Identification of two major QTL for yellow seed color in two crosses of resynthesized <Emphasis Type="Italic">Brassica napus</Emphasis> line No. 2127-17

Yellow seed color, which results from a thinner seed coat, is associated with improved feed quality of rapeseed (Brassica napus L.) meal and increased oil and protein content. As this trait follows various genetic models under different genetic backgrounds, a study was performed in two genetic backgrounds to gain a better understanding of the genetic mechanisms underlying yellow seed color. The quantitative trait locus (QTL) analysis was undertaken using two crosses, Quantum ×No. 2127-17 (HZ-1) and No. 2127-17 × 94,570 (HZ-2). In the HZ-1 population, three putative QTL were detected in linkage groups N18, N5, and N3, respectively. For all of them, yellow seed color arose from the No. 2127-17 alleles. Of these QTL, the one in linkage group N18 (Bnsc-18a) explained more than half of the phenotypic variation. In the HZ-2 population, three QTL were found in linkage groups N9, N18, and N8, respectively. Of these QTL, that in linkage group N9 (Bnsc-9a) explained more than half of the phenotypic variation, whereas the QTL Bnsc-18a had a low seed color value and explained only 9.03–11.72% of the phenotypic variation. Bulked segregant analysis (BSA) of the extremes of a BC1 population derived from the cross of No. 2127-17 × 94,570 (HZ-3) identified one major gene that was identical with the QTL Bnsc-9a detected in the HZ-2 population. The QTL Bnsc-18a was common in the HZ-1 and HZ-2 populations, and the others were population-specific. These results suggested that different black-seeded forms had different seed color genes.