The expression of a maize glutathione S-transferase gene in transgenic wheat confers herbicide tolerance, both in planta and in vitro

Milligan, A. S. and Daly, A. and Parry, M. A. J. and Lazzeri, P. A. and Jepson, I. (2001) The expression of a maize glutathione S-transferase gene in transgenic wheat confers herbicide tolerance, both in planta and in vitro. Molecular Breeding, 7 (4). pp. 301-315. ISSN 1380-3743

Abstract

Maize (Zea mays), in common with a number of other important crop species, has several glutathione S-transferase (GST) isoforms that have been implicated in the detoxification of xenobiotics via glutathione conjugation. A cDNA encoding the maize GST subunit GST-27, under the control of a strong constitutive promoter, was introduced into explants of the wheat (Triticum aestivum L.) lines cv. Florida and L88-31 via particle bombardment, using the phosphinothricin acetyltransferase (pat) gene as a selectable marker. All six independent transgenic wheat lines recovered expressed the GST-27 gene. T1 progeny of these wheat lines were germinated on solid medium containing the chloroacetanilide herbicide alachlor, and tolerance to this herbicide was correlated with GST-27 expression levels. In glasshouse sprays, homozygous T2 plants were resistant not only to alachlor but also to the chloroacetanilide herbicide dimethenamid and the thiocarbamate herbicide EPTC. These additional GST-27 activities, demonstrated via over-expression in a heterologous host, have not been described previously. T2 plants showed no enhanced tolerance to the herbicides atrazine (an s-triazine) or oxyfluorfen (a diphenyl ether). In further experiments, T2 wheat plants were recovered from immature transgenic scutella cultured on medium containing 100 mg/l alachlor, a concentration which killed null segregant and wild-type scutella. These data indicate the potential of the maize GST-27 gene as a selectable marker in wheat transformation.