Application of 5S Ribosomal DNA for Molecular Taxonomy of Subtribe Loliinae (Poaceae)

Abstract

The genus Festuca L. (subtribe Loliinae), which encompasses about 500 species, is one of the largest genera of the Poeae tribe and is distributed worldwide. The taxonomy of the genus Festuca and the subtribe Loliinae remains a subject of debate until now. Taking into account that the comparison of the 5S rDNA intergenic spacer (IGS) sequences is successfully used to estimate genetic distances between closely related plant taxa, we evaluated the possibility of its application in the study of the phylogeny of the Loliinae subtribe. Accordingly, we cloned and sequenced this region of F. ovina (subgenus Festuca) and F. carpatica (subgenus Leucopoa) genomes and compared them with the 5S rDNA of Lolium perenne and other members of the tribe Poeae. It was found that the genomes of F. ovina and F. carpatica contain only one structural class of 5S rDNA repeats. The level of IGS similarity between the two studied Festuca species ranges from 80.2 to 81.7%, and between these species and L. perenne—from 62.5 to 70.1%. Species of the genera Festuca and Lolium form a highly-supported monophyletic group on the phylodendrogram, which indicates their origin from a common ancestor. The high rate of the IGS evolution allows using of this nuclear genome region in studies on the molecular taxonomy of the subtribe Loliinae.