Fine Mapping And Physical Mapping For Fertility Restoring Gene Of CMS In Cotton

Cotton, one of the most important economical crops in the world, provides most fiber and some of oil resources for people. The heterosis in cotton hybrid is much significant, especially in improving yields, fiber qualities, disease-resistances and stress tolerance. The study on cytoplasmic male sterility (CMS) plays an important role on use of heterosis, cytoplasmic nuclear interaction as well as other inspects.Some hybrid strains of cotton with CMS have been applied in production, but the utilization of CMS is rather limited because of the low yield of restoring lines and the noxiousness of the exotic cytoplasm in the male sterile lines. Complied with the development of molecular genetics and modern biotechnology, the study on CMS in many important crops has become complete exploration on the physiology and biochemistry etc. into the molecular biological levels in a deep going way.A total of 2532 pairs of SSR primers were screened, utilizing 3 BC₁ mapping populations with 447 individuals [Xiang A ×(Xiang A ×0-613-2R), ZMS12A-3 × (ZMS12A-3 × 0-613-2R), and Tai 121A-2 × (Tai 121A-2 ×0-613-2R)], 5 new SSR molecular markers screening against the restoring gene was conducted. Integrating another markers linked with the Rf₁ gene identified by Liu et al (2003) and Feng et al (2005), fine map was made with Mapmaker software. The genetic mapping contained 13 makers that were 8 for SSR, 2 for RAPD, and 3 for STS and the total genetic distance was below 1.0 cM. Among the 13 markers, two RAPD markers (NAU/RAPD/Rf₁3 and NAU/RAPD/Rf₁5) and 4 SSR markers (NAU/SSR/1824, NAU/SSR/1034, NAU/SSR/441 and NAU/SSR/211_-215) showed co-segregation. The genetic distance between the other 3 SSR markers (NAU/SSR/790, NAU/SSR/1782...