A Mutation in the MYBL2-1 Gene Is Associated with Purple Pigmentation in Brassica oleracea

Abstract

Anthocyanins are well-known antioxidants that are beneficial for plants and consumers. Dihydroflavonol-4-reductase (DFR) is a key gene of anthocyanin biosynthesis, controlled by multiple transcription factors. Its expression can be enhanced by mutations in the negative regulator of anthocyanin biosynthesis myeloblastosis family transcription factor-like 2 (MYBL2). The expression profiles of the DFR gene were examined in 43 purple and green varieties of Brassica oleracea L., Brassica napus L., Brassica juncea L., and Brassica rapa L. MYBL2 gene expression was significantly reduced in purple varieties of B. oleracea, and green varieties of B. juncea. The MYBL2 gene sequences were screened for mutations that can affect pigmentation. Expression of the DFR gene was cultivar-specific, but in general it correlated with anthocyanin content and was higher in purple plants. Two single nucleotide polymorphysms (SNPs) were found at the beginning of the DNA-binding domain of MYBL2 gene in all purple varieties of B. oleracea. This mutation, leading to an amino acid substitution and the formation of a mononucleotide repeat (A)8, significantly affects RNA structure. No other noteworthy mutations were found in the MYBL2 gene in green varieties of B. oleracea and other studied species. These results bring new insights into the regulation of anthocyanin biosynthesis in genus Brassica and provide opportunities for generation of new purple varieties with precise mutations introduced via genetic engineering and CRISPR/Cas.

Research on Plant Genomics and Breeding

“…Khusnutdinov et al found that the DNA binding structure of transcription factor MYBL2-1 (a negative regulator of anthocyanin synthase Dihydroflavonol-4-reductase (DFR)) of purple varieties of Brassica oleracea L. had two SNP mutations, leading to an increase in DFRs expression. This is the reason for the high anthocyanin content of purple cabbage [16]. Ipomoea aquatica is a leafy vegetable rich in essential amino acids, flavonoids, and various mineral elements (calcium, potassium, phosphorus, etc.).…”