HIGH-EFFICIENCY TRANSFORMATION OF MAIZE (ZEA-MAYS L) MEDIATED BY AGROBACTERIUM-TUMEFACIENS

Transformants of maize inbred A188 were efficiently produced from imma ture embryos cocultivated with Agrobacterium tumefaciens that carried ''super-binary'' vectors. Frequencies of transformation (independent t ransgenic plants/embryos) were between 5% and 30%. Almost all transfor mants were normal in morphology, and more than 70% were fertile. Stabl e integration, expression, and inheritance of the transgenes were conf irmed by molecular and genetic analysis. Between one and three copies of the transgenes were integrated with little rearrangement, and the b oundaries of T-DNA were similar to those in transgenic dicotyledons an d rice. F1 hybrids between A188 and five other inbreds were transforme d at low frequencies.