Molecular Characterization Of Nsa Male Sterile Cytoplasm And Restorer Screening In Brassica Napus L.

Cytoplasmic male sterility (CMS) is a maternally inherited character of failure to produce viable pollens, which was found in many plant species. CMS is a main pollination control system for oilseed rape hybrids production in the application of heterosis. Although many cytoplasmic male sterile lines have been found in Brassica species, merely a few types are applied in oilseed rape hybrids production. Especially in China, most Brassica napus hybrid varieties were made by pol CMS. Since pol cytoplasm is sensitive to low temperature and the use of a single cytoplasm is in favor of disease spreading, the enrichment of cytoplasm types is necessary. Thus, exploiting and establishing novel CMS lines are of major importance for hybrid production in oilseed rape. In OCRI-CAAS, NSa male sterile cytoplasm obtained by somatic hybridzation is a potential CMS system for the breeding of hybrid variety with high production safety. Primary study showed that NSa is different from other CMS system. In order to further identify the distinctness of NSa CMS and to apply it in breeding and production, a series of studies was conducted and the main results are as following:1. The PCR result using specific primers showed that NSa is different from pol,Ogu and Ath cytoplasm. ERIC, a pair of rep-PCR primers, can amplify NSa-specific band. Using the amplification band patterns of two pairs of primers, which are REP and ERIC, six types of male sterile cytoplasm can be distinguished.2. A cDNA library for CMS-associated genes was constructed by suppression subtractive hybridzation with the sterile line (tester) and its isonuclear maintainer (driver). The library was evaluated and analysed primarily, laid a foundation for the identification of male sterile genes.3. An AFLP marker (EM107) linked to the restorer gene (Rf) of NSa CMS was obtained. Attempt to convert EM107 to a SCAR marker by traditional method and PCR walking was carried out. None of the primers amplified any bands specific to the fertility restored plants, too. This might probably due to the linkage between EM107 and Rf gene is not tight enough.4. Plants which can restore the fertility of NSa CMS were identified after screening a large number of varieties and offspring lines derived from somatic hybrids. After successive selection, stable restorer lines with high uniformity were obtained.