title: Modelling the genetic architecture of flowering time control in barley through nested association mapping.
abstract: BACKGROUND
  Barley, globally the fourth most important cereal, provides food and beverages for humans and feed for animal husbandry. Maximizing grain yield under varying climate conditions largely depends on the optimal timing of flowering. Therefore, regulation of flowering time is of extraordinary importance to meet future food and feed demands. We developed the first barley nested association mapping (NAM) population, HEB-25, by crossing 25 wild barleys with one elite barley cultivar, and used it to dissect the genetic architecture of flowering time.
  
  
  RESULTS
  Upon cultivation of 1,420 lines in multi-field trials and applying a genome-wide association study, eight major quantitative trait loci (QTL) were identified as main determinants to control flowering time in barley. These QTL accounted for 64% of the cross-validated proportion of explained genotypic variance (pG). The strongest single QTL effect corresponded to the known photoperiod response gene Ppd-H1. After sequencing the causative part of Ppd-H1, we differentiated twelve haplotypes in HEB-25, whereof the strongest exotic haplotype accelerated flowering time by 11 days compared to the elite barley haplotype. Applying a whole genome prediction model including main effects and epistatic interactions allowed predicting flowering time with an unmatched accuracy of 77% of cross-validated pG.
  
  
  CONCLUSIONS
  The elaborated causal models represent a fundamental step to explain flowering time in barley. In addition, our study confirms that the exotic biodiversity present in HEB-25 is a valuable toolbox to dissect the genetic architecture of important agronomic traits and to replenish the elite barley breeding pool with favorable, trait-improving exotic alleles.
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle Wittenberg, Betty-Heimann-Str. 3, 06120, Halle, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Maurer
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle Wittenberg, Betty-Heimann-Str. 3, 06120, Halle, Germany.|Interdisciplinary Center for Crop Plant Research (IZN), Betty-Heimann-Str. 3, 06120, Halle, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Draba
authors.affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Stadt Seeland, OT Gatersleben, Germany.
authors.forename: Yong
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle Wittenberg, Betty-Heimann-Str. 3, 06120, Halle, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Schnaithmann
authors.affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Stadt Seeland, OT Gatersleben, Germany.|Current address: University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle Wittenberg, Betty-Heimann-Str. 3, 06120, Halle, Germany.
authors.forename: Erika
authors.initials: E
authors.lastname: Schumann
authors.affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Stadt Seeland, OT Gatersleben, Germany.|Current address: Bayer CropScience NV, Technologiepark 38, 9052, Ghent, Belgium.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Kilian
authors.affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Stadt Seeland, OT Gatersleben, Germany.
authors.forename: Jochen Christoph
authors.initials: JC
authors.lastname: Reif
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle Wittenberg, Betty-Heimann-Str. 3, 06120, Halle, Germany. klaus.pillen@landw.uni-halle.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Pillen
mesh_terms: D002874:Chromosome Mapping; D004843:Epistasis, Genetic / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D014644:Genetic Variation; D018745:Genome, Plant; D055106:Genome-Wide Association Study; D006239:Haplotypes; D001467:Hordeum / Q000235:genetics* / Q000378:metabolism; D015810:Linkage Disequilibrium; D008957:Models, Genetic; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci