RFLP/AFLP mapping of a brown planthopper (Nilaparvata lugens St?l) resistance gene Bph1 in rice

We have constructed a linkage map of the rice brown planthopper (BPH) resistance gene, Bph1. RFLP and AFLP markers were selected by the bulked segregant analysis and used in the mapping study of 262 F2s that were derived from a cross of `Tsukushibareʹ, a susceptible japonica cultivar, and `Norin-PL3ʹ, an authentic japonica Bph1-introgression line. Twenty markers were mapped within a 28.9-cM region containing the Bph1 locus on the long arm of rice chromosome 12. Combining the result of segregation analysis of BPH resistance by the mass seedling test and that of the markers, the Bph1 locus was mapped within a 5.8-cM region between two flanking markers. The closest AFLP markers, em5814N and em2802N, was at 2.7 cM proximal to the Bph1 locus. Together with the previously constructed high-resolution map of bph2 locating the locus at ca. 10 cM proximal to the Bph1 locus, this improved version of the linkage map would facilitate pyramiding these two important BPH resistance genes.