DEVELOPMENTAL EXPRESSION OF GLUTATHIONE-S-TRANSFERASE IN MAIZE AND ITS POSSIBLE CONNECTION WITH HERBICIDE TOLERANCE

Crop improvement for tolerance to specific herbicides is an important breeding target, since molecules performing well with regard to enviro nmental safety are frequently not completely selective for crops. The glutathione (GSH)/glutathione-S-transferase (GST) system is a general mechanism of detoxification that in higher plants may confer tolerance to some herbicides. GSH level and GST activity were measured in diffe rent maize inbred lines, in the absence or in the presence of EPTC (a thiocarbamate) and of Alachlor (a chloroacetanilide); a wide genetic v ariability was observed for these parameters, which appear to be invol ved in plant tolerance to herbicides. Isozyme analysis was performed o n roots, leaves, scutellum, pollen, coleoptile, mesocotyl of the same inbreds: it revealed the presence of many GST forms in maize, showing high polymorphism; they are controlled by at least five genes, the exp ression of which is developmentally regulated in the different tissues analyzed.