Importance of the alternative oxidase (AOX) pathway in regulating cellular redox and ROS homeostasis to optimize photosynthesis during restriction of the cytochrome oxidase pathway in Arabidopsis thaliana.

摘要: Background and Aims The importance of the alternative oxidase (AOX) pathway, particularly AOX1A, in optimizing photosynthesis during de-etiolation, under elevated CO2, low temperature, high light or combined drought stress is well documented. In present study, role AOX1A was investigated when electron transport through cytochrome c (COX) pathway restricted at complex III. Methods Leaf discs wild-type (WT) aox1a knock-out mutants Arabidopsis thaliana were treated with antimycin A (AA) growth-light conditions. To identify impact deficiency photosynthesis, respiratory O2 uptake photosynthesis-related parameters measured along changes redox couples, reactive oxygen species (ROS), lipid peroxidation expression levels genes related to respiration, malate valve antioxidative system. Key Results absence AA, did not show any difference physiological, biochemical molecular compared WT. However, after AA treatment, plants showed a significant reduction both NaHCO3-dependent evolution. Chlorophyll fluorescence P700 studies revealed that contrast WT, incapable maintaining flow chloroplastic chain, thereby inefficient heat dissipation (low non-photochemical quenching) observed. Furthermore, exhibited disturbances cellular couples NAD(P)H ascorbate (Asc) consequently accumulation ROS malondialdehyde (MDA) content. By contrast, WT increase transcript CSD1, CAT1, sAPX, COX15 mutants. Conclusions These results suggest plays sustaining state energization optimize by regulating homeostasis generation COX disturbed III.