Association And Linkage Analysis Of Cottonseed Kernel Oil Content In Upland Cotton

Cotton is a major fiber and oilseed crop, and cottonseed kernel oil content is up to 25%-40%, which is similar to soybean. Former researches focused on fiber quality, agronomic and disease traits, but few attentions were paid to cottonseed kernel oil content. In this study, a set of 507 accessions was used to detect quantitative loci(QTL) related to oil content trait by association analysis. A recombinant inbred lines population was also used to identify QTL closely related to oil content trait by linkage analysis. The related markers and QTL will provide useful information to dissect genetic mechanism of cottonseed kernel oil content trait, and facilitate the high-oil breeding in upland cotton.Based on the natural panel collection from China, we combined 494 genotyped markers and oil content(OC) phenotype in 8 environments to detect quantitative loci(QTL) related to oil content trait by genome-wide association study. These markers were selected from the G. hirsutum × G. barbadense genetic linkage map with one marker approximately 10 c M intervals on each chromosome, which covered the 26 cotton chromosomes. The phonotype range of OC was 23.35% to 44.18%, which laid a good foundation for association analysis for OC trait. Of the 494 markers selected, only 179 markers amplified polymorphism. The allele number per marker ranged from 1 to 8 and the average was 2.379. The number of genotypes per marker ranged from 2 to 34 with an average of 4.413. The gene diversity per marker ranged from 0.012 to 0.893 and the average was 0.337. Polymorphism information content(PIC) fluctuated from 0.012 to 0.887 with an average of 0.336 per marker. The broad heritability estimated for OC trait measured in the natural population was high with above 0.9. There were 22 associated markers covering 15 chromosomes identified by mixed linear model analysis, which contributed to the phenotypic variation from 0.46% to 5.71% with an average of 1.59%.A total of 178 RILs derived from the cross of two upland cottons, DH962 and Jmian5, were used to identify QTL for cottonseed kernel oil content trait. The analysis of phenotype in 4 environments showed that the value of OC ranged from 23.16% to 37.05%. In the results of two-way ANOVA, OC trait revealed significant environmental effects. Based on a high density genetic map containing 616 markers and the oil content traits identified in four environments, six QTL associated with OC were detected and contributed to the phenotypic variation from 5.60% to 10.17%.