Integrated transcriptomics and metabolomics analysis of catechins, caffeine and theanine biosynthesis in tea plant (Camellia sinensis) over the course of seasons

An-Dong Gong,Nan-Nan Wu,Shi-Qi Zhao,Shuai-Bin Lian,Lin Cheng,Hong-Yu Yuan,Yong-Jie Zhou,Li-Min Zhang

doi:10.1186/s12870-020-02443-y

Abstract

BackgroundCatechins, caffeine, and theanine as three important metabolites in the tea leaves play essential roles in the formation of specific taste and shows potential health benefits to humans. However, the knowledge on the dynamic changes of these metabolites content over seasons, as well as the candidate regulatory factors, remains largely undetermined.ResultsAn integrated transcriptomic and metabolomic approach was used to analyze the dynamic changes of three mainly metabolites including catechins, caffeine, and theanine, and to explore the potential influencing factors associated with these dynamic changes over the course of seasons. We found that the catechins abundance was higher in Summer than that in Spring and Autumn, and the theanine abundance was significantly higher in Spring than that in Summer and Autumn, whereas caffeine exhibited no significant changes over three seasons. Transcriptomics analysis suggested that genes in photosynthesis pathway were significantly down-regulated which might in linkage to the formation of different phenotypes and metabolites content in the tea leaves of varied seasons. Fifty-six copies of nine genes in catechins biosynthesis, 30 copies of 10 genes in caffeine biosynthesis, and 12 copies of six genes in theanine biosynthesis were detected. The correlative analysis further presented that eight genes can be regulated by transcription factors, and highly correlated with the changes of metabolites abundance in tea-leaves.ConclusionSunshine intensity as a key factor can affect photosynthesis of tea plants, further affect the expression of major Transcription factors (TFs) and structural genes in, and finally resulted in the various amounts of catechins, caffeine and theaine in tea-leaves over three seasons. These findings provide new insights into abundance and influencing factors of metabolites of tea in different seasons, and further our understanding in the formation of flavor, nutrition and medicinal function.

Highlights

Catechins, caffeine, and theanine as three important metabolites in the tea leaves play essential roles in the formation of specific taste and shows potential health benefits to humans
The results showed that the length ratio in autumn was 4, which was higher than that in Summer (1.6) and Spring (0.8) (Fig. 1A)
Of predominantly detected 4840 peaks, 3083 peaks were identified by searching against the Human Metabolome Database (HMDB) and tea metabolome database

Summary

Introduction

Caffeine, and theanine as three important metabolites in the tea leaves play essential roles in the formation of specific taste and shows potential health benefits to humans. Some evidence indicates that these specific flavors are highly related to the abundance of specific secondary metabolites such as polyphenols, theanine, caffeine, vitamins, volatile oils, polysaccharides, and minerals [2, 3, 6]. Among these metabolites, polyphenols, caffeine, and theanine are usually considered as distinctive functional compounds, which play key roles in the formation of special taste, as well as nutritional and medicinal properties [6, 9,10,11]

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Discussion

Conclusion