Identification and physical mapping of QTLs associated with flowering time in Brassica napus L.

Abstract

Flowering time regulation is crucial to yield of rapeseed (Brassica napus L.). However, insight into the loci controlling flowering time variation in rapeseed is not clear enough. In this study, a recombinant inbred line population was used for quantitative trait locus (QTL) analysis associated with flowering time in five different environments. A total of 36 identified QTLs were obtained, and each explained 3.96–24.41% of the phenotypic variation (PV). The QTL meta-analysis showed that 36 identified QTLs were integrated into 24 consensus QTLs. Of these, eight consensus QTLs were stably expressed in at least two environments, and four with PV ≥ 10% were specifically expressed in a single environment—these 12 consensus QTLs were considered the key QTLs controlling flowering time in the AH population. Physical mapping indicated that the 12 key QTLs were mapped into 12 single genomic fragments in B. rapa and B. oleracea, and physical positions of these QTLs in the B. napus genome were further determined by referring to the B. rapa and B. oleracea genomes. Ultimately, seven candidate genes underlying the confidence intervals of five key QTLs were identified. These findings will contribute to further insight into the genetic architecture of flowering time in rapeseed.