Isolation and biochemical diagnosis of cell lines of groundnut (Arachis hypogaea L) selected on glyphosate

Three cell lines of groundnut (Arachis hypogaea L), an important oilseed le gume, were selected on glyphosate using in-vitro culture techniques. The ce ll lines isolated through single as well as stepwise selection procedures s howed c 20-fold increase in glyphosate tolerance as compared to the unselec ted control cell line. Studies on the biochemical mechanism of glyphosate t olerance in these cell lines showed a significant increase in the total ext ractable activity of the target enzyme, 5-enolpyruvyl shikimate-3-phosphate (EPSP) synthase (EC 2.5.1.19), which was further confirmed with immunologi cal data. The over-expressed EPSP synthase activity was, however, subject t o inhibition by glyphosate in vitro. Two other key regulated enzymes of the shikimic acid pathway, 3-deoxy-D-arabino heptulosonate 7-phosphate (DAHP) synthase (EC 4.1.2.15) and chorismate mutase (CM) (EC 5.4.99.5) did not sho w any change in specific activity in the selected cell lines. The enhanced activity of EPSP synthase in the tolerant cell lines was found to be stably inherited in the absence of selection pressure. (C) 1999 Society of Chemic al Industry.