Effects of Long-Term Non-Pruning on Main Quality Constituents in 'Dancong' Tea (Camellia sinensis) Leaves Based on Proteomics and Metabolomics Analysis.

Yiyong Chen,Lanting Zeng,Jinchi Tang,Jianlong Li,Jiayu Liu,Hao Tang,Bo Zhou,Yingying Cui,Qin Chen

doi:10.3390/foods10112649

Abstract

‘Dancong’ tea is a famous traditional Oolong tea. In order to keep the original taste of “ancient tea trees”, most of the ‘Dancong’ tea plants are planted in a single plant pattern without pruning. The objective of this study was to explore the effects of long-term non-pruning on main quality constituents in ‘Dancong’ tea. The results showed that the contents of free amino acids, chlorophylls, and floral-honey aromatic substances in tea leaves of unpruned tea plants were higher than those in every year pruned tea plants, while the catechin content in leaves of pruned tea plants was higher than that in leaves of unpruned tea plants. Quantitative proteomics analysis showed that most enzymes involved in biosynthesis of catechins were downregulated in leaves of unpruned tea plants. Five proteins involved in chlorophyll metabolism and 12 proteins related to photosynthesis were upregulated, and the results suggested that higher chlorophyll content and more efficient photosynthetic energy conversion may be important for the higher accumulation of special quality components in leaves of unpruned tea plants. The findings of this study will advance our understanding of the mechanism of formation of different metabolites in leaves of unpruned and pruned tea plants.

Highlights

Tea leaves, in principle a bud with two adjacent leaves, are processed into different types of tea products
Sensory characteristics of tea prepared with leaves from long-term unpruned a pruned tea plants was evaluated in terms of taste and flavor
The scores of tea infusio prepared with leaves from long-term unpruned tea plants were much higher than tho obtained by infusions prepared with leaves of pruned plants; all prof sional tea tasters consistently evaluated unpruned tea leaves as better in te6romf 16s of aro and taste (Figure 1B)

Summary

Introduction

In principle a bud with two adjacent leaves, are processed into different types of tea products. It has been reported that ester catechin content in tea leaves is much higher than non-ester catechins, while epigallocatechin gallate (EGCG) is the ester catechin present in the highest concentration in green tea [7,8,9]. Caffeine is another bitter tasting component in tea infusions, and the biosynthesis pathway of caffeine is part of purine metabolism [10,11]. Caffeine synthase is the crucial enzyme in the pathway, catalyzing the conversion of theobromine to caffeine [12] Amino acids comprise another tea-quality determination component that contribute to the umami taste of tea. Different metabolite compositions may be formed under the influence of various factors, including, soil conditions, climate change, and cultivation practices

Objectives

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Results

Conclusion