Mode of herbicidal and selective action of DPX-F5384 between rice and weeds.

Abstract

DPX-F5384 is the active ingredient in the rice herbicide Londax®. Growth inhibition promoted by DPX-F5384 in pea roots can be reversed by addition of valine and isoleucine, suggesting inhibition of the pathway for branched-chain amino acid biosynthesis. This compound readily inhibits an enzyme in this pathway, acetolactate synthase. Although acetolactate synthase from rice is also inhibited by DPX-F5384, the rice plant is tolerant due to its ability to metabolically demethylate DPX-F5384 to a relatively weak inhibitor of its acetolactate synthase.