Glyphosate-induced increase in glutathione S-transferase activity and glutathione content in groundnut (Arachis hypogaea L.)

The obvious sensitivity of most plant species to glyphosate suggests that t his phosphonate is poorly metabolized in plants. The effect of glyphosate o n glutathione S-transferase (GST, EC 2.5.1.18) and glutathione (GSH) levels was examined in groundnut (Arachis hypogaea L.), in view of the adaptive s ignificance of elevated thiol metabolism in catalyzing metabolism of severa l herbicides in vivo. Glyphosate treatment resulted in a significant and co ncentration-dependent increase in the activity of GST and GSH levels in the three groundnut cultivars, JL24, CO2, and TMV2, tested. The glyphosate-ind uced increase in the enzyme activity was maximum in the foliar explants of all three cultivars, but was not correlated to their sensitivity to the her bicide. Glyphosate-tolerant cell lines of groundnut (A. hypogaea cv. JL24) selected in vitro showed an elevated basal level of GST activity and nonpro tein thiol content, as opposed to the glyphosate-sensitive cell line. The g lyphosate-induced increase in GST activity could be prevented by cyclohexim ide and actinomycin D. (C) 2001 Academic Press.