Relationships Between Low Ploidy Poa Species and Kentucky Bluegrass.

Kentucky bluegrass (Poa pratensis) is an abundant cool season turf grass used across the United States, and belongs to the large Poa genus that contains up to 500 species.  Because of high polyploidy, including allo- and auto-polyploidy, little information is available regarding the evolution of Kentucky bluegrass, its genetic composition, or its phylogenetic relationship to lower ploidy Poa species. Although the genus Poa contains mostly polyploid species, several diploid species have been reported and are available in international gene banks. In our present analysis, we compared chloroplast and nuclear sequences of Kentucky bluegrass with low ploidy Poa species, to hone in on possible shared genomes.  We obtained seed from known and possible diploid species, confirmed their ploidy using root-tip chromosome counting and flow cytometry, and constructed phylogenies of their chloroplast and nuclear genes.   In Poa sections where diploids were unavailable, we garnered representative tetraploids. Our results show a relationship between polyploid Kentucky bluegrass and several low ploidy species that are candidates for shared genome ancestry.