Screening Marker Genotypes Of Elite Combining Ability For Yield Traits In Parents Of Hybrid Japonica Rice (Oryza Sativa L)

The area of japonica rice planted annually is 8 280000 ha and accounts for 27% of total rice area in China. The area planted with japonica hybrid rice occupied only 3% of the total area of japonica rice. The major reason for this situation was that competitive heterosis of hybrid cultivar was not conspicuous in yield and quality, compared with conventional cultivar in japonica rice. The key factor of enhancing competitive heterosis of hybrid cultivar in japonica rice was to improve combining ability of yield related traits and quality of restorer lines. These reasons realate with the base of japonica hybrid rice early. More studies on combining ability of restorer lines could found restorer lines including high combining ablity and adwance heterotic pattern, but these could not help us to improving combining ablity of restorer lines directly and efficiently. In order to improve combining ability of restorer lines more efficiently, SSR marker genotypes of elite combining ability for yield, yield components traits were screened in this study, by analyzing the data of combining ability and SSR markers in six CMS lines and twelve restorer lines. The 6 CMS lines and 12 restorer lines were genotyped using 115 pairs of SSR primers. Combining ability of the 18 parental lines was analyzed for the yield,yield components and quality traits, namely, daily yield per plant (DYP), panicles per plant (PP), total spikelets per panicle (TSP),filled spikelets per panicle (FSP),1000-grain weight (TGW) using the data of 72 Fls made with NCⅡgenetic design. The results were the fellows:1. The 6 CMS lines and 12 restorer lines were genotyped using 115 pairs of SSR primers. A total of 153 alleles were detected at fifty-nine SSR polymorphic loci. The rate of polymorphic loci detected was 51.3%, and the number of alleles per marker ranged from two to five, with an average of 2.59. There are one SSR loci with five alleles, six SSR loci with four alleles, twenty SSR loci with three alleles and thirty-two SSR loci with two alleles at fifty-nine SSR polymorphic loci.2. For 5 yield and yield component traits, BT-863A, BT-Wu 3A and BT-LiuqianxinA were elite CMS lines, and BT-863A was the best; 157TR-68, R254, C418, Ninhui8hao were excellent restorers, and 157TR-68 was the best.3. Twenty SSR marker genotypes were significantly associated with combining ability of 5 yield and yield components traits. Eight of them for only one trait, six for two traits, four for three traits and two for four traits. Marker genotypes associated with combining ability of multiple traits increase or decrease trait value of F1. RM152-165/170 is a marker genotype of elite combining ability for PP and DYP with the maximum increasing effect, which increased 20.6% of DYP and 12.7% of PP in F1 respectively(Table3-5, Table3-8). Those marker genotypes with increasing effect could be directly used to improve combining ability of restorer lines through the marker-assistant selection.