Glutathione S-Transferase Activity in Nontreated and CGA-154281- Treated Maize Shoots*

Fast protein liquid chromatography (anion exchange) was used to separate glutathione S-transferase isozymes in nontreated etiolated maize shoots and those treated with the herbi­ cide safener CGA-154281 4-(dichloroacetyl)-3,4-dihydro-3-methyl-2 H-l ,4-benzoxazine. Non­ treated shoots contained isozymes active with the following substrates: fra/?s-cinnamic acid (1 isozyme), atrazine (3 isozymes), l-chloro-2,4-dinitrobenzene (1 isozyme), metolachlor (2 isozymes) and the sulfoxide derivative of S-ethyl dipropylcarbamothioate (2 isozymes). Pre­ treatment of shoots with the safener CGA-154281 (1 (aM) had no effect on the activity of the isozymes selective for rratts-cinnamic acid and atrazine but increased the activity of the constitutively-expressed isozymes that exhibit activity with l-chloro-2,4-dinitrobenzene, metola­ chlor and the sulfoxide derivative of S-ethyl dipropylcarbamothioate. The safener pretreat­ ment also caused the appearance of one new isozyme active with l-chloro-2,4-dinitrobenzene and one new isozyme active with metolachlor. The results illustrate the complexity of gluta­ thione S-transferase activity in etiolated maize shoots, and the selective enhancement of gluta­ thione S-transferase isozymes by the safener CGA-154281.