Agrostis Species Relationships Based on trnL-trnF and atpI-atpH Intergenic Spacer Regions

The bentgrasses (Agrostis spp.) are among the most important species to the turfgrass industry. They have complex genomes resulting from polyploidization and high rates of interspecific hybridization. An understanding of species relationships would improve the efficiency of developing improved bentgrass cultivars. To elucidate the evolutionary relationships among Agrostis species, phylogenetic analyses were performed on sequences of two chloroplast-encoded intergenic spacer regions. A 298-bp region of the trnL-trnF intergenic spacer and a 451-bp region of the atpI-atpH intergenic spacer were included in the analyses. A total of 47 Agrostis accessions were included with both cultivated and unimproved material from the National Plant Germplasm System. Of these 47 Agrostis collections, there were 10 unique trnL-trnF haplotypes and eight distinct atpI-atpH haplotypes, indicating a high degree of shared sequence identity within these chloroplast intergenic regions. These findings suggest that the chloroplast genomes of A. canina and A. stolonifera are more closely related to each other than either species is to A. capillaris, incongruent with our previous understanding of genome relationships in the genus.