Antioxidant defence system and chloroplasts photochemical characteristics of wheat genotypes subjected to water stress

Abstract

Activities of catalase, ascorbate peroxidase, superoxide dismutase and glutathione reductase, as well as carotenoid content and photochemical activity of photosystem I and photosystem II were studied in leaves of durum and bread wheat genotypes. It was found out that dynamics of catalase and ascorbate peroxidase functioning in well-watered plants through ontogenesis practically did not change both among durum and among bread wheat cultivars. Functioning of these enzymes during ontogenesis under water deficit differed. Catalase activity increased in all stressed genotypes: In durum wheat cultivars maximal activity was observed in the milk ripeness and in bread wheat cultivars — in the end of flowering. Ascorbate peroxidase activity also increased under water deficit: In tolerant wheat genotypes maximal activity occurred in the end of flowering, in sensitive ones—in the end of ear formation. The maximum activity of glutathione reductase both as in the control, as well as in drought-subjected plants was observed in the anthesis stage. Superoxide dismutase activity was lower than the control during ontogenesis, excepting the last stages. It should be noted that PS I and PS II photochemical activity were also high in genotypes subjected to drought both in the end of ear formation and flowering stages.