Antioxidant defence system in wheat seedlings under sodium chloride stress: An inductive role of hydrogen peroxide

The effect of exogenously supplied hydrogen peroxide on the enzymes involved in antioxidant defense and other related processes in wheat seedlings under NaCl stress was examined. Treatment with hydrogen peroxide activates the antioxidants especially catalase, ascorbate peroxidase and glutathione reductase, however no such activation was observed in case of superoxide dismutase. Treatment with hydrogen peroxide lowers the endogenous level of hydrogen peroxide which is indicative of the activation of reactive oxygen species scavenging system in concomitant with improved growth of wheat seedlings leading to prevention of damage to membranes. However, hydrogen peroxide does not affect the osmotic potential and contents of mineral ions like K, Na and Cl. This clearly indicates that improved growth of wheat seedlings by hydrogen peroxide treatment does not involve osmotic adjustment. These results substantiate the contention that under salt stress conditions an “inductive pulse” of hydrogen peroxide treatment could partially alleviate the salt stress effects on plants.