Table II.
Effects of treating roots with Al, F, and AlFx on the plasma membrane H+-ATPase activity
| Parameter | Treatment
|
|||
|---|---|---|---|---|
| Control | AlCl3 | NaF | AlFx | |
| H+ gradient | ΔF (%) | |||
| Steady state | 25 ± 6 (n = 5) | 34 ± 8 (n = 4) | 22 ± 9 (n = 4) | 25 ± 5 (n = 5) |
| Initial velocity | F min−1 | |||
| 120 ± 16 (n = 5) | **235 ± 30 (n = 4) | 125 ± 27 (n = 4) | 127 ± 22 (n = 5) | |
| Hydrolysis | ||||
| Initial velocity | nmol mg−1 min−1) | |||
| 130 ± 16 (n = 5) | *191 ± 23 (n = 3) | 128 ± 26 (n = 3) | 132 ± 19 (n = 5) | |
H+-ATPase activity was determined in plasma membrane vesicles isolated from roots of seedlings grown in hydroponic medium alone (control), and supplemented either with 0.1 mm AlCl3, 1 mm NaF, or both (AlFx). Values are the means of n experiments ± se. *, Significance at P ≤ 0.01 confidence (Student's t test), compared with control membranes. **, Significance at P ≤ 0.001 confidence (Student's t test), compared with control membranes.