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

Abstract 

The brown planthopper (BPH), Nilaparvata lugens Stål, is a significant insect pest of rice (Oryza sa-tiva L.). bph2 is one of the 12 major BPH resistance genes so far identified in several indica cultivars and two wild relatives. 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 ’Norin-PL4’ (an authentic bph2-introgression line) was used. Segregation analysis by the mass seedling test showed that bph2 behaved as a single dominant gene. Through bulked segregant analysis and linkage analysis, bph2 was located 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 converted into a PCR-based sequence-tagged-site (STS) marker and its co-segregation with bph2 was validated.