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The relationship between phosphate uptake and changes in plasmalemma H~(+)-ATPase activities from the roots of tomato seedlings during phosphate starvation

Song Kemin, Jiao Xinzhi, Li Lin, Yan Jiqiong

Department of Agronomy,Huazhong Agricultural University.Wuhan 430070,Hubei；China；Department of Biology,East China Normal University.Shanghai 200062

Abstract

Phosphate starvation increased the activity of PM H~(+)-ATPase from tomato seedlings and enhanced the extrusion of H~(+) from the roots of the seedlings. Kinetic analysis of the PM H~(+)-ATPase from the roots of tomato seedlings showed that phosphate starvation obviously lowered the K_(m) value, which indicated that phosphate starvation increased the affinity of the enzyme to its substrate, but had no significant effect on the V_(max) value of the enzyme. In addition, phosphate starvation did not alter the optimum pH of the ATPase. Vanadate, a specific inhibitor of PM H~(+)-ATPase, strongly inhibited not only phosphate uptake but also PM ATPase activity from and H~(+)-extrusion by the roots of tomato seedlings. These results demonstrated that the PM H~(+)-ATPase is involved in the induction of high-affinity phosphate transport systems by phosphate starvation.

Key words: Tomato(Lycopersicon esculentum);Phosphate starvation;Plas malemma(PM) H~(+)-ATPase;Phosphate uptake

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Citing This Article：

Song Kemin, Jiao Xinzhi, Li Lin, Yan Jiqiong. The relationship between phosphate uptake and changes in plasmalemma H~(+)-ATPase activities from the roots of tomato seedlings during phosphate starvation. Acta Physiol Sin 2001; 53 (1): (in Chinese with English abstract).