Phylotranscriptomic Analyses Resolve Evolutionary History of <i>Eremopyrum</i> (Triticeae; Poaceae)

Disentangling the phylogenetic relationship of polyploid species is essential for understanding how such polyploid species evolved following their origin. To investigate the speciation and evolutionary history of <i>Eremopyrum</i>, we analyzed 36 transcriptomes from 9 polyploid accessions of <i>Eremopyrum</i> and 27 diploid taxa representing 12 basic genomes in Triticeae. Phylogenetic reconstruction, divergence time, and introgression event demonstrated that (1) <i>Eremopyrum</i> and <i>Agropyron</i> shared a common ancestor; (2) <i>Eremopyrum</i> has undergone ongoing evolutionary diversification since its origin in Late Miocene; (3) the diploid <i>E. triticeum</i> and <i>E. distans</i> were the genome donors of the tetraploid species of <i>Eremopyrum</i>; (4) both <i>Eremopyrum</i> and <i>Agropyron</i> contribute to the nonmonophyletic origin of tetraploid <i>E. orientale</i> via introgression events. Our results shed new light on our understanding of the diversity and ecological adaptation of the species in <i>Eremopyrum</i>.