title: Breeding patterns and cultivated beets origins by genetic diversity and linkage disequilibrium analyses.
abstract: Genetic diversity in worldwide population of beets is strongly affected by the domestication history, and the comparison of linkage disequilibrium in worldwide and elite populations highlights strong selection pressure. Genetic relationships and linkage disequilibrium (LD) were evaluated in a set of 2035 worldwide beet accessions and in another of 1338 elite sugar beet lines, using 320 and 769 single nucleotide polymorphisms, respectively. The structures of the populations were analyzed using four different approaches. Within the worldwide population, three of the methods gave a very coherent picture of the population structure. Fodder beet and sugar beet accessions were grouped together, separated from garden beets and sea beets, reflecting well the origins of beet domestication. The structure of the elite panel, however, was less stable between clustering methods, which was probably because of the high level of genetic mixing in breeding programs. For the linkage disequilibrium analysis, the usual measure (r (2)) was used, and compared with others that correct for population structure and relatedness (r S (2) , r V (2) , r VS (2)). The LD as measured by r (2) persisted beyond 10 cM within the elite panel and fell below 0.1 after less than 2 cM in the worldwide population, for almost all chromosomes. With correction for relatedness, LD decreased under 0.1 by 1 cM for almost all chromosomes in both populations, except for chromosomes 3 and 9 within the elite panel. In these regions, the larger extent of LD could be explained by strong selection pressure.
authors.affiliation: INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, 31326, Castanet-Tolosan, France.|CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, 31326, Castanet-Tolosan, France.|INRA, Mathématique et Informatique Appliquées de Toulouse (MIAT), UR875, 31326, Castanet-Tolosan, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Mangin
authors.affiliation: INRA, Mathématique et Informatique Appliquées de Toulouse (MIAT), UR875, 31326, Castanet-Tolosan, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Sandron
authors.affiliation: S.A.S. Florimond-Desprez Veuve and Fils, BP41, 59242, Cappelle-en-Pévèle, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Henry
authors.affiliation: S.A.S. Florimond-Desprez Veuve and Fils, BP41, 59242, Cappelle-en-Pévèle, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Devaux
authors.affiliation: SESVanderHave, Industriepark Soldatenplein Zone 2/Nr 15, 3300, Tienen, Belgium.
authors.forename: Glenda
authors.initials: G
authors.lastname: Willems
authors.affiliation: S.A.S. Florimond-Desprez Veuve and Fils, BP41, 59242, Cappelle-en-Pévèle, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Devaux
authors.affiliation: S.A.S. Florimond-Desprez Veuve and Fils, BP41, 59242, Cappelle-en-Pévèle, France. ellen.goudemand@florimond-desprez.fr.
authors.forename: Ellen
authors.initials: E
authors.lastname: Goudemand
mesh_terms: D027461:Beta vulgaris / Q000145:classification / Q000235:genetics*; D016172:DNA Fingerprinting; D018744:DNA, Plant / Q000235:genetics; D008040:Genetic Linkage; D005828:Genetics, Population; D005838:Genotype; D015810:Linkage Disequilibrium; D008957:Models, Genetic; D000069600:Plant Breeding; D020641:Polymorphism, Single Nucleotide; D012641:Selection, Genetic
chemical_list: D018744:DNA, Plant