title: Multiparental mapping of plant height and flowering time QTL in partially isogenic sorghum families.
abstract: Sorghum varieties suitable for grain production at temperate latitudes show dwarfism and photoperiod insensitivity, both of which are controlled by a small number of loci with large effects. We studied the genetic control of plant height and flowering time in five sorghum families (A-E), each derived from a cross between a tropical line and a partially isogenic line carrying introgressions derived from a common, temperate-adapted donor. A total of 724 F2:3 lines were phenotyped in temperate and tropical environments for plant height and flowering time and scored at 9139 SNPs using genotyping-by-sequencing. Biparental mapping was compared with multiparental mapping in different subsets of families (AB, ABC, ABCD, and ABCDE) using both a GWAS approach, which fit each QTL as a single effect across all families, and using a joint linkage approach, which fit QTL effects as nested within families. GWAS using all families (ABCDE) performed best at the cloned Dw3 locus, whereas joint linkage using all families performed best at the cloned Ma1 locus. Both multiparental approaches yielded apparently synthetic associations due to genetic heterogeneity and were highly dependent on the subset of families used. Comparison of all mapping approaches suggests that a GA2-oxidase underlies Dw1, and that a mir172a gene underlies a Dw1-linked flowering time QTL.
authors.affiliation: Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801 Energy Biosciences Institute, University of Illinois, Urbana, Illinois 61801.
authors.forename: R H
authors.initials: RH
authors.lastname: Higgins
authors.affiliation: Energy Biosciences Institute, University of Illinois, Urbana, Illinois 61801.
authors.forename: C S
authors.initials: CS
authors.lastname: Thurber
authors.affiliation: Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801.
authors.forename: I
authors.initials: I
authors.lastname: Assaranurak
authors.affiliation: Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801 Energy Biosciences Institute, University of Illinois, Urbana, Illinois 61801 pjb34@illinois.edu.
authors.forename: P J
authors.identifier: http://orcid.org/0000-0003-1332-711X
authors.initials: PJ
authors.lastname: Brown
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D035264:Flowers / Q000502:physiology; D008040:Genetic Linkage; D018745:Genome, Plant; D055106:Genome-Wide Association Study; D005838:Genotype; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D045868:Sorghum / Q000235:genetics* / Q000254:growth & development / Q000502:physiology
keywords: GWAS; MPP; Multiparent Advanced Generation Inter-Cross (MAGIC); Multiparental populations; allelic series; genetic heterogeneity; linkage; photoperiod