ABSTRACT
One of the most significant occurrences in herbicide resistance has been the advent of weeds resistant to herbicides that inhibit acetolactate synthase. The topic of herbicide-resistant crops in agriculture has been reviewed by B. J. Mazur and S. C. Falco. Evidence for the mode of action of the acetolactate synthase (ALS) inhibitor herbicides comes from several scientific disciplines. Uncompetitive binding is seen for imazaquin versus pyruvate using plant ALS, but noncompetitive binding has also been reported for the imidazolinones. Reduced sensitivity of plants to several herbicides is associated with lower rates of either uptake or translocation from the site of uptake to the site of action. The commercial form of the herbicide is a methyl ester that is inactive against ALS; the active form of the herbicide is imazamethabenz, the free acid. Sulfonylureas, imidazolinones, triazolopyrimidines, and pyrimidinyl thiobenzoates comprise the commercial ALS inhibitor herbicides currently or soon to be available.
