GLUTATHIONE REGULATION OF GLUTATHIONE-S-TRANSFERASE AND PEROXIDASE-ACTIVITY IN HERBICIDE-TREATED ZEA-MAYS

Glutathione (gamma-L-glutamyl-L-cysteinyl glycine: GSH) content and th e activity of glutathione S-transferase (GST, EC 2.5.1.18) and of pero xidase (donor: hydrogen peroxide oxidoreductase, EC 1.11.1.7) were inv estigated in corn (Zea mays L.) during a 10-day period following treat ments with atrazine, metolachlor and alachlor. The enzyme activities w ere also checked in response to external application of GSH instead of the herbicides. All the herbicides significantly enhanced the GSH con tent in shoots and roots of corn throughout the entire experimental pe riod with respect to the controls. This was more pronounced in roots, and alachlor was the most effective. Shoot height and root length as w ell as fresh weight of corn were generally decreased as a result of tr eatment with either atrazine or metolachlor, whereas alachlor showed n o significant action. At the same time, the activity of GST and peroxi dase was increased with all the applied herbicides. The externally sup plied GSH similarly increased the enzyme activities, particularly pero xidase. These results confirm the relationship of GSH with corn growth and support its importance for corn tolerance to atrazine, metolachlo r and alachlor and indicate the regulatory action of GSH on the activi ty of GST and peroxidase.