Genetic Diversity of High-Quality Rice Cultivars Based on SSR Markers Linked to Blast Resistance Genes

The epidemics of rice blast which occurred in south parts of Korea during the period from 1999 to 2001 and damaged several high quality rice cultivars developed using "Milyang 95" and/or "Milyang 96" as a parent. Genetic diversity of 23 rice cultivars including "Milyang 95" and it's relatives was assessed using 54 simple sequence repeats (SSR) markers reported to be linked to major blast resistance genes. Fifty-four SSR markers representing fifty-seven loci in the rice genome detected polymorphism among the 23 cultivars and revealed a total of 170 alleles with an average of 3.0 alleles per primer, The number of amplified bands ranged from 1 to 7. Several SSR markers including RM249, RM206 and OSR20 were informative for assessing the genetic diversity of relatively closed japonica rice cultivars. The 23 cultivars were classified into four groups by cluster analysis based on Nei's genetic distances, and the cultivars developed from same parents showed a tendency to cluster together that is consistant with genealogical information. High quality rice cultivars, Daesanbyeo, Donganbyeo, and Milyang 95 belonged to the same cluster, At the loci, RM254 and OSR32, all of the cultivars derived from the crosses using "Milyang 95" shared same alleles, suggesting that these japonica cultivars might carry alleles that are identical by descent. Evaluation of 23 rice cultivars against blast needs to be confirmed regarding the relationship between genotype and blast resistance.p between genotype and blast resistance.