Many crops are polyploid or have a polyploid ancestry. Recent phylogenetic analyses have found that polyploidy often preceded the domestication of crop plants. One explanation for this observation is that increased genetic diversity following polyploidy may have been important during the strong artificial selection that occurs during domestication. To test the connection between domestication and polyploidy, we identified and examined candidate genes associated with the domestication of the diverse crop varieties of Brassica rapa. Like all "diploid" flowering plants, B. rapa has a diploidized paleopolyploid genome and experienced many rounds of whole genome duplication (WGD). We analyzed transcriptome data of more than hundred cultivated B. rapa accessions. Using a combination of approaches, we identified more than 3,000 candidate genes associated with the domestication of four major B. rapa crop varieties. Consistent with our expectation, we found that the candidate genes were significantly enriched with genes derived from the Brassiceae mesohexaploidy. We also observed that paleologs contained significantly more genetic diversity than non-paleologs, suggesting that elevated genetic variation may explain why paleologs are enriched among domestication candidate genes. Our analyses demonstrate the key role of polyploidy in the domestication of B. rapa and provide support for its importance in the success of modern agriculture.

中文翻译：

---

来自古代多倍体的基因具有较高的遗传多样性，并且与芸苔属的驯化有关

许多农作物是多倍体或具有多倍体祖先。最近的系统发育分析发现，多倍体化通常发生在农作物的驯化之前。这种观察的一种解释是，多倍体后增加的遗传多样性在驯化过程中发生的强烈人工选择过程中可能很重要。为了测试驯化和多倍体之间的联系，我们鉴定并检查了与芸苔不同作物品种的驯化相关的候选基因。像所有“二倍体”开花植物一样，B。rapa具有二倍体化的古多倍体基因组，并经历了许多轮的全基因组复制（WGD）。我们分析了超过100个栽培的B. rapa的转录组数据加入。通过使用多种方法，我们确定了与3,000个主要B. rapa作物品种的驯化相关的3,000多个候选基因。与我们的预期一致，我们发现候选基因中富含来源于芸苔属中六倍体的基因。我们还观察到，古生物学比非古生物学包含的遗传多样性明显更多，这表明升高的遗传变异性可以解释为什么古生物学在驯化候选基因中富集的原因。我们的分析表明多倍体的关键作用在驯化芜菁和其在现代农业的成功提供重要支持。