Lorant Anne, Pedersen Sarah, Holst Irene, Hufford Matthew B, Winter Klaus, Piperno Dolores, Ross-Ibarra Jeffrey
Dept. of Plant Sciences, University of California Davis, Davis, CA, United States of America.
Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, United States of America.
PLoS One. 2017 Sep 8;12(9):e0184202. doi: 10.1371/journal.pone.0184202. eCollection 2017.
Domestication research has largely focused on identification of morphological and genetic differences between extant populations of crops and their wild relatives. Little attention has been paid to the potential effects of environment despite substantial known changes in climate from the time of domestication to modern day. In recent research, the exposure of teosinte (i.e., wild maize) to environments similar to the time of domestication, resulted in a plastic induction of domesticated phenotypes in teosinte. These results suggest that early agriculturalists may have selected for genetic mechanisms that cemented domestication phenotypes initially induced by a plastic response of teosinte to environment, a process known as genetic assimilation. To better understand this phenomenon and the potential role of environment in maize domestication, we examined differential gene expression in maize (Zea mays ssp. mays) and teosinte (Zea mays ssp. parviglumis) between past and present conditions. We identified a gene set of over 2000 loci showing a change in expression across environmental conditions in teosinte and invariance in maize. In fact, overall we observed both greater plasticity in gene expression and more substantial changes in co-expressionnal networks in teosinte across environments when compared to maize. While these results suggest genetic assimilation played at least some role in domestication, genes showing expression patterns consistent with assimilation are not significantly enriched for previously identified domestication candidates, indicating assimilation did not have a genome-wide effect.
驯化研究主要集中在识别现存作物种群与其野生近缘种之间的形态和遗传差异。尽管从驯化时期到现代气候发生了显著变化,但环境的潜在影响却很少受到关注。在最近的研究中,大刍草(即野生玉米)暴露于与驯化时期相似的环境中,导致其产生了驯化表型的可塑性诱导。这些结果表明,早期的农业从业者可能选择了一些遗传机制,这些机制巩固了最初由大刍草对环境的可塑性反应诱导产生的驯化表型,这一过程被称为遗传同化。为了更好地理解这一现象以及环境在玉米驯化中的潜在作用,我们研究了玉米(Zea mays ssp. mays)和大刍草(Zea mays ssp. parviglumis)在过去和现在条件下的差异基因表达。我们鉴定出了一组超过2000个位点的基因,这些基因在大刍草的不同环境条件下表现出表达变化,而在玉米中则保持不变。事实上,总体而言,与玉米相比,我们观察到在不同环境下大刍草的基因表达可塑性更强,共表达网络的变化也更显著。虽然这些结果表明遗传同化在驯化过程中至少起到了一定作用,但与同化一致的表达模式的基因在先前鉴定的驯化候选基因中并没有显著富集,这表明同化并没有产生全基因组范围的影响。