Mitochondrial Alternative Oxidase Modulates Ascorbate-Glutathione Metabolism and Energy Homeostasis in Arabidopsis thaliana Under High-Light Stress
DOI:
https://doi.org/10.65761/jbs.v2.i1.10Keywords:
Alternative oxidase; Ascorbate; Glutathione; Arabidopsis thaliana; High-light stressAbstract
Background: High-light stress induces reactive oxygen species (ROS) accumulation in plants, challenging both redox homeostasis and energy metabolism. Mitochondrial alternative oxidase (AOX) is a key regulator of respiratory flexibility, potentially modulating antioxidant networks and ATP production during stress.
Objective: This study aimed to investigate the role of AOX in regulating ascorbate–glutathione metabolism and energy balance in Arabidopsis thaliana under moderately high-light conditions.
Methods: AOX1a antisense (AS-12) and vitamin-C deficient (vtc2) mutant lines and AOX- initiative vtc2 plants were subjected to 400 2 s -1 light during 10 hours. Ascorbate peroxidase (APX) level, leaf levels of ascorbate, dehydroascorbate, ATP, and mitochondrial electron transport capacities were determined.
Results: AOX inhibition in AS-12 reduced the depleted ascorbate pool and ATP content, and increased the APX activity, which are signs of oxidative stress and inadequate energy. The levels of ascorbate were low in vtc2 and increased dehydroascorbate (DHA) but activation of AOX partially restored decreased ascorbate and enhanced energy homeostasis. The analysis of mitochondrial electron transport showed that the AOX activity was varied according to AOX and cytochrome pathway capacity to maintain the redox stability.
Conclusion: AOX functions as a central regulator linking mitochondrial respiration to the ascorbate–glutathione hub, enabling plants to maintain redox balance and energy homeostasis under high-light stress.
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