Lemmon Zachary H, Doebley John F
Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706
Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706.
Genetics. 2014 Sep;198(1):345-53. doi: 10.1534/genetics.114.165845. Epub 2014 Jun 20.
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.
驯化作物玉米及其野生祖先类蜀黍已被用于众多实验，以研究形态差异的本质。本研究利用特定于第五条染色体的数量性状基因座（QTL）定位群体，研究了玉米第五条染色体上一个了解较少的区域，该区域与驯化过程中多个受选择的性状相关。与玉米中其他主要驯化基因座不同，在这些基因座中，具有大效应、高度多效性的单个基因负责表型效应，我们的研究发现第五条染色体上的区域可分为多个QTL区域，没有一个具有单一的大效应。一个QTL的最小1.5-LOD支持区间包含54个基因，其中一个是MADS MIKC(C)转录因子，这是一类与许多发育程序有关的蛋白质家族。我们还使用模拟性状数据集来研究我们的定位群体识别具有单个潜在因果基因的QTL的能力。该分析表明，虽然由单个基因控制的性状的QTL可以被准确定位，但即使有100个因果基因，我们的群体设计每个性状最多只能检测到约4.5个QTL。因此，当一个性状在模拟数据中由≥5个基因控制时，检测到的QTL数量可能代表了潜在致病因素的简化。我们的结果表明，一个对多个驯化性状有影响的QTL区域可能是由于多个小效应的连锁QTL，而不是一个具有大效应和多效性的单个基因。
