The Brown planthopper (Bph) is one of the most serious pests of rice affecting rice yield and quality throughout the country. Combining the Bph resistance in the existing quality japonica cultivars is an important breeding target in Korea. Wide crosses using several strains of AA-genome wild rices, O.rufipogon have been used to produce the primary germplasm which is highly resistant to Bph. By repeated backcrossing, the resistance gene was introgressed in the background of two japonica cultivars, Ilpum and Hwaseong. Among the advanced backcross progenies, the ten BC2F3 lines were identified as the highest resistance in the comparative Bph bioassay with other resistant sources. The 24 polymorphic markers spanning the twelve chromosomes were tested for association with marker genotypes and resistance/susceptibility reaction in the 80 BC2F3 lines, RM3748 on the chromosome 7 showed the highest association.

The Brown planthopper (BPH) is one of the most serious pests of rice affecting rice yield and quality throughout the country. AA genome wild rice, O.rufipogon is a useful source of insect resistance to BPH. To broaden the BPH resistance in the existing quality japonica cultivars, crossess were made between a highly susceptible quality rice cultivar, Ilpumbyeo, and five accessions (acc.106109, 106286, 106424,105908,80671) of O.rufipogon. Among 126 F8 RIL lines evaluated for Bph resistance at NICS, the highly resistant 22 introgression lines were identified and Ilpumbyeo*2/O.rufipogon (acc.105908) showed different genotype at the marker loci of Bph1, Bph18 and the resistance reaction to BPH in the BC1F2 population fitted to 3:1 segregation mode, indicating the possible new dominant resistance gene might be involved. Polymorphism between Ilpumbyeo and resistant line was low with 36 (27%) SSR markers among 130 markers detected. Currently mapping population of BC2F2 is established and SSR marker analysis will be carried out to find out the resistance loci.