Introduction of a rice blight resistance gene, Xa21, into five Chinese rice varieties through an Agrobacterium-mediated system

A cloned gene, Xa21 was transferred into five widely-used Chinese rice vari eties through an Agrobacterium-mediated system, and over 110 independent tr ansgenic lines were obtained. PCR and Southern analysis of transgenic plant s revealed the integration of the whole Xa21 gene into the host genomes, Th e integrated Xa21 gene was stably inherited, and segregated in a 3:1 ratio in the selfed T-1 generation when one copy of the gene was integrated in th e transformants. Inoculation tests displayed that transgenic T-0 plants and Xa21 PCR-positive T-1 plants were highly resistant to bacterial blight dis ease. The selected Xa21 homozygous resistant transgenic lines with desirabl e qualities may be propagated as new varieties or utilized in hybrid rice b reeding.