Genetic And Physical Mapping Of The Fertility Restorer Gene Rf₃ For WA Cytoplasmic Male Sterility In Rice(Oryza Sativa)

Three-line hybrid rice based on cytoplasmic male sterility (CMS) plays an important role in food crop production. Cloning of fertility restorer genes (R~ will contribute to reveal the molecular mechanism of CMS. Using the restorer- gene-transfered variety as the restore line is a promising way to improve the production of hybrid rice. In addition, rice is the model plant of grass. So, the isolation of rice genes will undoubtedly promote gene cloning in other grass plants. Prof. Zhang bred near isogenic lines with 1R24 as a donor and ZS97A as a recurrent parent, and mapped one of the gene (Rf3) between two molecular markers (RG532 and RG14O) on chromosome 1. The object of this study is to fine-map RJ3 and constructe a TAC contig covering RJ3 region. So far, The following results were obtained: 1 Two regions of rice YAC physical map of Japan RGP were screened with RG532 and RG1 40 from Cornell University. The Results showed that RG532 is located on Y3841andY286lc, and RG14O is located on YAC343 lc.So we deduce that RJ? is located on the YAC contig consisting ofY3841 Y2861c Y1384 Y3431c. 2 The RFLP analysis with two markers from Cornell University and seven from RGP indicated that five markers was linked with RJ3, three of them haven抰 been reported before. 3 By subcloning the YAC DNA to TAC vector,40 and 39 subclones were acquired fromYl384 and Y2861c respectively. Three polymorphismic subclones were found by RFLP analysis. 4 Using a F2 population including 109 plants,a genetic map consisting of 8 RFLP markers and R13 locus was constructed. The RJ3 gene was mapped in somewhere of the region between R3 192 and Y223. 5 Two TAC genomic libraries were constructed utilizing ZSR1 1 and MingHui63 as plant materials, with an average insert size of about 70kb. 6 The libraries were screened using all the RFLP markers as well as the nonpolymorphismic subclones of single copy as probes. Five TAC contig islands covering about 550kb of the chromosome 1 region between RG532 and RG14O were constructed.