The potent inhibition of the shikimate pathway enzyme 5‐enolpyruvylshikimate‐3‐phosphate (EPSP) synthase by the broad‐spectrum herbicide glyphosate (N‐[phosphonomethyl]glycine) was confirmed for the enzymes extracted from various bacteria, a green alga and higher plants. However, 5 out of 6 species belonging to the genus Pseudomonas were found to have EPSP synthases with a 50‐ to 100‐fold decreased sensitivity to the inhibitor. Correspondingly, growth of these 5 species was not inhibited by 5 mM glyphosate, and the organisms did not excrete shikimate‐3‐phosphate in the presence of the herbicide.

SummaryA convenient and inexpensive method for the preparation of ["CC]-labelled shikirnic acid based on the photoassimilation of "CO, by henbane (ffyoscyamus niger L.) leaves in the presence of the herbicide glyphosate is described.Methanolic extracts were purified by successive anion exchange, paper and thin-layer chromatography to yield ["C]-labelled shikimic acid of 99.5% radiochemical purity, as shown by analytical HPLC. Under the conditions employed, the rate of incorporation of 14C0, into shikimic acid (0.7 -17.6%) showed a positive correlation with the size of the leaf used in the incubation (3.6 -146 mg fresh weight), while the specific activity of the acid (6 -12.7 GBq/mmol) was an inverse function of the leaf size.