Phylogeny and molecular evolution of the Acc1 gene within the StH genome species in Triticeae (Poaceae)

•Phylogeny of the StH genome species may associate with geographic distribution.•Dasypyrum has contributed to the nuclear genome of E. repens and E. mutabilis.•Nucleotide polymorphisms at Acc1 loci in polyploid is unlikely equivalent.•The Acc1 sequence may evolve faster in the polyploid species than in the diploids.

To estimate the phylogeny and molecular evolution of a single-copy gene encoding plastid acetyl-CoA carboxylase (Acc1) within the StH genome species, two Acc1 homoeologous sequences were isolated from nearly all the sampled StH genome species and were analyzed with those from 35 diploid taxa representing 19 basic genomes in Triticeae. Sequence diversity patterns and genealogical analysis suggested that (1) the StH genome species from the same areas or neighboring geographic regions are closely related to each other; (2) the Acc1 gene sequences of the StH genome species from North America and Eurasia are evolutionarily distinct; (3) Dasypyrum has contributed to the nuclear genome of Elymus repens and Elymus mutabilis; (4) the StH genome polyploids have higher levels of sequence diversity in the H genome homoeolog than the St genome homoeolog; and (5) the Acc1 sequence may evolve faster in the polyploid species than in the diploids. Our result provides some insight on evolutionary dynamics of duplicate Acc1 gene, the polyploidy speciation and phylogeny of the StH genome species.