| Rapeseed is one of the most important oilcrops worldwide, and has significant heterosis. The main approaches of utilizing heterosis of rapeseed included cytoplasmic male sterility (CMS), genic male sterility (GMS), chemical hybridizing, and self-incompatibility. Because GMS has stable sterility and isn't influenced by environment and cytoplasm,this approach was paid more and more attentions by the rapeseed breeders. Currently, the main GMS materials used for producing hybrid seeds are divided to two categories. The first category was the GMS materials controlled by two duplicate recessive genes. This kind of material has stable, complete male sterility, wide resource of its restorers, and isn't influenced by environment, but its disadvantage is that it hasn't complete restorers, and when it is used to produce hybrid seeds, 50% segregating fertile plants in the double purpose line are needed to be removed, which limits its utilization in the production of hybrid seeds. The second category was the GMS materials controlled by two duplicate recessive sterile genes and one recessive epistatic suppression gene interactively. With the existence of epistatic inhibitor gene, a 100% sterile line can be obtained. Three-line systems can be obtained for hybrid seeds production for this kind of materials.The research about verification of existence of inhibition of recessive epistatic suppression gene on two duplicate recessive sterile genes hasn't been reported currently. On the basis of previous researches, which reported that these genes controlled sterility of the above two materials are non-allelic, and the interaction of recessive epistatic suppression gene and duplicate recessive sterile genes in Brassica napus is non-specific, crosses were made between the two categories of materials in order to transfer the recessive epistatic suppression gene of the Reeessive Genic Male Sterility to the two duplicate recessive materials, and develop temporary maintainer lines for the two duplicate recessive sterile lines. The results obtained are as follows.In the 131 F3 lines obtained from F2 fertile plants of the two categories of materials, 39 lines displayed fertility segregation, 92 lines were fertile completely.χ2 test showed that the interaction of recessive epistatic suppression gene and duplicate recessive sterile genes in B. napus wasn't specific. In the 147 lines obtained from the testcross between F2 fertile plants of the two categories of materials and sterile plants of the two duplicate recessive sterile materials, 81 lines displayed fertility segregation, 66 lines were fertile completely. Inspected byχ2, our result doesn't meet the two assumptions. But our result met the inference that the testcross progenies won't have sterile completely lines if recessive epistatic suppression gene hasn't specific inhibition on two duplicate recessive sterile genes.These results revealed that the previous assumption, which assumed that the interaction of recessive epistatic suppression gene and duplicate recessive sterile genes in B. napus is non-specific, is not correct. Our results showed that the recessive epistatic suppression gene has specific suppression on its sterile genes in B. napus.In the second part, genetic diversity of 70 B. napus varieties of approvalled during recent years in China was analyzed with SSR. In total, 113 fragments were detected with size ranged from 100 to 600 bp and 104 were polymorphism, the polymorphism rate was 92%. On average, each primer combination generated 4.3 polymorphic fragments. Principal analysis revealed that all varieties scattered well in bi-plot, and accessions from the same geographic origin did not group together. There existed considerable variance among recently registered B. napus cultivars in China. The components of variation within populations was dominant over that among populations. Varieties in middle of Yangtze valley possessed the richest genetic variation in the present investigation. |
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