Ameliorative effect of exogenous nitric oxide on oxidative metabolism in NaCl treated chickpea plants

Accumulation of salts in irrigated soils is one of the primary factors limiting yield in South Asia. We investigated whether exogenous nitric oxide (NO) supplementation as sodium nitroprusside has any ameliorating effect against NaCl induced oxidative damage in chickpea leaves. NaCl treatment (250 mM) alone and in combination with two concentrations of SNP (0.2 and 1 mM) were given to 50 days old chickpea plants for 2, 4 and 6 days. Salt stress adversely affected the relative membrane injury, lipid peroxidation levels, relative water content (RWC) and H2O2 content. The effect was time dependent. SNP treatments could ameliorate the toxic effect of short term salt stress of 2 days on relative membrane injury and partial amelioration was observed with 4 and 6 day stress treatment. A partial ameliorative effect of SNP was observed with lipid peroxidation levels, H2O2 content and RWC. Salt stress activated the antioxidant system by increasing the activities of SOD, POX, APX and DHAR. However no obvious change was observed in GR activity and CAT activity decreased under salt stress. Both the SNP treatments had a positive effect on antioxidant enzymes SOD, CAT, APX, GR and DHAR under salt stress. NaCl treatment resulted in a decline in the GSH/GSSG and ASC/DHA ratio. SNP treatments increased the reduced form of both the metabolites thus elevating the ratio of GSH/GSSG and ASC/DHA. This study concludes that exogenous application of NO protects chickpea leaves from NaCl induced oxidative stress.