Differentiation of subgenomes in StY-genomic species of the genus Elymus (Triticeae, Poaceae) from the territory of Russia according to sequencing data of the nuclear gene GBSS1 (waxy)

According to the latest data, 55 species of the genus Elymus are distributed in Russia, carrying three subgenomic combinations (StH, StY, and StHY). Among them, the StY-genomic group comprises only 10 species, with varying degrees of understanding of their evolutionary relationships. Ancestral taxa of the genus Pseudoroegneria donated the St subgenome to all modern species of the genus Elymus. The StY-genomic group of species possesses an additional Y subgenome of unknown origin, which, according to some data, is close to the St subgenome. We studied the phylogenetic relationships between StY-genomic species from Russia, five species of the genus Pseudoroegneria, and five species of the genus Hordeum from the NCBI GenBank by comparing the nucleotide sequences of the nuclear gene GBSS1 from exons 9 to 14. One of the main objectives was a comparative analysis of phylogenetic patterns based on (i) more conservative exons and (ii) introns that do not encode the amino acid sequences of the enzyme. All gene variants from the St subgenomes of the studied species are divided into three clusters according to three marker groups of nucleotide sequence of clones in the genus Pseudoroegneria: Central Asian (St₁) with the reference species P. strigosa, North American (St₂) with the marker species P. spicata, and Middle Eastern (St₃) with two species, P. tauri and P. libanotica, to which the Eastern European species P. stipifolia gravitates. The H subgenome, originating from ancestral taxa of the genus Hordeum (Critesion), was not detected in any of the studied species. The cluster of Y subgenome in the “introns” variant is generally visually less differentiated than in the “exons” variant. This fact contradicts the established notion that gene regions responsible for the synthesis of enzymatic molecules are more conserved. Among the most notable characteristics in the comparison of nucleotide sequences is the presence of a special Far Eastern race of E. gmelinii with St₃ sequences instead of St₁ and the location of the sequences of all clones of the North Kazakhstan accession E. fedtschenkoi KSA-0935 in the St₂ cluster instead of St₃.

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