Identification of QTL influencing seed oil content, fatty acid profile and days to flowering in Brassica napus L.

The objective of this study was to identify quantitative trait loci (QTL) controlling oil content, fatty acid profile and flowering time in Brassica napus L. This research was conducted using a doubled haploid mapping population derived from a cross of Polo 9 Topas. The population was phenotyped in four environments. The composite interval method of QTL analysis was performed with a previously available genetic map that consisted of mainly simple sequence repeat markers with an average genetic distance of 3.7 cM. The markers were assembled and anchored to 19 chromosomes with a map coverage of 2244.1 cM. Fourteen QTL were identified for oil content, 131 QTL were found to be associated with six fatty acids and 14 QTL were associated with flowering time. A QTL, qOIL-A10a with a positive Topas-allele explained 26.99 % of the variation in oil content. Additionally, transgressive segregation for oil content was observed beyond the parental phenotypes (31.5-55.5 %). Two genomic regions on C3, at 147.83 and 154.55 cM were associated with QTL for all six fatty acids studied. We hypothesize this genomic region on C3 modulates the correlations between fatty acids and further investigation of this region could provide insight into the genes determining total seed oil content in B. napus. An early flowering QTL, qFLRa-A2c containing a Polo-allele was detected in the vicinity of a known Brassica vernalization gene that explained 43.22 % of the trait variation. The phenotypic correlation between traits and collocation of different QTL on thirty-four genomic regions suggests that the traits studied have genetic dependencies on each other.