Breeding Of A Restorer Line And Mapping Of Fertility Restorer(Rf) Genes In Japonica Rice With Cytoplasmic Male Sterility (CMS) Of Wild-abortive(WA) Type

At present, hybrid of three lines is still the main type to utilize the heterosis in rice. Hybrid in indica rice, varieties are mainly developed based on wild-abortive(WA) type CMS, while Chinsurah Boro(BT)-type CMS lines are mainly used in japonica rice. Because of unstability of fertility in japonica rice with Chinsurah Boro(BT)-type CMS, researches on japonica rice with wild-abortive(WA) type CMS are very important.In order to screen the restorer lines with wide restoring ability to different CMS Lines, one set of isonuclear alloplasmic CMS lines were wide test-crossed with Indica or Japonica restorer lines in this research. Afterward, SWR78 with wide compatibility and wide restoring ability had been bred through crosses followed by successive back-crosses.We developed F₂ population by wide compatibility variety Suqiu with wild-abortive(WA) type CMS and SWR78 to study the restore fertility genes of SWR78. The main results were as follows:1. By test-crossing and appraising, SWR78 had wide restoring ability to 10 indica and japonica CMS lines with 4 different kinds of cytoplasm(WA type , ID type , HL type , BT type) and wide compatibility.2. According to the fertility segeration of a F₂ population derived from a cross between Suqiu with wild-abortive(WA) type CMS and SWR78, it could be concluded that restoration of the fertility were controlled by three genes.3. Using bulk segeration analysis(BSA) and SSR markers, we preliminarily located two genes in SWR78 ,which were on chromosome 1 and chromosome 10 , respectively. Compared with the results which other researches had gained, we speculated that the gene on chromosome 10 might be Rf4, another gene on chromosome 1, designated as Rf(t), had not been reported.4. The molecular mapping of Rf4 showed that Rf4 was flanked between RM271and RM171 with genetic distances of 7.0cM, 0.25 cM, respectively. The linkage relationship of Rf(t) showed that Rf(t) was flanked between RM1329 and RM84 with genetic distances of 0.58cM, 2.28cM, respectively.5. To make fine mapping of Rf4, new markers such as SSR,CAPS and STS , were produced. The recombinants were identified by flanking markers analysis. Rf4 was finally mapping betweem RM171 and RM5629 with genetic distance 0.25 cM. Rf4 was co-segregated with RM6100,RM5373,SZ-8 and C1361. According to the results of fine mapping of Rf4, the phsical map covering Rf4 locus on chromosome 10 was constructed. The phsical distance was about 330kb beween RM171 and RM5629. By BLAST (Basic Local Alignment Search Tool) analysis, we intensively screened and identified 8 rice homologous ORFs which encoded proteins with PPR motifs, which colud be involved in Rf4 locus.