Water deficit-induced oxidative stress and differential response in antioxidant enzymes of tolerant and susceptible tea cultivars under field condition

Abstract

Tea (Camellia sinensis (L) O. Kuntze) sustainable production is threatened by frequent drought. Tolerance to drought is a complex phenotypic response, which is controlled by the interactive properties of the plant’s genetic makeup, environment and its growing stage. The present investigation aimed to identify the differential responses of antioxidative enzymes, non-enzymatic antioxidants and status of osmolytes in tea plants under water deficit condition with respect to gradually depleting soil moisture content (SMC) and leaf relative water content (RWC). We examined the consequences of water deficit on the physiological characteristics and biochemical compounds of C. sinensis leaves. Our results indicated that the tolerant genotypes maintained favorable water relations, relatively higher photosynthetic pigments and reduced membrane injury by lowering hydrogen peroxide (H2O2) accumulation compared to susceptible cultivars. The relatively lower efficiency of superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POX) in susceptible cultivars under subsequent water deficit stress make them more prone to magnified oxidative damage than the tolerant cultivars. Furthermore, a substantial enhancement in the accumulation of osmolytes (proline and glycine betaine) has a great contribution in tolerance during drought. These results provide the insight into the basic mechanisms necessary for induction of antioxidant defense system and accumulation of osmolytes under water deficit conditions.