ITS1–5.8S rDNA–ITS2 and trnL-trnF Sequences as Markers for the Study of Species Diversity of Altai Feather Grasses

Abstract

The ITS1–5.8S rDNA–ITS2 sequence of the 35S rRNA genes of 16 species of feather grasses and 2 species of false needlegrasses of the flora of the Altai Republic and Altai krai (Stipabaicalensis, S. borysthenica, S. capillata, S. consanguinea, S. dasyphylla, S. desertorum, S. glareosa, S. grandis, S. korshinskyi, S. krylovii, S. lessingiana, S. orientalis,S. pennata, S. praecapillata, S. pulcherrima, S. zalesskii, Ptilagrostisjunatovii, and P. mongholica), as well as four feather grass species from other regions of Russia (S. pontica, S. rubens, S. tirsa, and S. ucrainica), was sequenced. The trnL-trnF chloroplast sequences of S. capillata, S. borysthenica, S. glareosa, S. krylovii, S. lessingiana, S. orientalis, S. pulcherrima, and S. zalesskii were also determined. The trnL-trnF region, as well as the 5.8S rDNA, is highly conserved in feather grasses and cannot be used to differentiate sections and species within the genus. The ITS1 and ITS2 sequences, on the contrary, have some parsimony-informative substitutions and indels, which makes it possible to identify groups of ribotypes corresponding to sections and individual species within some sections. The clades corresponding to the Stipa and Leiostipa sections were separated; the species of the Barbatae and Subbarbatae sections composed the same clade, while the section Hemibarbatae turned out to be polyphyletic. Only in the section Stipa were no species-specific nucleotide substitutions and indels revealed. The isolation of the species S. desertorum, the taxonomic rank of which was previously unclear, was shown. The origin of polymorphic sites in the ITS sequences of feather grasses is discussed as possible evidence of distant hybridization.