Genes determining the coloration of different organs in wheat

The coloration of several wheat organs has an adaptive significance. Coloration characteristics are widely used in taxonomy and for certification of wheat varieties; they are also a convenient model for genetic and molecular genetic studies. Data on chromosomal localization, genetic mapping, and structural and functional organization of all known genes that determine coloration in wheat are presented in this review. To date, localization of approximately 30 wheat genes that determine the coloration of different organs have been described. These genes are mainly presented by homoeologous loci in the A, B, and D genomes; most of them are located in gene-rich 1S0.8 and 7S0.4 regions of the wheat genome. Comparative mapping in different species of cereals indicates that the orthologous genes that control coloration can both be found in individual members (a homeologous series of the Rg genes was found only in wheat and aegilops; the R genes, in wheat, aegilops, and rye) and be widely presented in the whole family of cereals (genes, which determine anthocyanins coloration). Data on comparative mapping in combination with the results of the latest studies aimed at cloning and study of the functions of genes that determine the coloration of wheat organs give reason to believe that these genes belong to the Myb- and Myc-like gene families; these genes encode transcriptional activators of the structural genes of the flavonoid pigment biosynthesis in plants.