title: Genetic dissection of a genomic region with pleiotropic effects on domestication traits in maize reveals multiple linked QTL.
abstract: The domesticated crop maize and its wild progenitor, teosinte, have been used in numerous experiments to investigate the nature of divergent morphologies. This study examines a poorly understood region on the fifth chromosome of maize associated with a number of traits under selection during domestication, using a quantitative trait locus (QTL) mapping population specific to the fifth chromosome. In contrast with other major domestication loci in maize where large-effect, highly pleiotropic, single genes are responsible for phenotypic effects, our study found the region on chromosome five fractionates into multiple-QTL regions, none with singularly large effects. The smallest 1.5-LOD support interval for a QTL contained 54 genes, one of which was a MADS MIKC(C) transcription factor, a family of proteins implicated in many developmental programs. We also used simulated trait data sets to investigate the power of our mapping population to identify QTL for which there is a single underlying causal gene. This analysis showed that while QTL for traits controlled by single genes can be accurately mapped, our population design can detect no more than ∼4.5 QTL per trait even when there are 100 causal genes. Thus when a trait is controlled by ≥5 genes in the simulated data, the number of detected QTL can represent a simplification of the underlying causative factors. Our results show how a QTL region with effects on several domestication traits may be due to multiple linked QTL of small effect as opposed to a single gene with large and pleiotropic effects.
authors.affiliation: Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706 zlemmon@gmail.com.
authors.forename: Zachary H
authors.initials: ZH
authors.lastname: Lemmon
authors.affiliation: Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: John F
authors.initials: JF
authors.lastname: Doebley
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics; D058685:Genetic Pleiotropy; D018745:Genome, Plant; D008957:Models, Genetic; D040641:Quantitative Trait Loci; D019655:Quantitative Trait, Heritable; D012641:Selection, Genetic; D003313:Zea mays / Q000235:genetics*
keywords: QTL; domestication; fractionation; maize; simulation