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Zhu Y, Narsai R, He C, Wang Y, Berkowitz O, Whelan J, Liew LC. Coordinated regulation of the mitochondrial retrograde response by circadian clock regulators and ANAC017. PLANT COMMUNICATIONS 2023; 4:100501. [PMID: 36463409 PMCID: PMC9860193 DOI: 10.1016/j.xplc.2022.100501] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 11/10/2022] [Accepted: 11/30/2022] [Indexed: 06/16/2023]
Abstract
Mitochondrial retrograde signaling (MRS) supports photosynthetic function under a variety of conditions. Induction of mitochondrial dysfunction with myxothiazol (a specific inhibitor of the mitochondrial bc1 complex) or antimycin A (an inhibitor of the mitochondrial bc1 complex and cyclic electron transport in the chloroplast under light conditions) in the light and dark revealed diurnal control of MRS. This was evidenced by (1) significantly enhanced binding of ANAC017 to promoters in the light compared with the dark in Arabidopsis plants treated with myxothiazol (but not antimycin A), (2) overlap in the experimentally determined binding sites for ANAC017 and circadian clock regulators in the promoters of ANAC013 and AOX1a, (3) a diurnal expression pattern for ANAC017 and transcription factors it regulates, (4) altered expression of ANAC017-regulated genes in circadian clock mutants with and without myxothiazol treatment, and (5) a decrease in the magnitude of LHY and CCA1 expression in an ANAC017-overexpressing line and protein-protein interaction between ANAC017 and PIF4. This study also shows a large difference in transcriptome responses to antimycin A and myxothiazol in the dark: these responses are ANAC017 independent, observed in shoots and roots, similar to biotic challenge and salicylic acid responses, and involve ERF and ZAT transcription factors. This suggests that antimycin A treatment stimulates a second MRS pathway that is mediated or converges with salicylic acid signaling and provides a merging point with chloroplast retrograde signaling.
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Affiliation(s)
- Yanqiao Zhu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; Department of Animal, Plant and Soil Science, ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora, VIC 3086, Australia
| | - Reena Narsai
- Department of Animal, Plant and Soil Science, ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora, VIC 3086, Australia
| | - Cunman He
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; Department of Animal, Plant and Soil Science, ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora, VIC 3086, Australia
| | - Yan Wang
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; Department of Animal, Plant and Soil Science, ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora, VIC 3086, Australia
| | - Oliver Berkowitz
- Department of Animal, Plant and Soil Science, ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora, VIC 3086, Australia
| | - James Whelan
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; Department of Animal, Plant and Soil Science, ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora, VIC 3086, Australia
| | - Lim Chee Liew
- Department of Animal, Plant and Soil Science, ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora, VIC 3086, Australia.
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2
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Ivanova A, O′Leary B, Signorelli S, Falconet D, Moyankova D, Whelan J, Djilianov D, Murcha MW. Mitochondrial activity and biogenesis during resurrection of Haberlea rhodopensis. THE NEW PHYTOLOGIST 2022; 236:943-957. [PMID: 35872573 PMCID: PMC9804507 DOI: 10.1111/nph.18396] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 07/11/2022] [Indexed: 06/01/2023]
Abstract
Haberlea rhodopensis is a resurrection plant that can tolerate extreme and prolonged periods of desiccation with a rapid restoration of physiological function upon rehydration. Specialized mechanisms are required to minimize cellular damage during desiccation and to maintain integrity for rapid recovery following rehydration. In this study we used respiratory activity measurements, electron microscopy, transcript, protein and blue native-PAGE analysis to investigate mitochondrial activity and biogenesis in fresh, desiccated and rehydrated detached H. rhodopensis leaves. We demonstrate that unlike photosynthesis, mitochondrial respiration was almost immediately activated to levels of fresh tissue upon rehydration. The abundance of transcripts and proteins involved in mitochondrial respiration and biogenesis were at comparable levels in fresh, desiccated and rehydrated tissues. Blue native-PAGE analysis revealed fully assembled and equally abundant OXPHOS complexes in mitochondria isolated from fresh, desiccated and rehydrated detached leaves. We observed a high abundance of alternative respiratory components which correlates with the observed high uncoupled respiration capacity in desiccated tissue. Our study reveals that during desiccation of vascular H. rhodopensis tissue, mitochondrial composition is conserved and maintained at a functional state allowing for an almost immediate activation to full capacity upon rehydration. Mitochondria-specific mechanisms were activated during desiccation which probably play a role in maintaining tolerance.
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Affiliation(s)
- Aneta Ivanova
- School of Molecular SciencesThe University of Western Australia35 Stirling Highway, CrawleyPerthWA6009Australia
- AgroBioInstituteAgricultural Academy8 Dragan Tzankov Blvd.1164SofiaBulgaria
| | - Brendan O′Leary
- School of Molecular SciencesThe University of Western Australia35 Stirling Highway, CrawleyPerthWA6009Australia
- Saskatoon Research and Development Centre, Agriculture and Agri‐Food Canada107 Science PlaceSaskatoonSKK1A 0C5Canada
| | - Santiago Signorelli
- School of Molecular SciencesThe University of Western Australia35 Stirling Highway, CrawleyPerthWA6009Australia
- Department of Plant Biology, School of AgricultureUniversidad de la RepúblicaE. Garzón 780, Sayago12900MontevideoUruguay
| | - Denis Falconet
- Cell and Plant Physiology Laboratory, CNRS, CEA, INRAE, IRIGUniversité Grenoble Alpes38054GrenobleFrance
| | - Daniela Moyankova
- AgroBioInstituteAgricultural Academy8 Dragan Tzankov Blvd.1164SofiaBulgaria
| | - James Whelan
- Department of Animal, Plant and Soil Science, School of Life Science, The ARC Centre of Excellence in Plant Energy BiologyLa Trobe UniversityBundoora3086VICAustralia
| | - Dimitar Djilianov
- AgroBioInstituteAgricultural Academy8 Dragan Tzankov Blvd.1164SofiaBulgaria
| | - Monika W. Murcha
- School of Molecular SciencesThe University of Western Australia35 Stirling Highway, CrawleyPerthWA6009Australia
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3
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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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4
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Borghi M, Fernie AR. Outstanding questions in flower metabolism. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1275-1288. [PMID: 32410253 DOI: 10.1111/tpj.14814] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/29/2020] [Accepted: 05/05/2020] [Indexed: 06/11/2023]
Abstract
The great diversity of flowers, their color, odor, taste, and shape, is mostly a result of the metabolic processes that occur in this reproductive organ when the flower and its tissues develop, grow, and finally die. Some of these metabolites serve to advertise flowers to animal pollinators, other confer protection towards abiotic stresses, and a large proportion of the molecules of the central metabolic pathways have bioenergetic and signaling functions that support growth and the transition to fruits and seeds. Although recent studies have advanced our general understanding of flower metabolism, several questions still await an answer. Here, we have compiled a list of open questions on flower metabolism encompassing molecular aspects, as well as topics of relevance for agriculture and the ecosystem. These questions include the study of flower metabolism through development, the biochemistry of nectar and its relevance to promoting plant-pollinator interaction, recycling of metabolic resources after flowers whiter and die, as well as the manipulation of flower metabolism by pathogens. We hope with this review to stimulate discussion on the topic of flower metabolism and set a reference point to return to in the future when assessing progress in the field.
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Affiliation(s)
- Monica Borghi
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam, 14476, Germany
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam, 14476, Germany
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5
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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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6
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Jayawardhane J, Cochrane DW, Vyas P, Bykova NV, Vanlerberghe GC, Igamberdiev AU. Roles for Plant Mitochondrial Alternative Oxidase Under Normoxia, Hypoxia, and Reoxygenation Conditions. FRONTIERS IN PLANT SCIENCE 2020; 11:566. [PMID: 32499803 PMCID: PMC7243820 DOI: 10.3389/fpls.2020.00566] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 04/16/2020] [Indexed: 05/19/2023]
Abstract
Alternative oxidase (AOX) is a non-energy conserving terminal oxidase in the plant mitochondrial electron transport chain (ETC) that has a lower affinity for oxygen than does cytochrome (cyt) oxidase. To investigate the role(s) of AOX under different oxygen conditions, wild-type (WT) Nicotiana tabacum plants were compared with AOX knockdown and overexpression plants under normoxia, hypoxia (near-anoxia), and during a reoxygenation period following hypoxia. Paradoxically, under all the conditions tested, the AOX amount across plant lines correlated positively with leaf energy status (ATP/ADP ratio). Under normoxia, AOX was important to maintain respiratory carbon flow, to prevent the mitochondrial generation of superoxide and nitric oxide (NO), to control lipid peroxidation and protein S-nitrosylation, and possibly to reduce the inhibition of cyt oxidase by NO. Under hypoxia, AOX was again important in preventing superoxide generation and lipid peroxidation, but now contributed positively to NO amount. This may indicate an ability of AOX to generate NO under hypoxia, similar to the nitrite reductase activity of cyt oxidase under hypoxia. Alternatively, it may indicate that AOX activity simply reduces the amount of superoxide scavenging of NO, by reducing the availability of superoxide. The amount of inactivation of mitochondrial aconitase during hypoxia was also dependent upon AOX amount, perhaps through its effects on NO amount, and this influenced carbon flow under hypoxia. Finally, AOX was particularly important in preventing nitro-oxidative stress during the reoxygenation period, thereby contributing positively to the recovery of energy status following hypoxia. Overall, the results suggest that AOX plays a beneficial role in low oxygen metabolism, despite its lower affinity for oxygen than cytochrome oxidase.
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Affiliation(s)
| | - Devin W. Cochrane
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Poorva Vyas
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Natalia V. Bykova
- Morden Research and Development Centre, Agriculture and Agri-Food Canada, Morden, MB, Canada
| | - Greg C. Vanlerberghe
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, Canada
| | - Abir U. Igamberdiev
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
- *Correspondence: Abir U. Igamberdiev,
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7
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Sweetman C, Soole KL, Jenkins CLD, Day DA. Genomic structure and expression of alternative oxidase genes in legumes. PLANT, CELL & ENVIRONMENT 2019; 42:71-84. [PMID: 29424926 DOI: 10.1111/pce.13161] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/22/2018] [Accepted: 01/25/2018] [Indexed: 05/26/2023]
Abstract
Mitochondria isolated from chickpea (Cicer arietinum) possess substantial alternative oxidase (AOX) activity, even in non-stressed plants, and one or two AOX protein bands were detected immunologically, depending on the organ. Four different AOX isoforms were identified in the chickpea genome: CaAOX1 and CaAOX2A, B and D. CaAOX2A was the most highly expressed form and was strongly expressed in photosynthetic tissues, whereas CaAOX2D was found in all organs examined. These results are very similar to those of previous studies with soybean and siratro. Searches of available databases showed that this pattern of AOX genes and their expression was common to at least 16 different legume species. The evolution of the legume AOX gene family is discussed, as is the in vivo impact of an inherently high AOX capacity in legumes on growth and responses to environmental stresses.
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Affiliation(s)
- Crystal Sweetman
- Australian Research Council Industrial Transformation Research Hub, Legumes for Sustainable Agriculture, College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia, GPO Box 2001, Australia
| | - Kathleen L Soole
- Australian Research Council Industrial Transformation Research Hub, Legumes for Sustainable Agriculture, College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia, GPO Box 2001, Australia
| | - Colin L D Jenkins
- Australian Research Council Industrial Transformation Research Hub, Legumes for Sustainable Agriculture, College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia, GPO Box 2001, Australia
| | - David A Day
- Australian Research Council Industrial Transformation Research Hub, Legumes for Sustainable Agriculture, College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia, GPO Box 2001, Australia
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8
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Brew-Appiah RAT, York ZB, Krishnan V, Roalson EH, Sanguinet KA. Genome-wide identification and analysis of the ALTERNATIVE OXIDASE gene family in diploid and hexaploid wheat. PLoS One 2018; 13:e0201439. [PMID: 30074999 PMCID: PMC6075773 DOI: 10.1371/journal.pone.0201439] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 07/16/2018] [Indexed: 11/19/2022] Open
Abstract
A comprehensive understanding of wheat responses to environmental stress will contribute to the long-term goal of feeding the planet. ALERNATIVE OXIDASE (AOX) genes encode proteins involved in a bypass of the electron transport chain and are also known to be involved in stress tolerance in multiple species. Here, we report the identification and characterization of the AOX gene family in diploid and hexaploid wheat. Four genes each were found in the diploid ancestors Triticum urartu, and Aegilops tauschii, and three in Aegilops speltoides. In hexaploid wheat (Triticum aestivum), 20 genes were identified, some with multiple splice variants, corresponding to a total of 24 proteins for those with observed transcription and translation. These proteins were classified as AOX1a, AOX1c, AOX1e or AOX1d via phylogenetic analysis. Proteins lacking most or all signature AOX motifs were assigned to putative regulatory roles. Analysis of protein-targeting sequences suggests mixed localization to the mitochondria and other organelles. In comparison to the most studied AOX from Trypanosoma brucei, there were amino acid substitutions at critical functional domains indicating possible role divergence in wheat or grasses in general. In hexaploid wheat, AOX genes were expressed at specific developmental stages as well as in response to both biotic and abiotic stresses such as fungal pathogens, heat and drought. These AOX expression patterns suggest a highly regulated and diverse transcription and expression system. The insights gained provide a framework for the continued and expanded study of AOX genes in wheat for stress tolerance through breeding new varieties, as well as resistance to AOX-targeted herbicides, all of which can ultimately be used synergistically to improve crop yield.
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Affiliation(s)
- Rhoda A. T. Brew-Appiah
- Department of Crop and Soil Sciences, Washington State University, Pullman, Washington, United States of America
| | - Zara B. York
- Department of Crop and Soil Sciences, Washington State University, Pullman, Washington, United States of America
| | - Vandhana Krishnan
- Stanford Center for Genomics and Personalized Medicine, Department of Genetics, Stanford University, Stanford, United States of America
| | - Eric H. Roalson
- School of Biological Sciences, Washington State University, Pullman, Washington, United States of America
| | - Karen A. Sanguinet
- Department of Crop and Soil Sciences, Washington State University, Pullman, Washington, United States of America
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9
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Selinski J, Scheibe R, Day DA, Whelan J. Alternative Oxidase Is Positive for Plant Performance. TRENDS IN PLANT SCIENCE 2018; 23:588-597. [PMID: 29665989 DOI: 10.1016/j.tplants.2018.03.012] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/15/2018] [Accepted: 03/22/2018] [Indexed: 05/02/2023]
Abstract
The alternative pathway of mitochondrial electron transport, which terminates in the alternative oxidase (AOX), uncouples oxidation of substrate from mitochondrial ATP production, yet plant performance is improved under adverse growth conditions. AOX is regulated at different levels. Identification of regulatory transcription factors shows that Arabidopsis thaliana AOX1a is under strong transcriptional suppression. At the protein level, the primary structure is not optimised for activity. Maximal activity requires the presence of various metabolites, such as tricarboxylic acid-cycle intermediates that act in an isoform-specific manner. In this opinion article we propose that the regulatory mechanisms that keep AOX activity suppressed, at both the gene and protein level, are positive for plant performance due to the flexible short- and long-term fine-tuning.
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Affiliation(s)
- Jennifer Selinski
- Department of Animal, Plant, and Soil Science, Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University Bundoora, VIC 3083, Australia.
| | - Renate Scheibe
- Division of Plant Physiology, Department of Biology/Chemistry, University of Osnabrueck, D-49069 Osnabrueck, Germany
| | - David A Day
- College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - James Whelan
- Department of Animal, Plant, and Soil Science, Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University Bundoora, VIC 3083, Australia
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10
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Del-Saz NF, Ribas-Carbo M, McDonald AE, Lambers H, Fernie AR, Florez-Sarasa I. An In Vivo Perspective of the Role(s) of the Alternative Oxidase Pathway. TRENDS IN PLANT SCIENCE 2018; 23:206-219. [PMID: 29269217 DOI: 10.1016/j.tplants.2017.11.006] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 10/18/2017] [Accepted: 11/15/2017] [Indexed: 05/02/2023]
Abstract
Despite intense research on the in vitro characterization of regulatory factors modulating the alternative oxidase (AOX) pathway, the regulation of its activity in vivo is still not fully understood. Advances concerning in vivo regulation of AOX based on the oxygen-isotope fractionation technique are reviewed, and regulatory factors that merit future research are highlighted. In addition, we review and discuss the main biological functions assigned to the plant AOX, and suggest future experiments involving in vivo activity measurements to test different hypothesized physiological roles.
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Affiliation(s)
- Néstor Fernández Del-Saz
- Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Spain
| | - Miquel Ribas-Carbo
- Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Spain
| | - Allison E McDonald
- Department of Biology, Wilfrid Laurier University, Science Building, 75 University Avenue West, Waterloo, ON N2L 3C5, Canada
| | - Hans Lambers
- School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley (Perth), Western Australia 6009, Australia
| | - Alisdair R Fernie
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Igor Florez-Sarasa
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
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11
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Selinski J, Hartmann A, Deckers-Hebestreit G, Day DA, Whelan J, Scheibe R. Alternative Oxidase Isoforms Are Differentially Activated by Tricarboxylic Acid Cycle Intermediates. PLANT PHYSIOLOGY 2018; 176:1423-1432. [PMID: 29208641 PMCID: PMC5813554 DOI: 10.1104/pp.17.01331] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/30/2017] [Indexed: 05/18/2023]
Abstract
The cyanide-insensitive alternative oxidase (AOX) is a non-proton-pumping ubiquinol oxidase that catalyzes the reduction of oxygen to water and is posttranslationally regulated by redox mechanisms and 2-oxo acids. Arabidopsis (Arabidopsis thaliana) possesses five AOX isoforms (AOX1A-AOX1D and AOX2). AOX1D expression is increased in aox1a knockout mutants from Arabidopsis (especially after restriction of the cytochrome c pathway) but cannot compensate for the lack of AOX1A, suggesting a difference in the regulation of these isoforms. Therefore, we analyzed the different AOX isoenzymes with the aim to identify differences in their posttranslational regulation. Seven tricarboxylic acid cycle intermediates (citrate, isocitrate, 2-oxoglutarate, succinate, fumarate, malate, and oxaloacetate) were tested for their influence on AOX1A, AOX1C, and AOX1D wild-type protein activity using a refined in vitro system. AOX1C is insensitive to all seven organic acids, AOX1A and AOX1D are both activated by 2-oxoglutarate, but only AOX1A is additionally activated by oxaloacetate. Furthermore, AOX isoforms cannot be transformed to mimic one another by substituting the variable cysteine residues at position III in the protein. In summary, we show that AOX isoforms from Arabidopsis are differentially fine-regulated by tricarboxylic acid cycle metabolites (most likely depending on the amino-terminal region around the highly conserved cysteine residues known to be involved in regulation by the 2-oxo acids pyruvate and glyoxylate) and propose that this is the main reason why they cannot functionally compensate for each other.
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Affiliation(s)
- Jennifer Selinski
- Division of Plant Physiology, Department of Biology/Chemistry, University of Osnabrueck, D-49069 Osnabrueck, Germany
| | - Andreas Hartmann
- Division of Plant Physiology, Department of Biology/Chemistry, University of Osnabrueck, D-49069 Osnabrueck, Germany
| | - Gabriele Deckers-Hebestreit
- Division of Microbiology, Department of Biology/Chemistry, University of Osnabrueck, D-49069 Osnabrueck, Germany
| | - David A Day
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5001, Australia
| | - James Whelan
- Department of Animal, Plant, and Soil Science, Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University, Bundoora, Victoria 3083, Australia
| | - Renate Scheibe
- Division of Plant Physiology, Department of Biology/Chemistry, University of Osnabrueck, D-49069 Osnabrueck, Germany
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12
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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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14
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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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15
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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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16
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Vishwakarma A, Bashyam L, Senthilkumaran B, Scheibe R, Padmasree K. Physiological role of AOX1a in photosynthesis and maintenance of cellular redox homeostasis under high light in Arabidopsis thaliana. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2014; 81:44-53. [PMID: 24560882 DOI: 10.1016/j.plaphy.2014.01.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/27/2014] [Indexed: 05/27/2023]
Abstract
As plants are sessile, they often face high light (HL) stress that causes damage of the photosynthetic machinery leading to decreased photosynthesis. The importance of alternative oxidase (AOX) in optimizing photosynthesis is well documented. In the present study, the role of AOX in sustaining photosynthesis under HL was studied using AOX1a knockout mutants (aox1a) of Arabidopsis thaliana. Under growth light (GL; 50 μmol photons m(-2) s(-1)) conditions, aox1a plants did not show any changes in photosynthetic parameters, NAD(P)/H redox ratios, or respiratory O2 uptake when compared to wild-type (WT). Upon exposure to HL (700 μmol photons m(-2) s(-1)), respiratory rates did not vary between WT and aox1a. But, photosynthetic parameters related to photosystem II (PSII) and NaHCO3 dependent O2 evolution decreased, while the P700 reduction state increased in aox1a compared to WT. Further, under HL, the redox state of cellular NAD(P)/H pools increased with concomitant rise in reactive oxygen species (ROS) and malondialdehyde (MDA) content in aox1a compared to WT. In presence of HL, the transcript levels of several genes related to antioxidant, malate-oxaloacetate (malate-OAA) shuttle, photorespiratory and respiratory enzymes was higher in aox1a compared to WT. Taken together, these results demonstrate that under HL, in spite of significant increase in transcript levels of several genes mentioned above to maintain cellular redox homeostasis and minimize ROS production, Arabidopsis plants deficient in AOX1a were unable to sustain photosynthesis as is the case in WT plants.
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Affiliation(s)
- Abhaypratap Vishwakarma
- Department of Plant Sciences, School of Life Sciences, Centre for Advanced Studies, University of Hyderabad, Hyderabad 500 046, India
| | - Leena Bashyam
- Genomics Facility, University of Hyderabad, Hyderabad 500 046, India
| | - Balasubramanian Senthilkumaran
- Department of Animal Sciences, School of Life Sciences, Centre for Advanced Studies, University of Hyderabad, Hyderabad 500 046, India
| | - Renate Scheibe
- Department of Plant Physiology, FB5, University of Osnabrueck, 49069 Osnabrueck, Germany
| | - Kollipara Padmasree
- Department of Plant Sciences, School of Life Sciences, Centre for Advanced Studies, University of Hyderabad, Hyderabad 500 046, India; Department of Plant Physiology, FB5, University of Osnabrueck, 49069 Osnabrueck, Germany; Department of Biotechnology and Bioinformatics, School of Life Sciences, Centre for Advanced Studies, University of Hyderabad, Hyderabad 500 046, India.
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17
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Florez-Sarasa I, Lambers H, Wang X, Finnegan PM, Ribas-Carbo M. The alternative respiratory pathway mediates carboxylate synthesis in white lupin cluster roots under phosphorus deprivation. PLANT, CELL & ENVIRONMENT 2014; 37:922-928. [PMID: 24118034 DOI: 10.1111/pce.12208] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/04/2013] [Accepted: 09/09/2013] [Indexed: 06/02/2023]
Abstract
Plant adaptations associated with a high efficiency of phosphorus (P) acquisition can be used to increase productivity and sustainability in a world with a growing population and decreasing rock phosphate reserves. White lupin (Lupinus albus) produces cluster roots that release carboxylates to efficiently mobilize P from P-sorbing soils. It has been hypothesized that an increase in the activity of the alternative oxidase (AOX) would allow for the mitochondrial oxidation of NAD(P)H produced during citrate synthesis in cluster roots at a developmental stage when there is a low demand for ATP. We used the oxygen-isotope fractionation technique to study the in vivo respiratory activities of the cytochrome oxidase pathway (COP) and the alternative oxidase pathway (AOP) in different root sections of white lupins grown hydroponically with and without P. In parallel, AOX protein levels and internal carboxylate concentrations were determined in cluster and non-cluster roots. Higher in vivo AOP activity was measured in cluster roots when malate and citrate concentrations were also high, thus confirming our hypothesis. AOX protein levels were not always correlated with in vivo AOP activity, suggesting post-translational regulation of AOX.
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Affiliation(s)
- Igor Florez-Sarasa
- Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122, Palma de Mallorca, Spain
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18
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Araújo WL, Nunes-Nesi A, Fernie AR. On the role of plant mitochondrial metabolism and its impact on photosynthesis in both optimal and sub-optimal growth conditions. PHOTOSYNTHESIS RESEARCH 2014; 119:141-156. [PMID: 23456269 DOI: 10.1007/s11120-013-9807-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 02/18/2013] [Indexed: 06/01/2023]
Abstract
Given that the pathways of photosynthesis and respiration catalyze partially opposing processes, it follows that their relative activities must be carefully regulated within plant cells. Recent evidence has shown that the components of the mitochondrial electron transport chain are essential for the proper maintenance of intracellular redox gradients, to allow considerable rates of photorespiration and in turn efficient photosynthesis. Thus considerable advances have been made in understanding the interaction between respiration and photosynthesis during the last decades and the potential mechanisms linking mitochondrial function and photosynthetic efficiency will be reviewed. Despite the fact that manipulation of various steps of mitochondrial metabolism has been demonstrated to alter photosynthesis under optimal growth conditions, it is likely that these changes will, by and large, not be maintained under sub-optimal situations. Therefore producing plants to meet this aim remains a critical challenge. It is clear, however, that although there have been a range of studies analysing changes in respiratory and photosynthetic rates in response to light, temperature and CO2, our knowledge of the environmental impact on these processes and its linkage still remains fragmented. We will also discuss the metabolic changes associated to plant respiration and photosynthesis as important components of the survival strategy as they considerably extend the period that a plant can withstand to a stress situation.
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Affiliation(s)
- Wagner L Araújo
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, 36570-000, Brazil
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19
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Selinski J, Scheibe R. Pollen tube growth: where does the energy come from? PLANT SIGNALING & BEHAVIOR 2014; 9:e977200. [PMID: 25482752 PMCID: PMC4622831 DOI: 10.4161/15592324.2014.977200] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 08/28/2014] [Indexed: 05/18/2023]
Abstract
This review focuses on the energy metabolism during pollen maturation and tube growth and updates current knowledge. Pollen tube growth is essential for male reproductive success and extremely fast. Therefore, pollen development and tube growth are high energy-demanding processes. During the last years, various publications (including research papers and reviews) emphasize the importance of mitochondrial respiration and fermentation during male gametogenesis and pollen tube elongation. These pathways obviously contribute to satisfy the high energy demand, and there are many studies which suggest that respiration and fermentation are the only pathways to generate the needed energy. Here, we review data which show for the first time that in addition plastidial glycolysis and the balancing of the ATP/NAD(P)H ratio (by malate valves and NAD(+) biosynthesis) contribute to satisfy the energy demand during pollen development. Although the importance of energy generation by plastids was discounted during the last years (possibly due to the controversial opinion about their existence in pollen grains and pollen tubes), the available data underline their prime role during pollen maturation and tube growth.
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Key Words
- 2-OG, 2-oxoglutarate
- 2-PGA, 2-phosphoglycerate
- 3-PGA, 3-phosphoglycerate
- ACS, acetyl-CoA synthase
- ADH, alcohol dehydrogenase
- ALDH, aldehyde dehydrogenase
- AOX, alternative oxidase
- BPGA, bisphosphoglyceric acid
- ENO, enolase
- GAPDH, glyceraldehyde-3-phosphate dehydrogenase
- GOGAT, glutamate synthase
- GPT, G-6-P/phosphate translocators
- Gln, glutamine
- Glu, glutamate
- MDH, malate dehydrogenase
- NDP, nucleotide diphosphate kinase
- NMNAT, nicotinate/nicotinamide mononucleotide adenyltransferase
- NTT, ATP/ADP transporters
- OAA, oxaloacetate
- OPP, oxidative pentose-phosphate pathway
- PDC, pyruvate decarboxylase
- PDH, pyruvate dehydrogenase
- PEP, phosphoenolpyruvate
- PGAM, phosphoglycerate mutase
- PGDH, 3-phosphoglycerate dehydrogenase
- PK, pyruvate kinase
- PPSB, phosphorylated pathway of serine biosynthesis
- PPT, phosphoenolpyruvate/phosphate translocator
- PSP, phosphoserine phosphatase
- RNS, reactive nitrogen species
- ROS, reactive oxygen species
- RPOT, T3/T7 phage-type RNA polymerases
- T, malate/oxaloacetate translocator
- TP, triose phosphate.
- energy metabolism
- malate
- plastidial glycolysis
- pollen tube growth
- respiration
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Affiliation(s)
- Jennifer Selinski
- Department of Plant Physiology; University of Osnabrueck; Osnabrueck, Germany
| | - Renate Scheibe
- Department of Plant Physiology; University of Osnabrueck; Osnabrueck, Germany
- Correspondence to: Renate Scheibe;
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21
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Vanlerberghe GC. Alternative oxidase: a mitochondrial respiratory pathway to maintain metabolic and signaling homeostasis during abiotic and biotic stress in plants. Int J Mol Sci 2013; 14:6805-47. [PMID: 23531539 PMCID: PMC3645666 DOI: 10.3390/ijms14046805] [Citation(s) in RCA: 405] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 03/08/2013] [Accepted: 03/12/2013] [Indexed: 02/07/2023] Open
Abstract
Alternative oxidase (AOX) is a non-energy conserving terminal oxidase in the plant mitochondrial electron transport chain. While respiratory carbon oxidation pathways, electron transport, and ATP turnover are tightly coupled processes, AOX provides a means to relax this coupling, thus providing a degree of metabolic homeostasis to carbon and energy metabolism. Beside their role in primary metabolism, plant mitochondria also act as "signaling organelles", able to influence processes such as nuclear gene expression. AOX activity can control the level of potential mitochondrial signaling molecules such as superoxide, nitric oxide and important redox couples. In this way, AOX also provides a degree of signaling homeostasis to the organelle. Evidence suggests that AOX function in metabolic and signaling homeostasis is particularly important during stress. These include abiotic stresses such as low temperature, drought, and nutrient deficiency, as well as biotic stresses such as bacterial infection. This review provides an introduction to the genetic and biochemical control of AOX respiration, as well as providing generalized examples of how AOX activity can provide metabolic and signaling homeostasis. This review also examines abiotic and biotic stresses in which AOX respiration has been critically evaluated, and considers the overall role of AOX in growth and stress tolerance.
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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.
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Chai TT, Simmonds D, Day DA, Colmer TD, Finnegan PM. A GmAOX2b antisense gene compromises vegetative growth and seed production in soybean. PLANTA 2012; 236:199-207. [PMID: 22307678 DOI: 10.1007/s00425-012-1601-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 01/20/2012] [Indexed: 05/21/2023]
Abstract
The alternative oxidase mediates the cyanide-resistant respiratory pathway in plant mitochondria. In non-thermogenic plants, the role of alternative oxidase in plant growth and development is not well understood. Soybean (Glycine max) lines carrying a GmAOX2b antisense gene had compromised vegetative growth and reproductive performance under typical glasshouse growth conditions. The reduction in vegetative growth was demonstrated by reduction in shoot height, the number of leaves per plant and the green leaf area. Antisense plants also had decreased pod formation and seed to pod ratios, which together led to a reduction in the number and total mass of seed produced. The negative effects of the antisense gene on pod set, seed set, ovule availability and total seed mass were primarily confined to the branches, rather than the main stem. The preferential effect of alternative oxidase suppression in the branches is discussed in relation to the reproductive potential of soybean under stress. Taken together, these results demonstrate that alternative oxidase provides the benefit of sustaining plant vegetative growth and reproductive capacity in soybean.
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Affiliation(s)
- Tsun-Thai Chai
- Faculty of Natural and Agricultural Sciences, School of Plant Biology and Institute of Agriculture, The University of Western Australia, Crawley, WA 6009, Australia
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Yoshida K, Watanabe CK, Terashima I, Noguchi K. Physiological impact of mitochondrial alternative oxidase on photosynthesis and growth in Arabidopsis thaliana. PLANT, CELL & ENVIRONMENT 2011; 34:1890-9. [PMID: 21707657 DOI: 10.1111/j.1365-3040.2011.02384.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The mitochondrial alternative oxidase (AOX) has been suggested to have a beneficial role in illuminated leaves, but its function has not yet been fully elucidated. In this study, we investigated the effects of a knockout of the AOX1a gene on photosynthesis and growth under several light conditions in Arabidopsis thaliana. The AOX-deficient aox1a mutant showed a lowered operating efficiency of photosystem II and an enhanced activity of cyclic electron transport around photosystem I (CET-PSI) at high irradiance. To further address the physiological association of AOX with CET-PSI, we crossed aox1a with the pgr5 mutant, which is impaired in CET-PSI activity. In the pgr5 mutant background, AOX deficiency did not affect the apparent photosynthetic efficiency, indicating that the direct contribution of AOX to photosynthesis is not so large compared with CET-PSI. Nevertheless, the growth of the aox1a pgr5 double mutant was significantly impaired depending on the light intensity under growth conditions. The possibility of a synergistic function of AOX with CET-PSI in supporting plant growth is discussed.
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Affiliation(s)
- Keisuke Yoshida
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
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Wang J, Rajakulendran N, Amirsadeghi S, Vanlerberghe GC. Impact of mitochondrial alternative oxidase expression on the response of Nicotiana tabacum to cold temperature. PHYSIOLOGIA PLANTARUM 2011; 142:339-51. [PMID: 21401618 DOI: 10.1111/j.1399-3054.2011.01471.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The plant mitochondrial electron transport chain (ETC) includes a non-energy conserving alternative oxidase (AOX) thought to dampen reactive oxygen species (ROS) generation by the ETC and/or facilitate carbon metabolism by uncoupling it from ATP turnover. When wild-type (WT) Nicotiana tabacum grown at 28°C/22°C (light/dark) were transferred to 12°C/5°C, they showed a large induction of leaf Aox1a mRNA and AOX protein within 24 h. Transfer to cold also resulted in a large accumulation of monosaccharides, an increase in transcript level of genes encoding important ROS-scavenging enzymes and a moderate increase in lipid peroxidation. Transgenic plants with suppressed AOX level showed less cold-induced sugar accumulation than WT while transgenic plants with enhanced AOX levels showed enhanced sugar accumulation. This is inconsistent with the hypothesis that AOX acts to burn excess carbohydrate, but rather suggests a role for AOX to aid sugar accumulation, at least during cold stress. At 28°C/22°C, plants with suppressed AOX had elevated levels of lipid peroxidation compared with WT, while plants with enhanced AOX had reduced lipid peroxidation. This is consistent with the hypothesis that AOX dampens ROS generation and oxidative damage. However, this inverse relationship between AOX level and lipid peroxidation did not hold upon shift to cold. Under this stress condition, plants with strong suppression of AOX show enhanced induction of ROS-scavenging enzymes compared with WT and decline in lipid peroxidation. These data suggest that, under stress conditions, the lack of AOX enhances a mitochondrial stress-signaling pathway able to increase the ROS-scavenging capacity of the cell.
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Affiliation(s)
- Jia Wang
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C1A4, Canada
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25
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Yoshida K, Watanabe CK, Hachiya T, Tholen D, Shibata M, Terashima I, Noguchi K. Distinct responses of the mitochondrial respiratory chain to long- and short-term high-light environments in Arabidopsis thaliana. PLANT, CELL & ENVIRONMENT 2011; 34:618-28. [PMID: 21251020 DOI: 10.1111/j.1365-3040.2010.02267.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
In order to ensure the cooperative function with the photosynthetic system, the mitochondrial respiratory chain needs to flexibly acclimate to a fluctuating light environment. The non-phosphorylating alternative oxidase (AOX) is a notable respiratory component that may support a cellular redox homeostasis under high-light (HL) conditions. Here we report the distinct acclimatory manner of the respiratory chain to long- and short-term HL conditions and the crucial function of AOX in Arabidopsis thaliana leaves. Plants grown under HL conditions (HL plants) possessed a larger ubiquinone (UQ) pool and a higher amount of cytochrome c oxidase than plants grown under low light conditions (LL plants). These responses in HL plants may be functional for efficient ATP production and sustain the fast plant growth. When LL plants were exposed to short-term HL stress (sHL), the UQ reduction level was transiently elevated. In the wild-type plant, the UQ pool was re-oxidized concomitantly with an up-regulation of AOX. On the other hand, the UQ reduction level of the AOX-deficient aox1a mutant remained high. Furthermore, the plastoquinone pool was also more reduced in the aox1a mutant under such conditions. These results suggest that AOX plays an important role in rapid acclimation of the respiratory chain to sHL, which may support efficient photosynthetic performance.
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Affiliation(s)
- Keisuke Yoshida
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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