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Genome assembly of wild tea tree DASZ reveals pedigree and selection history of tea varieties in China
2020-07-31

Tea, cocoa and coffee are known as the three major beverages in the world. Specially, the Chinese culture of tea has flourished for thousands of years. As an indispensable part of modern tea industry, ancient tea trees not only possess unique economic and cultural values, but also are considered as valuable resources for basic research, such as evolution and differentiation, and germplasm enhancement of tea tree. The authors assemble the first high-quality chromosome-scale reference genome of ancient tea tree. Further RNA sequencing of 217 diverse tea accessions clarifies the pedigree of tea cultivars and reveals key contributors in the breeding of Chinese tea. Candidate genes associated with catechin biosynthesis are also identified. The inconspicuous differentiation between ancient trees and cultivars at both genetic and metabolic levels implies that tea may not have undergone long-term artificial directional selection in terms of flavor-related metabolites.


A wild tea tree named DASZ, located in Baoshan City, Yunnan Province, is sampled for whole genome sequencing and de novo assembly. Further, 217 tea accessions (including both cultivated germplasms and wild species) collected from 16 provinces of China, are used for phenotyping and RNA sequencing. Parentage analysis uncovers a number of key contributors in the breeding of Chinese tea, including two elite tea cultivars “Fudingdabai” and “Tieguanyin”. Both phylogenetic and population structure analysis indicate that frequent genetic exchanges occurred among tea genetic resources. These 217 accessions are divided into five subpopulations based on population structure analysis. Rapid LD decay within all the five subpopulations suggests abundant genetic diversity in tea germplasms.



Catechins are the most representative metabolites in tea, which confer tea a unique flavor, and are beneficial for human health. The authors quantify the contents of eight catechins and gallic acid in the above mentioned tea accessions, and find several compounds are affected by leaf size or subpopulation. However, no significant difference is detected between arbor and shrub types. EGCG is significantly higher in ancient trees in Tukey’s test but this significance is not detected in mixed linear regression. A total of 176 loci associated with the content of catechins and gallic acid are identified using genome-wide association mapping. Candidate genes containing enzymes, transcription factors and transporters that may be involved in catechin biosynthesis are revealed. Specifically, diverse allelic function of CsANR, CsF3’5’H and CsMYB5 is verified by transient overexpression and enzymatic assays. The inconspicuous differentiation between ancient trees and cultivars at both genetic and metabolic levels implies that tea may not have undergone long-term artificial directional selection in terms of flavor-related metabolites. These genomic resources provide evolutionary insight into tea plants and lay the foundation for better understanding the biosynthesis of beneficial natural compounds.

Graduate students Weiyi Zhang, Haiji Qiu, Yafei Guo and Haoliang Wan from the Key Laboratory of Horticultural Biology of the Ministry of Education, and Dr. Youjun Zhang from the Bulgarian Systems Biology and Biotechnology Research Center are the co-first authors. Professor Weiwei Wen is the corresponding author. Professor Dejiang Ni, Dr. Fei Guo, Dr. Hua Zhao, Dr. Pu Wang, and Dr. Mingle Wang from the Department of Tea Science participated in the tea resource collection. Dr. Federico Scossa from Italian Agricultural Research and Economics Committee, Professor Bj?rn Usadel Forschungszentrum Jülich/HHU Düsseldorf and Professor Alisdair Fernie from Max Planck Institute of Molecular Plant Physiology also took part in this research. The research was supported by the National Key R&D Program of China and the Huazhong Agricultural University Scientific & Technological Self-Innovation Foundation.

      Correspondent:Weiwei Wen


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