Qtl Mapping For Oil Content, Silique Length And Seed Number Per Silique In Brassica Napus L

Rapeseed is one of the important oil crops in the world, the genetic mechanism of the yield and quality related traits is always emphasized in research. These traits are controlled by multiple genes and environmentally sensitive, it is difficult to do in-depth research. In recent years, the development of high-throughput SNP and the use of high density genetic linkage map provide very efficient means for the accurate localization of QTL.In this study, we developed a recombinant inbred lines population of192lines derived from a cross between M201(a high oil content-type cultivar) and352(a low oil content-type cultivar). On this basis, the population with parents were grown in Wuhan Hubei province (semi-winter environment) and Hezheng Gansu province (spring environment) respectively. We investigated three traits including oil content, silique length, and seed number per silique. We constructed a high density genetic linkage map using RILF6population, to perform QTL mapping. The main results are summarized as follows:1、In semi-winter environment, the two traits (oil content and silique length) displayed significant difference between two parents (M201and352), and seed number per silique displayed no significant difference. In the RIL population, the three traits showed continuous distribution in the two environments, indicating that the three traits were typical quantitative traits. Silique length displayed significant difference between the two environments, and the two traits (oil content and seed number per silique) displayed no significant difference.2、Heritability of oil content, silique length and seed number per silique was81.75%,86.37%and85.43%, respectively. At the same time the three traits were correlated with each other. In semi-winter environment, the positive correlation between oil content and seed number per silique showed no significant difference; In spring environment, the positive correlation with each other showed significant difference. For the same correlated trait pair-wise identified in the two environments, correlation coefficient identified in spring environment was higher than that in semi-winter environment.3、We analyzed the genotype of RILF6population using105SSR loci and1590SNP loci. The results showed that, the average heterozygosity of192lines was5.73%, no significant difference with the theoretical value of3.13%. Results of chi-square test revealed that the genotype segregation ratio of RILF6population was in line with expected ratio of1:1.4、We constructed a linkage map including19linkage groups, the map contained1684loci (94SSR loci and1590SNP loci), the total map length was1847.72cM, the average interval was1.70cM, the genetic distance of each linkage group was46.77-188.38cM, the number of markers in each linkage group was8-239.5、For each trait, the QTL analysis was carried out for the data in the two environments using CIM method respectively.22QTL were identified. In semi-winter environment,10QTL were detected, of these,3,5and2QTL associated with Oilc, SL and SS, respectively. A single QTL could explain4.44%-10,73%of phenotype variation. In spring environment,12QTL were detected, of these,4,4and4QTL associated with Oilc, SL and SS, respectively. A single QTL could explain5.09%-9.96%of phenotype variation. In the two environments, the positive and negative additive effects of QTL from M201were dispersed in the three traits.6、The QTLxenvironment interaction was analyzed in the two environments, the location and LOD value of the QTL for the same trait in the two environments were compared, the results indicated that4QTL (2pairs) were both identified in the two environments, the other QTL were semi-winter or spring environment specific.