Molecular mapping of four blast resistance genes using recombinant inbred lines of 93-11 and nipponbare

Molecular mapping of new blast resistance genes is important for developing resistant rice cultivars using marker-assisted selection. In this study, 259 recombinant inbred lines (RILs) were developed from a cross between Nipponbare and 93-11, and were used to construct a 1165.8-cM linkage map with 131 polymorphic simple sequence repeat (SSR) markers. Four major quantitative trait loci (QTLs) for resistance to six isolates of Magnaporthe oryzae were identified: qPi93-1, qPi93-2, qPi93-3, and qPiN-1. For the three genes identified in 93-11, qPi93-1 is linked with SSR marker RM116 on the short arm of chromosome 11 and explains 33% of the phenotypic variation in resistance to isolate CHE86. qPi93-2 is linked with SSR marker RM224 on the long arm of chromosome 11 and accounts for 31% and 25% of the phenotypic variation in resistance to isolates 162-8B and ARB50, respectively. qPi93-3 is linked with SSR marker RM7102 on chromosome 12 and explains 16%, 53%, and 28% of the phenotypic variation in resistance to isolates CHE86, ARB52, and ARB94, respectively. QTL qPiN-1 from Nipponbare is associated with SSR marker RM302 on chromosome 1 and accounts for 34% of the phenotypic variation in resistance to isolate PO6-6. These new genes can be used to develop new varieties with blast resistance via marker-aided selection and to explore the molecular mechanism of rice blast resistance.