Role of Glutathione-Ascorbate Cycle and Photosynthetic Electronic Transfer in Alternative Oxidase-Manipulated Waterlogging Tolerance in Watermelon Seedlings

Alternative oxidase (AOX) has been documented to mitigate the oxidative stress caused by abiotic stresses. However, it remains unknown how AOX regulates antioxidant system and photosynthesis under waterlogging. To address this issue, we used two watermelon (Citrullus lanatus L.) cultivars (waterlogging tolerant cultivar ‘YL’ sensitive ‘Zaojia8424’) as materials inhibitor salicylhydroxamic acid (SHAM) investigate effects of on reactive oxygen species metabolism We found that waterlogging decreased leaf quantum yield in watermelon, showed higher expression level ClaAOX than ‘Zaojia8424’. Net rate was Moreover, induced photoinhibition ‘Zaojia8424’ but not ‘YL’. Meanwhile, promoted accumulation superoxide peroxide hydrogen, triggered damage. suffered from less severe damage due increased contents ascorbate, a ratio reduced glutathione (GSH) oxidized (GSSG), activity ascorbate peroxidase (APX) catalase (CAT), enhanced levels CAT APX expression, relative alleviation damage, content GSH/GSSG were abolished SHAM. Our results suggested photosynthetic electronic transfer glutathione-ascorbate cycle are involved tolerance mediated pathway watermelon.