Target-Site Resistance for Acetolactate Synthase Inhibitor Herbicides

Acetolactate synthase (ALS) is the first enzyme common to the biosynthesis of the branched-chain amino acids, leucine, valine, and isoleucine. Currently, there are four commercial classes of herbicides which inhibit this enzyme including sulfonylureas, imidazolinones, triazolopyrimidines, and pyrimidinyl thiobenzoates.