| Chinese cabbage(Brassica rapa L. ssp. pekinensis) is an important vegetable crop in China,which has quite strong heterosis. Male sterile lines are widely used in F1 seed production. Multi-allele genic male sterility lines which can produce 100% male sterility lines were used in Chines cabbage breeding, but it costs amounts of time to confirm the genotype according to the phenotype identification in transferring. Marker Assisted Selection(MAS) can be used to speed up.A F2 segregating population derived from a cross between a male sterile line 939 A and a fertile line yellow sason in this thesis was used to confirm the genetic models, to find the molecular markers linked to the male sterility gene, and to map this gene. The main conclusions are as follows:1. The plants of F1(939A×yellow sason) were sterile, which indicating that the genotype of yellow sason in this allelc is msms. The sterility was unstable by the environment.. The F1 produced a few functional pollens in the later phase of flowing. There were 884 individuals in the F2 population, containing 198 fertile plants and 686 sterile plants. The result of χ2 was fit for the ratio of 1:3(χ2=3.1916<χ20.05=3.84), which confirmed the genetic model of F2 population was Dominant Genic Male Sterile(DGMS),influenced by environment.2. Two different methods were used to map Ms: 390 sterile individuales and 240 fertility individuals in F2 were used to construct S-pool and F-pool for resequencing. Heterozygosity analysis and SNP-index analysis methods were used to measure the heterozygosity in F-pool and S-pool. Finally Ms was mapped in 2.4M, from 19,250,000 to 21,670,000 in the end of chromosome A08.3. Population Ⅰ and Ⅱ(297 individuals were used) were used to screen markers linked to Ms.Three In Del markers were found in Population Ⅰ linked to Ms among 88 markers. The closest distance between marker and Ms was 2.5c M; While these three markers showed no polymorphic in Population Ⅱ.265 In Del and 28 SSR markers in chromosome A08 were designed and screened in PopulationⅡ. 8 markers were found linked to Ms. Two flanking markers SSR60514 and Br19747979 were tightly link to Ms. The genetic and physical distances between these markers were 5.8 c M and 387.5kb. MS were mapped in the same region in chromosome A08 between population Ⅰ and Ⅱ.4. 22 SSR and 42 In Del designed in F-pool and S-pool using resequencing data were used for fine mapping. Br19499732 and Br19553530 were found tightly linked to Ms. The distance between markers and Ms were 0.7c M and 1.3c M, respectively, the physical distance between these two markers was 53.8kb.5. Finally, other individuals(581) in population Ⅱwere used to confirm the fine mapping region. Br19470306 and Br19625857 were screened first. 52 recombinants were found. Then all the 10 markers were screened in this 52 individuals. After recombination analysis, Ms were mapped between Br19499732 and marker Br19553530, which result is same as the result analyzed by Join Map software.The distance between these markers was 53 kb, containing 12 predicted genes. Bra016849, Bra030803 and Bra030805 were highly expressed in anthers based on the annotation, TAIR and KEGG database. |
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