Glutathione transferases in wheat (Triticum) species with activity toward fenoxaprop-ethyl and other herbicides.
1996
Edwards R. | Cole D.J.
Glutathione transferases (GSTs, EC 2.5.1.18) with activity toward multiple xenobiotic substrates, including the herbicides fenoxaprop, metolachlor, and fluorodifen, have been determined in wheat flour and in seedlings of hexaploid wheat (Triticum aestivum L.) and other Triticum species. Specific activities of the GSTs were in the order roots > shoots > flour with fenoxaprop being the preferred herbicide substrate in all tissues. The enzyme activity responsible for detoxifying fenoxaprop was 10 times less active toward fenoxaprop-ethyl and showed a pH dependence similar to that of the GST which detoxified fluorodifen. The GSTs with activities toward fluorodifen and fenoxaprop, but not that toward the chloroacetanilide herbicides, were elevated threefold in the roots and shoots of wheat seedlings treated with the wheat safener fenchlorazole-ethyl. A similar selective elevation of activity toward fenoxaprop was observed with the maize safener dichlormid. In contrast, treatment with naphthalic anhydride did not increase any of the GST activities, while butylate increased only the activity toward the chloroacetanilides, but did not affect the conjugation of fenoxaprop. GSTs with similar activities were determined in both durum wheat and wild wheat species, but the responsiveness to safeners varied with the genotype. The origins and potential role for these GSTs in herbicide detoxification and selectivity in wheat are discussed.
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