Mr. Hull et Ah. Cobb, AN INVESTIGATION OF HERBICIDE INTERACTION WITH THE H-ATPASE ACTIVITY OF PLANT PLASMA-MEMBRANES(), Pesticide science, 53(2), 1998, pp. 155-164
This study has investigated the activity of several herbicide classes
at the plant plasma membrane. Two-phase partitioning was used to prepa
re highly purified plasma membrane vesicles from the monocotyledon wee
d black-grass (Alopecurus myosuroides Huds.) and the dicotyledon crop
sugar beet (Beta vulgaris L. cv. Celt). The purity of the plasma membr
ane H+-ATPase activity was characterised with respect to inhibitors, p
H and substrate specificity. In both species, contamination of the pla
sma membrane by tonoplast fragments was largely eliminated and chlorop
hyll was absent. In addition, the plasma membrane H+-ATPase from black
-grass and sugar beet exhibited high vanadate sensitivity and a sharp
pH profile around 6.5. Subsequently, H+-ATPase activity was assayed in
the presence (100 mu M) and absence of four graminicide classes and a
uxin-type herbicides. Graminicides, including the aryloxyphenoxypropio
nate diclofop-methyl and the thiocarbamate triallate, inhibited H+-ATP
ase activity by 50-80% in both species. However, other graminicides, i
ncluding the cyclohexanediones and the chloroacetamide alachlor, had n
o affect. Similarly, auxin-type herbicides such as 2,4-D and MCPA did
not inhibit H+-ATPase activity. Results are discussed in relation to t
he proposed mode of action of these herbicides. (C) 1998 SCI.