade de ÉvoraPólo da Mitra, Évora, Portugal
| | - Birgit Arnholdt-Schmitt
- EU Marie Curie Chair, ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Universidade de ÉvoraPólo da Mitra, Évora, Portugal
- Birgit Arnholdt-Schmitt
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Long BM, Bahar NHA, Atkin OK. Contributions of photosynthetic and non-photosynthetic cell types to leaf respiration in Vicia faba L. and their responses to growth temperature. PLANT, CELL & ENVIRONMENT 2015; 38:2263-2276. [PMID: 25828647 DOI: 10.1111/pce.12544] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 03/19/2015] [Indexed: 06/04/2023]
Abstract
In intact leaves, mitochondrial populations are highly heterogeneous among contrasting cell types; how such contrasting populations respond to sustained changes in the environment remains, however, unclear. Here, we examined respiratory rates, mitochondrial protein composition and response to growth temperature in photosynthetic (mesophyll) and non-photosynthetic (epidermal) cells from fully expanded leaves of warm-developed (WD) and cold-developed (CD) broad bean (Vicia faba L.). Rates of respiration were significantly higher in mesophyll cell protoplasts (MCPs) than epidermal cell protoplasts (ECPs), with both protoplast types exhibiting capacity for cytochrome and alternative oxidase activity. Compared with ECPs, MCPs contained greater relative quantities of porin, suggesting higher mitochondrial surface area in mesophyll cells. Nevertheless, the relative quantities of respiratory proteins (normalized to porin) were similar in MCPs and ECPs, suggesting that ECPs have lower numbers of mitochondria yet similar protein complement to MCP mitochondria (albeit with lower abundance serine hydroxymethyltransferase). Several mitochondrial proteins (both non-photorespiratory and photorespiratory) exhibited an increased abundance in response to cold in both protoplast types. Based on estimates of individual protoplast respiration rates, combined with leaf cell abundance data, epidermal cells make a small but significant (2%) contribution to overall leaf respiration which increases twofold in the cold. Taken together, our data highlight the heterogeneous nature of mitochondrial populations in leaves, both among contrasting cell types and in how those populations respond to growth temperature.
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Affiliation(s)
- Benedict M Long
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
| | - Nur H A Bahar
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
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Pu X, Lv X, Tan T, Fu F, Qin G, Lin H. Roles of mitochondrial energy dissipation systems in plant development and acclimation to stress. ANNALS OF BOTANY 2015; 116:583-600. [PMID: 25987710 PMCID: PMC4577992 DOI: 10.1093/aob/mcv063] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/16/2015] [Accepted: 03/27/2015] [Indexed: 05/18/2023]
Abstract
BACKGROUND Plants are sessile organisms that have the ability to integrate external cues into metabolic and developmental signals. The cues initiate specific signal cascades that can enhance the tolerance of plants to stress, and these mechanisms are crucial to the survival and fitness of plants. The adaption of plants to stresses is a complex process that involves decoding stress inputs as energy-deficiency signals. The process functions through vast metabolic and/or transcriptional reprogramming to re-establish the cellular energy balance. Members of the mitochondrial energy dissipation pathway (MEDP), alternative oxidases (AOXs) and uncoupling proteins (UCPs), act as energy mediators and might play crucial roles in the adaption of plants to stresses. However, their roles in plant growth and development have been relatively less explored. SCOPE This review summarizes current knowledge about the role of members of the MEDP in plant development as well as recent advances in identifying molecular components that regulate the expression of AOXs and UCPs. Highlighted in particular is a comparative analysis of the expression, regulation and stress responses between AOXs and UCPs when plants are exposed to stresses, and a possible signal cross-talk that orchestrates the MEDP, reactive oxygen species (ROS), calcium signalling and hormone signalling. CONCLUSIONS The MEDP might act as a cellular energy/metabolic mediator that integrates ROS signalling, energy signalling and hormone signalling with plant development and stress accumulation. However, the regulation of MEDP members is complex and occurs at transcriptional, translational, post-translational and metabolic levels. How this regulation is linked to actual fluxes through the AOX/UCP in vivo remains elusive.
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Affiliation(s)
- Xiaojun Pu
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Xin Lv
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Tinghong Tan
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Faqiong Fu
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Gongwei Qin
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Honghui Lin
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
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Keunen E, Schellingen K, Van Der Straeten D, Remans T, Colpaert J, Vangronsveld J, Cuypers A. ALTERNATIVE OXIDASE1a modulates the oxidative challenge during moderate Cd exposure in Arabidopsis thaliana leaves. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:2967-2977. [PMID: 25743159 DOI: 10.1093/jxb/erv035] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This study aims to unravel the functional significance of alternative oxidase1a (AOX1a) induction in Arabidopsis thaliana leaves exposed to cadmium (Cd) by comparing wild-type (WT) plants and aox1a knockout mutants. In the absence of AOX1a, differences in stress-responsive transcript and glutathione levels suggest an increased oxidative challenge during moderate (5 µM) and prolonged (72h) Cd exposure. Nevertheless, aox1a knockout leaves showed lower hydrogen peroxide (H2O2) accumulation as compared to the WT due to both acute (24h) and prolonged (72h) exposure to 5 µM Cd, but not to 10 µM Cd. Taken together, we propose a working model where AOX1a acts early in the response to Cd and activates or maintains a mitochondrial signalling pathway impacting on cellular antioxidative defence at the post-transcriptional level. This fine-tuning pathway is suggested to function during moderate (5 µM) Cd exposure while being overwhelmed during more severe (10 µM) Cd stress. Within this framework, ethylene is required - either directly or indirectly via NADPH oxidase isoform C - to fully induce AOX1 expression. In addition, reciprocal crosstalk between these components was demonstrated in leaves of A. thaliana plants exposed to Cd.
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Affiliation(s)
- Els Keunen
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium
| | - Kerim Schellingen
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium
| | - Dominique Van Der Straeten
- Laboratory of Functional Plant Biology, Ghent University, Karel Lodewijk Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Tony Remans
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium
| | - Jan Colpaert
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium
| | - Jaco Vangronsveld
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium
| | - Ann Cuypers
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium
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Zulet A, Gil-Monreal M, Zabalza A, van Dongen JT, Royuela M. Fermentation and alternative oxidase contribute to the action of amino acid biosynthesis-inhibiting herbicides. JOURNAL OF PLANT PHYSIOLOGY 2015; 175:102-12. [PMID: 25544587 DOI: 10.1016/j.jplph.2014.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 12/05/2014] [Accepted: 12/06/2014] [Indexed: 05/11/2023]
Abstract
Acetolactate synthase inhibitors (ALS-inhibitors) and glyphosate (GLP) are two classes of herbicide that act by the specific inhibition of an enzyme in the biosynthetic pathway of branched-chain or aromatic amino acids, respectively. The physiological effects that are detected after application of these two classes of herbicides are not fully understood in relation to the primary biochemical target inhibition, although they have been well documented. Interestingly, the two herbicides' toxicity includes some common physiological effects suggesting that they kill the treated plants by a similar pattern despite targeting different enzymes. The induction of aerobic ethanol fermentation and alternative oxidase (AOX) are two examples of these common effects. The objective of this work was to gain further insight into the role of fermentation and AOX induction in the toxic consequences of ALS-inhibitors and GLP. For this, Arabidopsis T-DNA knockout mutants of alcohol dehydrogenase (ADH) 1 and AOX1a were used. The results found in wild-type indicate that both GLP and ALS-inhibitors reduce ATP production by inducing fermentation and alternative respiration. The main physiological effects in the process of herbicide activity upon treated plants were accumulation of carbohydrates and total free amino acids. The effects of the herbicides on these parameters were less pronounced in mutants compared to wild-type plants. The role of fermentation and AOX regarding pyruvate availability is also discussed.
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Affiliation(s)
- Amaia Zulet
- Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain
| | - Miriam Gil-Monreal
- Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain
| | - Ana Zabalza
- Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain
| | - Joost T van Dongen
- Institute of Biology 1, RWTH Aachen University, Worringerweg 1, D 52074 Aachen, Germany
| | - Mercedes Royuela
- Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain.
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Rurek M, Woyda-Ploszczyca AM, Jarmuszkiewicz W. Biogenesis of mitochondria in cauliflower (Brassica oleracea var. botrytis) curds subjected to temperature stress and recovery involves regulation of the complexome, respiratory chain activity, organellar translation and ultrastructure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:399-417. [PMID: 25617518 DOI: 10.1016/j.bbabio.2015.01.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 12/05/2014] [Accepted: 01/16/2015] [Indexed: 12/30/2022]
Abstract
The biogenesis of the cauliflower curd mitochondrial proteome was investigated under cold, heat and the recovery. For the first time, two dimensional fluorescence difference gel electrophoresis was used to study the plant mitochondrial complexome in heat and heat recovery. Particularly, changes in the complex I and complex III subunits and import proteins, and the partial disintegration of matrix complexes were observed. The presence of unassembled subunits of ATP synthase was accompanied by impairment in mitochondrial translation of its subunit. In cold and heat, the transcription profiles of mitochondrial genes were uncorrelated. The in-gel activities of respiratory complexes were particularly affected after stress recovery. Despite a general stability of respiratory chain complexes in heat, functional studies showed that their activity and the ATP synthesis yield were affected. Contrary to cold stress, heat stress resulted in a reduced efficiency of oxidative phosphorylation likely due to changes in alternative oxidase (AOX) activity. Stress and stress recovery differently modulated the protein level and activity of AOX. Heat stress induced an increase in AOX activity and protein level, and AOX1a and AOX1d transcript level, while heat recovery reversed the AOX protein and activity changes. Conversely, cold stress led to a decrease in AOX activity (and protein level), which was reversed after cold recovery. Thus, cauliflower AOX is only induced by heat stress. In heat, contrary to the AOX activity, the activity of rotenone-insensitive internal NADH dehydrogenase was diminished. The relevance of various steps of plant mitochondrial biogenesis to temperature stress response and recovery is discussed.
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Affiliation(s)
- Michal Rurek
- Department of Cellular and Molecular Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University in Poznań, Umultowska 89, 61-614 Poznań, Poland.
| | - Andrzej M Woyda-Ploszczyca
- Department of Bioenergetics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University in Poznań, Umultowska 89, 61-614 Poznań, Poland
| | - Wieslawa Jarmuszkiewicz
- Department of Bioenergetics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University in Poznań, Umultowska 89, 61-614 Poznań, Poland
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Velada I, Ragonezi C, Arnholdt-Schmitt B, Cardoso H. Reference genes selection and normalization of oxidative stress responsive genes upon different temperature stress conditions in Hypericum perforatum L. PLoS One 2014; 9:e115206. [PMID: 25503716 PMCID: PMC4263753 DOI: 10.1371/journal.pone.0115206] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 11/19/2014] [Indexed: 01/17/2023] Open
Abstract
Reverse transcription-quantitative real-time PCR (RT-qPCR) is a widely used technique for gene expression analysis. The reliability of this method depends largely on the suitable selection of stable reference genes for accurate data normalization. Hypericum perforatum L. (St. John's wort) is a field growing plant that is frequently exposed to a variety of adverse environmental stresses that can negatively affect its productivity. This widely known medicinal plant with broad pharmacological properties (anti-depressant, anti-tumor, anti-inflammatory, antiviral, antioxidant, anti-cancer, and antibacterial) has been overlooked with respect to the identification of reference genes suitable for RT-qPCR data normalization. In this study, 11 candidate reference genes were analyzed in H. perforatum plants subjected to cold and heat stresses. The expression stability of these genes was assessed using GeNorm, NormFinder and BestKeeper algorithms. The results revealed that the ranking of stability among the three algorithms showed only minor differences within each treatment. The best-ranked reference genes differed between cold- and heat-treated samples; nevertheless, TUB was the most stable gene in both experimental conditions. GSA and GAPDH were found to be reliable reference genes in cold-treated samples, while GAPDH showed low expression stability in heat-treated samples. 26SrRNA and H2A had the highest stabilities in the heat assay, whereas H2A was less stable in the cold assay. Finally, AOX1, AOX2, CAT1 and CHS genes, associated with plant stress responses and oxidative stress, were used as target genes to validate the reliability of identified reference genes. These target genes showed differential expression profiles over time in treated samples. This study not only is the first systematic analysis for the selection of suitable reference genes for RT-qPCR studies in H. perforatum subjected to temperature stress conditions, but may also provide valuable information about the roles of genes associated with temperature stress responses.
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Affiliation(s)
- Isabel Velada
- EU Marie Curie Chair, ICAAM, Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA, Instituto de Investigação e Formação Avançada, Universidade de Évora, Ap. 94, 7006-554 Évora, Portugal
| | - Carla Ragonezi
- EU Marie Curie Chair, ICAAM, Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA, Instituto de Investigação e Formação Avançada, Universidade de Évora, Ap. 94, 7006-554 Évora, Portugal
| | - Birgit Arnholdt-Schmitt
- EU Marie Curie Chair, ICAAM, Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA, Instituto de Investigação e Formação Avançada, Universidade de Évora, Ap. 94, 7006-554 Évora, Portugal
| | - Hélia Cardoso
- EU Marie Curie Chair, ICAAM, Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA, Instituto de Investigação e Formação Avançada, Universidade de Évora, Ap. 94, 7006-554 Évora, Portugal
- * E-mail:
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49
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Rurek M. Plant mitochondria under a variety of temperature stress conditions. Mitochondrion 2014; 19 Pt B:289-94. [DOI: 10.1016/j.mito.2014.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 02/12/2014] [Accepted: 02/14/2014] [Indexed: 10/25/2022]
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50
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Dahal K, Wang J, Martyn GD, Rahimy F, Vanlerberghe GC. Mitochondrial alternative oxidase maintains respiration and preserves photosynthetic capacity during moderate drought in Nicotiana tabacum. PLANT PHYSIOLOGY 2014; 166:1560-74. [PMID: 25204647 PMCID: PMC4226348 DOI: 10.1104/pp.114.247866] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 09/07/2014] [Indexed: 05/18/2023]
Abstract
The mitochondrial electron transport chain includes an alternative oxidase (AOX) that is hypothesized to aid photosynthetic metabolism, perhaps by acting as an additional electron sink for photogenerated reductant or by dampening the generation of reactive oxygen species. Gas exchange, chlorophyll fluorescence, photosystem I (PSI) absorbance, and biochemical and protein analyses were used to compare respiration and photosynthesis of Nicotiana tabacum 'Petit Havana SR1' wild-type plants with that of transgenic AOX knockdown (RNA interference) and overexpression lines, under both well-watered and moderate drought-stressed conditions. During drought, AOX knockdown lines displayed a lower rate of respiration in the light than the wild type, as confirmed by two independent methods. Furthermore, CO2 and light response curves indicated a nonstomatal limitation of photosynthesis in the knockdowns during drought, relative to the wild type. Also relative to the wild type, the knockdowns under drought maintained PSI and PSII in a more reduced redox state, showed greater regulated nonphotochemical energy quenching by PSII, and displayed a higher relative rate of cyclic electron transport around PSI. The origin of these differences may lie in the chloroplast ATP synthase amount, which declined dramatically in the knockdowns in response to drought. None of these effects were seen in plants overexpressing AOX. The results show that AOX is necessary to maintain mitochondrial respiration during moderate drought. In its absence, respiration rate slows and the lack of this electron sink feeds back on the photosynthetic apparatus, resulting in a loss of chloroplast ATP synthase that then limits photosynthetic capacity.
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Affiliation(s)
- Keshav Dahal
- Departments of Biological Sciences and Cell and Systems Biology, University of Toronto, Scarborough, Toronto, Ontario, Canada M1C1A4
| | - Jia Wang
- Departments of Biological Sciences and Cell and Systems Biology, University of Toronto, Scarborough, Toronto, Ontario, Canada M1C1A4
| | - Greg D Martyn
- Departments of Biological Sciences and Cell and Systems Biology, University of Toronto, Scarborough, Toronto, Ontario, Canada M1C1A4
| | - Farkhunda Rahimy
- Departments of Biological Sciences and Cell and Systems Biology, University of Toronto, Scarborough, Toronto, Ontario, Canada M1C1A4
| | - Greg C Vanlerberghe
- Departments of Biological Sciences and Cell and Systems Biology, University of Toronto, Scarborough, Toronto, Ontario, Canada M1C1A4
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