AGROBACTERIUM-TUMEFACIENS-MEDIATED BARLEY TRANSFORMATION

Genetically transformed barley was produced by co-cultivating immature embryo explants with Agrobacterium tumefaciens carrying a binary vect or coding for chimaeric bacterial genes, bar and gus, and selecting fo r bialaphos-resistant cultures from which plants were regenerated. Int egration of both genes was confirmed by gel blot hybridization analysi s of DNA from the transformed plants and their progenies. From 1282 em bryos, plants were recovered for 54 independently transformed lines, g iving a transformation efficiency of 4.2%. Transgene numbers in the di fferent lines ranged from single copy insertion to at least ten copies . Sixteen out of 18 plants grown to maturity were fully fertile. Both marker genes, bar and gus, were expressed and co-segregated in the T-1 progeny plants. In the majority of cases, the genes showed Mendelian segregation predicted for transgene insertion at a single locus. In on e family with multiple transgene insertions, molecular analysis of T-1 and T-2 plants suggested that the T-DNA had inserted at two unlinked loci.