Construction of a high-resolution linkage map of a rice brown planthopper (Nilaparvata lugens Stal) resistance gene bph2

The brown planthopper (BPH), Nilaparvata lugens Stal, is a significant inse ct pest of rice (Oryza sativa L.). bph2 is one of the 12 major BPH resistan ce aeries so far identified in several indica cultivars and two wild relati ves. We have constructed a high-resolution linkage map as a foundation for map-based cloning of the bph2 locus. An advanced mapping population derived from a cross of 'Tsukushibare' (a susceptible japonica cultivar) with 'Nor in-PL4' (an authentic bph2-introgression line) was used. Segregation analys is by the mass seedling test showed that bph2 behaved as a single dominant gene. Through bulked segregant analysis and linkage analysis, bph2 was loca ted within a 3.2-cM region containing eight AFLP markers. One marker (KAM4) showed complete co-segregation with bph2, and bph2 was mapped within a 1.0 -cM region delimited by KAM3 and KAM5, two flanking markers. KAM4 was conve rted into a PCR-based sequence-tagged-site (STS) marker and its co-segregat ion with bph2 was validated.