Molecular organization of 5S rDNA of perennial ryegrass Lolium perenne L.

Abstract

Aim. Ribosomal DNA (rDNA) is an important tool for molecular taxonomy and represents a convenient model for studying the evolution of repeated sequences. However, for many groups of angiosperms, 5S rDNA remains poorly studied, in particular for such a large group as the Poaceae (Gramineae) family. Accordingly, it was decided to analyze the molecular organization of 5S rDNA in the widespread and economically important species Lolium perenne. Methods. DNA extraction, PCR amplification, cloning and sequencing. Results. Two clones of L. perenne 5S rDNA were sequenced. It was shown that only one variant of 5S rDNA repeats with a 188–189 bp-long intergenic spacer (IGS) is present in the genome of L. perenne. Putative RNA polymerase III promoter elements were detected in the IGS. The level of IGS sequence similarity between representatives of different genera of the tribe Poeae ranges from 46 to 63 %. Conclusions. Comparison of IGS can be used to clarify the phylogenetic relationship between taxa of low ranks, in particular, between species and genera of the tribe Poeae. Keywords: 5S rDNA, intergenic spacer, molecular evolution, Lolium, Poaceae.