title: The genetic architecture of response to long-term artificial selection for oil concentration in the maize kernel.
abstract: In one of the longest-running experiments in biology, researchers at the University of Illinois have selected for altered composition of the maize kernel since 1896. Here we use an association study to infer the genetic basis of dramatic changes that occurred in response to selection for changes in oil concentration. The study population was produced by a cross between the high- and low-selection lines at generation 70, followed by 10 generations of random mating and the derivation of 500 lines by selfing. These lines were genotyped for 488 genetic markers and the oil concentration was evaluated in replicated field trials. Three methods of analysis were tested in simulations for ability to detect quantitative trait loci (QTL). The most effective method was model selection in multiple regression. This method detected approximately 50 QTL accounting for approximately 50% of the genetic variance, suggesting that >50 QTL are involved. The QTL effect estimates are small and largely additive. About 20% of the QTL have negative effects (i.e., not predicted by the parental difference), which is consistent with hitchhiking and small population size during selection. The large number of QTL detected accounts for the smooth and sustained response to selection throughout the twentieth century.
authors.affiliation: Monsanto Company, St. Louis, Missouri 63167, USA. cathylaurie@pqgen.com <cathylaurie@pqgen.com>
authors.forename: Cathy C
authors.initials: CC
authors.lastname: Laurie
authors.forename: Scott D
authors.initials: SD
authors.lastname: Chasalow
authors.forename: John R
authors.initials: JR
authors.lastname: LeDeaux
authors.forename: Robert
authors.initials: R
authors.lastname: McCarroll
authors.forename: David
authors.initials: D
authors.lastname: Bush
authors.forename: Brian
authors.initials: B
authors.lastname: Hauge
authors.forename: Chaoqiang
authors.initials: C
authors.lastname: Lai
authors.forename: Darryl
authors.initials: D
authors.lastname: Clark
authors.forename: Torbert R
authors.initials: TR
authors.lastname: Rocheford
authors.forename: John W
authors.initials: JW
authors.lastname: Dudley
mesh_terms: D003198:Computer Simulation; D003314:Corn Oil / Q000235:genetics* / Q000378:metabolism; D004843:Epistasis, Genetic; D005799:Genes, Dominant; D005819:Genetic Markers; D014644:Genetic Variation; D015810:Linkage Disequilibrium; D010641:Phenotype; D040641:Quantitative Trait Loci; D012044:Regression Analysis; D012639:Seeds / Q000378:metabolism*; D012641:Selection, Genetic; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
chemical_list: D005819:Genetic Markers; D003314:Corn Oil