Genetic Diversity and Genetic Relationship of Inbred Japonica Rice Varieties in Ningxia

A total of 36 SSR markers distributed in 12 chromosomes were used to analyze genetic diversity and genetic relationship in 31 inbred rice varieties of Ningxia.159 alleles were revealed.The mean number of alleles per locus was 4.4.Total genetic diversity index of Nei varied greatly among loci from 0.031 7 to 0.844 4,with an average 0.508 8.The 31 rice varieties were divided into 3 groups for released by years.As the time goes on,the number of alleles and genetic diversity showed an increasing trend,and the number of allele increased significantly(P=0.006 3).UPGMA cluster analysis showed that five categories were clustered in the level of genetic similarity coefficient of 0.50.The Ⅰ,Ⅱ and Ⅳ categories are a variety or line,respectively.Most varieties were clustered into the Ⅲ and Ⅴ categories.The Ⅲ included seven species.21 varieties or lines were clustered in the Ⅴ,which percent was 67.7% in the tested varieties.The major rice inbred varieties or lines were clustered into this category.Compared the pedigree of rice varieties,SSR markers reflected the real rice genetic diversity and genetic relationship in Ningxia.Although the genetic diversity of rice is an increasing trend in recent years,the genetic base of rice varieties is still narrow in Ningxia.The similarity coefficient of majority varieties is 0.5 or more,up to 0.94.Breeders must introduce and innovate in more rice parental materials in addition to considering the genetic relationship between the parents in the future.