Localization of the rice stripe disease resistance gene, Stv-bi, by graphical genotyping and linkage analyses with molecular markers

We used graphical genotyping and linkage analyses with molecular markers to determine the chromosomal location of the rice stripe disease resistance gene, Stv-b(i). The stripe resistance gene from the indica rice (Oryza sativa) cv 'Modan' was introgressed into several Japanese rice varieties. We found 4 RFLP markers in 'Modan', five susceptible parental rice varieties ('Norin No. 8', 'Sachihikari', 'Kanto No. 98', 'Hokuriku No.103' and 'Koganebare') and four resistant progeny varieties ('St. No. 1', 'Aichi No. 6', 'Aoisora' and 'Asanohikari'). Graphical genotyping of the resistant progeny revealed a chromosomal segment ascribable to 'Modan' and associated with stripe resistance. The chromosomal segment from 'Modan' was located at 35.85 cM on chromosome 11. Linkage analysis using 120 F-2 individuals from a cross between 'Koshihikari' (susceptible) and 'Asanohikari' (resistant) revealed another 8 RFLP markers in the same chromosome. We performed a bioassay for rice stripe resistance in F-3 lines of the F-2 individuals using infective small brown planthoppers and identified an 1.8-cM segment harboring the rice stripe disease resistance gene, Stv-b(i), between XNpb220 and XNpb257/XNpb254. Furthermore, Stv-b(i) was linked by 0.0 cM to a RFLP marker, ST10, which was developed on the basis of the results of RAPD analysis. These DNA markers near the Stv-b(i) locus may be useful in marker-assisted selection and map-based cloning of the Stv-b(i) gene.