XVI International Botanical Congess

A huge part of the genomes of most Triticeae species is formed by the different classes of the repetitive sequences. These sequences are widely used for studying of the phylogenetic relationships since even one probe marks a significant piece of genome. In most cases, due to their dispersed distribution across genomes, retrotransposons depict the existent Triticeae phylogeny complementary and gave the new contribution to the understanding of the generation of the genetic biodiversity. Another class of repeats, tandemly organized DNA sequences, as a rule, cluster at the functionally important regions of chromosomes, centromeres and telomeres. According to the common criteria - homology of primary structure and copy number - the distribution of a number of tandem DNA families in Triticeae could not be placed in the frame of generally accepted phylogenetic relationships. We suggest that the tremendous variation in copy numbers of these class of the repeats have been assiciated with a formation of specific chromosomal regions which are important for chromosome behavior and stabilization of species-specific karyotype. Therefore, the evolution of these regions may occur largely independently of the evolution of gene-rich regions.