Assessment of Variability in Tall Fescue and Its Relatives with Molecular Markers.

Tall fescue [Lolium arundinaceum (Schreb.) Darbysh] is an important cool-season perennial forage grass species throughout the temperate regions of the world. There are two major germplasm pools, i.e., Continental and Mediterranean. Continental germplasms are relatively winter-hardy and remain in active growth throughout the year. Mediterranean ecotypes generally show summer dormancy and grow well at moderately low temperatures and/or short nights. The objective of this study is the molecular dissection of a collection of tall fescue germplasms and its relatives originated at different geographic locations. Tall fescue cultivars, accessions and related species were collected from the GRIN and other commercial sources. A total of 94 of these collections were assayed with tall fescue EST-SSR, genomic SSR, and candidate gene specific sequenced tag site (STS) markers along with two check lines. Pooled DNA from five plants in each collection was used for the molecular marker profiling. All of the genomic SSR, 86% of EST-SSR and 50% of the STS primers amplified clean products. An average, each primer amplified 20 fragments in this collection. A total of 1318 markers were used to construct a dendogram based on genetic similarity matrix using the Dice similarity coefficient. Four distinct clusters were identified at the least similarity coefficient of 0.15. Genotypes were clustered according to the functional groups. All of Festuca mairei loosely clustered with some other related species. Relationship of these classifications with summer-dormancy will be evaluated.