Grouping Of Parental Lines And Establishment Of Heterotic Patterns In Indica Hybrid Rice (Oryza Sativa L.)

SSR analysis, pedigree analysis, morphological traits cluster analysis and heterosis analysis were conducted to assign heterotic groups and establish heterotic patterns for 48 parental lines widely used in indica hybrid rice breeding and production in China. Correlations between GD based on SSR data and heterosis of combinations were studied. In addition, 100 parental lines of hybrid rice widely used in hybrid breeding and commercial production during 1976-2003 were studied by COP analysis. The main results were as follows:1. 48 parental lines were classified into maintainer line group (M-G), TGMS line group (TGMS-G), restorer line group (R-G) and 9308 based on SSR analysis, and maintainer line group, restorer line group was further divided into three subgroups respectively, which was approximately in agreement with pedigree information. Furthermore, eight heterotic patterns were recommended according to the grouping result and hybrid rice production. 72 SSR primers having stable amplified profiles detected 330 alleles among the lines tested, and the number of alleles per SSR locus ranged from 2 to 13, with the mean 4.58. The polymorphism information content (PIC) per SSR locus ranged from 0.117 to 0.882 with the mean 0.570. The genetic similarities among 48 parental lines ranged from 0.633-0.928 with the mean 0.740.2. There were considerable genetic difference among thermo-sensitive genie male sterile line group (TGMS-G) and 9308, Zhenshan97 sub-group (ZS97-SG), Xieqingzao sub-group (XQZ-SG), exotic sub-group (E-SG), Minghui63 sub-group (MH63-SG), IR24 sub-group (IR24-SG) and two-line restorer line sub-group (TR-SG) by F₁ heterosis analysis. These heterotic groups or sub-groups could constitute 28 kinds of potential heterosis patterns. The heterotic patterns of MH63-SGxM-G, TGMS-GxTR-SG and ZS97-SGxTR-SG, widely used in hybrid rice production exhibited a higher degree of heterosis. The combinations crossed by the heterotic pattern of M-GxTGMS-G also showed considerable heterosis, this new heterotic pattern could be promising. The combinations...