Transcriptomic and metabolomic analyses reveal novel R2R3-MYB transcription factors control anthocyanin biosynthesis in broccoli

Green broccoli is a very frequently consumed, nutrient-rich vegetable, whereas purple broccoli, known for its high anthocyanin content, is not so common. To investigate the anthocyanin biosynthesis in broccoli, one green broccoli and four purple broccolis were subjected to integrative analyses with metabolomics and transcriptomics. Our comprehensive examination revealed that in difference to other Brassica vegetables, the main anthocyanins accumulating in purple broccoli are delphinidin compounds, especially delphinidin-3-O-glucoside-5-O-galactoside. Transcriptomic analysis demonstrated significant variations in the expression levels of genes such as BoF3'H, BoDFR, and BoANS among the samples, suggesting the involvement of upstream transcription factors, regulating these genes. Furthermore, the integration of transcriptomic data and transient functional validation identified two MYB transcription factors, BoMYB147 and BoMYB148, as key regulators of anthocyanin biosynthesis. In conclusion, this study identifies the types of anthocyanins present in purple broccoli and enhances the understanding of the regulatory genes involved in anthocyanin synthesis. It provides genetic insights and a conceptual framework for future molecular breeding strategies directed toward enhancing the quality of purple broccoli varieties.