Anthocyanin profiles and transcriptional control in anthocyanin-rich Brassica carinata

Brassica carinata has gained traction as an alternative biofuel feedstock in many countries, and serves as a well-known dual-purpose crop for both oilseed and leafy vegetable production. The purple varieties, which are rich in anthocyanins, are usually more eye-catching and beneficial to health. In this study, eleven cyanidin 3-glycoside-5-glucoside derivatives with different acyl modifications were characterized in two purple varieties of B. carinata (ZJC, which has an obvious purple stem, and ZJ, which has both purple stems and leaves) using an ultra-high performance liquid chromatography (UHPLC) system coupled with a high-resolution mass spectrometer (HRMS). In ZJ, the main anthocyanins are modified with a malonyl group at the C5 position, whereas such modifications are not found in ZJC. A total of 141 anthocyanin biosynthetic genes (ABGs) were identified in the B. carinata genome, and these genes were combined with the comparative transcriptome analysis based on RNA-Seq of leaves and stem peel from two purple varieties and one green variety to investigate the mechanisms underlying anthocyanin accumulation. A comprehensive synthetic and regulatory pathway for anthocyanin biosynthesis was proposed for B. carinata, and the ABGs in the pathway, particularly the late biosynthetic and transport genes, were predominantly regulated at the transcriptional level in pigmented tissues. Furthermore, the R2R3 MYB transcription factor BcaB05. MYB114 was verified as a crucial and conserved regulator of anthocyanin biosynthesis through its interactions with TT8 and TTG1 in Brassica species. This study opens new avenues for engineering anthocyanin-enriched B. carinata with improved horticultural quality.