Molecular Marker-Assisted Breeding of Restorer Lines with Bacterial Blight Resistance in Oryza sativa

Backcross populations were constructed using four kinds of Indica-compatible Japonica lines(ICJLs) and lines with two restorer genes,Rf3,Rf4 and four bacterial blight(BB) resistance genes,Xa4,xa5,xa13 and Xa21.Molecular marker-assisted selection(MAS) was conducted using polymorphic PCR markers tightly linked with six genes mentioned above.Nineteen plants with all six heterozygous target genotypes were selected in BC_1F_1 and developed to BC_1F_2 lines.These lines were detected further.Twenty-eight plants with at least four homozygous target genotypes were obtained.Among them three plants were found to contain six homozygous genotypes,thus indicated successful pyramiding of restorer and BB genes.The test showed that 2 selected plants with six homozygous loci were good restorative to wild abortion type cytoplasmic male sterility(CMS)lines.