Organization of 5S rDNA of field maple (Acer campestre L.)

Abstract

In recent decades, molecular methods have been widely used to study plant speciation and taxonomy. The 5S rDNA, which belongs to the class of repeated sequences present in the genomes of all eukaryotes, represents a convenient model for studying the patterns of molecular evolution in plants. Each of 5S rDNA repeated units consist of a coding region and an intergenic spacer (IGS). The coding sequence is highly conserved in evolution, whereas the IGS can differ between related species and even between populations of the same species. The molecular organization of the 5S rDNA in representatives of genus Acer is still poorly explored. Accordingly, the aim of the study was to investigate the organization and variability of the 5S rDNA of the European species Acer campestre. Analysis of the obtained sequences showed, that the 5S rDNA clones of A. campestre are identical. The level of IGS sequence similarity between A. сampestre and A. platanoides amounts to 96.1%, whereas the similarity between these species and A. pseudoplatanus is lower, namely – 81,9–82,4%. Therefore, A. campestre and A. platanoides can be considered as closely related species. Only one class of 5S rDNA repeats is present in the genome of A. сampestre. The potential external elements of the RNA polymerase III promoter localized in the IGS differ from those described early for representatives of other families of angiosperms.