Diversity of tall fescue and relationships within festuca subgenus schedonourus based on nuclear and chloroplast simple sequence repeat markers

Tall fescue (Festuca arundinacea Schreb. syn. Lolium arundinaceaum [Schreb.] Darbysh. syn. Schedonourus arundinaceus [Schreb.] Dumort.) is an allohexaploid grass species that is found throughout Europe, much of Asia, and North Africa. As it is currently understood, there are two gene pools within Festuca subgenus, the Continental morphotype, which can be found in Europe and Asia, and the Mediterranean morphotype, which can be found in Northern Africa. The aims of this thesis were to investigate the level of diversity present in a tall fescue germplasm collection from the center of origin for the species and recent cultivars and to determine the relationships between the collections and cultivars, as well as between the species and subspecies within the subgenus Schedonorus. Sixteen individuals from ninety-eight collections, cultivars, and accessions of Festuca and Lolium were genotyped using two tall fescue nuclear EST-SSRs, eleven tall fescue nuclear genomic SSRs, and eighteen tall fescue chloroplast SSRs. One chloroplast marker was used to assign each cultivars, collection, or accession to a morphotype. The nuclear SSR markers found that the turf-type cultivars of tall fescue were closely related but still genetically distinct from each other, agreeing with known pedigree information. The collections generally clustered by geographic origin. Bayesian cluster analysis showed that the cultivars and collections exhibit a high level of admixture. Chloroplast microsatellites were not capable of discriminating between cultivars and collections, as the nuclear satellites were. Both marker systems, separated the collections from North Africa from the other collections, as well as other species and subspecies from that region, suggesting they are not closely related. This work showed that nuclear SSRs were capable of distinguishing between cultivars and collections of tall fescue, while chloroplast SSRs were only capable of distinguishing between species and subspecies.M.S.Includes bibliographical referencesby Vincenzo Averello I