Relatively, little is known about the genetic variation of woody trees during domestication. Castor bean (Ricinus communis L. Euphorbiaceae) is a commercially important nonedible annual oilseed crop and differs from its wild progenitors that have a perennial woody habit. Although castor bean is one of the oldest cultivated crops, its domestication origin, genomic variation, and potential targets of selection underlying domestication traits remain unknown. Here, we performed a phylogenetic analysis, which suggests that the wild accessions were distinctively separated from the cultivated accessions. Genome sequencing of three accessions (one each wild, landrace, and cultivar) showed a large number of genetic variants between wild and cultivated castor bean (ZB306 or Hale), and relatively few variants between cultivar ZB306 and Hale. Comparative genome analysis revealed many candidate genes of selection and key pathways potentially involved in the transition from a perennial woody tree to annual crop. Interestingly, among 16 oil‐related genes only three showed evidence of selection and the remainder showed low genetic variation at the population level, suggesting strong purifying selection in both the wild and domesticated gene pools. These results extend our understanding of the origin, genomic variation, and domestication, and provide a valuable resource for future gene–trait associations and castor bean breeding.

中文翻译：

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基因组分析揭示了蓖麻子从多年生木本树到一年生半木本作物驯化过程中丰富的遗传变异和潜在的选择目标。

相对而言，人们对木本树木在驯化过程中的遗传变异知之甚少。蓖麻子（Ricinus commis L. Euphorbiaceae）是一种商业上重要的非食用一年生油籽作物，与其具有多年生木本习性的野生祖先不同。尽管蓖麻子是最古老的栽培作物之一，但其驯化起源、基因组变异和驯化性状潜在选择目标仍然未知。在这里，我们进行了系统发育分析，表明野生材料与栽培材料明显分开。三个种质（野生、地方品种和栽培品种各一个）的基因组测序显示野生和栽培蓖麻子（ZB306 或 Hale）之间存在大量遗传变异，而栽培品种 ZB306 和 Hale 之间的变异相对较少。比较基因组分析揭示了许多可能参与从多年生木本树木向一年生作物转变的选择候选基因和关键途径。有趣的是，在 16 个与石油相关的基因中，只有 3 个显示出选择的证据，其余的在群体水平上显示出较低的遗传变异，这表明野生和驯化基因库中都存在强烈的纯化选择。这些结果扩展了我们对起源、基因组变异和驯化的理解，并为未来的基因性状关联和蓖麻子育种提供了宝贵的资源。