Genetic Diversity of the Species of the Genus Deschampsia P.Beauv. (Poaceae) Based on the Analysis of the ITS Region: Polymorphism Proves Distant Hybridization

The species of the genus Deschampsia are difficult for identification, and the genus is difficult for taxonomic treatment. The regions of 35S rRNA genes were studied for the species of the genus Deschampsia of different geographical origin with a method of sequencing by Sanger (ITS1-5.8S rRNA gene-ITS2, 14 species) and with a method of a locus-specific next-generation sequencing (NGS) on the Illumina platform (ITS1-5.8S rRNA, 7 species). All species of Deschampsia formed one clade; the species, referred by some authors on the basis of morphological characters to the species D. cespitosa s.l., entered one subclade. Subantarctic species formed a separate subclade and their ribotypes formed their own subnetwork. Avenella flexuosa, earlier referred to Deschampsia, entered the other clade, though this species contains some ribotypes common with some Deschampsia species. Deschampsia pamirica and related mountain species have their own specific ribotype groups. On the network of the ribotypes, one can see that D. cespitosa from Great Britain forms a network with some species, but D. cespitosa from the USA forms its own network. Ribotype analysis of each sample revealed traces of introgression with Deyeuxia/Calamagrostis in D. cespitosa and with A. flexuosa and probable introgression of Northern and subantarctic species.