Different responses of photosystem and antioxidant defense system to three environmental stresses in wheat seedlings

To investigate the adaptive mechanism of wheat under high light, osmotic stress, and salt stress, redox regulation, and photosynthesis were compared. Under high light, the activities of antioxidant enzymes, except for catalase, significantly increased and then decreased after 1 and 3 h, respectively. Under osmotic stress, antioxidant enzyme activities significantly increased and subsequently declined. Except for superoxide dismutase, salt stress induced a significant increase in all the antioxidant enzyme activities. A significant decrease of D1 protein by high light and osmotic stress, strong photophosphorylation of D1 and D2 under high light and salt stress were observed, while all the stresses induced upregulation of PsbS protein. Eight stress-associated genes (TaMYB73, TaABC1, TaOPR1, TaASR1, TaWRKY44, TaWRKY2, TaWRKY19, and TaCIPK29) showed different expression levels under all the stresses. We conclude that the wheat plant adopted various strategies by regulating the antioxidant system, expression of stress-responsive genes, and photosystems under different abiotic stresses.