The distribution and identification of brown planthopper resistance genes in rice.

A collection of 515 rice landraces originating from Vietnam and China were screened for the reaction to brown planthopper (BPH) infestation. Most of the resistant landraces were indica types from Vietnam and the Guangxi province in China. An F(2) mapping population was created from the cross between a BPH resistant Vietnamese landrace Yagyaw and the susceptible cultivar Cpslo17. Four quantitative trait loci (QTL) contributing to BPH resistance were mapped on chromosomes 2, 4, 7 and 9, respectively. The individual QTL accounted 5.64% to 12.77% of the phenotypic variance, and three resistant alleles were harbored in the resistant landrace Yagyaw. Two QTL located on chromosomes 2 and 4 were identified with significant additive effects and are useful in breeding new rice inbred lines. One resistant allele was harbored by the susceptible parent Cpslo17. This gene is important in selecting rice inbred lines with stronger resistances to BPH.