Genetic Diversity of Tall Fescue Using Diversity Arrays Technology (DArT) Markers.

Tall fescue (Festuca arundinacea Shreb.) is the preferred lawn species in California and other warm climates because of its drought avoidance, shade tolerance, and ability to maintain lush green color year-round with supplemental irrigation. However, germplasm that is available both commercially and in variety trials appears surprisingly similar in quality and performance. To test genetic variation present, we sampled 94 entries from the 2006 National Tall Fescue Trial in Riverside, CA. Diversity Arrays Technology (DArT) is a low-cost, high-throughput, sequence-independent method for discovering and scoring genetic polymorphic markers in plants. The analysis revealed only 46 polymorphic DArT markers compared to 512 DArT markers discovered for 40 accessions of forage-type tall fescue. Since sampling was designed to discover differences in marker presence/absence, as opposed to differences in allelic frequencies, 6-15 individual plants were then sampled from 12 of the 94 entries. While there were differences in allelic frequencies when looking at individual plants, there was not much differentiation between members of different populations sampled sufficiently. Low polymorphism of turf germplasm indicates a very close relationship regardless of the origin of a cultivar. These data are in agreement with field observations showing very few distinguishable differences in turf quality and leaf texture among the entries, with the exception of Kentucky-31 and Aristotle. These two cultivars rank at or near the bottom for these traits and showed the highest polymorphism of DArT markers. Such low genetic diversity in turf germplasm may have been caused by either a severe genetic bottleneck in the conversion of germplasm from pasture/fodder use to turfgrass, or to extensive sharing of germplasm among breeders. More concerted efforts need to be undertaken to rapidly expand the genetic basis of turf-type tall fescue germplasm if breeding progress is to be sustained.