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Samant SB, Yadav N, Swain J, Joseph J, Kumari A, Praveen A, Sahoo RK, Manjunatha G, Seth CS, Singla-Pareek SL, Foyer CH, Pareek A, Gupta KJ. Nitric oxide, energy, and redox-dependent responses to hypoxia. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:4573-4588. [PMID: 38557811 DOI: 10.1093/jxb/erae139] [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: 11/23/2023] [Accepted: 03/30/2024] [Indexed: 04/04/2024]
Abstract
Hypoxia occurs when oxygen levels fall below the levels required for mitochondria to support respiration. Regulated hypoxia is associated with quiescence, particularly in storage organs (seeds) and stem cell niches. In contrast, environmentally induced hypoxia poses significant challenges for metabolically active cells that are adapted to aerobic respiration. The perception of oxygen availability through cysteine oxidases, which function as oxygen-sensing enzymes in plants that control the N-degron pathway, and the regulation of hypoxia-responsive genes and processes is essential to survival. Functioning together with reactive oxygen species (ROS), particularly hydrogen peroxide (H2O2) and reactive nitrogen species (RNS), such as nitric oxide (·NO), nitrogen dioxide (·NO2), S-nitrosothiols (SNOs), and peroxynitrite (ONOO-), hypoxia signaling pathways trigger anatomical adaptations such as formation of aerenchyma, mobilization of sugar reserves for anaerobic germination, formation of aerial adventitious roots, and the hyponastic response. NO and H2O2 participate in local and systemic signaling pathways that facilitate acclimation to changing energetic requirements, controlling glycolytic fermentation, the γ-aminobutyric acid (GABA) shunt, and amino acid synthesis. NO enhances antioxidant capacity and contributes to the recycling of redox equivalents in energy metabolism through the phytoglobin (Pgb)-NO cycle. Here, we summarize current knowledge of the central role of NO and redox regulation in adaptive responses that prevent hypoxia-induced death in challenging conditions such as flooding.
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Affiliation(s)
- Sanjib Bal Samant
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Nidhi Yadav
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Jagannath Swain
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Josepheena Joseph
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Aprajita Kumari
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Afsana Praveen
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Ranjan Kumar Sahoo
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | | | | | - Sneh Lata Singla-Pareek
- International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Christine H Foyer
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston B15 2TT, UK
| | - Ashwani Pareek
- National Agri-Food Biotechnology Institute, Mohali, Punjab, 140306, India
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Xiao F, Zhou H. Plant salt response: Perception, signaling, and tolerance. FRONTIERS IN PLANT SCIENCE 2023; 13:1053699. [PMID: 36684765 PMCID: PMC9854262 DOI: 10.3389/fpls.2022.1053699] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 12/05/2022] [Indexed: 05/14/2023]
Abstract
Salt stress is one of the significant environmental stressors that severely affects plant growth and development. Plant responses to salt stress involve a series of biological mechanisms, including osmoregulation, redox and ionic homeostasis regulation, as well as hormone or light signaling-mediated growth adjustment, which are regulated by different functional components. Unraveling these adaptive mechanisms and identifying the critical genes involved in salt response and adaption are crucial for developing salt-tolerant cultivars. This review summarizes the current research progress in the regulatory networks for plant salt tolerance, highlighting the mechanisms of salt stress perception, signaling, and tolerance response. Finally, we also discuss the possible contribution of microbiota and nanobiotechnology to plant salt tolerance.
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Affiliation(s)
- Fei Xiao
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi, China
| | - Huapeng Zhou
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
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Flores-Cotera LB, Chávez-Cabrera C, Martínez-Cárdenas A, Sánchez S, García-Flores OU. Deciphering the mechanism by which the yeast Phaffia rhodozyma responds adaptively to environmental, nutritional, and genetic cues. J Ind Microbiol Biotechnol 2021; 48:kuab048. [PMID: 34302341 PMCID: PMC8788774 DOI: 10.1093/jimb/kuab048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/16/2021] [Indexed: 11/13/2022]
Abstract
Phaffia rhodozyma is a basidiomycetous yeast that synthesizes astaxanthin (ASX), which is a powerful and highly valuable antioxidant carotenoid pigment. P. rhodozyma cells accrue ASX and gain an intense red-pink coloration when faced with stressful conditions such as nutrient limitations (e.g., nitrogen or copper), the presence of toxic substances (e.g., antimycin A), or are affected by mutations in the genes that are involved in nitrogen metabolism or respiration. Since cellular accrual of ASX occurs under a wide variety of conditions, this yeast represents a valuable model for studying the growth conditions that entail oxidative stress for yeast cells. Recently, we proposed that ASX synthesis can be largely induced by conditions that lead to reduction-oxidation (redox) imbalances, particularly the state of the NADH/NAD+ couple together with an oxidative environment. In this work, we review the multiple known conditions that elicit ASX synthesis expanding on the data that we formerly examined. When considered alongside the Mitchell's chemiosmotic hypothesis, the study served to rationalize the induction of ASX synthesis and other adaptive cellular processes under a much broader set of conditions. Our aim was to propose an underlying mechanism that explains how a broad range of divergent conditions converge to induce ASX synthesis in P. rhodozyma. The mechanism that links the induction of ASX synthesis with the occurrence of NADH/NAD+ imbalances may help in understanding how other organisms detect any of a broad array of stimuli or gene mutations, and then adaptively respond to activate numerous compensatory cellular processes.
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Affiliation(s)
- Luis B Flores-Cotera
- Department of Biotechnology and Bioengineering, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, México city 07360, México
| | - Cipriano Chávez-Cabrera
- Department of Biotechnology and Bioengineering, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, México city 07360, México
| | - Anahi Martínez-Cárdenas
- Department of Biotechnology and Bioengineering, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, México city 07360, México
| | - Sergio Sánchez
- Department of Molecular Biology and Biotechnology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México city 04510, México
| | - Oscar Ulises García-Flores
- Department of Biotechnology and Bioengineering, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, México city 07360, México
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Sun LJ, Zhao XY, Ren J, Yan SP, Zhao XY, Song XS. Overexpression of Cerasus humilis ChAOX2 improves the tolerance of Arabidopsis to salt stress. 3 Biotech 2021; 11:316. [PMID: 34123695 DOI: 10.1007/s13205-021-02871-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 05/31/2021] [Indexed: 12/19/2022] Open
Abstract
Alternative oxidase (AOX) has a well-established involvement in plant growth and stress tolerance in many studies. In this study, we isolated and characterized the AOX2 from Cerasus humilis. The ChAOX2 Open Reading Frame (ORF) contains 1029 nucleotides and encodes 342 amino acid residues. The inferred amino acid sequence of ChAOX2 shared the highest sequence similarity with a homolog from Prunus yedoensis. The ChAOX2 transcripts were relatively abundant in the old leaves and significantly up-regulated by salt stress. Subcellular localization analysis showed that ChAOX2 was located in the mitochondria. We transformed ChAOX2 into wild-type Arabidopsis thaliana and found that compared with wild-type and aox mutant lines, heterotopic expression of ChAOX2 increased proline content, and peroxidase and superoxide dismutase activities, while decreasing relative conductivity and the reactive oxygen species level. Further, the ratio of alternate respiration to the total respiration in plants that overexpressed ChAOX2 was significantly higher than that in wild-type and mutant plants under salt stress. These results indicate that ChAOX2 plays a key role in salt tolerance.
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Keep Calm and Survive: Adaptation Strategies to Energy Crisis in Fruit Trees under Root Hypoxia. PLANTS 2020; 9:plants9091108. [PMID: 32867316 PMCID: PMC7570223 DOI: 10.3390/plants9091108] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 08/19/2020] [Accepted: 08/22/2020] [Indexed: 01/05/2023]
Abstract
Plants are permanently facing challenges imposed by the environment which, in the context of the current scenario of global climate change, implies a constant process of adaptation to survive and even, in the case of crops, at least maintain yield. O2 deficiency at the rhizosphere level, i.e., root hypoxia, is one of the factors with the greatest impact at whole-plant level. At cellular level, this O2 deficiency provokes a disturbance in the energy metabolism which has notable consequences on the yield of plant crops. In this sense, although several physiological studies describe processes involved in plant adaptation to root hypoxia in woody fruit trees, with emphasis on the negative impacts on photosynthetic rate, there are very few studies that include -omics strategies for specifically understanding these processes in the roots of such species. Through a de novo assembly approach, a comparative transcriptome study of waterlogged Prunus spp. genotypes contrasting in their tolerance to root hypoxia was revisited in order to gain a deeper insight into the reconfiguration of pivotal pathways involved in energy metabolism. This re-analysis describes the classically altered pathways seen in the roots of woody fruit trees under hypoxia, but also routes that link them to pathways involved with nitrogen assimilation and the maintenance of cytoplasmic pH and glycolytic flow. In addition, the effects of root hypoxia on the transcription of genes related to the mitochondrial oxidative phosphorylation system, responsible for providing adenosine triphosphate (ATP) to the cell, are discussed in terms of their roles in the energy balance, reactive oxygen species (ROS) metabolism and aerenchyma formation. This review compiles key findings that help to explain the trait of tolerance to root hypoxia in woody fruit species, giving special attention to their strategies for managing the energy crisis. Finally, research challenges addressing less-explored topics in recovery and stress memory in woody fruit trees are pointed out.
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Liu Y, Gong Q, He J, Sun X, Li X, Zhao S, Meng Q, Lin H, Zhou H. PpAOX regulates ER stress tolerance in Physcomitrella patens. JOURNAL OF PLANT PHYSIOLOGY 2020; 251:153218. [PMID: 32559711 DOI: 10.1016/j.jplph.2020.153218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/29/2020] [Accepted: 05/31/2020] [Indexed: 06/11/2023]
Abstract
Severe environments disturb the folding or assembly of newly synthesized proteins, resulting in accumulation of misfolded or unfolded proteins in the endoplasmic reticulum (ER) as well as cytotoxic aggregation of abnormal proteins. Therefore, ER stress is evoked due to disturbed ER homeostasis. Alternative oxidase (AOX) plays an important role in coping with various abiotic stresses and plant growth. Our previous study has reported that PpAOX is involved in the regulation of salt tolerance in moss Physcomitrella patens (P. patens), but its biological functions in modulating ER stress remain unknown. Here we report that the gametophyte of P. patens displays severe growth inhibition and developmental deficiency under tunicamycin (Tm, an elicitor of ER stress)-induced ER stress conditions. PpAOX and selected ER stress response-like genes in P. patens were induced under Tm treatment. PpAOX knockout (PpAOX KO) plants exhibited decreased resistance to Tm-induced ER stress, whereas PpAOX-overexpressing lines (PpAOX OX) plants were more tolerant to Tm-induced ER stress. Data showed that PpAOX contributes to redox homeostasis under Tm treatment. In addition, we observed that PpAOX completely restores the Tm-sensitive phenotype of Arabidopsis AOX1a mutant (Ataox1a). Taken together, our work reveals a functional link between PpAOX and ER stress tolerance regulation in P. patens.
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Affiliation(s)
- Yunhong Liu
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Qianyuan Gong
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Jiaxian He
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Xia Sun
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Xiaochuan Li
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Shuangshuang Zhao
- Key Laboratory of Plant Stress, Life Science College, Shandong Normal University, Jinan 250014, China
| | - Qingwei Meng
- State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Tai'an, 271018, China
| | - Honghui Lin
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Huapeng Zhou
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China.
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Gong Q, Li S, Zheng Y, Duan H, Xiao F, Zhuang Y, He J, Wu G, Zhao S, Zhou H, Lin H. SUMOylation of MYB30 enhances salt tolerance by elevating alternative respiration via transcriptionally upregulating AOX1a in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:1157-1171. [PMID: 31951058 DOI: 10.1111/tpj.14689] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/28/2019] [Accepted: 01/07/2020] [Indexed: 05/27/2023]
Abstract
Salt stress reduces crop growth and productivity globally. Here we report that a R2R3-MYB transcription factor MYB30 participates in salt tolerance in Arabidopsis. MYB30 can be SUMOylated by SIZ1 in response to salt stress and the lysine (K)283 of MYB30 is essential for its SUMOylation. In contrast to wild-type MYB30, the MYB30K283R mutant failed to rescue the salt-sensitive phenotype of the myb30-2 mutant, indicating that SUMOylation of MYB30 is required for the salt-stress response. Through transcriptomic analysis, we identified a MYB30 target, alternative oxidase 1a (AOX1a). MYB30 binds the promoter of AOX1a and upregulates its expression in response to salt stress; however, MYB30K283R cannot bind the promoter of AOX1a. The cyanide (CN)-resistant alternative respiration (Alt) mediated by AOX is significantly reduced in the myb30-2 mutant through the loss of function of MYB30. As a result, the redox homeostasis is disrupted in the myb30-2 mutant compared with that in wild-type seedlings (WT) under salt conditions. The artificial elimination of excess reactive oxygen species partially rescues the salt-sensitive phenotype of the myb30-2 mutant, whereas after the exogenous application of SHAM, an inhibitor of AOXs and Alt respiration, the salt tolerance of Col-0 and the complemented plants decreased to a level similar to that observed in myb30-2. Finally, overexpression of AOX1a in myb30-2 confers WT-like salt tolerance compared with that of the myb30-2 mutant. Taken together, our results revealed a functional link between MYB30 and AOX1a, and indicated that SIZ1-mediated SUMOylation of MYB30 enhances salt tolerance by regulating Alt respiration and cellular redox homeostasis via AOX1a in Arabidopsis.
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Affiliation(s)
- Qianyuan Gong
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Sha Li
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Yuan Zheng
- Department of Biology, Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, Henan University, Kaifeng, 475004, China
| | - Hongqin Duan
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Fei Xiao
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Yufen Zhuang
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Jiaxian He
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Guochun Wu
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Shuangshuang Zhao
- Key Laboratory of Plant Stress, Life Science College, Shandong Normal University, Jinan, 250014, China
| | - Huapeng Zhou
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Honghui Lin
- Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
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Farooq MA, Niazi AK, Akhtar J, Farooq M, Souri Z, Karimi N, Rengel Z. Acquiring control: The evolution of ROS-Induced oxidative stress and redox signaling pathways in plant stress responses. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2019; 141:353-369. [PMID: 31207496 DOI: 10.1016/j.plaphy.2019.04.039] [Citation(s) in RCA: 157] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 04/23/2019] [Accepted: 04/30/2019] [Indexed: 05/18/2023]
Abstract
Reactive oxygen species (ROS) - the byproducts of aerobic metabolism - influence numerous aspects of the plant life cycle and environmental response mechanisms. In plants, ROS act like a double-edged sword; they play multiple beneficial roles at low concentrations, whereas at high concentrations ROS and related redox-active compounds cause cellular damage through oxidative stress. To examine the dual role of ROS as harmful oxidants and/or crucial cellular signals, this review elaborates that (i) how plants sense and respond to ROS in various subcellular organelles and (ii) the dynamics of subsequent ROS-induced signaling processes. The recent understanding of crosstalk between various cellular compartments in mediating their redox state spatially and temporally is discussed. Emphasis on the beneficial effects of ROS in maintaining cellular energy homeostasis, regulating diverse cellular functions, and activating acclimation responses in plants exposed to abiotic and biotic stresses are described. The comprehensive view of cellular ROS dynamics covering the breadth and versatility of ROS will contribute to understanding the complexity of apparently contradictory ROS roles in plant physiological responses in less than optimum environments.
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Affiliation(s)
- Muhammad Ansar Farooq
- Institute of Soil & Environmental Sciences, University of Agriculture, Faisalabad, Pakistan.
| | - Adnan Khan Niazi
- Center of Agricultural Biochemistry and Biotechnology, University of Agriculture, Faisalabad, Pakistan
| | - Javaid Akhtar
- Institute of Soil & Environmental Sciences, University of Agriculture, Faisalabad, Pakistan
| | - Muhammad Farooq
- Department of Crop Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Oman
| | - Zahra Souri
- Laboratory of Plant Physiology, Department of Biology, Faculty of Science, Razi University, Kermanshah, Iran
| | - Naser Karimi
- Laboratory of Plant Physiology, Department of Biology, Faculty of Science, Razi University, Kermanshah, Iran
| | - Zed Rengel
- School of Agriculture and Environment, University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
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Pham HM, Kebede H, Ritchie G, Trolinder N, Wright RJ. Alternative oxidase (AOX) over-expression improves cell expansion and elongation in cotton seedling exposed to cool temperatures. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2018; 131:2287-2298. [PMID: 30069595 DOI: 10.1007/s00122-018-3151-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/23/2018] [Indexed: 06/08/2023]
Abstract
KEY MESSAGE Evidence that supports a relation between AOX expression and improvement in plant height, internode length, and total leaf area under cool temperature is shown. Cell expansion and elongation appear to be enhanced when AOX expression was increased. Cotton growth is sensitive to cool temperature during germination and early seedling development. Delayed emergence, seedling damage, and increased risk to disease are common. Late seasonal cool weather is a major factor limiting the consistent production of high-quality cotton lint in West Texas. Alternative oxidase functions in the inner membrane of the mitochondria via an alternative respiration pathway and serves as a multifunctional system for amelioration of abiotic and biotic stresses. Cotton seedling emergence and growth exposed to cool temperatures was examined in plants with enhanced AOX expression. Thirteen T1 seed lines showed 3 to 1 segregation for the T-DNA containing the tobacco AOX1 gene. Two over-expressing, single-copy, homozygous AOX lines (94-20T and 66-6T) and Null line (94-3N) were selected for examination. The transcript levels were ≈ 2 to 6 fold higher in the AOX lines compared to those of the Null line and wild-type in stem, leaf, root and boll tissues. The research examined the hypothesis that transgenic cotton with enhanced AOX expression will have enhanced growth traits under suboptimal cool temperatures. Improved plant height, internode length, plant height and internode length from second node, and total leaf area under cool temperatures were observed in AOX over-expression lines. This may be attributed to improved cell expansion and elongation characteristics in the AOX line.
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Affiliation(s)
- Hanh M Pham
- Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, 79409, USA
| | - Hirut Kebede
- Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, 79409, USA
| | - Glen Ritchie
- Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, 79409, USA
| | - Norma Trolinder
- Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, 79409, USA
| | - Robert J Wright
- Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, 79409, USA.
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Gupta KJ, Kumari A, Florez-Sarasa I, Fernie AR, Igamberdiev AU. Interaction of nitric oxide with the components of the plant mitochondrial electron transport chain. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:3413-3424. [PMID: 29590433 DOI: 10.1093/jxb/ery119] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 03/20/2018] [Indexed: 05/03/2023]
Abstract
Mitochondria are not only major sites for energy production but also participate in several alternative functions, among these generation of nitric oxide (NO), and its different impacts on this organelle, is receiving increasing attention. The inner mitochondrial membrane contains the chain of protein complexes, and electron transfer via oxidation of various organic acids and reducing equivalents leads to generation of a proton gradient that results in energy production. Recent evidence suggests that these complexes are sources and targets for NO. Complex I and rotenone-insensitive NAD(P)H dehydrogenases regulate hypoxic NO production, while complex I also participates in the formation of a supercomplex with complex III under hypoxia. Complex II is a target for NO which, by inhibiting Fe-S centres, regulates reactive oxygen species (ROS) generation. Complex III is one of the major sites for NO production, and the produced NO participates in the phytoglobin-NO cycle that leads to the maintenance of the redox level and limited energy production under hypoxia. Expression of the alternative oxidase (AOX) is induced by NO under various stress conditions, and evidence exists that AOX can regulate mitochondrial NO production. Complex IV is another major site for NO production, which can also be linked to ATP generation via the phytoglobin-NO cycle. Inhibition of complex IV by NO can prevent oxygen depletion at the frontier of anoxia. The NO production and action on various complexes play a major role in NO signalling and energy metabolism.
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Affiliation(s)
| | - Aprajita Kumari
- National Institute for Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - Igor Florez-Sarasa
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
- Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Abir U Igamberdiev
- Department of Biology, Memorial University of Newfoundland, St. John's, NL, A1B, Canada
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Samuilov VD, Kiselevsky DB. Salicylhydroxamic acid enhances the NADH-oxidase activity of peroxidase in pea mitochondrial and chloroplast suspensions. ACTA ACUST UNITED AC 2016. [DOI: 10.3103/s0096392516010089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Nogales A, Nobre T, Cardoso HG, Muñoz-Sanhueza L, Valadas V, Campos MD, Arnholdt-Schmitt B. Allelic variation on DcAOX1 gene in carrot (Daucus carota L.): An interesting simple sequence repeat in a highly variable intron. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.plgene.2015.11.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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13
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Samuilov VD, Kiselevsky DB. Effect of cationic plastoquinone SkQ1 on electron transfer reactions in chloroplasts and mitochondria from pea seedlings. BIOCHEMISTRY. BIOKHIMIIA 2015; 80:417-23. [PMID: 25869358 DOI: 10.1134/s0006297915040045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Plastoquinone bound with decyltriphenylphosphonium cation (SkQ1) penetrating through the membrane in nanomolar concentrations inhibited H2O2 generation in cells of epidermis of pea seedling leaves that was detected by the fluorescence of 2',7'-dichlorofluorescein. Photosynthetic electron transfer in chloroplasts isolated from pea leaves is suppressed by SkQ1 at micromolar concentrations: the electron transfer in chloroplasts under the action of photosystem II or I (with silicomolybdate or methyl viologen as electron acceptors, respectively) is more sensitive to SkQ1 than under the action of photosystem II + I (with ferricyanide or p-benzoquinone as electron acceptors). SkQ1 reduced by borohydride is oxidized by ferricyanide, p-benzoquinone, and, to a lesser extent, by silicomolybdate, but not by methyl viologen. SkQ1 is not effective as an electron acceptor supporting O2 evolution from water in illuminated chloroplasts. The data on suppression of photosynthetic O2 evolution or consumption show that SkQ1, similarly to phenazine methosulfate, causes conversion of the chloroplast redox-chain from non-cyclic electron transfer mode to the cyclic mode without O2 evolution. Oxidation of NADH or succinate in mitochondria isolated from pea roots is stimulated by SkQ1.
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Affiliation(s)
- V D Samuilov
- Lomonosov Moscow State University, Faculty of Biology, Moscow, 119991, Russia.
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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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15
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Physiological uncoupling of mitochondrial oxidative phosphorylation. Studies in different yeast species. J Bioenerg Biomembr 2011; 43:323-31. [PMID: 21556887 DOI: 10.1007/s10863-011-9356-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Under non-phosphorylating conditions a high proton transmembrane gradient inhibits the rate of oxygen consumption mediated by the mitochondrial respiratory chain (state IV). Slow electron transit leads to production of reactive oxygen species (ROS) capable of participating in deleterious side reactions. In order to avoid overproducing ROS, mitochondria maintain a high rate of O(2) consumption by activating different exquisitely controlled uncoupling pathways. Different yeast species possess one or more uncoupling systems that work through one of two possible mechanisms: i) Proton sinks and ii) Non-pumping redox enzymes. Proton sinks are exemplified by mitochondrial unspecific channels (MUC) and by uncoupling proteins (UCP). Saccharomyces. cerevisiae and Debaryomyces hansenii express highly regulated MUCs. Also, a UCP was described in Yarrowia lipolytica which promotes uncoupled O(2) consumption. Non-pumping alternative oxido-reductases may substitute for a pump, as in S. cerevisiae or may coexist with a complete set of pumps as in the branched respiratory chains from Y. lipolytica or D. hansenii. In addition, pumps may suffer intrinsic uncoupling (slipping). Promising models for study are unicellular parasites which can turn off their aerobic metabolism completely. The variety of energy dissipating systems in eukaryote species is probably designed to control ROS production in the different environments where each species lives.
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16
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Kruse J, Rennenberg H, Adams MA. Steps towards a mechanistic understanding of respiratory temperature responses. THE NEW PHYTOLOGIST 2011; 189:659-677. [PMID: 21223283 DOI: 10.1111/j.1469-8137.2010.03576.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Temperature crucially affects the speed of metabolic processes in poikilotherm organisms, including plants. The instantaneous temperature responses of O(2)-reduction and CO(2)-release can be approximated by Arrhenius kinetics, even though respiratory gas exchange of plants is the net effect of many constituent biochemical processes. Nonetheless, the classical Arrhenius equation must be modified to account for a dynamic response to measurement temperatures. We show that this dynamic response is readily explained by combining Arrhenius and Michaelis-Menten kinetics, as part of a fresh appraisal of metabolic interpretations of instantaneous temperature responses. In combination with recent experimental findings, we argue that control of mitochondrial electron flow is shared among cytochrome oxidase and alternative oxidase under in vivo conditions, and is continuously coordinated. In this way, upstream carbohydrate metabolism and downstream electron transport appear to be optimized according to the demand of ATP, TCA-cycle intermediates and anabolic reducing power under differing metabolic states. We provide a link to the 'Growth and Maintenance Paradigm' of respiration and argue that respiratory temperature responses can be used as a tool to probe metabolic states of plant tissue, such that we can learn more about the mechanisms that govern longer-term acclimatization responses of plant metabolism.
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Affiliation(s)
- Jörg Kruse
- Institute of Forest Botany, Chair of Tree Physiology, Albert-Ludwigs-University Freiburg, Georges-Koehler-Allee 53-54, D-79110 Freiburg, Germany
| | - Heinz Rennenberg
- Institute of Forest Botany, Chair of Tree Physiology, Albert-Ludwigs-University Freiburg, Georges-Koehler-Allee 53-54, D-79110 Freiburg, Germany
| | - Mark A Adams
- Faculty of Agriculture, Food and Natural Resources, The University of Sydney, Sydney, NSW 2006, Australia
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17
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Sanz A, Fernández-Ayala DJM, Stefanatos RK, Jacobs HT. Mitochondrial ROS production correlates with, but does not directly regulate lifespan in Drosophila. Aging (Albany NY) 2010; 2:200-23. [PMID: 20453260 PMCID: PMC2880708 DOI: 10.18632/aging.100137] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 04/12/2010] [Indexed: 11/25/2022]
Abstract
The Mitochondrial Free Radical Theory of Aging (MFRTA) is currently one of the most widely accepted theories used to explain aging. From MFRTA three basic predictions can be made: long-lived individuals or species should produce fewer mitochondrial Reactive Oxygen Species (mtROS) than short-lived individuals or species; a decrease in mtROS production will increase lifespan; and an increase in mtROS production will decrease lifespan. It is possible to add a further fourth prediction: if ROS is controlling longevity separating these parameters through selection would be impossible. These predictions have been tested in Drosophila melanogaster. Firstly, we studied levels of mtROS production and lifespan of three wild-type strains of Drosophila, Oregon R, Canton S and Dahomey. Oregon R flies live the longest and produce significantly fewer mtROS than both Canton S and Dahomey. These results are therefore in accordance with the first prediction. A new transgenic Drosophila model expressing the Ciona intestinalis Alternative Oxidase (AOX) was used to test the second prediction. In fungi and plants, AOX expression regulates both free radical production and lifespan. In Drosophila, AOX expression decreases mtROS production, but does not increase lifespan. This result contradicts the second prediction of MFRTA. The third prediction was tested in flies mutant for the gene dj-1beta. These flies are characterized by an age-associated decline in locomotor function and increased levels of mtROS production. Nevertheless, dj-1beta mutant flies do not display decreased lifespan, which again is in contradiction with MFRTA. In our final experiment we utilized flies with DAH mitochondrial DNA in an OR nuclear background, and OR mitochondrial DNA in DAH nuclear background. From this, Mitochondrial DNA does not control free radical production, but it does determine longevity of females independently of mtROS production. In summary, these results do not systematically support the predictions of the MFRTA. Accordingly, MFRTA should be revised to accommodate these findings.
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Affiliation(s)
- Alberto Sanz
- Institute of Medical Technology and Tampere University Hospital, FI-33014 University of Tampere, Finland.
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18
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Vasil'ev LA, Dzyubinskaya EV, Zinovkin RA, Kiselevsky DB, Lobysheva NV, Samuilov VD. Chitosan-induced programmed cell death in plants. BIOCHEMISTRY. BIOKHIMIIA 2009; 74:1035-43. [PMID: 19916915 DOI: 10.1134/s0006297909090120] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Chitosan, CN(-), or H(2)O(2) caused the death of epidermal cells (EC) in the epidermis of pea leaves that was detected by monitoring the destruction of cell nuclei; chitosan induced chromatin condensation and marginalization followed by the destruction of EC nuclei and subsequent internucleosomal DNA fragmentation. Chitosan did not affect stoma guard cells (GC). Anaerobic conditions prevented the chitosan-induced destruction of EC nuclei. The antioxidants nitroblue tetrazolium or mannitol suppressed the effects of chitosan, H(2)O(2), or chitosan + H(2)O(2) on EC. H(2)O(2) formation in EC and GC mitochondria that was determined from 2',7'-dichlorofluorescein fluorescence was inhibited by CN(-) and the protonophoric uncoupler carbonyl cyanide m-chlorophenylhydrazone but was stimulated by these agents in GC chloroplasts. The alternative oxidase inhibitors propyl gallate and salicylhydroxamate prevented chitosan- but not CN(-)-induced destruction of EC nuclei; the plasma membrane NADPH oxidase inhibitors diphenylene iodonium and quinacrine abolished chitosan- but not CN(-)-induced destruction of EC nuclei. The mitochondrial protein synthesis inhibitor lincomycin removed the destructive effect of chitosan or H(2)O(2) on EC nuclei. The effect of cycloheximide, an inhibitor of protein synthesis in the cytoplasm, was insignificant; however, it was enhanced if cycloheximide was added in combination with lincomycin. The autophagy inhibitor 3-methyladenine removed the chitosan effect but exerted no influence on the effect of H(2)O(2) as an inducer of EC death. The internucleosome DNA fragmentation in conjunction with the data on the 3-methyladenine effect provides evidence that chitosan induces programmed cell death that follows a combined scenario including apoptosis and autophagy. Based on the results of an inhibitor assay, chitosan-induced EC death involves reactive oxygen species generated by the NADPH oxidase of the plasma membrane.
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Affiliation(s)
- L A Vasil'ev
- Biological Faculty, Lomonosov Moscow State University, Moscow, 119991, Russia
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19
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Petrussa E, Casolo V, Peresson C, Krajnáková J, Macrì F, Vianello A. Activity of a KATP+ channel in Arum spadix mitochondria during thermogenesis. JOURNAL OF PLANT PHYSIOLOGY 2008; 165:1360-9. [PMID: 18177980 DOI: 10.1016/j.jplph.2007.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Accepted: 10/06/2007] [Indexed: 05/19/2023]
Abstract
This report demonstrates that mitochondria isolated from thermogenic Arum spadices possess an ATP-sensitive potassium channel--responsible for electrical potential (DeltaPsi) collapse and mitochondrial swelling--whose characteristics are similar to those previously described in pea and wheat mitochondria. In order to study the relationship between this K(ATP)(+) channel and the uncoupled respiration, linked to thermogenesis, K(+) transport activities were compared with those of mitochondria that were isolated from pea stems, soybean suspension cell cultures and Arum tubers. The channel from Arum spadices is highly active and its major features are (i) potassium flux is performed primarily in an inward-rectifying manner; (ii) the influx of K(+) is associated with a matrix volume increase in both energized and non-energized mitochondria; and (iii) its activity depends on the redox state of electron transport chain (ETC) and oxygen availability. In particular, this paper shows that the K(ATP)(+) channel is inwardly activated in parallel with the alternative oxidase (AO). The activation is linked to an ETC-oxidized state and to high oxygen consumption. The putative role of this K(ATP)(+) channel is discussed in relation to flowering of thermogenic Arum spadices.
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Affiliation(s)
- Elisa Petrussa
- Department of Biology and Plant Protection, Section of Plant Biology, University of Udine, Udine, Italy
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20
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Armstrong AF, Badger MR, Day DA, Barthet MM, Smith PMC, Millar AH, Whelan J, Atkin OK. Dynamic changes in the mitochondrial electron transport chain underpinning cold acclimation of leaf respiration. PLANT, CELL & ENVIRONMENT 2008; 31:1156-1169. [PMID: 18507806 DOI: 10.1111/j.1365-3040.2008.01830.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We examined the effect of short- and long-term changes in temperature on gene expression, protein abundance, and the activity of the alternative oxidase and cytochrome oxidase pathways (AOP and COP, respectively) in Arabidopsis thaliana. The AOP was more sensitive to short-term changes in temperature than the COP, with partitioning to the AOP decreasing significantly below a threshold temperature of 20 degrees C. AOP activity was increased in leaves, which had been shifted to the cold for several days, but this response was transient, with AOP activity subsiding (and COP activity increasing) following the development of leaves in the cold. The transient increase in AOP activity in 10-d cold-shifted leaves was not associated with an increase in alternative oxidase (AOX) protein or AOX1a transcript abundance. By contrast, the amount of uncoupling protein was significantly increased in cold-developed leaves. In conjunction with this, transcript levels of the uncoupling protein-encoding gene UCP1 and the external NAD(P)H dehydrogenase-encoding gene NDB2 exhibited sustained increases following growth in the cold. The data suggest a role for each of these alternative non-phosphorylating bypasses of mitochondrial electron transport at different points in time following exposure to cold, with increased AOP activity being important only in the early stages of cold treatment.
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Affiliation(s)
- Anna F Armstrong
- Department of Biology, University of York, PO Box 373, York, YO10 5YW, UK
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21
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Wagner AM, Krab K, Wagner MJ, Moore AL. Regulation of thermogenesis in flowering Araceae: the role of the alternative oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:993-1000. [PMID: 18440298 DOI: 10.1016/j.bbabio.2008.04.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2008] [Revised: 03/31/2008] [Accepted: 04/01/2008] [Indexed: 11/24/2022]
Abstract
The inflorescences of several members of the Arum lily family warm up during flowering and are able to maintain their temperature at a constant level, relatively independent of the ambient temperature. The heat is generated via a mitochondrial respiratory pathway that is distinct from the cytochrome chain and involves a cyanide-resistant alternative oxidase (AOX). In this paper we have used flux control analysis to investigate the influence of temperature on the rate of respiration through both cytochrome and alternative oxidases in mitochondria isolated from the appendices of intact thermogenic Arum maculatum inflorescences. Results are presented which indicate that at low temperatures, the dehydrogenases are almost in full control of respiration but as the temperature increases flux control shifts to the AOX. On the basis of these results a simple model of thermoregulation is presented that is applicable to all species of thermogenic plants. The model takes into account the temperature characteristics of the separate components of the plant mitochondrial respiratory chain and the control of each process. We propose that 1) in all aroid flowers AOX assumes almost complete control over respiration, 2) the temperature profile of AOX explains the reversed relationship between ambient temperature and respiration in thermoregulating Arum flowers, 3) the thermoregulation process is the same in all species and 4) variations in inflorescence temperatures can easily be explained by variations in AOX protein concentrations.
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Affiliation(s)
- Anneke M Wagner
- Institute of Molecular Cell Biology, VU Universiteit, de Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
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22
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Delpérée C, Lutts S. Growth inhibition occurs independently of cell mortality in tomato (Solanum lycopersicum) exposed to high cadmium concentrations. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2008; 50:300-310. [PMID: 18713362 DOI: 10.1111/j.1744-7909.2007.00625.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In order to analyze the adaptation potential of tomato shoots to a sudden increase in Cd concentration, tomato plants (Solanum lycopersicum L. var. Ailsa Craig) were exposed under controlled environmental conditions to a high dose of this heavy metal (250 microM CdCl2) in nutrient solution for 7 and 14 d. Both root and shoot growth was completely inhibited but all plants remained alive until the end of the treatment. Cell viability remained unaffected but the activity of the mitochondrial alternative pathway was stimulated by Cd stress at the expense of the cytochrome pathway. Cadmium concentration was higher in roots than in shoots and a decrease in the rate of net Cd translocation was noticed during the second week of stress. Cadmium decreased both leaf conductance (g(l)) and chlorophyll concentration. However, the effect on net CO2 assimilation remained limited and soluble sugars accumulated in leaves. Photochemical efficiency of PSII (Fv/Fm) was not affected despite a decrease in the number of reaction centers and an inhibition of electron transfer to acceptors of PSII. It is concluded that tomato shoot may sustain short term exposure to high doses of cadmium despite growth inhibition. This property implies several physiological strategies linked to both avoidance and tolerance mechanisms.
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Affiliation(s)
- Christine Delpérée
- (Unité de Biologie végétale, Université catholique de Louvain, 5 (Bte 13) Place Croix du Sud, 1348 Louvain-la-Neuve, Belgium)
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23
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Onda Y, Kato Y, Abe Y, Ito T, Ito-Inaba Y, Morohashi M, Ito Y, Ichikawa M, Matsukawa K, Otsuka M, Koiwa H, Ito K. Pyruvate-sensitive AOX exists as a non-covalently associated dimer in the homeothermic spadix of the skunk cabbage, Symplocarpus renifolius. FEBS Lett 2007; 581:5852-8. [PMID: 18060878 DOI: 10.1016/j.febslet.2007.11.061] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 11/20/2007] [Accepted: 11/20/2007] [Indexed: 11/25/2022]
Abstract
The cyanide-resistant alternative oxidase (AOX) is a homodimeric protein whose activity can be regulated by the oxidation/reduction state and by alpha-keto acids. To further clarify the role of AOX in the skunk cabbage, Symplocarpus renifolius, we have performed expression and functional analyses of the encoding gene. Among the various tissues in the skunk cabbage, SrAOX transcripts were found to be specifically expressed in the thermogenic spadix. Moreover, our data demonstrate that the SrAOX protein exists as a non-covalently associated dimer in the thermogenic spadix, and is more sensitive to pyruvate than to other carboxylic acids. Our results suggest that the pyruvate-mediated modification of SrAOX activity plays a significant role in thermoregulation in the skunk cabbage.
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Affiliation(s)
- Yoshihiko Onda
- United Graduate School of Agricultural Science, Iwate University, Ueda, Morioka, Iwate 020 8550, Japan
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24
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Gomez-Casanovas N, Blanc-Betes E, Gonzalez-Meler MA, Azcon-Bieto J. Changes in respiratory mitochondrial machinery and cytochrome and alternative pathway activities in response to energy demand underlie the acclimation of respiration to elevated CO2 in the invasive Opuntia ficus-indica. PLANT PHYSIOLOGY 2007; 145:49-61. [PMID: 17660349 PMCID: PMC1976584 DOI: 10.1104/pp.107.103911] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Accepted: 07/11/2007] [Indexed: 05/07/2023]
Abstract
Studies on long-term effects of plants grown at elevated CO(2) are scarce and mechanisms of such responses are largely unknown. To gain mechanistic understanding on respiratory acclimation to elevated CO(2), the Crassulacean acid metabolism Mediterranean invasive Opuntia ficus-indica Miller was grown at various CO(2) concentrations. Respiration rates, maximum activity of cytochrome c oxidase, and active mitochondrial number consistently decreased in plants grown at elevated CO(2) during the 9 months of the study when compared to ambient plants. Plant growth at elevated CO(2) also reduced cytochrome pathway activity, but increased the activity of the alternative pathway. Despite all these effects seen in plants grown at high CO(2), the specific oxygen uptake rate per unit of active mitochondria was the same for plants grown at ambient and elevated CO(2). Although decreases in photorespiration activity have been pointed out as a factor contributing to the long-term acclimation of plant respiration to growth at elevated CO(2), the homeostatic maintenance of specific respiratory rate per unit of mitochondria in response to high CO(2) suggests that photorespiratory activity may play a small role on the long-term acclimation of respiration to elevated CO(2). However, despite growth enhancement and as a result of the inhibition in cytochrome pathway activity by elevated CO(2), total mitochondrial ATP production was decreased by plant growth at elevated CO(2) when compared to ambient-grown plants. Because plant growth at elevated CO(2) increased biomass but reduced respiratory machinery, activity, and ATP yields while maintaining O(2) consumption rates per unit of mitochondria, we suggest that acclimation to elevated CO(2) results from physiological adjustment of respiration to tissue ATP demand, which may not be entirely driven by nitrogen metabolism as previously suggested.
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Affiliation(s)
- Nuria Gomez-Casanovas
- Unitat de Fisiologia Vegetal, Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain 08028.
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25
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Costa JH, Jolivet Y, Hasenfratz-Sauder MP, Orellano EG, da Guia Silva Lima M, Dizengremel P, Fernandes de Melo D. Alternative oxidase regulation in roots of Vigna unguiculata cultivars differing in drought/salt tolerance. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:718-27. [PMID: 16716451 DOI: 10.1016/j.jplph.2006.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Accepted: 04/05/2006] [Indexed: 05/09/2023]
Abstract
The alternative oxidase (Aox) was studied at different levels (transcript, protein and capacity) in response to an osmotic shock applied to roots of cowpea (Vigna unguiculata). Two cultivars of V. unguiculata were used, Vita 3 and Vita 5, tolerant and sensitive to drought/saline stress respectively. The seedlings (17-day-old) were grown in hydroponic conditions and submitted to NaCl (100 and 200 mM) or 200.67 g L(-1) PEG 6000 (iso-osmotic condition to 100 mM NaCl). The VuAox1 and VuAox2a mRNA were not detected in either cultivar under all tested conditions while the VuAox2b gene was differently expressed. In the tolerant cultivar (Vita 3), the expression of VuAox2b gene was stimulated by an osmotic stress induced by PEG which was associated with a higher amount and capacity of the Aox protein. In the same cultivar, this gene was under-expressed in salt stress conditions with poor effect on the protein level. In the sensitive cultivar (Vita 5), the transcript level of the VuAox2b was unchanged in response to PEG treatment, even though the protein and the capacity tended to increase. Upon salt stress, the VuAox2b gene was over-expressed. At 100mM NaCl, this VuAox2b gene over-expression led to a higher amount and capacity of Aox. This effect was reduced at 200 mM NaCl. Overall, these results suggest complex mechanisms (transcriptional, translational and post-translational) for Aox regulation in response to osmotic stress.
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Affiliation(s)
- José Hélio Costa
- Department of Biochemistry and Molecular Biology, Federal University of Ceará, P.O. Box 6029, 60455-760 Fortaleza Ceará, Brazil
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26
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Rhoads DM, Umbach AL, Subbaiah CC, Siedow JN. Mitochondrial reactive oxygen species. Contribution to oxidative stress and interorganellar signaling. PLANT PHYSIOLOGY 2006; 141:357-66. [PMID: 16760488 PMCID: PMC1475474 DOI: 10.1104/pp.106.079129] [Citation(s) in RCA: 279] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Revised: 03/24/2006] [Accepted: 03/27/2006] [Indexed: 05/10/2023]
Affiliation(s)
- David M Rhoads
- School of Life Sciences, Arizona State University, Tempe, 85287-4501, USA.
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27
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Watling JR, Robinson SA, Seymour RS. Contribution of the alternative pathway to respiration during thermogenesis in flowers of the sacred lotus. PLANT PHYSIOLOGY 2006; 140:1367-73. [PMID: 16461386 PMCID: PMC1435819 DOI: 10.1104/pp.105.075523] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 01/19/2006] [Accepted: 01/20/2006] [Indexed: 05/06/2023]
Abstract
We report results from in vivo measurements, using oxygen isotope discrimination techniques, of fluxes through the alternative and cytochrome respiratory pathways in thermogenic plant tissue, the floral receptacle of the sacred lotus (Nelumbo nucifera). Fluxes through both pathways were measured in thermoregulating flowers undergoing varying degrees of thermogenesis in response to ambient temperature. Significant increases in alternative pathway flux were found in lotus receptacles with temperatures 16 degrees C to 20 degrees C above ambient, but not in those with lesser amounts of heating. Alternative pathway flux in the hottest receptacles was 75% of the total respiratory flux. In contrast, fluxes through the cytochrome pathway did not change significantly during thermogenesis. These data support the hypothesis that increased flux through the alternative pathway is responsible for heating in the lotus and that it is unlikely that uncoupling proteins, which would have produced increased fluxes through the cytochrome pathway, contribute significantly to heating in this tissue. Comparisons of actual flux, with capacity determined using inhibitors, suggested that the alternative pathway was operating at close to maximum capacity in heating tissues of lotus. However, in nonheating tissues the inhibitor data significantly overestimated the alternative pathway flux. This confirms that isotopic measurements are necessary for accurate determination of fluxes through the two pathways.
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Affiliation(s)
- Jennifer R Watling
- School of Earth and Environmental Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
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28
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Jiang K, Ballinger T, Li D, Zhang S, Feldman L. A role for mitochondria in the establishment and maintenance of the maize root quiescent center. PLANT PHYSIOLOGY 2006; 140:1118-25. [PMID: 16443698 PMCID: PMC1400572 DOI: 10.1104/pp.105.071977] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Mitochondria in the oxidizing environment of the maize (Zea mays) root quiescent center (QC) are altered in function, but otherwise structurally normal. Compared to mitochondria in the adjacent, rapidly dividing cells of the proximal root tissues, mitochondria in the QC show marked reductions in the activities of tricarboxylic acid cycle enzymes. Pyruvate dehydrogenase activity was not detected in the QC. Use of several mitochondrial membrane potential (DeltaPsi(m)) sensing probes indicated a depolarization of the mitochondrial membrane in the QC, which suggests a reduction in the capacity of QC mitochondria to generate ATP and NADH. We postulate that modifications of mitochondrial function are central to the establishment and maintenance of the QC.
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Affiliation(s)
- Keni Jiang
- Department of Plant and Microbial Biology, University of California, Berkeley, 94720, USA
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29
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Shen W, Wei Y, Dauk M, Tan Y, Taylor DC, Selvaraj G, Zou J. Involvement of a glycerol-3-phosphate dehydrogenase in modulating the NADH/NAD+ ratio provides evidence of a mitochondrial glycerol-3-phosphate shuttle in Arabidopsis. THE PLANT CELL 2006; 18:422-41. [PMID: 16415206 PMCID: PMC1356549 DOI: 10.1105/tpc.105.039750] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
A mitochondrial glycerol-3-phosphate (G-3-P) shuttle that channels cytosolic reducing equivalent to mitochondria for respiration through oxidoreduction of G-3-P has been extensively studied in yeast and animal systems. Here, we report evidence for the operation of such a shuttle in Arabidopsis thaliana. We studied Arabidopsis mutants defective in a cytosolic G-3-P dehydrogenase, GPDHc1, which, based on models described for other systems, functions as the cytosolic component of a G-3-P shuttle. We found that the gpdhc1 T-DNA insertional mutants exhibited increased NADH/NAD+ ratios compared with wild-type plants under standard growth conditions, as well as impaired adjustment of NADH/NAD+ ratios under stress simulated by abscisic acid treatment. The altered redox state of the NAD(H) pool was correlated with shifts in the profiles of metabolites concerning intracellular redox exchange. The impairment in maintaining cellular redox homeostasis was manifest by a higher steady state level of reactive oxygen species under standard growth conditions and by a significantly augmented hydrogen peroxide production under stress. Loss of GPDHc1 affected mitochondrial respiration, particularly through a diminished capacity of the alternative oxidase respiration pathway. We propose a model that outlines potential involvements of a mitochondrial G-3-P shuttle in plant cells for redox homeostasis.
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Affiliation(s)
- Wenyun Shen
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon, Canada, S7N OW9
| | - Yangdou Wei
- Department of Biology, University of Saskatchewan, Saskatoon, Canada, S7N 5E2
| | - Melanie Dauk
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon, Canada, S7N OW9
| | - Yifang Tan
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon, Canada, S7N OW9
| | - David C. Taylor
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon, Canada, S7N OW9
| | - Gopalan Selvaraj
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon, Canada, S7N OW9
| | - Jitao Zou
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon, Canada, S7N OW9
- To whom correspondence should be addressed. E-mail ; fax 306-975-4839
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Shen W, Wei Y, Dauk M, Tan Y, Taylor DC, Selvaraj G, Zou J. Involvement of a glycerol-3-phosphate dehydrogenase in modulating the NADH/NAD+ ratio provides evidence of a mitochondrial glycerol-3-phosphate shuttle in Arabidopsis. THE PLANT CELL 2006. [PMID: 16415206 DOI: 10.1105/tpc.105.039750.similation] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A mitochondrial glycerol-3-phosphate (G-3-P) shuttle that channels cytosolic reducing equivalent to mitochondria for respiration through oxidoreduction of G-3-P has been extensively studied in yeast and animal systems. Here, we report evidence for the operation of such a shuttle in Arabidopsis thaliana. We studied Arabidopsis mutants defective in a cytosolic G-3-P dehydrogenase, GPDHc1, which, based on models described for other systems, functions as the cytosolic component of a G-3-P shuttle. We found that the gpdhc1 T-DNA insertional mutants exhibited increased NADH/NAD+ ratios compared with wild-type plants under standard growth conditions, as well as impaired adjustment of NADH/NAD+ ratios under stress simulated by abscisic acid treatment. The altered redox state of the NAD(H) pool was correlated with shifts in the profiles of metabolites concerning intracellular redox exchange. The impairment in maintaining cellular redox homeostasis was manifest by a higher steady state level of reactive oxygen species under standard growth conditions and by a significantly augmented hydrogen peroxide production under stress. Loss of GPDHc1 affected mitochondrial respiration, particularly through a diminished capacity of the alternative oxidase respiration pathway. We propose a model that outlines potential involvements of a mitochondrial G-3-P shuttle in plant cells for redox homeostasis.
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Affiliation(s)
- Wenyun Shen
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon, Canada, S7N OW9
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Umbach AL, Fiorani F, Siedow JN. Characterization of transformed Arabidopsis with altered alternative oxidase levels and analysis of effects on reactive oxygen species in tissue. PLANT PHYSIOLOGY 2005; 139:1806-20. [PMID: 16299171 PMCID: PMC1310561 DOI: 10.1104/pp.105.070763] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The alternative oxidase (AOX) of plant mitochondria transfers electrons from the ubiquinone pool to oxygen without energy conservation. AOX can use reductant in excess of cytochrome pathway capacity, preventing reactive oxygen species (ROS) formation from an over-reduced ubiquinone pool, and thus may be involved in acclimation to oxidative stresses. The AOX connection with mitochondrial ROS has been investigated only in isolated mitochondria and suspension culture cells. To study ROS and AOX in whole plants, transformed lines of Arabidopsis (Arabidopsis thaliana) were generated: AtAOX1a overexpressors, AtAOX1a anti-sense plants, and overexpressors of a mutated, constitutively active AtAOX1a. In the presence of KCN, leaf tissue of either mutant or wild-type AOX overexpressors showed no increase in oxidative damage, whereas anti-sense lines had levels of damage greater than those observed for untransformed leaves. Similarly, ROS production increased markedly in anti-sense and untransformed, but not overexpressor, roots with KCN treatment. Thus, AOX functions in leaves and roots, as in suspension cells, to ameliorate ROS production when the cytochrome pathway is chemically inhibited. However, in contrast with suspension culture cells, no changes in leaf transcript levels of selected electron transport components or oxidative stress-related enzymes were detected under nonlimiting growth conditions, regardless of transformation type. Further, a microarray study using an anti-sense line showed AOX influences outside mitochondria, particularly in chloroplasts and on several carbon metabolism pathways. These results illustrate the value of expanding AOX transformant studies to whole tissues.
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Affiliation(s)
- Ann L Umbach
- Developmental, Cell, and Molecular Biology Group, Biology Department, Duke University, Durham, North Carolina 27708-1000, USA.
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Fiorani F, Umbach AL, Siedow JN. The alternative oxidase of plant mitochondria is involved in the acclimation of shoot growth at low temperature. A study of Arabidopsis AOX1a transgenic plants. PLANT PHYSIOLOGY 2005; 139:1795-805. [PMID: 16299170 PMCID: PMC1310560 DOI: 10.1104/pp.105.070789] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The alternative oxidase (AOX) pathway of plant mitochondria uncouples respiration from mitochondrial ATP production and may ameliorate plant performance under stressful environmental conditions, such as cold temperatures, by preventing excess accumulation of reactive oxygen species. We tested this model in whole tissues by growing AtAOX1a-transformed Arabidopsis (Arabidopsis thaliana) plants at 12 degrees C. For the first time, to our knowledge, in plants genetically engineered for AOX, we identified a vegetative shoot growth phenotype. Compared with wild type at day 21 after sowing, anti-sense and overexpressing lines showed, on average, 27% reduced leaf area and 25% smaller rosettes versus 30% increased leaf area and 33% larger rosette size, respectively. Lines overexpressing a mutated, constitutively active AOX1a showed smaller phenotypic effects. These phenotypic differences were not the result of a major alteration of the tissue redox state because the changes in levels of lipid peroxidation products, reflecting oxidative damage, and the expression of genes encoding antioxidant and electron transfer chain redox enzymes did not correspond with the shoot phenotypes. However, the observed phenotypes were correlated with the amount of total shoot anthocyanin at low temperature and with the transcription of the flavonoid pathway genes PAL1 and CHS. These results demonstrate that (1) AOX activity plays a role in shoot acclimation to low temperature in Arabidopsis, and that (2) AOX not only functions to prevent excess reactive oxygen species formation in whole tissues under stressful environmental conditions but also affects metabolism through more pervasive effects, including some that are extramitochondrial.
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Affiliation(s)
- Fabio Fiorani
- Developmental, Cell, and Molecular Biology Group/Biology Department, Duke University, Durham, North Carolina 27708-1000, USA
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Ribas-Carbo M, Taylor NL, Giles L, Busquets S, Finnegan PM, Day DA, Lambers H, Medrano H, Berry JA, Flexas J. Effects of water stress on respiration in soybean leaves. PLANT PHYSIOLOGY 2005; 139:466-73. [PMID: 16126857 PMCID: PMC1203395 DOI: 10.1104/pp.105.065565] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 06/20/2005] [Accepted: 06/20/2005] [Indexed: 05/04/2023]
Abstract
The effect of water stress on respiration and mitochondrial electron transport has been studied in soybean (Glycine max) leaves, using the oxygen-isotope-fractionation technique. Treatments with three levels of water stress were applied by irrigation to replace 100%, 50%, and 0% of daily water use by transpiration. The levels of water stress were characterized in terms of light-saturated stomatal conductance (g(s)): well irrigated (g(s) > 0.2 mol H(2)O m(-2) s(-1)), mildly water stressed (g(s) between 0.1 and 0.2 mol H(2)O m(-2) s(-1)), and severely water stressed (g(s) < 0.1 mol H(2)O m(-2) s(-1)). Although net photosynthesis decreased by 40% and 70% under mild and severe water stress, respectively, the total respiratory oxygen uptake (V(t)) was not significantly different at any water-stress level. However, severe water stress caused a significant shift of electrons from the cytochrome to the alternative pathway. The electron partitioning through the alternative pathway increased from 10% to 12% under well-watered or mild water-stress conditions to near 40% under severe water stress. Consequently, the calculated rate of mitochondrial ATP synthesis decreased by 32% under severe water stress. Unlike many other stresses, water stress did not affect the levels of mitochondrial alternative oxidase protein. This suggests a biochemical regulation (other than protein synthesis) that causes this mitochondrial electron shift.
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Affiliation(s)
- Miquel Ribas-Carbo
- Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Universitat de les Illes Balears, Spain.
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Helmerhorst EJ, Stan M, Murphy MP, Sherman F, Oppenheim FG. The concomitant expression and availability of conventional and alternative, cyanide-insensitive, respiratory pathways in Candida albicans. Mitochondrion 2005; 5:200-11. [PMID: 16050985 DOI: 10.1016/j.mito.2005.04.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Revised: 03/25/2005] [Accepted: 04/05/2005] [Indexed: 10/25/2022]
Abstract
The opportunistic oral pathogen Candida albicans expresses a cyanide-insensitive alternative oxidase (AOX) upon exposure to respiratory inhibitors that act downstream from coenzyme Q, and upon ageing of cells. To investigate whether the conventional pathway is retained when the alternative pathway is induced, cells were grown in the presence of sodium cyanide, a reversible inhibitor of cytochrome oxidase. AOX expression was monitored by Western blotting and the presence of cytochromes associated with complexes III and IV of the conventional pathway was monitored by recording spectra between 500 and 650 nm at 77K. The activities of complexes III and IV were determined in polarographic and enzyme-kinetic experiments using specific respiratory substrates and inhibitors. Results indicated that complexes III and IV are constitutively expressed and are functional in cells expressing AOX. Furthermore, the enzymatic activities of complexes III and IV were similar in mitochondrial preparations from cells grown with or without cyanide. We next investigated whether both pathways are simultaneously available for electron transfer from the Q pool to molecular oxygen. Respiration was virtually completely inhibited by the combination of cyanide and salicyl hydroxamic acid (SHAM) or antimycin A and SHAM, but only partly inhibited by either of these inhibitors alone. This indicates that electrons can in principle flow either through the conventional or the alternative respiratory pathway. The availability of two electron pathways in C. albicans and the potential use of either pathway endows this pleomorphic fungus with another level at which it can rapidly adjust to altered environmental conditions.
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Affiliation(s)
- Eva J Helmerhorst
- Department of Periodontology and Oral Biology, Goldman School of Dental Medicine, Boston University, 700 Albany Street W201, Boston, MA 02118, USA.
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Buchanan-Wollaston V, Page T, Harrison E, Breeze E, Lim PO, Nam HG, Lin JF, Wu SH, Swidzinski J, Ishizaki K, Leaver CJ. Comparative transcriptome analysis reveals significant differences in gene expression and signalling pathways between developmental and dark/starvation-induced senescence in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 42:567-85. [PMID: 15860015 DOI: 10.1111/j.1365-313x.2005.02399.x] [Citation(s) in RCA: 644] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
An analysis of changes in global gene expression patterns during developmental leaf senescence in Arabidopsis has identified more than 800 genes that show a reproducible increase in transcript abundance. This extensive change illustrates the dramatic alterations in cell metabolism that underpin the developmental transition from a photosynthetically active leaf to a senescing organ which functions as a source of mobilizable nutrients. Comparison of changes in gene expression patterns during natural leaf senescence with those identified, when senescence is artificially induced in leaves induced to senesce by darkness or during sucrose starvation-induced senescence in cell suspension cultures, has shown not only similarities but also considerable differences. The data suggest that alternative pathways for essential metabolic processes such as nitrogen mobilization are used in different senescent systems. Gene expression patterns in the senescent cell suspension cultures are more similar to those for dark-induced senescence and this may be a consequence of sugar starvation in both tissues. Gene expression analysis in senescing leaves of plant lines defective in signalling pathways involving salicylic acid (SA), jasmonic acid (JA) and ethylene has shown that these three pathways are all required for expression of many genes during developmental senescence. The JA/ethylene pathways also appear to operate in regulating gene expression in dark-induced and cell suspension senescence whereas the SA pathway is not involved. The importance of the SA pathway in the senescence process is illustrated by the discovery that developmental leaf senescence, but not dark-induced senescence, is delayed in plants defective in the SA pathway.
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Geisler DA, Johansson FI, Svensson ÅS, Rasmusson AG. Antimycin A treatment decreases respiratory internal rotenone-insensitive NADH oxidation capacity in potato leaves. BMC PLANT BIOLOGY 2004; 4:8. [PMID: 15140267 PMCID: PMC424582 DOI: 10.1186/1471-2229-4-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Accepted: 05/12/2004] [Indexed: 05/20/2023]
Abstract
BACKGROUND The plant respiratory chain contains several energy-dissipating enzymes, these being type II NAD(P)H dehydrogenases and the alternative oxidase, not present in mammals. The physiological functions of type II NAD(P)H dehydrogenases are largely unclear and little is known about their responses to stress. In this investigation, potato plants (Solanum tuberosum L., cv. Desiree) were sprayed with antimycin A, an inhibitor of the cytochrome pathway. Enzyme capacities of NAD(P)H dehydrogenases (EC 1.6.5.3) and the alternative oxidase were then analysed in isolated leaf mitochondria. RESULTS We report a specific decrease in internal rotenone-insensitive NADH dehydrogenase capacity in mitochondria from antimycin A-treated leaves. External NADPH dehydrogenase and alternative oxidase capacities remained unaffected by the treatment. Western blotting revealed no change in protein abundance for two characterised NAD(P)H dehydrogenase homologues, NDA1 and NDB1, nor for two subunits of complex I. The alternative oxidase was at most only slightly increased. Transcript levels of nda1, as well as an expressed sequence tag derived from a previously uninvestigated closely related potato homologue, remained unchanged by the treatment. As compared to the daily rhythm-regulated nda1, the novel homologue displayed steady transcript levels over the time investigated. CONCLUSIONS The internal rotenone-insensitive NADH oxidation decreases after antimycin A treatment of potato leaves. However, the decrease is not due to changes in expression of known nda genes. One consequence of the lower NADH dehydrogenase capacity may be a stabilisation of the respiratory chain reduction level, should the overall capacity of the cytochrome and the alternative pathway be restricted.
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Affiliation(s)
- Daniela A Geisler
- Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden
| | - Fredrik I Johansson
- Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden
| | - Å Staffan Svensson
- Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden
- Dept of Plant Biology, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, Frederiksberg C, (DK-1871), Denmark
| | - Allan G Rasmusson
- Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden
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Finnegan PM, Soole KL, Umbach AL. Alternative Mitochondrial Electron Transport Proteins in Higher Plants. PLANT MITOCHONDRIA: FROM GENOME TO FUNCTION 2004. [DOI: 10.1007/978-1-4020-2400-9_9] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Thirkettle-Watts D, McCabe TC, Clifton R, Moore C, Finnegan PM, Day DA, Whelan J. Analysis of the alternative oxidase promoters from soybean. PLANT PHYSIOLOGY 2003; 133:1158-69. [PMID: 14551329 PMCID: PMC281611 DOI: 10.1104/pp.103.028183] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2003] [Revised: 08/01/2003] [Accepted: 08/01/2003] [Indexed: 05/18/2023]
Abstract
Alternative oxidase (Aox) is a nuclear-encoded mitochondrial protein. In soybean (Glycine max), the three members of the gene family have been shown to be differentially expressed during normal plant development and in response to stresses. To examine the function of the Aox promoters, genomic fragments were obtained for all three soybean genes: Aox1, Aox2a, and Aox2b. The regions of these fragments immediately upstream of the coding regions were used to drive beta-glucuronidase (GUS) expression during transient transformation of soybean suspension culture cells and stable transformation of Arabidopsis. The expression patterns of the GUS reporter genes in soybean cells were in agreement with the presence or absence of the various endogenous Aox proteins, determined by immunoblotting. Deletion of different portions of the upstream regions identified sequences responsible for both positive and negative regulation of Aox gene expression in soybean cells. Reporter gene analysis in Arabidopsis plants showed differential tissue expression patterns driven by the three upstream regions, similar to those reported for the endogenous proteins in soybean. The expression profiles of all five members of the Arabidopsis Aox gene family were examined also, to compare with GUS expression driven by the soybean upstream fragments. Even though the promoter activity of the upstream fragments from soybean Aox2a and Aox2b displayed the same tissue specificity in Arabidopsis as they do in soybean, the most prominently expressed endogenous genes in all tissues of Arabidopsis were of the Aox1 type. Thus although regulation of Aox expression generally appears to involve the same signals in different species, different orthologs of Aox may respond variously to these signals. A comparison of upstream sequences between soybean Aox genes and similarly expressed Arabidopsis Aox genes identified common motifs.
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Affiliation(s)
- David Thirkettle-Watts
- Plant Molecular Biology Group, Biochemistry and Molecular Biology, School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
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Gaston S, Ribas-Carbo M, Busquets S, Berry JA, Zabalza A, Royuela M. Changes in mitochondrial electron partitioning in response to herbicides inhibiting branched-chain amino acid biosynthesis in soybean. PLANT PHYSIOLOGY 2003; 133:1351-9. [PMID: 14576285 PMCID: PMC281629 DOI: 10.1104/pp.103.027805] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Revised: 06/20/2003] [Accepted: 07/01/2003] [Indexed: 05/18/2023]
Abstract
The adaptation of the respiratory metabolism in roots of soybean (Glycine max L. Merr. cv Ransom) treated with herbicides that inhibit the enzyme acetolactate synthase (ALS) was analyzed. A new gas phase dual-inlet mass spectrometry system for simultaneous measurement of 34O2 to 32O2 and O2 to N2 ratios has been developed. This system is more accurate than previously described systems, allows measurements of much smaller oxygen gradients, and, as a consequence, works with tissues that have lower respiration rates. ALS inhibition caused an increase of the alternative oxidase (AOX) protein and an accumulation of pyruvate. The combination of these two effects is likely to induce the activation of the alternative pathway and its participation in the total respiration. Moreover, the start of the alternative pathway activation and the increase of AOX protein were before the decline in the activity of cytochrome pathway. The possible role of AOX under ALS inhibition is discussed.
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Affiliation(s)
- Susana Gaston
- Departamento de Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain
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Holtzapffel RC, Castelli J, Finnegan PM, Millar AH, Whelan J, Day DA. A tomato alternative oxidase protein with altered regulatory properties. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2003; 1606:153-62. [PMID: 14507436 DOI: 10.1016/s0005-2728(03)00112-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We have investigated the expression and regulatory properties of the two alternative oxidase (Aox) proteins that are expressed in tomato (Lycopersicon esculentum L. Mill cv. Sweetie) after storage of green fruit at 4 degrees C. Four Aox genes were identified in the tomato genome, of which two (LeAox1a and LeAox1b) were demonstrated to be expressed in cold-treated fruit. The activity and regulatory properties of LeAox1a and LeAox1b were assayed after expression of each protein in yeast cells (Saccharomyces cerevisiae), proving that each is an active Aox protein. The LeAox1b protein was shown to have altered regulatory properties due to the substitution of a Ser for the highly conserved Cys(I) residue. LeAox1b could not form inactive disulfide-linked dimers and was activated by succinate instead of pyruvate. This is the first example of a dicot species expressing a natural Cys(I)/Ser isoform. The implications of the existence and expression of such Aox isoforms is discussed in the light of the hypothesised role for Aox in plant metabolism.
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Affiliation(s)
- Ruth C Holtzapffel
- Plant Molecular Biology Group, Biochemistry and Molecular Biology, School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, WA, Australia
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Josse EM, Alcaraz JP, Labouré AM, Kuntz M. In vitro characterization of a plastid terminal oxidase (PTOX). EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:3787-94. [PMID: 12950262 DOI: 10.1046/j.1432-1033.2003.03766.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The plastid terminal oxidase (PTOX) encoded by the Arabidopsis IMMUTANS gene was expressed in Escherichia coli cells and its quinone/oxygen oxidoreductase activity monitored in isolated bacterial membranes using NADH as an electron donor. Specificity for plastoquinone was observed. Neither ubiquinone, duroquinone, phylloquinone nor benzoquinone could substitute for plastoquinone in this assay. However, duroquinol (fully reduced chemically) was an accepted substrate. Iron is also required and cannot be substituted by Cu(2+), Zn(2+) or Mn(2+). This plastoquinol oxidase activity is independent of temperature over the 15-40 degrees C range but increases with pH (from 5.5 to 9.0). Unlike higher plant mitochondrial alternative oxidases, to which PTOX shows sequence similarity (but also differences, especially in a putative quinone binding site and in cysteine conservation), PTOX activity does not appear to be regulated by pyruvate or any other tested sugar, nor by AMP. Its activity decreases, however, with increasing salt (NaCl or KCl) concentration. Various quinone analogues were tested for their inhibitory activity on PTOX. Pyrogallol analogues were found to be inhibitors, especially octyl gallate (I50 = 0.4 microM ) that appears far more potent than propyl gallate or gallic acid. Thus, octyl gallate is a useful inhibitor for future in vivo or in organello studies aimed at studying the roles of PTOX in chlororespiration and as a cofactor for carotenoid biosynthesis.
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Veiga A, Arrabaça JD, Loureiro-Dias MC. Cyanide-resistant respiration, a very frequent metabolic pathway in yeasts. FEMS Yeast Res 2003; 3:239-45. [PMID: 12689632 DOI: 10.1016/s1567-1356(03)00036-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
It has recently been shown that cyanide-resistant respiration (CRR) is very common in Crabtree-negative yeasts (incapable of aerobic fermentation) and in non-fermentative yeasts. It is conferred by a salicylhydroxamic acid-sensitive alternative oxidase that transfers electrons from ubiquinol to oxygen, bypassing the cytochrome chain. An interesting finding is that, in general, whenever CRR is present, complex I is also present. In this article we briefly review the occurrence of CRR, the biochemistry and molecular biology of the alternative oxidase, and summarise the putative functions that have been attributed to this ubiquitous metabolic pathway, whose usefulness for the yeast cells still remains obscure.
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Affiliation(s)
- Alexandra Veiga
- Laboratório de Microbiologia, Departamento de Botânica e Engenharia Biológica, Instituto Superior de Agronomia, 1349-017 Lisbon, Portugal
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Karpova OV, Kuzmin EV, Elthon TE, Newton KJ. Differential expression of alternative oxidase genes in maize mitochondrial mutants. THE PLANT CELL 2002; 14:3271-84. [PMID: 12468742 PMCID: PMC151217 DOI: 10.1105/tpc.005603] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2002] [Accepted: 09/20/2002] [Indexed: 05/18/2023]
Abstract
We have examined the expression of three alternative oxidase (aox) genes in two types of maize mitochondrial mutants. Nonchromosomal stripe (NCS) mutants carry mitochondrial DNA deletions that affect subunits of respiratory complexes and show constitutively defective growth. Cytoplasmic male-sterile (CMS) mutants have mitochondrial DNA rearrangements, but they are impaired for mitochondrial function only during anther development. In contrast to normal plants, which have very low levels of AOX, NCS mutants exhibit high expression of aox genes in all nonphotosynthetic tissues tested. The expression pattern is specific for each type of mitochondrial lesion: the NADH dehydrogenase-defective NCS2 mutant has high expression of aox2, whereas the cytochrome oxidase-defective NCS6 mutant predominantly expresses aox3. Similarly, aox2 and aox3 can be induced differentially in normal maize seedlings by specific inhibitors of these two respiratory complexes. Translation-defective NCS4 plants show induction of both aox2 and aox3. AOX2 and AOX3 proteins differ in their ability to be regulated by reversible dimerization. CMS mutants show relatively high levels of aox2 mRNAs in young tassels but none in ear shoots. Significant expression of aox1 is detected only in NCS and CMS tassels. The induction pattern of maize aox genes could serve as a selective marker for diverse mitochondrial defects.
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Affiliation(s)
- Olga V Karpova
- Division of Biological Sciences, Tucker Hall, University of Missouri, Columbia, Missouri 6521, USA
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44
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Gaston S, Zabalza A, González EM, Arrese-Igor C, Aparicio-Tejo PM, Royuela M. Imazethapyr, an inhibitor of the branched-chain amino acid biosynthesis, induces aerobic fermentation in pea plants. PHYSIOLOGIA PLANTARUM 2002; 114:524-532. [PMID: 11975725 DOI: 10.1034/j.1399-3054.2002.1140404.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Acetolactate synthase (ALS; EC 4.1.3.18) inhibition is the primary mechanism of action of imazethapyr (IM). However, the precise mechanisms that links ALS inhibition with plant death have not been elucidated. Supply of IM to pea (Pisum sativum L) plants produced an immediate cessation of growth, caused a 50% inhibition of the in vivo ALS activity within 1 day of treatment, and a remarkable accumulation (2.7-times) of free amino acids after 3 days. Carbohydrates (soluble and starch) were accumulated in both leaves and roots. Accumulation of soluble sugars in roots preceded that of starch in leaves, suggesting that the accumulation of carbohydrates in leaves is not the reason for the arrested root growth. A transient pyruvate accumulation was observed in roots, 1 day after the onset of IM supply. This was coincident with an increase in pyruvate decarboxylase (EC 4.1.1.1), and later increases in alcohol dehydrogenase (EC 1.1.1.1), lactate dehydrogenase (EC 1.1.1.27), and alanine amino transferase (EC 2.6.1.2) activities. This enhancement of fermentative activities was coincident with a slight decrease in aerobic respiration. The overall data suggest that the impairment of ALS activity may lead to a fermentative metabolism that may be involved in growth inhibition and plant death.
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Affiliation(s)
- Susana Gaston
- Departamento de Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain
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Vanlerberghe GC, Ordog SH. Alternative Oxidase: Integrating Carbon Metabolism and Electron Transport in Plant Respiration. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2002. [DOI: 10.1007/0-306-48138-3_11] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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46
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Juszczuk IM, Wagner AM, Rychter AM. Regulation of alternative oxidase activity during phosphate deficiency in bean roots (Phaseolus vulgaris). PHYSIOLOGIA PLANTARUM 2001; 113:185-192. [PMID: 12060295 DOI: 10.1034/j.1399-3054.2001.1130205.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Cyanide-resistant respiration was studied in mitochondria isolated from the roots of bean plants (Phaseolus vulgaris L. cv. Złota Saxa) grown hydroponically up to 16 days on a phosphate-sufficient (+P, control) or phosphate-deficient (-P) medium. Western blotting indicated that the alternative oxidase (AOX) was present only in its reduced (active) form, both in phosphate-sufficient and phosphate-deficient roots, but in the latter, the amount of AOX protein was greater. Addition of pyruvate to the isolation, washing and reaction media made mitochondria from +P roots cyanide-insensitive, similar to mitochondria from -P roots. The doubled activity of NAD-malic enzyme (NAD-ME) in -P compared with +P root mitochondria may suggest increased pyruvate production in -P mitochondria. Lower cytochrome c oxidase (COX) activity and no uncoupler effect on respiration indicated limited cytochrome chain activity in -P mitochondria. In -P mitochondria, the oxygen uptake decreased and the level of Q reduction increased from 60 to 80%. With no pyruvate present (AOX not fully activated), inhibition of the cytochrome pathway resulted in an increased level of the ratio of reduced ubiquinone (Qr) to total ubiquinone (Qt) (Qr/Qt) in +P mitochondria, but did not change Qr/Qt in -P mitochondria. When pyruvate was present, the kinetics for AOX were similar in mitochondria from -P and +P roots. It is suggested that AOX participation in -P respiration may provide an acclimation to phosphate deficiency. Stabilization of the ubiquinone reduction level by AOX might prevent the harmful effect of an increased formation of reactive oxygen species.
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Affiliation(s)
- Izabela M. Juszczuk
- Institute of Experimental Plant Biology, University of Warsaw, Miecznikowa 1, PL-02-096 Warsaw, Poland Department of Molecular Cell Physiology, Free University, De Boelelaan 1087, NL-1081 HV Amsterdam, The Netherlands
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Moller IM. PLANT MITOCHONDRIA AND OXIDATIVE STRESS: Electron Transport, NADPH Turnover, and Metabolism of Reactive Oxygen Species. ANNUAL REVIEW OF PLANT PHYSIOLOGY AND PLANT MOLECULAR BIOLOGY 2001; 52:561-591. [PMID: 11337409 DOI: 10.1146/annurev.arplant.52.1.561] [Citation(s) in RCA: 890] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The production of reactive oxygen species (ROS), such as O2- and H2O2, is an unavoidable consequence of aerobic metabolism. In plant cells the mitochondrial electron transport chain (ETC) is a major site of ROS production. In addition to complexes I-IV, the plant mitochondrial ETC contains a non-proton-pumping alternative oxidase as well as two rotenone-insensitive, non-proton-pumping NAD(P)H dehydrogenases on each side of the inner membrane: NDex on the outer surface and NDin on the inner surface. Because of their dependence on Ca2+, the two NDex may be active only when the plant cell is stressed. Complex I is the main enzyme oxidizing NADH under normal conditions and is also a major site of ROS production, together with complex III. The alternative oxidase and possibly NDin(NADH) function to limit mitochondrial ROS production by keeping the ETC relatively oxidized. Several enzymes are found in the matrix that, together with small antioxidants such as glutathione, help remove ROS. The antioxidants are kept in a reduced state by matrix NADPH produced by NADP-isocitrate dehydrogenase and non-proton-pumping transhydrogenase activities. When these defenses are overwhelmed, as occurs during both biotic and abiotic stress, the mitochondria are damaged by oxidative stress.
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Affiliation(s)
- Ian M Moller
- Department of Plant Physiology, Lund University, Lund, Box 117, S-221 00 Sweden;, Plant Biology and Biogeochemistry Department, Riso National Laboratory, Building 301, P.O. Box 49, DK-4000 Roskilde, Denmark; e-mail:
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Millenaar FF, Gonzàlez-Meler MA, Fiorani F, Welschen R, Ribas-Carbo M, Siedow JN, Wagner AM, Lambers H. Regulation of alternative oxidase activity in six wild monocotyledonous species. An in vivo study at the whole root level. PLANT PHYSIOLOGY 2001; 126:376-87. [PMID: 11351100 PMCID: PMC102311 DOI: 10.1104/pp.126.1.376] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2000] [Revised: 10/20/2000] [Accepted: 01/23/2001] [Indexed: 05/17/2023]
Abstract
The activity of the alternative pathway is affected by a number of factors, including the level and reduction state of the alternative oxidase (AOX) protein, and the reduction state of the ubiquinone pool. To investigate the significance of these factors for the rate of alternative respiration in vivo, we studied root respiration of six wild monocotyledonous grass species that were grown under identical controlled conditions. The activity of the alternative pathway was determined using the oxygen isotope fractionation technique. In all species, the AOX protein was invariably in its reduced (high activity) state. There was no correlation between AOX activity and AOX protein concentration, ubiquinone (total, reduced, or oxidized) concentration, or the reduction state of the ubiquinone pool. However, when some of these factors are combined in a linear regression model, a good fit to AOX activity is obtained. The function of the AOX is still not fully understood. It is interesting that we found a positive correlation between the activity of the alternative pathway and relative growth rate; a possible explanation for this correlation is discussed. Inhibition of the AOX (with salicylhydroxamic acid) decreases respiration rates less than the activity present before inhibition (i.e. measured with the 18O-fractionation technique).
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Affiliation(s)
- F F Millenaar
- Plant Ecophysiology, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.
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Karaffa L, Váczy K, Sándor E, Biró S, Szentirmai A, Pócsi I. Cyanide-resistant alternative respiration is strictly correlated to intracellular peroxide levels in Acremonium chrysogenum. Free Radic Res 2001; 34:405-16. [PMID: 11328676 DOI: 10.1080/10715760100300341] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
A strict correlation between the intensity of the cyanide-resistant alternative respiratory pathway and the intracellular peroxide levels in the cephalosporin C producer filamentous fungus Acremonium chrysogenum was demonstrated. Intracellular peroxide levels increased in a dose-dependent manner after addition of H2O2 to the culture media. A similar phenomenon was observed due to the specific inhibition of catalase by salicylic acid. In both cases, cyanide-resistant respiration was markedly stimulated. On the other hand, both cyanide-resistant respiration and intracellular peroxide levels were effectively suppressed by the lipid peroxyl radical scavenger DL-alpha-tocopherol, which breaks lipid peroxidation chains effectively. Our findings firmly supported the assumption that there is a connection between the intracellular peroxide levels and the intensity of the alternative respiratory pathway in fungi.
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Affiliation(s)
- L Karaffa
- Department of Microbiology and Biotechnology Faculty of Sciences University of Debrecen P.O. Box 63, H-4010, Debrecen, Hungary.
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López-Millán AF, Morales F, Andaluz S, Gogorcena Y, Abadía A, De Las Rivas J, Abadía J. Responses of sugar beet roots to iron deficiency. Changes in carbon assimilation and oxygen use. PLANT PHYSIOLOGY 2000; 124:885-98. [PMID: 11027736 PMCID: PMC59192 DOI: 10.1104/pp.124.2.885] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2000] [Accepted: 06/10/2000] [Indexed: 05/17/2023]
Abstract
Different root parts with or without increased iron-reducing activities have been studied in iron-deficient and iron-sufficient control sugar beet (Beta vulgaris L. Monohil hybrid). The distal root parts of iron-deficient plants, 0 to 5 mm from the root apex, were capable to reduce Fe(III)-chelates and contained concentrations of flavins near 700 microM, two characteristics absent in the 5 to 10 mm sections of iron-deficient plants and the whole root of iron-sufficient plants. Flavin-containing root tips had large pools of carboxylic acids and high activities of enzymes involved in organic acid metabolism. In iron-deficient yellow root tips there was a large increase in carbon fixation associated to an increase in phosphoenolpyruvate carboxylase activity. Part of this carbon was used, through an increase in mitochondrial activity, to increase the capacity to produce reducing power, whereas another part was exported via xylem. Root respiration was increased by iron deficiency. In sugar beet iron-deficient roots flavins would provide a suitable link between the increased capacity to produce reduced nucleotides and the plasma membrane associated ferric chelate reductase enzyme(s). Iron-deficient roots had a large oxygen consumption rate in the presence of cyanide and hydroxisalycilic acid, suggesting that the ferric chelate reductase enzyme is able to reduce oxygen in the absence of Fe(III)-chelates.
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Affiliation(s)
- A F López-Millán
- Department of Plant Nutrition, Aula Dei Experimental Station-Consejo Superior de Investigaciones Científicas, Apartado 202, E-50080 Zaragoza, Spain
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