Fine mapping and candidate gene analysis of the orange petal colour gene Bnpc2 in spring rapeseed (Brassica napus)
Solangi, Z.A.; Zhang, Y.; Li, K.; Du, D.; Yao, Y.
Petal colour is considered as an important trait and major visual signal for insect-pollinated plants and landscaping. In previous study, we isolated and identified two genes (BnPC1 and BnPC2) that control the orange petal colour (OPC) in rapeseed. To identify the molecular markers linked to the orange petal colour, we constructed a B. napus linkage map with four newly developed simple sequence repeat (SSR) markers and nine insertion-deletion (InDel) markers using BC5II, a near isogenic line population segregated at the BnPC2 locus. The BnPC2 gene was flanked by Indel-3 and Indel-20 and was found to represent a 27-kb (3.721-3.748 Mb) region on A09 of B. napus. High-pressure liquid chromatography analysis revealed that, compared to yellow petals, orange petals exhibit significantly increased zeaxanthin, beta-carotene and lutein contents and a relatively decreased violaxanthin content. Expression profiling confirmed that BnaA09.ZEP (zeaxanthin epoxidase) is an important candidate gene for BnPC2 and is predominantly expressed in floral tissues. Overall, our results provide a basis for understanding the molecular mechanisms underlying the orange petal colour trait in B. napus.