Use of aroA-M1 as a selectable marker for Brassica napus transformation

The aroA-M1 mutant consisting of an N-terminal portion of Escherichia coli 5-enolpyruvylshkimate-3-phosphate synthase (EPSPS) and a C-terminal portion of Salmonella typhimurium EPSPS confers high resistance to glyphosate because of a decrease in the K-m(PEP) and an increase in the K-i(glyphosate). In this paper, we constructed a binary vector carrying the aroA-M1 mutant gene under the control of the CaMV 35S promoter for Agrobacterium-mediated gene transfer to Brassica napus L. Transgenic Brassica plants with increased resistance to glyphosate were obtained by cocultivation of hypocotyl explants with Agrobacterium tumefaciens and direct selection on media containing glyphosate. Southern blot and western blot analyses confirmed gene integration and expression in T-0 transgenic Brassica plants. Transgenic plants exhibited increased resistance to glyphosate compared with untransformed plants. Our results also indicated the aroA-M1 mutant gene may be a useful selectable marker for the transformation of plants and for the production of herbicide-resistant plants.