PDF(Pubmed)
Abstract：
Barley is one of the founder crops of the Neolithic transition in West Asia. While recent advances in genomics have provided a rather detailed picture of barley domestication, there are contradictory views on how the domestication process affected genetic diversity. We set out to revisit this question by integrating public DNA sequencing data from ancient barley and wide collections of extant wild and domesticated accessions. Using two previously overlooked approaches - analyses of chloroplast genomes and genome-wide proportions of private variants - we found that the barley cultivated six millennia ago was genetically unique and more diverse when compared to extant landraces and cultivars. Moreover, the chloroplast genomes revealed a link between the ancient barley, an obscure wild genotype from north-eastern Libya, and a distinct population of barley cultivated in Ethiopia/Eritrea. Based on these results, we hypothesize past existence of a wider North African population that included both wild and cultivated types and suffered from genetic erosion in the past six millennia, likely due to a rapid desertification that ended the Holocene African humid period. Besides providing clues about the origin of Ethiopian landraces, the hypothesis explains the post-domestication loss of diversity observed in barley. Analyses of additional samples will be necessary to resolve the history of African barley and its contribution to the extant cultivated gene pool.
摘要：
大麦是西亚新石器时代过渡的主要农作物之一。虽然基因组学的最新进展提供了大麦驯化的相当详细的图片，关于驯化过程如何影响遗传多样性的观点存在矛盾。我们着手通过整合来自古代大麦的公共DNA测序数据以及现存的野生和驯化种质的广泛集合来重新审视这个问题。使用两种以前被忽视的方法-分析叶绿体基因组和私有变异的全基因组比例-我们发现六千年前种植的大麦在遗传上是独特的，与现存的地方品种和品种相比更加多样化。此外，叶绿体基因组揭示了古代大麦之间的联系，来自利比亚东北部的一种晦涩的野生基因型，以及在埃塞俄比亚/厄立特里亚种植的不同大麦种群。基于这些结果,我们假设过去存在更广泛的北非人口，包括野生和栽培类型，并在过去六千年中遭受遗传侵蚀，可能是由于结束了全新世非洲潮湿时期的快速荒漠化。除了提供有关埃塞俄比亚地方品种起源的线索外，该假设解释了在大麦中观察到的驯化后多样性损失。需要对其他样品进行分析，以解决非洲大麦的历史及其对现有栽培基因库的贡献。
