Parental Cluster Analysis in Indica Hybrid Rice(Oryza sativa L.) by SSR Analysis

Heterotic groups and patterns among breeding materials provide fundamental information while utilizing heterosis in plant breeding. However, research on heterotic groups in indica rice is scarce compared with that in maize. Simple sequence repeat （SSR） analysis of the 72 loci covering the entire rice genome was carried out for 47 parental lines normally utilized in making hybrid rice in China in order to study the classification of parental lines. Seventy-two SSR primers having stable amplified profiles detected 328 alleles among the lines tested, and the number of alleles per SSR locus ranged from 2 to 13, with the mean of 4.56. The polymorphism information content （PIC） per SSR locus ranged from 0.120 to 0.878 with the mean of 0.567. The genetic similarities among 47 parental lines ranged from 0.633 to 0.928 with the mean of 0.741. The 47 parental lines were classified into three main groups （i.e. maintainer line group, TGMS line group and restorer line group） by un-weighted pair-group method using an arithmetic average （UPGMA） clustering method, which was approximately in agreement with pedigree information. Furthermore, seven patterns of heterotic combinations were recommended according to the grouping and hybrid rice production. SSR analysis is an effective way for heterotic grouping of hybrid parental lines in rice. The results of grouping can be used to choose parents in making hybrid rice.