Fine mapping of genes controlling pigments accumulation in oilseed rape (Brassica napus L.)

Abstract Purple/red appearance is one of the common phenotypic variations in leaves, stems, and siliques of oilseed rape (Brassica napusL.) but very rare in flowers. In this study, the causal genes for the purple/red traits in stems and flowers in two accessions of oilseed rape (DH_PR and DH_GC001, respectively) derived from the wide hybridization were fine mapped and candidate genes were determined by methods combined with bulked segregant analysis (BSA) and RNA-seq analysis. Both purple stem trait and red flowers trait were mapped to the locus as the AtPAP2 homologous genes (BnaPAP2.C6a and BnaPAP2.A7b, respectively) belonging to the R2R3-MYB family. Sequencing of the BnaPAP2.C6a gene in purple stem accession revealed several Indels and SNPs in its promoter region, intron 1 as well as exons. However, only a 211bp insertion was identified in promoter region of BnaPAP2.A7b of DH_GC001. Our results not only contribute to a better understanding of anthocyanin inheritance in B. napus, but also provide a useful toolbox for future breeding of cultivars with purple/red traits through combination of different functional alleles and homologs.