ABSTRACT
The herbicidal activity of glyphosate and its salts was first described in 1971.' Conversely, if glyphosate-resistant cultivars are marketed and viewed as an integral component of an integrated weed management system that includes other herbicides, nonresistant crops, and nonchemical control measures, these cultivars may well become incorporated into modern agricultural practices. The intense and widespread interest in glyphosate has led to a substantial body of literature on its biochemical mechanism of action. Early studies on the mechanism of action of glyphosate were closely followed by efforts to select resistant strains of enteric bacteria. Elevated resistance levels and gene amplification have been demonstrated in plants regenerated from selected cell cultures. However, there are no confirmed reports of glyphosate-resistant weeds developing in field situations. The suggestion was also made that development of resistance in weeds would require a combination of two mutations, one for mutation of enolpyruvylshikimate to confer resistance and another mutation for overproduction of the mutant enzyme.
