The effect of graminicides on plant plasma membrane H+-ATPase activity in vitro

In this study we have screened the H+-ATPase activity of purified plasma membrane vesicles from the dicotyledon sugar beet (Beta vulgaris cv Celt) and the monocotyledon black-grass (Alopecurus myosuroides) against different graminicide classes. The thiocarbamates, diallate and triallate had the greatest effect on H+-ATPase activity with a 70-80% inhibition at 100 mu M in both species. A third thiocarbamate EPTC, did not inhibit activity. Aryloxyphenoxypropionates such as diclofop-methyl inhibited H+-ATPase activity by approximately 40-50% in both species. Cyclohexanediones and chloroacetamides generally had no effect. Results are discussed in relation to proposed modes of action of graminicides.