title: Genome-wide association mapping of quantitative resistance to sudden death syndrome in soybean.
abstract: BACKGROUND
  Sudden death syndrome (SDS) is a serious threat to soybean production that can be managed with host plant resistance. To dissect the genetic architecture of quantitative resistance to the disease in soybean, two independent association panels of elite soybean cultivars, consisting of 392 and 300 unique accessions, respectively, were evaluated for SDS resistance in multiple environments and years. The two association panels were genotyped with 52,041 and 5,361 single nucleotide polymorphisms (SNPs), respectively. Genome-wide association mapping was carried out using a mixed linear model that accounted for population structure and cryptic relatedness.
  
  
  RESULTS
  A total of 20 loci underlying SDS resistance were identified in the two independent studies, including 7 loci localized in previously mapped QTL intervals and 13 novel loci. One strong peak of association on chromosome 18, associated with all disease assessment criteria across the two panels, spanned a physical region of 1.2 Mb around a previously cloned SDS resistance gene (GmRLK18-1) in locus Rfs2. An additional variant independently associated with SDS resistance was also found in this genomic region. Other peaks were within, or close to, sequences annotated as homologous to genes previously shown to be involved in plant disease resistance. The identified loci explained an average of 54.5% of the phenotypic variance measured by different disease assessment criteria.
  
  
  CONCLUSIONS
  This study identified multiple novel loci and refined the map locations of known loci related to SDS resistance. These insights into the genetic basis of SDS resistance can now be used to further enhance durable resistance to SDS in soybean. Additionally, the associations identified here provide a basis for further efforts to pinpoint causal variants and to clarify how the implicated genes affect SDS resistance in soybean.
authors.forename: Zixiang
authors.initials: Z
authors.lastname: Wen
authors.forename: Ruijuan
authors.initials: R
authors.lastname: Tan
authors.forename: Jiazheng
authors.initials: J
authors.lastname: Yuan
authors.forename: Carmille
authors.initials: C
authors.lastname: Bales
authors.forename: Wenyan
authors.initials: W
authors.lastname: Du
authors.forename: Shichen
authors.initials: S
authors.lastname: Zhang
authors.forename: Martin I
authors.initials: MI
authors.lastname: Chilvers
authors.forename: Cathy
authors.initials: C
authors.lastname: Schmidt
authors.forename: Qijian
authors.initials: Q
authors.lastname: Song
authors.forename: Perry B
authors.initials: PB
authors.lastname: Cregan
authors.affiliation: Department of Plant, Soil and Microbial Sciences, Michigan State University, 1066 Bogue St,, Rm, A384-E, East Lansing, MI 48824, USA. wangdech@msu.edu.
authors.forename: Dechun
authors.initials: D
authors.lastname: Wang
mesh_terms: D060467:Disease Resistance / Q000235:genetics*; D005670:Fusarium / Q000502:physiology; D017343:Genes, Plant / Q000235:genetics; D005819:Genetic Markers / Q000235:genetics; D014644:Genetic Variation; D055106:Genome-Wide Association Study; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D040641:Quantitative Trait Loci / Q000235:genetics; D013025:Glycine max / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*
chemical_list: D005819:Genetic Markers