title: Analysis of genome-wide linkage disequilibrium in the highly polyploid sugarcane.
abstract: Linkage disequilibrium (LD) in crops, established by domestication and early breeding, can be a valuable basis for mapping the genome. We undertook an assessment of LD in sugarcane (Saccharum spp), characterized by one of the most complex crop genomes, with its high ploidy level (>or=8) and chromosome number (>100) as well as its interspecific origin. Using AFLP markers, we surveyed 1,537 polymorphisms among 72 modern sugarcane cultivars. We exploited information from available genetic maps to determine a relevant statistical threshold that discriminates marker associations due to linkage from other associations. LD is very common among closely linked markers and steadily decreases within a 0-30 cM window. Many instances of linked markers cannot be recognized due to the confounding effect of polyploidy. However, LD within a sample of cultivars appears as efficient as linkage analysis within a controlled progeny in terms of assigning markers to cosegregation groups. Saturating the genome coverage remains a challenge, but applying LD-based mapping within breeding programs will considerably speed up the localization of genes controlling important traits by making use of phenotypic information produced in the course of selection.
authors.affiliation: CIRAD (Centre de coopération internationale en recherche agronomique pour le développement), UMR PVBMT, Saint-Pierre, 97410, Reunion, France.
authors.forename: Louis-Marie
authors.initials: LM
authors.lastname: Raboin
authors.forename: Jérôme
authors.initials: J
authors.lastname: Pauquet
authors.forename: Mike
authors.initials: M
authors.lastname: Butterfield
authors.forename: Angélique
authors.initials: A
authors.lastname: D'Hont
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Glaszmann
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D002874:Chromosome Mapping; D003198:Computer Simulation; D005819:Genetic Markers; D018745:Genome, Plant / Q000235:genetics*; D006239:Haplotypes; D015810:Linkage Disequilibrium / Q000235:genetics*; D010802:Phylogeny; D011123:Polyploidy; D011157:Population Dynamics; D031786:Saccharum / Q000235:genetics*
chemical_list: D005819:Genetic Markers