Indications for Three Independent Domestication Events for the Tea Plant (Camellia sinensis (L.) O. Kuntze) and New Insights into the Origin of Tea Germplasm in China and India Revealed by Nuclear Microsatellites.

M K Meegahakumbura,J B Yang,M M Li,M Möller,B Y Liu,L M Gao,J C Xu,J Liu,K K Thapa,M C Wambulwa,S Ranjitkar,D Z Li

doi:10.1371/journal.pone.0155369

Abstract

BackgroundTea is the world’s most popular non-alcoholic beverage. China and India are known to be the largest tea producing countries and recognized as the centers for the domestication of the tea plant (Camellia sinensis (L.) O. Kuntze). However, molecular studies on the origin, domestication and relationships of the main teas, China type, Assam type and Cambod type are lacking.Methodology/Principal FindingsTwenty-three nuclear microsatellite markers were used to investigate the genetic diversity, relatedness, and domestication history of cultivated tea in both China and India. Based on a total of 392 samples, high levels of genetic diversity were observed for all tea types in both countries. The cultivars clustered into three distinct genetic groups (i.e. China tea, Chinese Assam tea and Indian Assam tea) based on STRUCTURE, PCoA and UPGMA analyses with significant pairwise genetic differentiation, corresponding well with their geographical distribution. A high proportion (30%) of the studied tea samples were shown to possess genetic admixtures of different tea types suggesting a hybrid origin for these samples, including the Cambod type.ConclusionsWe demonstrate that Chinese Assam tea is a distinct genetic lineage from Indian Assam tea, and that China tea sampled from India was likely introduced from China directly. Our results further indicate that China type tea, Chinese Assam type tea and Indian Assam type tea are likely the result of three independent domestication events from three separate regions across China and India. Our findings have important implications for the conservation of genetic stocks, as well as future breeding programs.

Highlights

Plant domestication has shaped human history over the past 13,000 years, accelerating the codependence between human societies on the one hand and plants on the other [1, 2]
Our results further indicate that China type tea, Chinese Assam type tea and Indian Assam type tea are likely the result of three independent domestication events from three separate regions across China and India
The Camellia sinensis cultivars used in the current study are not an endemic or endangered species and authorization for their collection had been granted by the diverse germplasm centers

Summary

Introduction

Plant domestication has shaped human history over the past 13,000 years, accelerating the codependence between human societies on the one hand and plants on the other [1, 2]. Domesticated crops comprised mostly annuals while long-lived perennial and tree crops were domesticated only later [4]. While for long-lived perennials and tree crops, such as tea and coffee, secondary metabolites were the primary sources of variation that were selected for during their domestication [9]. Some food crops, such as common bean and coconut, were domesticated multiple times [10,11], while many others, such as rice, maize, sunflower, potato, olive, and grapes this occurred only once [12,13,14,15,16,17]. Molecular studies on the origin, domestication and relationships of the main teas, China type, Assam type and Cambod type are lacking

Methods

Results

Conclusion