Chilling-induced H2O2 signaling activates the antioxidant enzymes in alleviating the photooxidative damage caused by loss of function of 2-Cys peroxiredoxin in watermelon

Abstract

Cold stress signal transduction refers to a process that involves various physiological and molecular changes. Hydrogen peroxide (H2O2) signaling is stimulated by plants in adapting to various environmental stresses. Here, nine respiratory burst oxidase homolog (ClRboh) genes were identified from the watermelon genome. Chilling stress induced increased gene expression of ClRbohD and H2O2 accumulation in watermelon plants. By using virus-induced gene silencing (VIGS), we found that H2O2-induced chilling tolerance is dependent on ClRbohD by increased electrolyte leakage, membrane lipid peroxidation, and reduced photosystem II activity in ClRbohD-silenced plants compared with control. In addition, silencing of 2-Cys peroxiredoxin (Cl2-CP) increased the chilling sensitivity, while exogenous H2O2 treatment compromised the silencing of Cl2-CP-induced photooxidative damage in watermelon plants. The gene expression and enzyme activities of Cu/Zn-SOD and GR were significantly increased in Cl2-CP-silenced plants rather than pV190 control plants upon H2O2 treatment under chilling stress, suggesting that the activation of antioxidant enzymes by H2O2 serves as an alternative pathway to compensate for the deficiency of Cl2-CP during chilling stress response in watermelon.

Keywords

• Chilling stress
• H2O2 signaling
• 2-Cys peroxiredoxin
• Antioxidant enzymes
• Watermelon