Objective  The rice cultivar Gufeng B confers strong, broad-spectrum, durable resistance against various rice blast isolates. The present study was aim to identify and map the blast resistance gene(s) in Gufeng B.

  Method   The F1 and F2 population were obtained by crossing Gufeng B and Nipponbare, and the genetic model of blast resistance was analyzed after inoculating with 7 strains of Magnaporthe grisea. Subsequently, F2 population was used to construct a resistant pool and a sensitive pool respectively, and to map the associated loci via the method of bulked segregation analysis.

  Result   Gufeng B exhibited high resistance to all of the tested strains, such as KJ201, RB22, CHNOS, RB6, 2Y838-1, 501-3 and IR16-1, suggesting that Gufeng B may carry the broad-spectrum and high resistance genes. The F1 progenies from the cross between Gufeng B and Nipponbare conferred resistance against the strains 501-3 and IR16-1, and the segregation ratio of resistance and susceptibility among F2 progenies does not fit 3:1, assuming that the resistance against the strains 501-3 and IR16-1 were controlled by multiple locus in Gufeng B. Whole genome re-sequencing of the two parental lines Gufeng B and Nipponbare identified 1,756,964 SNPs. Calculation results of △SNP-index showed that there were two candidate loci conferring resistance to rice blast disease, which were located at Chr.6: 10,082-11,397Kb, corresponding to the Pi2/9 locus, and Chr.11: 120-266Kb. 4006 SNPs and 623 InDels markers were searched within the interval of Chromosome 6, 752 SNPs and 195 InDels within the corresponding region of Chromosome 11, respectively.

  Conclusion  The resistance of Gufeng B to 501-3 strain may be controlled by two resistance genes on chromosomes 6 and 11. Our results laid the foundation for finely mapping and cloning the resistance genes in Gufeng B, and provided marker resources for molecular marker-assisted selection.