Enhancement of Catalase Activity under Salt Stress in Germinating Seeds of Vigna radiata

Catalase(CAT) (EC 1.11.1.6) is an important cellular antioxidant enzyme that defends against oxidative stress. Hydrogen peroxide, although not a free radical, is highly reactive. It serves to protect the cell from toxic effects of high concentrations of hydrogen peroxide by catalyzing its decomposition into molecular oxygen and water, without the production of free radicals. The effects of presoaking of seeds in salt solution on germination and catalase activity of Vigna radiata were studied. NaCl and CaCl2 soaked seeds showed reduced germination (less than 1cm) as indicated by decreased shoot length when compared to controls. 5g seeds of Vigna radiata were presoaked for 24 hours in presence of NaCl (1, 5,10,15,20 M) and CaCl2 (0.5, 1, 1.5, 2.0 M). After two days of germination, the filtered water extracts (25ml) were tested for qualitative catalase activity. Further catalase assay of respective extracts was monitored in terms of decay in H2O2 concentration at 240 nm (Jasco-V- 530) and compared with the decay in the absence of stress. There was nearly 40% increase in extent of decay of H2O2 at concentration of 1M NaCl and 33.9% increase in decay at 1M concentration of CaCl2. Further study includes different combinations of NaCl and CaCl2 to be tested followed by increase in germination period and catalase activity monitoring in partially purified and dialyzed extracts. There was an enhancement of catalase activity in presence of the salt stress.