Metabolism of Ascorbic Acid and Glutathione in Leaves of Grafted Eggplant Seedlings under NaCl Stress

Using 'Torvum Vigor'(Solanum torvum Swartz) as rootstock and eggplant cultivar 'Suqiqie'(Solanum melongena L.) as scion,we studied the effects of NaCl stress on the contents of antioxidants,generation of hydrogen peroxide(H2O2) and H2O2-scavenging system in leaves of both grafted and own-root seedlings.The results showed that NaCl stress induced generation of H2O2 and accumulation of malondiadehyde(MDA) both in grafted and own-root seedlings.However,contents of H2O2 and MDA in leaves of grafted seedlings were significantly lower than those of own-root seedlings.The activities of glutathione reductase(GR) and ascorbate-specific peroxidase(APX) in leaves of grafted seedlings were significantly increased whereas those of own-root seedlings were decreased under NaCl stress.NaCl stress stimulated the synthesis of ascorbic acid(AsA) and reduced glutathione(GSH) in grafted seedlings.Contents of AsA and GSH in leaves of grafted seedlings were significantly higher than those of own-root seedlings.It was concluded that a rapid cycle of AsA-GSH which ensured regeneration of AsA and GSH to reduce oxidative damage might be involved in the stronger salt tolerance of grafted eggplant seedlings.