EFFECTS OF DICLOFOP AND HALOXYFOP ON LIPID-SYNTHESIS IN CORN (ZEA-MAYS) AND BEAN (PHASEOLUS-VULGARIS)

Diclofop-methyl and haloxyfop-methyl (0.001 to 10-mu-M) caused 9 to 61% inhibition of C-14-acetate incorporation into lipids in corn leaf segments within 1 h of herbicide treatment, while neither herbicide affected this process in bean leaf segments. The herbicides did not affect C-14-malonate incorporation into lipids in corn leaf segments. Diclofop-methyl and haloxyfop-methyl reduced C-14-acetate incorporation into polar lipids and triglycerides in corn while incorporation into sterols was increased. In vitro activity of acetyl-coenzyme A carboxylase (EC 6.4.1.2) was inhibited from 26 to 94% within 5 min of exposure to the herbicides (1 to 10-mu-M). Diclofop acid inhibited this enzyme activity more than did haloxyfop acid. Differences in field activity between diclofop-methyl and haloxyfop-methyl are not related to differential sensitivity of acetyl-coenzyme A carboxylase to the two herbicides.