| Effects of exogenous nitric oxide(NO) donor sodium nitroprusside(SNP) on growth of Peganum multisectum Bobr seedlings and protecting them from oxidative damage under salt stress were investigated.The results indicated that spraying SNP on leaves increased the growth of P.multisectum seedlings in normal growth conditions,but exogenous methylene blue,the inhibitor of the key enzyme guanylyl cyclase during signal transfer of NO,decreased significantly the growth of P.multisectum seedlings.Spraying SNP pretreatment alleviated obviously the inhibition of P.multisectum seedlings growth under NaCl stress,the contents of malondiadehyde(MDA) and H2O2,the O-2 producing rate and catalase(CAT) active were decreased while the activities of superoxide dismutase(SOD),peroxidase(POD) and ascorbate peroxidase(APX),the contents of ascorbate acid(ASA) and reduced glutathione(GSH),and(Spd+Spm)/Put ratio were significantly increased in P.multisectum leaves under NaCl stress.But methylene blue reversed some effects of exogenous SNP under NaCl stress,such as the plant biomass amount and POD activity,the contents of ASA and GSH,(Spd+Spm)/Put were decreased,the contents of MDA and H2O2 and CAT activity were significantly increased,however,the O2· producing rate and the activities of SOD and APX were not markedly affected under NaCl stress.These results suggested that NO might involve in regulation of reactive oxygen species metabolism through cyclic guanosine monophosphate(cGMP)-dependent and cGMP-independent pathways to alleviate the oxidative damage and the inhibition of P.multisectum seedlings growth under salt stress. |