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Proc Natl Acad Sci U S A. 2018 May 1;115(18):E4151-E4158. doi: 10.1073/pnas.1719622115. Epub 2018 Apr 20.

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

Author information

1
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 230036 Hefei, China.
2
BGI Genomics, BGI-Shenzhen, 518083 Shenzhen, China.
3
College of Fisheries and Life Science, Shanghai Ocean University, 201306 Shanghai, China.
4
National Center for Gene Research, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200032 Shanghai, China.
5
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 230036 Hefei, China; xcwan@ahau.edu.cn zhaoshancen@genomics.cn maize@uga.edu.
6
Department of Genetics, University of Georgia, Athens, GA 30602.
7
BGI Genomics, BGI-Shenzhen, 518083 Shenzhen, China; xcwan@ahau.edu.cn zhaoshancen@genomics.cn maize@uga.edu.

Abstract

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.

KEYWORDS:

catechins biosynthesis; comparative genomics; genome evolution; tea quality; theanine biosynthesis

PMID:
29678829
PMCID:
PMC5939082
DOI:
10.1073/pnas.1719622115
[Indexed for MEDLINE]
Free PMC Article

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