title: In vivo cytochrome and alternative pathway respiration in leaves of Arabidopsis thaliana plants with altered alternative oxidase under different light conditions.
abstract: The in vivo activity of the alternative pathway (ν(alt)) has been studied using the oxygen isotope fractionation method in leaves of Arabidopsis thaliana modified for the expression of the AtAOX1a gene by anti-sense (AS-12) or overexpression (XX-2). Under non-stressful conditions, ν(alt) was similar in all plant lines regardless of its different alternative pathway capacities (V(alt)). Total leaf respiration (V(t)) and V(alt) were directly related to growth light conditions while electron partitioning between the cytochrome pathway (CP) and alternative pathway (AP) was unchanged by light levels. Interestingly, the AP functioned at full capacity in anti-sense plants under both growth light conditions. The role of the AP in response to a high light stress induced by short-term high light treatment (HLT) was also studied. In wild type and XX-2, both CP and AP rates increased proportionally after HLT while in AS-12, where the AP was unable to increase its rate, the CP accommodated all the increase in respiration. The results obtained under high light stress suggest that flexibility in the response of the mitochondrial electron transport chain is involved in sustaining photosynthetic rates in response to this stress while the saturated AP in AS-12 plants may contribute to the observed increase in photoinhibition.
authors.affiliation: 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.
authors.forename: Igor
authors.initials: I
authors.lastname: Florez-Sarasa
authors.forename: Jaume
authors.initials: J
authors.lastname: Flexas
authors.forename: Allan G
authors.initials: AG
authors.lastname: Rasmusson
authors.forename: Ann L
authors.initials: AL
authors.lastname: Umbach
authors.forename: James N
authors.initials: JN
authors.lastname: Siedow
authors.forename: Miquel
authors.initials: M
authors.lastname: Ribas-Carbo
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D003580:Cytochromes / Q000378:metabolism*; D004579:Electron Transport; D018506:Gene Expression Regulation, Plant; D008027:Light; D053858:Metabolic Networks and Pathways; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018526:Plant Transpiration; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological; D000099188:Alternative Oxidase
chemical_list: D003580:Cytochromes; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D000099188:Alternative Oxidase