Changes of H⁺ pumps of tonoplast vesicle from wheat roots in vivo and in vitro under aluminum treatment and effect of calcium

Abstract

Wheat seedlings were treated with 0.1 mM Al for 7 days. Tonoplast vesicles were isolated from apical segments of roots and activities of H⁺‐ATPase and H⁺‐PPase measured. Compared with the control, 0.1 mM Al increased H⁺‐ATPase activity and decreased H⁺‐PPase activity. High external supply of calcium (Ca) (5 mM) diminished the extent of the stimulation of H⁺‐ATPase activity and alleviated the reduction of H⁺‐PPase activity under Al treatment. However, 0.1 mM Al treatment in vitro resulted in the inhibition of H⁺‐ATPase activity with the decrease of Vmax and Km for ATP. In vitro treatment with 0.1 mM Al also decreased the H⁺‐PPase activity, but increased the Km for PPi.

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