Role of antioxidative enzymes activity in salt stress and salinity screening in rice grown under in vitro condition

Role of antioxidative enzyme activity in salt stress and salinity screening was studied in the callus of two rice cultivars (White ponni and BPT-5204). The antioxidant activities of the rice callus were determined by analyzing three enzymes activity namely, Superoxide Dismutase (SOD), Catalase (CAT) and Ascorbate Peroxidase (APX) grown under saline condition. Enzymes were analysed in 15 days old rice callus culture grown under salt stress and non-saline conditions. All the three enzyme activities were varied according to salt concentrations in the medium. SOD and CAT activities were higher in BPT-5204 but APX activities were higher in White ponni. Among the NaCl treatment, medium containing 40 mM NaCl observed higher enzyme activity than 20 and 30 mM NaCl. Under non saline condition there is no significant difference was noticed in the enzymatic activities and callus growth parameter in both the cultivars. Observation was carried out on the change in callus growth parameter like weight and color of the callus. There was a significant reduction in weight and also change in colour of the callus was noticed with respect to higher salt concentrations (30 and 40 mM NaCl) in the medium for both the cultivars. The observed data indicated that rice plant responds well to salt-induced oxidative stress by increasing their enzymatic antioxidant defense systems. The antioxidant enzyme activity play vital role in defense against salt stress and this may help to screen the salt tolerant line grown under in vitro condition in early callus stage itself.