Origin of the Camellia sinensis plant

Have been intrigued by the question of where the tea plant originated, so have been exploring the available papers on the subject. There are two basic science-based (as against expertise-based) approaches to this question. One is to look at the biochemistry of the tea leaves, and the other is to look at tea plant DNA. 

With respect to the the first approach, found a fascinating study that compared polyphenol content among 89 wild, hybrid, and cultivated tea trees.* It turns out that you can derive a “family tree” showing the relationships among tea tree lines using the relative amounts of (-)-epigallocatechin 3-O-gallate (EGCG), (􏰀-)-epigallocatechin (EGC), (-􏰀)-epicatechin 3-O-gallate (ECG), and (-􏰀)-epicatechin (EC).  The older lines of plants have less of the first two polyphenols and more of the the third and fourth. This analysis led to the conclusion that “the Puer City and Xishuangbanna [in Yunnan] districts are among the original sites of tea tree species.”

With respect to the second approach, there have been a number of DNA studies. A micro satellite study of 392 tea samples pointed to the strong possibility that the tea tree was domesticated three different times, yielding the Camellia sinensis var. sinensis on the one hand, and Camellia sinensis var. assamica from China and Camellia sinensis var. assamica from India on the other.** These differences were evidenced by three different micro satellite patterns. A microsatellite is a stretch of DNA made up of a repeated pattern of (usually) 2 to 5 bases. An example would be TATATATA where T is the base thymine and A is the base adenine. Microsatellites are common throughout genomes of living beings, and are subject to a high mutation rate. That is why they are used for tracing lineages. 

If you look at the diagram below, from this study, which shows how all the tested plants are related, you will notice a first split between the Camellia sinensis var. sinensis, and the two var. assamica. According to those authors, the Chinese var. assamica originally developed in Yunnan as well. 

This diagram, from **, shows the three different genetic patterns of Camellia sinensis. The length of the lines represents the genetic distance from the original plant. The pink lines among the green represent Camellia sinensis var, sinensis growing in India. Note that the Indian var. assamica is closer to the putative original plant, differentiated in Yunnan into the Indian and Chinese versions, and then somehow migrated to India, where it became an isolate. 

A further look at the genetic diversity among wild trees point to Yunnan as the origin of the Camellia sinensis var. sinensis: this province shows the greatest genetic diversity among the wild trees—the longer a species  is present in an area the greater the chance to accumulate mutations, and the greater the differences among individuals of the present day populations.***

These data all suggest that Yunnan was the center of the evolution of Camellia sinensis, and that its variants in all their glory spread from there. 

 *Jia-Hua Li, Atsushi Nesumi, Keiichi Shimizu, Yusuke Sakata, Ming-Zhi Liang, Qing-Yuan He, Hong-Jie Zhou, Fumio Hashimoto, Chemosystematics of tea trees based on tea leaf polyphenols as phenetic markers, Phytochemistry, Volume 71, Issues 11–12, August 2010, Pages 1342-1349, ISSN 0031-9422, http://dx.doi.org/10.1016/j.phytochem.2010.05.002.

** M. K. Meegahakumbura, M. C. Wambulwa, K. K. Thapa, M. M. Li, M. Möller, J. C. Xu, J. B. Yang, B. Y. Liu, S. Ranjitkar, J. Liu, D. Z. Li, L. M. Gao. 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. PLOSone. Published: May 24, 2016. http://dx.doi.org/10.1371/journal.pone.0155369.

*** Liu, B., Sun, X., Wang, Y., Li, Y., Cheng, H., Xiong, C., & Wang, P. (2012). Genetic diversity and molecular discrimination of wild tea plants from Yunnan province based on inter-simple sequence repeats (ISSR) markers. African Journal of Biotechnology, 11(53), 11566-11574.

Yao, M., Ma, C., Qiao, T. et al. Diversity distribution and population structure of tea germplasms in China revealed by EST-SSR markers. Tree Genetics & Genomes (2012) 8: 205. doi:10.1007/s11295-011-0433-z.