Identification of QTL for seed coat colour and oil content in Brassica napus by association mapping using SSR markers

Qu, C., Hasan, M., Lu, K., Liu, L., Zhang, K., Fu, F., Wang, M., Liu, S., Bu, H., Wang, R., Xu, X., Chen, L. and Li, J. 2015. Identification of QTL for seed coat colour and oil content in Brassica napus by association mapping using SSR markers. Can. J. Plant Sci. 95: 387–395. Association mapping identifies quantitative trait loci (QTL) based on the strength of linkage disequilibrium (LD) between markers and functional polymorphisms across a set of diverse germplasms. In this study, we used association mapping to detect QTL and genome-wide simple sequence repeat (SSR) markers linked to seed coat colour and oil content in a population of 217 oilseed rape (Brassica napus L.) accessions. We corrected for the population structure of B. napus using 389 genome-wide SSR markers. In total, 25 and 11 SSR markers linked to seed coat colour and oil content were detected, respectively, and these two sets of markers were in different linkage groups. Nine of these markers for seed coat colour spanned the major QTL region for seed coat colour, and been mapped to chromosome A9. Six of these markers showed high levels of association with both seed coat colour and oil content, and markers H081N08.8 and KS20291 were mapped to the major QTL region for seed coat colour on chromosome A9. Another marker, CB10364, was in high LD with all determined seed coat colour and oil content traits, and was mapped to the co-localized QTL region for them on chromosome A8. These data indicate that seed coat colour was found to be an important contributor to seed oil content. Further, we show that association mapping using a heterogeneous set of genotypes is a suitable approach for complementing and enhancing previously obtained QTL information for marker-assisted selection.