Overexpression of kale (Brassica oleracea L. var. acephala) BoMYB increases anthocyanin content in Arabidopsis thaliana

Anthocyanins are among the most important factors affecting the leaf colour of kale, and MYB proteins are key transcription factors regulating their synthesis in plants. In this study, purple-leaf kale 'D07' was used as a test material, and the complete coding sequence of BoMYB was determined by homologous cloning. Bioinformatics analysis showed that the cDNA sequence of the BoMYB coding region was 753 base pairs in length and encoded a predicted 250-amino acid protein with a mass of 25 kDa and an isoelectric point of 9.08. The BoMYB protein was predicted to contain two MYB conserved domains and to be localized in the cell nucleus. A phylogenetic tree indicated that the amino acid sequence encoded by BoMYB in kale was most closely related to the MYB protein sequence of Brassica napus. The expression patterns of BoMYB were evaluated in different tissues of 'D07' by quantitative real-time polymerase chain reaction, and the results showed that BoMYB was expressed in kale roots, stems, inner leaves, and outer leaves. However, the expression levels were tissue specific and correlated with the anthocyanin content in each tissue. To confirm the effect of BoMYB on anthocyanin synthesis and accumulation, ectopic expression in Arabidopsis was performed. Morphological observation showed that overexpression of BoMYB increased the accumulation of anthocyanidins in transgenic Arabidopsis. Thus, BoMYB may encode an MYB transcription factor, which positively regulates the synthesis of anthocyanins in kale.