Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
BMC Plant Biol. 2014 Jan 9;14:14. doi: 10.1186/1471-2229-14-14.
Tea is one of the most popular beverages in the world. Many species in the Thea section of the Camellia genus can be processed for drinking and have been domesticated. However, few investigations have focused on the genetic consequence of domestication and geographic origin of landraces on tea plants using credible wild and planted populations of a single species. Here, C. taliensis provides us with a unique opportunity to explore these issues.
Fourteen nuclear microsatellite loci were employed to determine the genetic diversity and domestication origin of C. taliensis, which were represented by 587 individuals from 25 wild, planted and recently domesticated populations. C. taliensis showed a moderate high level of overall genetic diversity. The greater reduction of genetic diversity and stronger genetic drift were detected in the wild group than in the recently domesticated group, indicating the loss of genetic diversity of wild populations due to overexploitation and habitat fragmentation. Instead of the endangered wild trees, recently domesticated individuals were used to compare with the planted trees for detecting the genetic consequence of domestication. A little and non-significant reduction in genetic diversity was found during domestication. The long life cycle, selection for leaf traits and gene flow between populations will delay the emergence of bottleneck in planted trees. Both phylogenetic and assignment analyses suggested that planted trees may have been domesticated from the adjacent central forest of western Yunnan and dispersed artificially to distant places.
This study contributes to the knowledge about levels and distribution of genetic diversity of C. taliensis and provides new insights into genetic consequence of domestication and geographic origin of planted trees of this species. As an endemic tea source plant, wild, planted and recently domesticated C. taliensis trees should all be protected for their unique genetic characteristics, which are valuable for tea breeding.
茶是世界上最受欢迎的饮料之一。许多山茶属茶组植物的物种都可以加工饮用，并已被驯化。然而，很少有研究关注使用单一物种的可信野生和种植群体对茶树的驯化和地理起源的遗传后果。在这里，厚叶茶为我们提供了一个独特的机会来探索这些问题。
使用 14 个核微卫星标记来确定厚叶茶的遗传多样性和驯化起源，其中包括来自 25 个野生、种植和最近驯化的种群的 587 个个体。厚叶茶表现出中等高水平的总体遗传多样性。在野生群体中检测到遗传多样性的更大减少和更强的遗传漂变，而在最近驯化的群体中则没有，这表明由于过度开发和栖息地破碎化，野生种群的遗传多样性丧失。野生种群濒危，最近驯化的个体被用于与种植的个体比较，以检测驯化的遗传后果。在驯化过程中发现遗传多样性略有且不显著减少。长的生命周期、对叶性状的选择以及种群之间的基因流将延缓种植树木中瓶颈的出现。系统发育和分配分析都表明，种植的树木可能是从云南西部的中心森林驯化而来，并人工传播到遥远的地方。
本研究有助于了解厚叶茶的遗传多样性水平和分布情况，并为该物种的驯化遗传后果和种植树木的地理起源提供了新的见解。作为一种特有茶源植物，野生、种植和最近驯化的厚叶茶树都应该因其独特的遗传特征而受到保护，这些特征对茶的培育具有重要价值。
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