Wang Ya, Chen Fei, Ma Yuanchun, Zhang Taikui, Sun Pengchuan, Lan Meifang, Li Fang, Fang Wanping
College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China.
College of Life Sciences, Fudan University, Shanghai, 200433, China.
Hortic Res. 2021 Aug 1;8(1):176. doi: 10.1038/s41438-021-00613-z.
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.
茶、咖啡和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。最近已对四个茶树品种的基因组进行了测序，但关于茶树中全基因组复制（WGD）事件的特征存在一些争议。茶树中的WGD是否与杜鹃花目其他植物共有，以及它如何促进茶树进化仍未得到解答。在这里，我们重新分析了茶树基因组，并提供证据表明茶树在核心真双子叶植物全基因组三倍化（WGT）事件之后仅经历了一次WGD事件。这一WGD由花荵科-报春花科-核心杜鹃花目（PPC）分支共享，涵盖杜鹃花目中至少17个科。此外，我们的研究在儿茶素生物合成途径中鉴定出八对重复基因，在茶氨酸生物合成途径中鉴定出四对重复基因，在咖啡因生物合成途径中鉴定出一对基因，这些基因在此次WGD之后发生了扩增并保留了下来。几乎所有这些基因对都在茶树中表达，这意味着WGD的作用。这项研究表明，除了近期串联基因复制在茶风味相关基因积累中的作用外，WGD可能是推动茶风味进化的另一个主要因素。
