Abstract: The effects of spraying exogenous NO with the donor of sodium nitroprusside(SNP) on the ascorbate-glutathione cycle dependent antioxidant system and the contents of H₂O₂ and malondialdehyde(MDA) in Peganum multisectum Bobr under salt stress were investigated. The results showed that the activities of ascorbate peroxidase(APX), glutathione reductase(GR), glutathione-S-transferase(GST) and the contents of ascorbic acid(ASA) and reduced glutathione(GSH), the ratios of ASA/DHA and GSH/GSSG in leaves of P.multisectum with 0.15 mmol·L^-1 SNP treatment under 300 mmol·L^-1 NaCl stress were increased while the contents of oxidized ascorbic acid(DHA), oxidized glutathione(GSSG), H₂O₂ and MDA were decreased, the activities of monodehydroascorbate reductase(MDAR) and dehydroascorbate reductas(DHAR) were not affected under NaCl stress. However, the effects of SNP on the activities of APX, GR, GST, the contents of ASA, GSH, DHA，H₂O₂, MDA, and the ratios of ASA/DHA and GSH/GSSG under NaCl stress were reversed by methylene blue(MB), inhibitor of the key enzyme guanylyl cyclase(GC) during signal transfer of NO. It is suggested that NO is involved in regulation of the ascorbate-glutathione cycle dependent antioxidant system through cyclic guanosine monophosphate(cGMP) pathway to alleviate the oxidative damage of P.multisectum seedlings from salt stress.

Key words: Nitric oxide, NaCl stress, the ascorbate-glutathione cycle, Peganum multisectum