A phylogenomic assessment of ancient polyploidy and genome evolution across the Poales

Comparisons of flowering plant genomes reveal multiple rounds of ancient polyploidy characterized by large intra-genomic syntenic blocks. Three such whole genome duplication (WGD) events, designated as rho (ρ), sigma (σ), and tau (τ), have been identified in the genomes of cereal grasses. Precise dating of these WGD events is necessary to investigate how they have influenced diversification rates, evolutionary innovations, and genomic characteristics such as the GC profile of protein coding sequences. The timing of these events has remained uncertain due to the paucity of monocot genome sequence data outside the grass family (Poaceae). Phylogenomic analysis of protein coding genes from sequenced genomes and transcriptome assemblies from 35 species, including representatives of all families within the Poales, has resolved the timing ofrho and sigma relative to speciation events and placed tau prior to divergence of Asparagales and the commelinids but after divergence with eudicots. Exami...