Rice blast disease caused by the fungal pathogen Magnaporthe oryzae is one of the most destructive rice diseases worldwide. Resistance to rice blast pathogen mostly shows a quantitative trait controlled by several genes. A total of 13 major blast resistance (R) genes were reported in a number of Korean rice varieties using molecular markers. The Pi-ta gene, which locates near to the centromere of chromosome 12, was haplotyping using 1790 accessions including cultivated and wild varieties in previous research. However, the genetic variations of other R genes in rice still not clear. Three R genes, Pi9, Pia, and Pib on chromosome 6, 11 and 2 respectively, were resequenced among 84 accessions of rice core set. Different types of halotype among the 84 accessions were detected. Some new SNPs and InDels found in exon part of R genes were expected to result into amino acid changes following analysis of the genetic code variations, and the germplam in this rice core set which are resistance to blast were explored. We are expecting to develop the new functional markers and incorporate of resistance genes into existing rice cultivars and finally these apply outcomes in breeding rice resistance to blast diseases.

The objective of this study was to determine the genetic diversities of major rice blast resistance genes among 84 accessions of aromatic rice germplasm. Eighty four accessions were characterized by a dominant 11 set of PCR-based SNP and CAPS marker, which showed the broad spectrum resistance and closest linkage to seven major rice blast resistance (R) genes, Pia, Pib, Pii, Pi5 (Pi3), Pita (Pita-2), and Pi9 (t). The allele specific PCR markers assay genotype of SCAR and STS markers was applied to estimate the presence or absence of PCR amplicons detected with a pair of PCR markers. One indica accession, Basmati (IT211194), showed the positive amplicons of five major rice blast resistance genes, Pia, Pi5 (Pi3), Pib, Pi-ta (Pi-ta2), and Pik-5 (Pish). Among 48 accessions of the PCR amplicons detected with yca72 marker, only five accessions were identified to Pia gene on chromosome 11. The Pib gene was estimated with the NSb marker and was detected in 65 of 84 accessions. This study showed that nine of 84 accessions contained the Pii gene and owned Pi5 (Pi3) in 42 of 84 accessions by JJ817 and JJ113-T markers, which is coclosest with Pii on chromosome 9. Only six accessions were detected two alleles of the Pita or Pita-2 genes. Three of accessions were identified as the Pi9 (t) gene locus.