Genome relationships in polyploid Poa pratensis and other Poa species inferred from phylogenetic analysis of nuclear and chloroplast DNA sequences
Jason T. Patterson, Steven R. Larson, and Paul G. Johnson
The genus Poa comprises approximately 500 species that occur throughout the world, including the widely
grown Kentucky bluegrass (P. pratensis L.). Hybridization and polyploidization have played a prominent role in the
evolution of this complex genus, but limited information is available regarding genome relationships in Poa. Thus, we
amplified, cloned, and compared the DNA sequences of 2 nuclear genes (CDO504 and thioredoxin-like protein) and 2
chloroplast genome loci (ndhF and trnT–trnF) from 22 Poa species. Four distinct classes of sequences corresponding to
4 putative homoeologous loci from each nuclear gene were found within polyploid P. pratensis. Nuclear sequences
from 15 other Poa species were found to group with at least 1 P. pratensis homoeolog, whereas 6 species displayed sequences
not present in P. pratensis. The nuclear genome phylogenies presented here show the first evidence of
diverse and related genomes in the genus Poa.
