Studies On Rapeseed Variety Fingerprints And Mapping Of Gene Of The Down-Curly Leaf By Use Of SNP Markers In Brassica Napus L

Single Nucleotide Polymorphism (SNP) refers to the DNA sequence polymorphism caused by a single nucleotide mutation in the genomic level, and it is the most accurate method to detect the polymorphism of species to date. It has been widely applied in areas such as genetic map construction, molecular marker-assisted selection and so on. In this study, the fingerprintings of different rapeseed varieties were established and the down-curly leaf mutant gene in rapeseed was genetically mapped using SNP markers. The main results were as follows:1. The fingerprintings of construction rapeseed varieties.57fingerprintings of rapeseed materials were constructed base on SNP markers and SSR markers.(1) The fingerprintings of rapeseed varieties constructed by SSR markers.40pairs of core SSR markers were used and different fingerprintings of22varieties were obtained. The result based on the SSR markers showed that the genetic similarity coefficient was only0.52between Tapidor and Zhenyou7,0.87between Zhenyou6and7,0.76between Shiliji and Shilifeng. The genetic similarity coefficient was range from0.70to0.77among3varieties of Nannongyou and0.64to0.87among4varieties of Zhenyou. These genetic coefficient information provided some useful reference for the parent selection in rapeseed breeding.(2) The fingerprintings of rapeseed varieties constructed by SNP markers.52127SNP markers were used to construct the fingerprints of44varieties. The results based on the SNP marker showed that the smallest and the similarity coefficient was0.51, which was between Zhenyou5and Zhongshuang11. The biggest coefficient was0.78, which was between Dongyou1and Zhenyou6as well as Zhenyou7and Dongyou1. The coefficient among the four varieties of Zhenyou and Zhongshuang11ranged from0.56to0.59, while it was0.61between Zhongshuang11and Nannongyou2as well as Nannongyou3, and0.62between Shilijia and Qinyou9. These results indicated that when the varieties came from different areas, the similarity coefficient among them was small, which suggested that different environment might have certain influence to the genetic relationship among varieties.(3) The comparison between fingerprintings by using of two kinds of markers:9fingerprintings of rapeseed varieties were established by SNP and SSR markers, the genetic similarity coefficient and the correlation coefficient between the two kinds were calculated. The genetic similarity coefficient was0.3269(p-values=0.0517), suggested that the two method were consistent with each other. No significant difference has been shown between the dendrogram by cluster analysis based on two markers for9rapeseed varieties. There were52127SNP markers and only40pairs of SSR primers, therefore, the genetic similarity coefficient by use of SNP marker was more accurate and the results were more reliable.2. Mapping of the down-curly leaf mutant gene. An F2segregating population had been established basing on the down-curly leaf mutant M423obtained from the mutant library in our laboratory. There were266down-curly leaf plants and78normal plants in mis population. The separation ratio of the F2was consistent with the3:1ratio of Mendelian inheritance through Chi-Square Test, suggested that the down-curly leaf mutation gene was a single dominant gene. By SNP marker identification,80individual samples were randomly selected for DNA extraction using the CTAB method, from which the SNP marker data was obtained.10013polymorphic markers were obtained among the52127SNP markers.16SNP markers were found to be related with the mutant trait through Chi-Square Test by use of the data of SNP markers. The results provided a foundation for the fine mapping of the down-curly leaf mutant gene in M423.