[Adaptive changes in activity of tonoplast H(+)-ATPase from the roots of tomato seedlings under phosphorus starvation].
We studied the growth state of tomato seedlings and the adaptive changes in activity of tonoplast H(+)-ATPase on different days (5 d, 7 d, 9 d, 11 d, 13 d) sampling from the roots of tomato seedlings under phosphorus starvation. The results indicated that the average height of the seedlings decreased under phosphorus starvation, while the main roots of the seedlings were significantly longer than those of the control. The phosphorus uptake rates of tomato seedlings under phosphorus starvation significantly increased and were much higher than those of controls and reached maximum values under the starvation for 7 days. The tonoplast H(+)-ATPase activity in the roots of tomato seedlings increased under phosphorus starvation and reached maximum values under the starvation for 7 days, while the activity of the control changed little. Kinetic analysis of tonoplast H(+)-ATPase showed that phosphorus starvation significantly lowered the K(m) value, but had no significant effect on the V(max) value of the enzyme. The results showed that phosphorus starvation increased the affinity of the enzyme to its substrate. In addition, phosphorus starvation did not alter the optimum pH (7.5) of the ATPase activity.
Shan
Shu-Hua
SH
College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Song
Ke-Min
KM
Liu
Jing-Ru
JR
Xu
Han-Bing
HB
D000222:Adaptation, Physiological; D006863:Hydrogen-Ion Concentration; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology* / Q000378:metabolism; D036226:Seedlings / Q000201:enzymology* / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism*
D010940:Plant Proteins; D010758:Phosphorus; D025262:Vacuolar Proton-Translocating ATPases