DNA contents in Texas bluegrass (Poa arachnifera) selected in Texas and Oklahoma determined by flow cytometry

Texas bluegrass (Poa arachnifera Torr.) is a dioecious, perennial, cool-season grass native to southern Kansas, Oklahoma, western Arkansas and most of Texas. Its major use has been for forage on rangelands in Texas and Oklahoma. More recently, interspecific hybrids between Texas bluegrass and Kentucky bluegrass (P. pratensis L.) have been developed and commercially released as heat tolerant turfgrass. Currently, the 2C nuclear DNA content of Texas bluegrass is unknown. Therefore, flow cytometry was performed on an assortment of male and female Texas bluegrass genotypes (n = 24) collected from fourteen locations in Texas and Oklahoma to estimate DNA content in picograms (pg). The DNA content of Texas bluegrass fell into two groups based on collection location. Plants collected from northwest Oklahoma and five other locations west of 33.75, -98.39 (latitude, longitude) ranged from 9.64 +/- A 0.04 to 10.07 +/- A 0.09 pg. Plants collected from four sites in Texas, east of 33.20, -98.16 contained a DNA content that ranged from 14.02 +/- A 0.04 to 14.75 +/- A 0.13 pg. Based on a root tip chromosome count, a male Texas bluegrass plant estimated to be 9.96 pg, appeared to contain 56 chromosomes, indicating the smaller DNA content plants may be octaploids (2n = 8x = 56). Significant differences were not detected between male and female plants based on DNA content. Knowledge of the DNA content in Texas bluegrass should be useful in a breeding program for characterizing germplasm and identifying desired DNA content levels among parental genotypes.