Effects of NaCl stress on ATPase activities of root plasma and tonoplast membranes in grafted tomato seedlings

The effects of NaCl stress on root vigor, H+-ATPase activities of plasma membrane and tonoplast membrane, H+-PPase activities of tonoplast membrane, Ca2+-ATPase activities of plasma membrane and tonoplast membrane, plasma membrane redox system in roots of grafted and own-root tomato (Lycopersicon esculentum Mill.) seedlings were investigated. Results showed that root vigor of grafted seedlings was significantly higher than that of own-root seedlings during the whole stage of stress. In the early stage of stress, H+-ATPase activities of plasma membrane and tonoplast membrane, H+-PPase activities of tonoplast membrane, Ca2+-ATPase activities of plasma membrane and tonoplast membrane, NADH oxidation rate, Fe(CN)63- reduction rate in roots of grafted seedling were significantly increased, H+-ATPase, H+-PPase and Ca2+-ATPase activities of tonoplast membrane, NADH oxidation rate, Fe(CN)63- reduction rate of own-root seedling roots were significantly increased as well. In the late stage of stress, the activities of all indices of both grafted and own-root seedlings were inhibited, but the inhibition of grafted seedlings was later and significantly lighter than those of own-root seedlings during the whole stage of stress. All these results indicated that the tolerance of grafted tomato seedlings to NaCl stress was stronger than that of own-root seedlings.