Marker-Assisted Selection For Fertility Restoration In Rice (Oryza Sativa L.)

Cytoplasmic male sterility (CMS) and its restoration are bases for the breeding and commercial application of three-line hybrid rice. Wild abortive CMS (WA-CMS) was firstly used in the commercial production of hybrid rice and has always been most extensively applied.In present study, an F2 population derived from the cross Zhenshan97A/Minghui63 was used. The mapping was performed using the recessive class consisting of 119 extreme sterile individuals. Parental polymorphism survey was conducted using 37 SSRs located in the probable region for Rf3 on the short arm of rice chromosome 1. Of the 16 polymorphic SSRs detected, 9 were selected to test the extreme sterile individuals. RM10353, RM1195 and RM3746 which were located consecutively in the segmental map each showed 8 single crossover with Rf3, and this number was the lowest among the number of recombinant observed between the 9 SSRs and Rf3. This result indicates that Rf3 was located in the genomic region covered by interval RM10353-RM1195-RM3746 and its flanking markers. Thus, the Rf3 locus was mapped between RM10338 and RM10376 that have a physical distance of 679.9kb.Based on the mapping of fertility-restoring genes, 11 markers linked to Rf3 or Rf1/Rf4 were selected to test 103 major rice varieties and parents in China. The main results listed as follows: 41 alleles of 11 linkage markers were observed in the 103 varieties and parents; there were 2-7 alleles of each marker the average was 3.7. The FP of the markers ranged from 0.16 to 0.68, and the average is 0.48. All the japonica materials performed the same genotype at the locus of Rf3, and there were no variation between the sterile restorer lines and the CMS lines. However, they performed polymorphism at the locus of Rf1/Rf4. Therefore, Rf3 was contained in the indica materials and Rf4 was contained in the two types. The clustering analysis of the 103 varieties and parents based on the 41 alleles indicated that the primers that linked to Rf genes could distinguish CMS lines from its restorers and the similarity of the two types was low.The MAS of the identification to blast resistence gene and Rf genes were based on the 106 RILs selected by the markers linked to Pi25-Pi26 (t). The 106 plants were inoculated with mixed M. griseai in two different environments. The result showed that all the plants were resistance. The efficiency of MAS was 100%. The markers linked to Rf3 or Rf4 were selected to test the 106 plants. According to the result of the test, 78 plants which were chosen as the female parents were crossed to Zhong9A and XieqingzaoA, respectively. Two F1 groups were obtained, and then the SF of F2 was inspected. The result shows: the SF were higher when the two Rf genes existing than the absence of them. Therefore, the MAS is efficient.