Variations in Physiological Response, Lipid Peroxidation, Antioxidant Enzyme Activities, Proline and Isoflavones Content in Soybean Varieties Subjected to Drought Stress

Drought stress is one of the crucial factors affecting the global plant growth and crop productivity. In the present study, Indian soybean varieties (cv. JS 335 and cv. KHSb-2) were examined for the changes in their antioxidant enzyme activity, total isoflavone content and also the influence on its growth under drought stress. Several physiological responses, malondialdehyde, proline contents and antioxidant activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase were estimated under mild drought stress and recovery stage respectively. Mild water deficit stress for 5 days during late vegetative stage increased total superoxide dismutase activity in KHSb-2 than in JS 335 variety. Water deficit stress triggered the activities of catalase, peroxidase, ascorbate peroxidase and glutathione reductase enzymes in KHSb-2 than in JS 335. High accumulation of proline and lower level of lipid peroxidation were also observed in KHSb-2 than in JS 335. The root and shoot fresh and dry weight along with leaf relative water content of cultivar KHSb-2 exhibited lesser reduction than in JS 335. The partial recovery of antioxidant enzyme activities, elevated relative water content and growth parameters in both varieties were compared to stress plants. Moderate enhancement in total isoflavone content was observed in KHSb-2 (3.44 % increase) and JS 335 (2.84 % increase) in seeds subjected to mild stress. From nutraceutical point of view, the results investigated would be vital for development of soybean cultivar with drought tolerance and moderate enhancement of isoflavone content under drought stress. © 2013, The National Academy of Sciences, India.