Protective Effects of Exogenous Nitric Oxide on Oxidative Damage in Tomato Seedling Leaves under NaCl Stress

The effects of sodium nitropprusside(SNP),an exogenous nitric oxide donor,at the concentration of 0.05 mmol/L,0.10 mmol/L and 0.80 mmol/L on the oxidative damage in tomato(Lycopersicon esculentum Mill.) seedling leaves under 100 mmol/L NaCl stress were studied.The results showed that after the treatment of NaCl stress for 8 h and 24 h.SNP at the concentration of 0.05 mmol/ L and 0.10 mmol/L significantly increased the activities of antioxidant enzymes(including SOD,POD,CAT and APX) and the contents of proline and soluble sugar in leaves,while significantly decreased malondialdehyde(MDA) content and active oxygen(O_2·~-) producing rate in leaves.SNP concentration of 0.10 mmol/L was better than that of 0.05 mmol/L in the alleviation of NaCl stress.However,SNP concentration of 0.80 mmol/L had no significant effects.The above results indicated that effect of exogenous nitric oxide donor(SNP) existed in a dose-dependent manner in the alleviation of NaCl stress,and the effect of 0.10 mmol/L SNP was the best of all SNP concentrations in elevating the leaf antioxidation ability of tomato seedlings.