Tea, coffee, and cocoa are the three most popular nonalcoholic beverages in the world and have extremely high economic and cultural value. The genomes of four tea plant varieties have recently been sequenced, but there is some debate regarding the characterization of a whole-genome duplication (WGD) event in tea plants. Whether the WGD in the tea plant is shared with other plants in order Ericales and how it contributed to tea plant evolution remained unanswered. Here we re-analyzed the tea plant genome and provided evidence that tea experienced only WGD event after the core-eudicot whole-genome triplication (WGT) event. This WGD was shared by the Polemonioids-Primuloids-Core Ericales (PPC) sections, encompassing at least 17 families in the order Ericales. In addition, our study identified eight pairs of duplicated genes in the catechins biosynthesis pathway, four pairs of duplicated genes in the theanine biosynthesis pathway, and one pair of genes in the caffeine biosynthesis pathway, which were expanded and retained following this WGD. Nearly all these gene pairs were expressed in tea plants, implying the contribution of the WGD. This study shows that in addition to the role of the recent tandem gene duplication in the accumulation of tea flavor-related genes, the WGD may have been another main factor driving the evolution of tea flavor.

中文翻译：

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一个古老的全基因组复制事件及其对茶树（Camellia sinensis）风味化合物的贡献


茶、咖啡、可可是世界上最受欢迎的三种非酒精饮料，具有极高的经济和文化价值。最近对四种茶树品种的基因组进行了测序，但关于茶树全基因组复制（WGD）事件的表征存在一些争议。茶树中的 WGD 是否与杜鹃目中的其他植物共享以及它如何促进茶树的进化仍然没有答案。在这里，我们重新分析了茶树基因组，并提供了证据表明茶在核心真双子叶植物全基因组三倍体（WGT）事件之后仅经历了WGD事件。该 WGD 被 Polemonioids-Primuloids-Core Ericales (PPC) 部分共享，涵盖杜鹃目中至少 17 个科。此外，我们的研究还确定了儿茶素生物合成途径中的八对重复基因、茶氨酸生物合成途径中的四对重复基因以及咖啡因生物合成途径中的一对基因，这些基因在本次全基因组测序后得到了扩展和保留。几乎所有这些基因对都在茶树中表达，这表明 WGD 的贡献。本研究表明，除了近期串联基因重复在茶风味相关基因积累中的作用外，WGD可能是驱动茶风味进化的另一个主要因素。