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

Glutathione (gamma-L-glutamyl-L-cysteinyl glycine: GSH) content and the activity of glutathione S-transferase (GST, EC 2.5.1.18) and of peroxidase (donor: hydrogen peroxide oxidoreductase, EC 1.11.1.7) were investigated in corn (Zea mays L.) during a 10-day period following treatments with atrazine, metolachlor and alachlor. The enzyme activities were also checked in response to external application of GSH instead of the herbicides. All the herbicides significantly enhanced the GSH content in shoots and roots of corn throughout the entire experimental period with respect to the controls. This was more pronounced in roots, and alachlor was the most effective. Shoot height and root length as well as fresh weight of corn were generally decreased as a result of treatment with either atrazine or metolachlor, whereas alachlor showed no significant action. At the same time, the activity of GST and peroxidase was increased with all the applied herbicides. The externally supplied GSH similarly increased the enzyme activities, particularly peroxidase. These results confirm the relationship of GSH with corn growth and support its importance for corn tolerance to atrazine, metolachlor and alachlor and indicate the regulatory action of GSH on the activity of GST and peroxidase.