Effects of sethoxydim on the metabolism of isolated leaf cells of soybean [Glycine max (L.) Merr].

The effects of the herbicide sethoxydim {2-[1-ethoxyimino)-butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexen-1-one} on selected metabolic processes of enzymatically isolated leaf cells from soybeans [Glycine max (L.) Merr., cv. "Essex"] were studied. Photosynthesis, protein, ribonucleic acid (RNA), and lipid synthesis were measured by the incorporation of NaH(14)CO3, [(14)C]leucine, [(14)C]uracil, and [(14)C]acetic acid into the isolated soybean cells, respectively. Time-course and concentration studies included incubation times of 30, 60, and 120 min and concentrations of 0.1, 1, 10, and 100 μM of sethoxydim. Lipid synthesis was the most sensitive and first metabolic process inhibited by the lowest concentration of sethoxydim. Photosynthesis was not affected significantly by sethoxydim and did not appear to be a target site involved in its herbicidal action. RNA and protein syntheses were inhibited significantly but only by the high concentrations of sethoxydim. It is suggested that sethoxydim exhibits its phytotoxic action by altering or modifying the lipid composition of plant membranes.