Exogenous NO Mediated GSH-PCs And Polyamine Synthesis Pathway In Tomato Under Copper Stress

Nitric oxide(NO), as a biologically active molecule, widely involved in the biotic and abiotic stresses.By using solution culture, this paper reported the dynamic changes in enzyme activity and metabolite related to GSH – PCs、Polyamine synthesis way mediated by exogenous NO in tomato(Lycopersicon esculentum Mill.).1. The results showed that exogenous NO could affect the metabolic pathway of GSH- PCs in tomato seedlings under copper stress. Compared with CK, the activity of γ-ECS and GS was significantly activated, consequently a sharp rise in GSH and PCs content in tomato root. Moreoverγ-ECS and GS activity, GSH and PCs content constantly rise as the extension of processing time under copper stress; Adding exogenous SNP could further improveγ-ECS and GS activity in tomato, and promote the production of GSH and PCs, which contributed to enhance the ability of removing superoxide and chelating excess Cu2+ to reduce its biological toxicity. In a certain extent, GSH- PCs metabolic changes in leaf lagged behind that in roots. Exogenous BSO could significantly inhibitγ-ECS activity, and applying SNP could significantly reverse the inhibition to GSH and PCs synthesis by BSO. BSO had little effects on PCs content in leaf. Under copper stress, exogenous NO may start a certain signal mechanism, and through activating or enhancing the enzyme or non-enzymatic system in the GSH-PCs synthetic pathway, so as to reduce biological toxicity and oxidative damage induced by excess Cu2 +.2. These results suggest that adding exogenous SNP(Sodium N itroprusside, Exogenous NO donor)can modulate the Arginine Decarboxylase(ADC), Ornithine Decarboxylase(ODC) and N itric O xide Synthase(NOS) activity in tomato root and leaf under copper stress. In the root exogenous SNP can induced an increase in ADC, ODC activity, while raises NOS activity, but L- arginine metabolism was toward Polyamine synthesis direction. In the leaf,exogenous SNP showed an increased ADC, ODC and NOS activity, meanwhile, promoted the synthesis of PA and NO, regulating the co ntent of NO and PA in both tomato root and leaf and consequently reduced biological toxicity induced by copper stress. In addition, adding exogenous SNP can increase L-arginine content in tomato. As PA and NO synthetic precursor, arginine content rise will undoubtedly indirectly promote the PA and NO synthesis and thus improve the tomato resistance ability under copper stress.