Phylogenetic reconstruction and diversification of the Triticeae (Poaceae) based on single-copy nuclear Acc1 and Pgk1 gene data

Two single-copy nuclear gene (Acc1 and Pgk1) sequences were used to estimate the phylogeny and diversification patterns of the Triticeae. Phylogenetic analyses and diversification patterns suggested that (1) a major radiation occurring in the Triticeae about 6.1-9.2 MYA might have been triggered by the late Miocene climate oscillations; (2) the Triticeae lineages from Mediterranean and Arctic-temperate regions were evolutionarily distinct; (3) the relationship between Thinopyrum bessarabicum and Triticum/Aegilops is more closely than that between Lophopyrum elongatum and Triticum/Aegilops; (4) Pseudoroegneria is closely related to Australopyrum and Lophopyrum; (5) Australopyrum might originate from colonization via South-east Asia during the late Miocene; (6) Habitats, mating systems, and climate oscillations may associated with the diversification rate shifts leading to the majority of Mediterranean lineage. Diversification rate shifts in Mediterranean lineage of the Triticeae not only spur the occurrence of many endemic lineages but also provide opportunity for polyploid crop origin and domestication.