Identification of QTL and alleles for agronomic and seed quality traits in C genome using a Brassica napus population diversified with B. oleracea.

A genome‐wide association study (GWAS) was carried out by using a Brassica napus population of 175 lines, developed from six B. napus × B. oleracea interspecific crosses, and 5,743 single nucleotide polymorphism (SNP) markers to identify quantitative trait loci (QTL) for agronomic and seed quality traits and to understand the effect of B. oleracea alleles on these traits. Heritability of these traits varied from 52.9 to 84.1%. About 79% of the SNPs were positioned to the nine C genome chromosomes, while only 21% to the 10 A genome chromosomes; this was largely due to little genetic variation in the A genome of this population, as expected. However, the SNPs were distributed throughout the entire length of the chromosomes suggesting their usefulness in GWAS. The C genome SNPs detected nine genomic regions affecting these traits. This included the genomic regions of C2 and C5 affecting days to flowering, C1 affecting the duration of grain‐filling period, C1, C5, and C8 affecting oil content, and C1, C2, and C6 affecting glucosinolate content; among these, some of the loci has not been reported previously. The QTL alleles of B. oleracea which can be beneficial in oilseed B. napus, such as the C5 QTL allele for the earliness of flowering, were also identified. Several putative candidate genes were identified in the QTL regions. Thus, the results provided evidence of the utility of the B. oleracea gene pool for use in unveiling the unidentified QTL in B. napus as well as its use in breeding. Core Ideas: C genome alleles from six vegetable Brassica oleracea accessions were introgressed into oilseed B. napus.Quantitative trait loci for agronomic and seed quality traits were mapped and the effect of Brassica oleracea alleles in B. napus were detected.Beneficial quantitative trait loci allele of Brassica oleracea were identified for use in B. napus breeding.C genome quantitative trait loci that has not been reported previously were disclosed. [ABSTRACT FROM AUTHOR]