Genetic Dissection of a Genomic Region with Pleiotropic Effects on Domestication Traits in Maize Reveals Multiple Linked QTL
Zachary H. Lemmon, John F. Doebley

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 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 MIKCC transcription factor, a family of proteins implicated in many developmental programs. We also used simulated trait datasets 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 or more 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.

  • Received May 5, 2014.
  • Accepted June 16, 2014.