Nitric Oxide Stimulates Antioxidant System and Osmotic Adjustment in Soybean Under Drought Stress

The target of the present study was to determine the effect of nitric oxide (NO) on drought stress amelioration in soybean plant. Plants were treated with different polyethylene glycol (PEG) concentrations (0, 5, 10, and 15%) without or with NO (100 μM). Based on our results, drought stress significantly decreased growth in soybean plants. Increase in hydrogen peroxide, malondialdehyde, and aldehyde content indicated drought-induced oxidative stress in soybean plants. Drought stress enhanced the activities of catalase, ascorbate peroxidase, accumulation of proline and glycine betaine, and lipoxygenase activity as well as total phenol and tocopherol content. NO had a beneficial effect on drought tolerance and promoted growth in soybean plants. NO treatment maintained soybean against drought-induced oxidative hurt, thereby improving the antioxidant defense mechanism (enzymatic and non-enzymatic antioxidants). NO application caused osmotic adjustment by up-regulation accumulation of compatible solutes in stressed plants. Enhanced plant growth was linked with induction of phenylalanine ammonia-lyase and tyrosine ammonia-lyase activity and decrease in electrolyte leakage by NO application. Our results revealed that NO had ability to alleviate the destructive effects in soybean plants under drought stress.