Bialaphos-Resistant Transgenic Soybeans Produced By the Agrobacterium-Mediated Cotyledonary-Node Method

A stable agrobacterium-mediated transformation system was established usingbialaphos as the selective agent in soybeans [glycine max (l.) merr.]. the cotyledonarynode explants of the soybean cultivar ‘ny-1001’ were inoculated with the agrobacteriumtumefaciens strain eha105, harboring the vector pcambia3301 containing the gus geneas the reporter gene and the bar gene conferring bialaphos resistance. the highestfrequency of gus transient expression (92%) was obtained after inoculation and 4-dayco-cultivation with a. tumefaciens strain eha105. efficient gus expression was observedin regenerated shoots from explants after 4-day co-cultivation combined with culturing onshoot induction medium (sim) without bialaphos for 7 days followed by 4 mg.l-1bialaphos for 2 weeks. bialaphos (4 mg.l-1 in sim; 2 mg.l-1 in shoot elongation medium(sem)) effectively selected the transformants. the putative transformants and escapescould be exactly distinguished by using a half-leaf gus assay method to detect gusexpression in the elongated resistant shoots, which resulted in the shortening of cultureperiod for the early detection of transformed shoots. the transformation efficiency of thissystem was 1.06%. the transgenic plants were verified by polymerase chain reaction(pcr), southern blotting, and herbicide-resistant responses. all four t0 transgenic plantswere fertile and transmitted the phenotypes of both gus and bar in a 3:1 ratio to their progeny. these results indicate that the established system is suitable for further breeding of herbicide-resistant transgenic cultivars, as well as for functional genomics studies of soybeans.