Evaluation of Oxidative Stress Tolerance in Two Wheat (Triticum aestivum) Cultivars in Response to Drought

Acclimation of plants to mild or sub-lethal stress condition leads to development of resistance to severe or lethal stress condition. Present study was conducted to evaluate the role of oxidative stress management in two wheat (Triticum aestivum L.) cultivars; Veery (drought resistant) and Sids (drought susceptible). The activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT), as well as the levels of ascorbate pool (ASA) and hydrogen peroxide (H2O2) were studied after exposure to drought stress phases interrupted by rewatering period (drought acclimation). Drought stress induced oxidative stress for plants which exhibited high H2O2 and oxidized ascorbate levels in relation with the prolonged drought period. Also, weak antioxidant enzymes response leading to enhanced membrane damage during severe drought stress, indicated by the accumulation of malondialdehyde (MDA). The drought acclimated leaves exhibited systematic increase in the activity of H2O2 scavenging enzymes particularly APX and CAT and maintenance of ascorbate redox pool by efficient function of APX enzyme. As a result, lower membrane injury indicated by lower NMA content was observed in drought acclimated plants. Results showed the ability of wheat plants to acclimate and induce the antioxidant defense system under drought stress.