title: Adaptation to climate through flowering phenology: a case study in Medicago truncatula.
abstract: Local climatic conditions likely constitute an important selective pressure on genes underlying important fitness-related traits such as flowering time, and in many species, flowering phenology and climatic gradients strongly covary. To test whether climate shapes the genetic variation on flowering time genes and to identify candidate flowering genes involved in the adaptation to environmental heterogeneity, we used a large Medicago truncatula core collection to examine the association between nucleotide polymorphisms at 224 candidate genes and both climate variables and flowering phenotypes. Unlike genome-wide studies, candidate gene approaches are expected to enrich for the number of meaningful trait associations because they specifically target genes that are known to affect the trait of interest. We found that flowering time mediates adaptation to climatic conditions mainly by variation at genes located upstream in the flowering pathways, close to the environmental stimuli. Variables related to the annual precipitation regime reflected selective constraints on flowering time genes better than the other variables tested (temperature, altitude, latitude or longitude). By comparing phenotype and climate associations, we identified 12 flowering genes as the most promising candidates responsible for phenological adaptation to climate. Four of these genes were located in the known flowering time QTL region on chromosome 7. However, climate and flowering associations also highlighted largely distinct gene sets, suggesting different genetic architectures for adaptation to climate and flowering onset.
authors.affiliation: UMR 232 DIADE/DYNADIV, Institut de Recherche pour le Developpement (IRD), 911 avenue Agropolis, BP 64501, 34394, Montpellier, France.|UMR AGAP, Equipe Génomique évolutive et gestion des populations, Institut national de Recherche Agronomique (INRA), 34060, Montpellier, France.
authors.forename: Concetta
authors.initials: C
authors.lastname: Burgarella
authors.affiliation: UMR AGAP, Equipe Génomique évolutive et gestion des populations, Institut national de Recherche Agronomique (INRA), 34060, Montpellier, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Chantret
authors.affiliation: UMR AGAP, Equipe Génomique évolutive et gestion des populations, Institut national de Recherche Agronomique (INRA), 34060, Montpellier, France.
authors.forename: Laurène
authors.initials: L
authors.lastname: Gay
authors.affiliation: UMR AGAP, Equipe Génomique évolutive et gestion des populations, Institut national de Recherche Agronomique (INRA), 34060, Montpellier, France.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Prosperi
authors.affiliation: UPS, Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, BP42617, Auzeville, F-31326, Castanet-Tolosan, France.|Laboratoire de Recherche en Sciences Végétales, CNRS, BP42617, Auzeville, F-31326, Castanet-Tolosan, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Bonhomme
authors.affiliation: Department of Plant Biology, University of Minnesota, St. Paul, MN, 55108, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Tiffin
authors.affiliation: Department of Plant Biology, University of Minnesota, St. Paul, MN, 55108, USA.|Department of Plant Pathology, University of Minnesota, St. Paul, MN, 55108, USA.
authors.forename: Nevin D
authors.initials: ND
authors.lastname: Young
authors.affiliation: UMR AGAP, Equipe Génomique évolutive et gestion des populations, Institut national de Recherche Agronomique (INRA), 34060, Montpellier, France.
authors.forename: Joelle
authors.initials: J
authors.lastname: Ronfort
mesh_terms: D000064:Acclimatization / Q000235:genetics*; D000352:Africa, Northern; D002980:Climate; D005060:Europe; D035264:Flowers / Q000502:physiology*; D005828:Genetics, Population; D046913:Medicago truncatula / Q000235:genetics* / Q000502:physiology; D008957:Models, Genetic; D005810:Multigene Family; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci
keywords: association genetics; candidate genes; climate adaptation; flowering time; mixed model