title: Precisely mapping a major gene conferring resistance to Hessian fly in bread wheat using genotyping-by-sequencing.
abstract: BACKGROUND
  One of the reasons hard red winter wheat cultivar 'Duster' (PI 644016) is widely grown in the southern Great Plains is that it confers a consistently high level of resistance to biotype GP of Hessian fly (Hf). However, little is known about the genetic mechanism underlying Hf resistance in Duster. This study aimed to unravel complex structures of the Hf region on chromosome 1AS in wheat by using genotyping-by-sequencing (GBS) markers and single nucleotide polymorphism (SNP) markers.
  
  
  RESULTS
  Doubled haploid (DH) lines generated from a cross between two winter wheat cultivars, 'Duster' and 'Billings' , were used to identify genes in Duster responsible for effective and consistent resistance to Hf. Segregation in reaction of the 282 DH lines to Hf biotype GP fit a one-gene model. The DH population was genotyped using 2,358 markers developed using the GBS approach. A major QTL, explaining 88% of the total phenotypic variation, was mapped to a chromosome region that spanned 178 cM and contained 205 GBS markers plus 1 SSR marker and 1 gene marker, with 0.86 cM per marker in genetic distance. The analyses of GBS marker sequences and further mapping of SSR and gene markers enabled location of the QTL-containing linkage group on the short arm of chromosome 1A. Comparative mapping of the common markers for the gene for QHf.osu-1A (d) in Duster and the Hf-resistance gene for QHf.osu-1A (74) in cultivar '2174' showed that the two Hf resistance genes are located on the same chromosome arm 1AS, only 11.2 cM apart in genetic distance. The gene at QHf.osu-1A (d) in Duster has been delimited within a 2.7 cM region.
  
  
  CONCLUSIONS
  Two distinct resistance genes exist on the short arm of chromosome 1A as found in the two hard red winter cultivars, 2174 and Duster. Whereas the Hf resistance gene in 2174 is likely allelic to one or more of the previously mapped resistance genes (H9, H10, H11, H16, or H17) in wheat, the gene in Duster is novel and confers a more consistent phenotype than 2174 in response to biotype GP infestation in controlled-environment assays.
authors.affiliation: Department of Plant and Soil Sciences, Oklahoma State University, 368 AG Hall, Stillwater, OK, 74078, USA. genqiao.li@okstate.edu.
authors.forename: Genqiao
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Plant and Soil Sciences, Oklahoma State University, 368 AG Hall, Stillwater, OK, 74078, USA. ying.wang@okstate.edu.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Hard Winter Wheat Genetics Research Unit, USDA-ARS, Manhattan, KS, 66506, USA. mchen@ksu.edu.
authors.forename: Ming-Shun
authors.initials: MS
authors.lastname: Chen
authors.affiliation: Hard Winter Wheat Genetics Research Unit, USDA-ARS, Manhattan, KS, 66506, USA. erenae@ksu.edu.
authors.forename: Erena
authors.initials: E
authors.lastname: Edae
authors.affiliation: Department of Plant Pathology, Kansas State University, Manhattan, KS, 66506, USA. jpoland@ksu.edu.
authors.forename: Jesse
authors.initials: J
authors.lastname: Poland
authors.affiliation: Department of Plant Pathology, Kansas State University, Manhattan, KS, 66506, USA. eakhunov@ksu.edu.
authors.forename: Edward
authors.initials: E
authors.lastname: Akhunov
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Cereal Crops Research Unit, Fargo, ND, 58102, USA. Shiaoman.Chao@ars.usda.gov.
authors.forename: Shiaoman
authors.initials: S
authors.lastname: Chao
authors.affiliation: Hard Winter Wheat Genetics Research Unit, USDA-ARS, Manhattan, KS, 66506, USA. gbai@ksu.edu.
authors.forename: Guihua
authors.initials: G
authors.lastname: Bai
authors.affiliation: Department of Plant and Soil Sciences, Oklahoma State University, 368 AG Hall, Stillwater, OK, 74078, USA. brett.carver@okstate.edu.
authors.forename: Brett F
authors.initials: BF
authors.lastname: Carver
authors.affiliation: Department of Plant and Soil Sciences, Oklahoma State University, 368 AG Hall, Stillwater, OK, 74078, USA. liuling.yan@okstate.edu.
authors.forename: Liuling
authors.initials: L
authors.lastname: Yan
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification; D004175:Diptera / Q000502:physiology*; D017343:Genes, Plant; D008040:Genetic Linkage; D005819:Genetic Markers; D005838:Genotype; D006790:Host-Parasite Interactions / Q000235:genetics; D018895:Microsatellite Repeats / Q000235:genetics; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D017422:Sequence Analysis, DNA; D014908:Triticum / Q000235:genetics* / Q000469:parasitology
chemical_list: D005819:Genetic Markers; D010940:Plant Proteins; D004247:DNA