September 22, 2019  |  

Draft genome sequence of Camellia sinensis var. sinensis provides insights into the evolution of the tea genome and tea quality.

Authors: Wei, Chaoling and Yang, Hua and Wang, Songbo and Zhao, Jian and Liu, Chun and Gao, Liping and Xia, Enhua and Lu, Ying and Tai, Yuling and She, Guangbiao and Sun, Jun and Cao, Haisheng and Tong, Wei and Gao, Qiang and Li, Yeyun and Deng, Weiwei and Jiang, Xiaolan and Wang, Wenzhao and Chen, Qi and Zhang, Shihua and Li, Haijing and Wu, Junlan and Wang, Ping and Li, Penghui and Shi, Chengying and Zheng, Fengya and Jian, Jianbo and Huang, Bei and Shan, Dai and Shi, Mingming and Fang, Congbing and Yue, Yi and Li, Fangdong and Li, Daxiang and Wei, Shu and Han, Bin and Jiang, Changjun and Yin, Ye and Xia, Tao and Zhang, Zhengzhu and Bennetzen, Jeffrey L and Zhao, Shancen and Wan, Xiaochun

Tea, one of the world's most important beverage crops, provides numerous secondary metabolites that account for its rich taste and health benefits. Here we present a high-quality sequence of the genome of tea, Camellia sinensis var. sinensis (CSS), using both Illumina and PacBio sequencing technologies. At least 64% of the 3.1-Gb genome assembly consists of repetitive sequences, and the rest yields 33,932 high-confidence predictions of encoded proteins. Divergence between two major lineages, CSS and Camellia sinensis var. assamica (CSA), is calculated to ~0.38 to 1.54 million years ago (Mya). Analysis of genic collinearity reveals that the tea genome is the product of two rounds of whole-genome duplications (WGDs) that occurred ~30 to 40 and ~90 to 100 Mya. We provide evidence that these WGD events, and subsequent paralogous duplications, had major impacts on the copy numbers of secondary metabolite genes, particularly genes critical to producing three key quality compounds: catechins, theanine, and caffeine. Analyses of transcriptome and phytochemistry data show that amplification and transcriptional divergence of genes encoding a large acyltransferase family and leucoanthocyanidin reductases are associated with the characteristic young leaf accumulation of monomeric galloylated catechins in tea, while functional divergence of a single member of the glutamine synthetase gene family yielded theanine synthetase. This genome sequence will facilitate understanding of tea genome evolution and tea metabolite pathways, and will promote germplasm utilization for breeding improved tea varieties. Copyright © 2018 the Author(s). Published by PNAS.

Journal: Proceedings of the National Academy of Sciences of the United States of America
DOI: 10.1073/pnas.1719622115
Year: 2018

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