Study On V-PPase Activities Of Tomato Seedlings Under Phosphate Starvation

The effects of phosphate stress on V-PPase Activities and Changes in H⁺-pumps were studied in this paper. The results are as follows:1 The results revealed that the phosphate starvation had a significantly effect on the Pi-uptake rates of the tomato seedlings. Tomato seedlings of phosphate starvation distinctly increased their Pi uptake rates that were much higher than the controls.While controls had no obvious changes.2 The result in this paper also indicated that the early days of phosphate starvation the V-PPase activities had a markedly decese, however the late days of starvation the V-PPase activities of the seedlings decesed. The V-PPase activities of control had no obviously changes.The root activity in tomato seedings improved by phosphate starvation3 The kinetic analysis of V-PPase of the seedlings showed that phosphate stress decreased the Km value, but had little effect on the V_max value of the enzyme.The results indicated that the the affinity of the enzyme to pi may be one of factors in phosphate starvation tolerance.4 The phosphate starvation had little effect on the optimum pH (Ph=8.5) of V-PPase, but V-PPase activity greatly was influence by different pH.5 The result of experiment showed that the significant difference in the vacuolar proton pumps activity in response to different levels of Pi supplement occurred on the seven days after treatment.the hydrolytic activity of V-PPase had a obvious decrease after plant being treated for 9d.This was may be regulated by the concentration of PPi and ATP.