Fifty-two Korean japonica rice cultivars were analyzed for leaf blast resistance and genotyped with 4 STS and 26 SSR markers flanking the specific chromosome sites linked with blast resistance genes. In our analysis of resistance genes in 52 japonica cultivars using STS markers tightly linked to Pib, Pita, Pi5(t) and Pi9(t), the blast nursery reaction of the cultivars possessing the each four major genes were not identical to that of the differential lines. Eight of the 26 SSR markers were associated with resistant phenotypes against the isolates of blast nursery as well as the specific Korean blast isolates, 90-008 (KI-1113), 03-177 (KJ-105). These markers were linked to Pit, Pish, Pib, Pi5(t), Piz, Pia, Pik, Pi18, Pita and Pi25(t) resistance gene loci. Three of the eight SSR markers, MRG5836, RM224 and RM7102 only showed significantly associated with the phenotypes of blast nursery test for two consecutive years. These three SSR markers also could distinguish between resistant and susceptible japonica cultivars. These results demonstrate the usefulness of marker-assisted selection and genotypic monitoring for blast resistance of rice in blast breeding programs.

• Jung-Pil Suh(National Institute of Crop Science, RDA, Suwon 441-857, Korea, IRRI-Korea Office, National Institute of Crop Science, Suwon 441-857, Korea) Corresponding author
• Jae-Hwan Roh(National Institute of Crop Science, RDA, Suwon 441-857, Korea)
• Young-Chan Cho(National Institute of Crop Science, RDA, Suwon 441-857, Korea)
• Seong-Sook Han(National Institute of Agricultural Science and Technology, Suwon 441-707, Korea)
• Yong-Hee Jeon(National Institute of Crop Science, RDA, Suwon 441-857, Korea)
• Kyung-Ho Kang(National Institute of Crop Science, RDA, Suwon 441-857, Korea)
• Yeon-Gyu Kim(National Institute of Crop Science, RDA, Suwon 441-857, Korea)