title: Evidence for a large-scale population structure among accessions of Arabidopsis thaliana: possible causes and consequences for the distribution of linkage disequilibrium.
abstract: The existence of a large-scale population structure was investigated in Arabidopsis thaliana by studying patterns of polymorphism in a set of 71 European accessions. We used sequence polymorphism surveyed in 10 fragments of approximately 600 nucleotides and a set of nine microsatellite markers. Population structure was investigated using a model-based inference framework. Among the accessions studied, the presence of four groups was inferred using genetic data, without using prior information on the geographical origin of the accessions. Significant genetic isolation by geographical distance was detected at the group level, together with a geographical gradient in allelic richness across groups. These results are discussed with respect to the previously proposed scenario of postglacial colonization of Europe from putative glacial refugia. Finally, the contribution of the inferred structure to linkage disequilibrium among 171 pairs of essentially unlinked markers was also investigated. Linkage disequilibrium analysis revealed that significant associations detected in the whole sample were mainly due to genetic differentiation among the inferred groups. We discuss the implication of this finding for future association studies in A. thaliana.
authors.affiliation: UMR 1097 Diversité et Génomes des Plantes Cultivées, INRA, Domaine de Melgueil, Mauguio, France. marie-france.ostrowski@ensam.inra.fr
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Ostrowski
authors.forename: Jacques
authors.initials: J
authors.lastname: David
authors.forename: Sylvain
authors.initials: S
authors.lastname: Santoni
authors.forename: Heather
authors.initials: H
authors.lastname: McKhann
authors.forename: Xavier
authors.initials: X
authors.lastname: Reboud
authors.forename: Valerie
authors.initials: V
authors.lastname: Le Corre
authors.forename: Christine
authors.initials: C
authors.lastname: Camilleri
authors.forename: Dominique
authors.initials: D
authors.lastname: Brunel
authors.forename: David
authors.initials: D
authors.lastname: Bouchez
authors.forename: Benoit
authors.initials: B
authors.lastname: Faure
authors.forename: Thomas
authors.initials: T
authors.lastname: Bataillon
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D005843:Geography; D015810:Linkage Disequilibrium; D018895:Microsatellite Repeats; D008957:Models, Genetic; D010802:Phylogeny; D011110:Polymorphism, Genetic