Department of Biology, Washington University, Campus Box 1137, St. Louis, MO, 63130, USA.
Minnesota Poultry Testing Laboratory, P.O. Box 126, 622 Bus. Hwy 71 NE, Wilmar, MN, 56201, USA.
Am J Bot. 2021 Apr;108(4):616-627. doi: 10.1002/ajb2.1636. Epub 2021 Apr 10.
During plant domestication, traits can be subject to a variety of types of selection, ranging from strong directional selection for traits such as seed or fruit size to diversifying selection for traits like color or flavor. These types of selection interact with other evolutionary processes including genetic bottlenecks and interspecific gene flow to generate different levels of genetic diversity across the genome and at target genes in domesticated lineages, but little is known about the impacts of these processes in perennial fruit crops.
We used sequence capture by hybridization to examine patterns of diversity at a suite of candidate domestication and anonymous background genes in domesticated apple (Malus ×domestica) in comparison to its wild relatives Malus sieversii and Malus orientalis.
We found no change in average diversity at these candidate domestication genes across the three species. However, a subset of the genes did exhibit patterns of very high or very low diversity in M. ×domestica compared to its progenitor, M. sieversii. Of the genes with characterized function, the low-diversity genes mainly contributed to fruit quality traits like color and flavor, predicted to be under conscious, directional selection relatively late in the domestication process, while the high-diversity genes included a variety of functions.
Overall, these results are consistent with predictions based on the likely timing and nature of selection during domestication and open new avenues for understanding genes with high diversity in a perennial crop compared to its wild relatives.
在植物驯化过程中，性状可能会受到多种类型的选择，从针对种子或果实大小等性状的强烈定向选择到针对颜色或风味等性状的多样化选择不等。这些类型的选择与其他进化过程相互作用，包括遗传瓶颈和种间基因流，从而在整个基因组和驯化谱系中的目标基因中产生不同水平的遗传多样性，但对于这些过程在多年生水果作物中的影响知之甚少。
我们使用杂交序列捕获技术，研究了一系列候选驯化基因和匿名背景基因在驯化苹果（Malus × domestica）与野生近缘种 M. sieversii 和 M. orientalis 中的多样性模式。
我们没有发现这些候选驯化基因在三个物种中的平均多样性发生变化。然而，与亲本 M. sieversii 相比，这些基因中的一部分表现出非常高或非常低的多样性模式。在具有特征功能的基因中，低多样性基因主要与果实品质性状有关，如颜色和风味，这些性状被预测是在驯化过程的后期受到有意识的、定向选择的影响，而高多样性基因则包括各种功能。
总体而言，这些结果与基于驯化过程中选择的可能时间和性质的预测一致，并为理解多年生作物中与野生近缘种相比具有高度多样性的基因开辟了新的途径。
