Origin and evolutionary dynamic of Elymus ciliaris, E. pendulinus and E. longearistatus (Triticeae: Poaceae)

Abstract

Evidence accumulated over the last decade has shown that allopolyploid genomes may undergo complex reticulate evolution. Elymus, a genus with rampant interspecific hybridization, is an ideal model for examining the impact of gene introgression and polyploidization on species diversification. Although five basic genomes (St, H, Y, P and W) have so far been identified in species of the genus Elymus, the origin of the Y genome in species with a StY genome is still unknown and under debate. Previous studies suggested that the St and Y genomes may share a common progenitor genome.To test this hypothesis and explore genome evolutionary dynamic,we analyzed three tetraploid StY Elymus species, E. ciliaris, E. pendulinus and E. longearistatus,using molecular markers.The results rejected the suggestion of the same origin of the St and Y genomes. Our data revealed multiple origins and complex reticulate evolutionary dynamic of each species, also indicated that geographic isolation strongly influenced the evolution of the Y genome in these Elymus species.