Effect of Glyphosate on Protein and Nucleic Acid Synthesis and ATP Levels in Common Cocklebur (Xanthium pensylvanicum) Root Tissue

Abstract

Common cocklebur (Xanthium pensylvanicumWallr.) root tissue was used to investigate the mechanism of action of glyphosate [N- (phosphonomethyl)glycine]. Arrival of glyphosate in the root-tip was followed closely by a rise in ATP levels to 136% of control levels by 2 h after treatment. Incorporation, but not uptake, of14C-leucine was significantly decreased within 2 h after treatment. Incorporation declined steadily over a 32 -h time course. Uptake of33P by the roots was temporarily stimulated by glyphosate, and as a percent of the total33P taken up, there was decreased incorporation into RNA and DNA fractions by 8 h. Our results indicate that glyphosate may cause the rapid rise in ATP level primarily by inhibiting protein synthesis.