Study of <i>Myb114</i> Gene Polymorphism in the Cole Crops (<i>Brassica oleracea</i> L.) in Connection with Anthocyanin Biosynthesis Regulation Based on Comparison with the MYB Factors of Vegetable Nightshades (Solanaceae)

Abstract

In order to study a regulation mechanism for one of the most ancient processes of anthocyanin biosynthesis in plants based on comparison of R2R3-MYB genes in Solanaceae (S. lycopersicum: An1, An2; S. melongena: Myb1; C. annuum: Myb113-like1 и Myb113-like2) and Brassicaeae crops, a search for orthologous sequences in Brassica oleracea was performed. A sequence encoding MYB114 TF was found to be the closest in a nucleotide structure to the previously investigated genes in Solanaceae. Primers were selected and a comparative analysis of Myb114 gene sequences was performed in B. oleracea varieties (white cabbage, red cabbage, kale, cauliflower, broccoli, and kohlrabi) with a wide intraspecies diversity by the anthocyanin accumulation in leaves and various food organs: heads, curds and stems. Alignment of Myb114 sequences revealed a number of gene polymorphisms that closely correlate with high anthocyanin accumulation in B. oleracea leaves, including 3 SNPs in exon regions and a 271 bp deletion in the 1st intron. The identified SNPs lead to the replacement of two amino acids located in the region of DNA-binding domains, which leads to a change in the binding efficiency of this transcription factor with the promoters of structural biosynthesis genes and a decrease in their expression level in the forms without anthocyanin accumulation in leaves compared with the forms with their accumulation in vegetative plant parts. A molecular marker MYB114.2 has been proposed that may be used for the identification of headed cabbages and kales with high/low anthocyanin accumulation. By the amino acid structure and phenotypic manifestation (regulation of anthocyanin accumulation in leaves), Myb114 B. oleracea is the closest to Ant2 tomato, Myb2 eggplant and Myb113-like2 pepper alleles. A high degree of conservatism of the SANT DNA-binding domains of MYB114 TF of B. oleracea and R2R3-MYB TF of nightshades was established.