Preliminary study on breeding hybrid rice by pyramiding brown planthopper resistance genes through molecular marker-assisted selection.

In this study,rice line ME1 contained two brown planthopper resistance genes bph2 and Bph3 was used as resistance donor to cross and backcross with six receptor parents of hybrid rice including maintainer line Meng B,Xian B,Tian B,sterile line RT 300 and RT 181,and restorer line R 29,and genes bph2 and Bph3 were transferred to six receptor parents by molecular marker-assisted selection. The results showed that a total of 13 BC2F1 lines with bph2 and Bph3 heterozygous genotype was obtained from six backcross combinations. Combined with agronomic trait selection at the adult plant stage,six inbred seeds of BC2F1 were seeded to identify the BPH resistance at seedling stage. The results indicated that all of six BC2F2 lines had moderate resistance to BPH,the genotypes of 309 resistant plants were mapped and 21 homozygous strains with bph2 and Bph3 were successfully obtained. These homozygous materials would be useful in breeding hybrid rice resistance to BPH.