Two R2R3-MYB transcription factors, CsMYB33 and CsMYB78 are involved in the regulation of anthocyanin biosynthesis in Cannabis sativa L.

Cannabis sativa L. is an economically important plant which is renowned for its wide range of uses. Anthocyanins , a class of flavonoids , impart pigmentation to the plant parts and play important roles in plant environment interactions. However, to the best of our knowledge, the molecular basis of anthocyanin biosynthesis in C. sativa remains elusive. Since MYB family of transcription factors plays a vital role in regulating anthocyanin biosynthesis, herein, we identified 99 R2R3-MYB genes in the C. sativa genome. Based on the phylogeny as well as the expression profiling of genes in two accessions of C. sativa differing in the content of anthocyanin pigmentation in sugar leaves, two putative regulators of anthocyanin biosynthesis, named as CsMYB33 and CsMYB78 were identified. Transient overexpression of CsMYB33 and CsMYB78 activate anthocyanin biosynthesis in the leaves of Nicotiana benthamiana . As compared to CsMYB78, CsMYB33 was found to be stronger in terms of activation of anthocyanin biosynthesis. Constitutive expression of CsMYB33 also resulted in the enhanced anthocyanin pigmentation in the leaves and sepals of transgenic lines of Nicotiana tabacum . Taken together, the present study provides valuable insights into the regulatory genes of anthocyanin biosynthesis in C. sativa , which will be useful for its biotechnological improvement. • A total of 99 R2R3-MYB family of transcription factor genes were identified in Cannabis sa tiva L. genome. • The phylogeny, gene structure and gene expression analyses revealed putative function of some of the R2R3-CsMYB genes. • CsMYB33 and CsMYB78 are the two key transcriptional activators of anthocyanin biosynthesis in C. sativa . • In comparison of CsMYB78, CsMYB33 was found to be more effective in activation of anthocyanin biosynthesis.