Genetic Relationships among 206 Korean Rice Varieties Developed from 1933 to 2000 Based on Coefficient of Parentage

Abstract

A total of 206 paddy rice varieties was developed from 1933 to 2000 in Korea. However, genetic diversity and relationships among the varieties were not well characterized. The objectives of this study were to quantify genetic diversity and genetic relationship of Korean rice varieties in terms of breeding sites and developed eras based on the coefficient of parentage (CP). A very low average CP of 0.032 among Korean rice varieties suggested the potential high level of genetic diversity. The CP analysis showed that genetic diversity of Korean rice varieties is greater among varietal groups developed in the different eras than among varietal groups developed at three breeding sites. The greater average CPs of Tongil type varieties released during 1970s~1990s indicated the much lower genetic diversity than japonica varieties released in the same eras. The 177 rice varieties, except 29 varieties which formed groups including only 1~2 varieties, could be classified into 8 varietal groups through the cluster analysis. Cluster VIII was the largest group with 37 Tongil type rice varieties developed during 1970s~1990s, followed by cluster I of 34 japonica varieties released mainly before 1960s and cluster III of 31 varieties of early-maturing and cold-tolerant varieties, while clusters II, V and VII were small groups with 4~9 varieties. The large average CPs within each group (0.126~0.375) and small average CPs between varietal groups (0.00~0.042) indicated that the genetic diversity was very low within each variety group but very great between varietal groups. Therefore, the overall high genetic diversity of Korean rice varieties was mainly due to the larger genetic diversity among varietal groups. The information obtained from this study may be useful for the selection of parents in rice breeding programs and, thus, to enhance the genetic diversity among new rice varieties in the future.