Nucleotide diversity and genetic relationships of orchardgrass (Dactylis glomerata) inferred from two non-coding regions of the chloroplast

Abstract

Orchardgrass (Dactylis glomerata L.), an important member of the Poaceae family, is a cool-season perennial forage grass, and is widely used for hay production throughout temperate and subtropical regions of the world. Despite its economic importance, nucleotide diversity of orchardgrass species remains largely unexplored. In this study, we characterized nucleotide diversity of orchardgrass species using the chloroplast rps16 intron and Asp(GUC) – Thr(GGU) intergenic region. Genetic relationships among 40 orchardgrass accessions of eight Dactylis glomerata subspecies were examined. The estimates of nucleotide diversity ([pi]) for trnD – trntW and rps16 varied from 0.00073 for Dactylis glomerata subsp. glomerata to 0.00484 for Dactylis glomerata subsp. smithii, 0.00011 for Dactylis glomerata subsp. glomerata to 0.00393 for Dactylis glomerata subsp. lusitanica and Dactylis glomerata subsp. woronowii respectively. A dendrogram based on genetic distance of the Asp(GUC) – Thr(GGU) intergenic region revealed that four accessions, two from Dactylis glomerata subsp. hispanica, one from Dactylis glomerata subsp. glomerata, and one from Dactylis glomerata subsp. woronowii were more closely related to one another than the rest of the Dactylis glomerata subspecies/accessions. A dendrogram based on genetic distance of the rps16 intron revealed that four accessions, two from Dactylis glomerata subsp. glomerata, one from Dactylis glomerata subsp. lusitanica and one from Dactylis glomerata subsp. woronowii were more closely related to one another than to the rest of the Dactylis glomerata subspecies/accessions.