Variability of the ITS1-5.8S rDNA-ITS2 sequence during the divergence of sweet-grass species (Glyceria R. Br.)

Sequencing and comparative analysis of the ITS1-5.8S rDNA-ITS2 sequence of the nuclear genome of 13 species of genus Glyceria, 4 species of genus Melica, and one species of genus Pleuropogon demonstrated the presence of three haplotypes in the species of Glyceria: (1) haplotype A was detected only in species of the section Glyceria of subgenus Glyceria (G. septentrionalis, G. fluitans, G. declinata, G. occidentalis, G. notata, G. borealis, G. leptostachya) and in Pleuropogon sabinei; (2) haplotype C was characteristic for section Hydropoa of subgenus Hydropoa (G. grandis, G. x amurensis, G. triflora, G. maxima) and for sect. Lithuanicae (G. leptolepis); and (3) haplotype B was observed in species of sect. Striatae of subgenus Hydropoa (G. elata, G. striata, G. neogaea, G. canadensis), sect. Scolochloiformes (G. alnasteretum, G. spiculosa) and in G. lithuanica of sect. Lithuanicae. Species carrying haplotype B are located at the base of the phylogenetic tree of genus Glyceria and are clustered into a clade with low bootstrap support. According to the nucleotide sequences of the ITS and 5.8S rRNA gene, species of sections Glyceria and Hydropoa represent two sister monophyletic branches in genus Glyceria that originated independently, with Pleuropogon sabinei species belonging to the branch of sect. Glyceria.