5S rDNA of Dactylus glomerata (Poaceae): molecular organization and taxonomic application
Aim. During the last decades, extensive use of molecular methods resulted in significant elucidation of evolution and taxonomy of Poaceae, but determination of boundaries between related tribes still represent an actual problem. Especially, application of variable genes like 5S rDNA is necessary for further improvement of existing knowledge about the phylogeny of Poaceae. In order to clarify the phylogenetic position of the subtribe Dactylidinae within the tribe Poeae, we describe molecular organization of 5S rDNA of Dactylis glomerata. Methods. The 5S rDNA repeated units were amplified by PCR, cloned and sequenced. Results. It was shown that only one 258 bp-long variant of 5S rDNA repeats is present in the genome of D. glomerata and the level of intragenomic similarity of the repeats is high, ranging from 96,8 to 98,8%. The repeats appear to be functionally active since they contain all known elements of external promoter for RNA polymerase III. According to sequence comparison the 5S rDNA of D. glomerata appears to be similar to that one of distantly related Aveninae species. Conclusions. The data indicate a possible hybridization between representatives of subtribes Dactylidinae and Aveninae.
Keywords: Dactylis, 5S rDNA, intergenic spacer, molecular evolution and taxonomy, hybridization.