Hufford Kristina M, Canaran Payan, Ware Doreen H, McMullen Michael D, Gaut Brandon S
Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.
Plant Physiol. 2007 Jul;144(3):1642-53. doi: 10.1104/pp.107.098988. Epub 2007 May 11.
The domestication of maize (Zea mays sp. mays) from its wild progenitors represents an opportunity to investigate the timing and genetic basis of morphological divergence resulting from artificial selection on target genes. We compared sequence diversity of 30 candidate selected and 15 reference loci between the three populations of wild teosintes, maize landraces, and maize inbred lines. We inferred an approximately equal ratio of genes selected during early domestication and genes selected during modern crop breeding. Using an expanded dataset of 48 candidate selected and 658 neutral reference loci, we tested the hypothesis that candidate selected genes in maize are more likely to have transcriptional functions than neutral reference genes, but there was no overrepresentation of regulatory genes in the selected gene dataset. Electronic northern analysis revealed that candidate genes are significantly overexpressed in the maize ear relative to vegetative tissues such as maize shoot, leaf, and root tissue. The maize ear underwent dramatic morphological alteration upon domestication and has been a continuing target of selection for maize yield. Therefore, we hypothesize that genes targeted by selection are more likely to be expressed in tissues that experienced high levels of morphological divergence during domestication and crop improvement.
玉米(Zea mays sp. mays)从其野生祖先驯化而来,这为研究针对目标基因的人工选择所导致的形态分化的时间和遗传基础提供了契机。我们比较了野生类蜀黍、玉米地方品种和玉米自交系这三个群体中30个候选选择位点和15个参考位点的序列多样性。我们推断,在早期驯化过程中选择的基因与现代作物育种过程中选择的基因比例大致相等。使用一个包含48个候选选择位点和658个中性参考位点的扩展数据集,我们检验了这样一个假设:玉米中的候选选择基因比中性参考基因更有可能具有转录功能,但在选择基因数据集中调控基因并没有过度富集。电子北方分析表明,相对于玉米茎、叶和根组织等营养组织,候选基因在玉米穗中显著过表达。玉米穗在驯化过程中经历了显著的形态改变,并且一直是玉米产量选择的持续目标。因此,我们推测,被选择靶向的基因更有可能在驯化和作物改良过程中经历高度形态分化的组织中表达。