Wang R L, Stec A, Hey J, Lukens L, Doebley J
Department of Plant Biology, University of Minnesota, St Paul 55108, USA.
Nature. 1999 Mar 18;398(6724):236-9. doi: 10.1038/18435.
The domestication of all major crop plants occurred during a brief period in human history about 10,000 years ago. During this time, ancient agriculturalists selected seed of preferred forms and culled out seed of undesirable types to produce each subsequent generation. Consequently, favoured alleles at genes controlling traits of interest increased in frequency, ultimately reaching fixation. When selection is strong, domestication has the potential to drastically reduce genetic diversity in a crop. To understand the impact of selection during maize domestication, we examined nucleotide polymorphism in teosinte branched1, a gene involved in maize evolution. Here we show that the effects of selection were limited to the gene's regulatory region and cannot be detected in the protein-coding region. Although selection was apparently strong, high rates of recombination and a prolonged domestication period probably limited its effects. Our results help to explain why maize is such a variable crop. They also suggest that maize domestication required hundreds of years, and confirm previous evidence that maize was domesticated from Balsas teosinte of southwestern Mexico.
所有主要农作物的驯化都发生在大约1万年前人类历史上的一个短暂时期。在此期间，古代农民选择了优良形态的种子，并淘汰了不良类型的种子来培育每一代后代。因此，控制感兴趣性状的基因上的有利等位基因频率增加，最终达到固定状态。当选择作用强烈时，驯化有可能大幅降低作物的遗传多样性。为了了解玉米驯化过程中选择的影响，我们研究了teosinte branched1（tb1）基因的核苷酸多态性，该基因参与玉米的进化。我们在此表明，选择的影响仅限于该基因的调控区域，在蛋白质编码区域无法检测到。尽管选择作用显然很强，但高重组率和漫长的驯化期可能限制了其影响。我们的结果有助于解释为什么玉米是一种如此多变的作物。它们还表明玉米驯化需要数百年时间，并证实了之前的证据，即玉米是由墨西哥西南部的巴尔萨斯类蜀黍驯化而来的。
