The mode of action of chlorsulfuron: The lack of direct inhibition of plant DNA synthesis

Abstract

Chlorsulfuron (2-chloro- N-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbonyl]benzene-sulfonamide), the active ingredient in DuPont Glean Weed Killer, has been proposed to act by inhibiting plant cell division. In order to further define the mode of action of this new herbicide, studies were made of the effects of chlorsulfuron on processes associated with plant DNA synthesis. No inhibitory effects were observed on DNA synthesis in isolated plant nuclei, and the enzymes DNA polymerase and thymidine kinase. Nucleoside precursors of DNA were not effective in lessening chlorsulfuron inhibition of thymidine incorporation into DNA of corn root tips. These results indicate that chlorsulfuron does not inhibit plant cell division by a direct inhibition of DNA synthesis.