MYC gene family in cereals: Transformations during evolution of hexaploid bread wheat and its relatives

详细

The transcription factors of the MYC gene family are an integral part of the MYB + MYC + WD40 regulatory complex required to activate the genes of plant flavonoid biosynthesis. The TaMyc1 gene, which controls the synthesis of flavonoid pigments in the grain pericarp, is known in bread wheat (Triticum aestivum L., BBAADD genome, 2n = 6x = 42). In the present work, we identified 10 copies of this gene in the T. aestivum genome, 22 copies in the nearest bread wheat relatives (T. durum, T. urartu, T. monococcum, Aegilops speltoides, Ae. sharonensis, Ae. tauschii). The analysis of genetic similarity of all these genes demonstrated that the MYC gene duplication occurred for the first time in the common diploid ancestor of the Triticeae tribe with the formation of copies in the second and fourth chromosomes. In the members of the Triticum and Aegilops genera, these genes underwent from two to four duplication acts that resulted in the formation of paralogous copies. The orthologs of the MYC genes obtained from ancestral diploid species exist in polyploid species of the Triticum genus (in addition to paralogues). The time of the emergence of individual MYC family members was calculated based on the average speed of accumulation of nucleotide substitutions (k) in the MYC genes (established in this work) and certain number of synonymous substitutions between individual copies.