Phylogeny and molecular evolution of the DMC1 gene in the polyploid genus Roegneria and its affinitive genera (Poaceae: Triticeae)

Roegneria is a large genus of polyploid perennials in Poaceae tribe Triticeae. There are different opinions regarding whether Roegneria should be treated as a separate genus or included in Elymus. To investigate the phylogenetic relationships among Roegneria spp. and related genera and the possible genomic constitutions of questionable Roegneria spp., phylogenetic and network analyses of disrupted meiotic cDNA (DMC1) gene sequences of Roegneria spp. and species of related genera were carried out in this study. The St and H genome homoeologous types were grouped with the sequences of Pseudoroegneria (St genome) and Hordeum (H genome), respectively. The Y genome homoeologous types were grouped independently, with no diploid species. The results suggested that the Y and St genomes might have originated from distinct diploid species. The DMC1 sequence data presented here provide evidence for those Roegneria spp. for which genome constitutions were unknown. Roegneria serotina, R. sinica and R. schugnanica appear to contain the StY genomes, whereas E. calcicolus might contain the StYH genomes and should be transferred to Campeiostachys. The data indicate that it is reasonable to treat species containing the StY genomes as Roegneria; species with the StH genomes should be included in Elymus and species containing the StYH genomes should be treated as Campeiostachys.