Construction Of Genetic Linkage Maps And QTL Analysis For Oil Content-related Traits In Brassica Napus

Rape (Brassica napus L.) is an important oilseed crop, which is grown widely in the world, it is the third largest source of plant oil, in our country, the planting area and total output both are the first in the world, it is also an important source of edible oil. The development of rape production and improve the production efficiency, it is an extremely important significance to improve people’s health level and solve the energy shortage problem that restricted the economic development for china. Improving the oil and protein content of rape varieties is an important way to improve the economic effectiveness of rape, but cellulose and hemicellulose have not nutritional value in rapeseed meal, and they share common photosynthetic product with protein and oil content in the metabolism, showed significant negative correlation with oil content. In this research, a molecular genetic linkage map of Brassica napus L. were construct using SSR primers and the QTL of oil, protein, cellulose and hemicellulose content was analyzed. The main conclusions are as follows:1. In order to study Oil, Protein, Cellulose and Hemicellulose Content of rapeseed, recombinant inbred lines (RILs) were developed after successive selfing up to8generations from yellow seeded female parent GH06and black seeded male parent P174.176lines were used as mapping population, the SSR markers were used to construct the linkage map, which contained31linkage groups and369markers locus, the total map length is1437.1cM with an average distance of3.89cM. The length of linkage map varied from N7of14.4cM to N8of87.7cM, the average markers interval distance varied from2.66cM-10.93cM, the average distance of LG27(N14) was largest, and the average distance of LG19(N17) was smallest, the number of markers was most in LG3which included19markers, and the number of markers was least in LG21, LG27, LG28, LG29, LG30which only included3markers. Moreover,5gaps larger than20cM were observed in linkage31groups.2. Oil content showed significantly negative correlation with protein, cellulose and hemicellulose content in RIL8population in four environments, correlation coefficients were-0.501,-0.180,-0.797respectively, protein content showed significantly negative correlation with cellulose content, but significantly positive correlation with hemicellulose content, correlation coefficients were-0.318,0.408respectively, cellulose content showed significantly negative correlation with hemicellulose content, correlation coefficient was-0.268.3. Using software Windows QTL Cartographer2.5and the method of composite interval mapping (CIM) to analysis oil, protein, cellulose and hemicellulose content of rapeseed in four environments, a total of thirty QTL (quantitative trait locus) for the seven traits were detected in linkage group N1, N2, N3, N8, N9, N11, N13, N16and N17, phenotypic variation explained by the single putative QTL varied from3.12%to21.83%with thirteen QTL were higher than10%.(1) A total of nine QTL related to oil content were detected in linkage groups N8, N9, N11and N13in four environments, the LOD score of nine QTL varied from2.31to8.54, and the phenotypic variation was explained by the single putative QTL varied from4.96%to21.83%, qO08Gi-1had the highest contribution to phenotype.(2) Eight QTL were detected for protein content in linkage groups N1, N2, N3, N8, N9and N16, the LOD score of eight QTL varied from2.06to5.92, and the phenotypic variation was explained by the single putative QTL varied from3.12%to14.28%, qP08Ho-1had the highest contribution to phenotype.(3) Five QTL were detected for cellulose content in linkage groups N9, N13and N16, among the five QTL, the LOD score ranged from2.10to5.77, and the phenotypic variation was explained by the single putative QTL varied from4.60%to17.29%, qC08Ho-1had the highest contribution.(4) Eight QTL were detected for hemicellulose content in linkage groups N8and N9, among the eight QTL, the LOD score ranged from3.04to6.44, and the phenotypic variation was explained by the single putative QTL varied from6.66%～16.68%, qHC08Ho-1had the highest contribution.Our research mapped the valuable traits of oil content and protein content and the unprofitable traits of cellulose and hemicellulose, and the results provide new ideas and theoretical basis for improving molecular breeding of economic benefits for Brassica napus L.