Effect of glyphosate on lipoxygenase of cowpea seed

Abstract

The predominant cowpea seed lipoxygenase was optimally activated by calcium at 0.68 mM and at pH 7.5. Seeds were analyzed during germinaton and showed a decrease in lipoxygenase specific activity with time. Seeds from plants treated with the herbicide glyphosate (N - (phosphonomethyl) glycine) showed a significant increase in lipoxygenase content. This could have been a result of senescence, or the effects of the herbicide on those plants. Such a conclusion is basead on findings that a. lipoxygenase, the activity of which was enhanced by glyphosate, has been reported to promote formation of 12-oxo-phytodienoic acid, and b. 12-oxo-phytodienoic acid has been proposed to be a precursor of jasmonic acid, a growth regulator which promotes senescence of plants. With the assay technique utilized, no lipoxygenase was found in mature leaves.