Molecular Genetic Map Construction And QTL Mapping Of Agronomic Traits In Brassica Napus L.

Brassica napus L. is one of the most important oil crops in the world, and the linkage map construction is meaningful for the development of rape breeding program. In this research, a genetic linkage map of Brassica napus L. was constructed and the QTL of seven important agronomic traits was analyzed. The main conclusions are as follows:1. Based on the recombinant inbred line population (F_2:6) with 188 lines derived from the cross of GH₀₆×P₁₄₇ (yellow-seeded line crossed with black-seeded line of B. napus L.) , a genetic linkage map of Brassica napus L. (2n=38) was constructed, which was made up of 19 linkage groups, including 202 SRAP markers, 65 SSR markers, 23 AFLP markers and 10 TRAP markers, covering 1248.5cM in total with an average interval of 4.16cM between adjacent loci. As for the different linkage groups, the length varied from LG1 of 109.2 cM to LG9 of 39.5 cM, the number of markers varied from 4 (LG17, LG19) to 56 (LG1) and the average marker interval distance varied from 1.80cM (LG6) to 14.20cM (LG12) , and moreover, 6 gaps larger than 20cM were observed in the 19 linkage groups.2. Among the 300 markers on the linkage map, the majority (67.67%) of the markers showed 1:1 segregation for the two parental alleles (P < 0.01) and the remaining 32.33% (97 markers) deviated from the expected 1:1 ratio, showing distortion in the segregation values. The segregation analysis of each marker indicated that the number of markers came from male parent and female parent was close, and not deflected to either parent. It concluded that the population has no obvious distorted segregation in general.3. Composite interval mapping method of Windows QTL Cartographer V2.5 was employed in QTL analysis of seven agronomical traits including seed oil content, protein content, hull content, seed coat color, seed coat lignin content, 1000-seeds weight and sigle plant yield in Brassica napus L. A total of thirty-one QTLs were mapped on eleven linkage groups for the seven triats with LOD>2.0. Phenotypic variation explained by the single putative QTL varied from 3.51% to 14.66 % with 3 QTLs were higher than 10 %, and the LOD score ranged from 2.1 to 7.4.1) A total of seven QTLs (Pro1^Pro7) affecting protein content were detected in five different linkage groups including LG1 , LG4,LG8, LG11 and LG15, explaining 3.51 %¹4.66% of the phenotypic variation. Pro7 had the highest contribution. Pro5 and Pro6 showed negative additive effect, while the others showed positive additive effect. The LOD score of seven QTLs varied from 2.1 to 7.4.2) Seven QTLs (Oil1^Oil7) locating on five different linkage groups including LG2,LG5, LG6,LG8 and LG9 were found to be responsible for seed oil content with the single contribution to...