# Revealing novel insights into the improvement of greenhouse tea quality through exogenous substance interventions using targeted and untargeted metabolomics and microbial community analyses

## TL;DR

This study explores how using seaweed fertilizer improves greenhouse tea quality by affecting tea metabolites and microbes, making it taste better than using gibberellin.

## Contribution

The study reveals how seaweed fertilizer (CF) improves tea quality by down-regulating key flavor-related metabolites and enriching microbial metabolism.

## Key findings

- CF tea was mellow and less astringent with lower levels of Catechin, −(−)Epicatechin, and Epigallocatechin.
- Phenylpropanoid biosynthesis was a key pathway linked to flavor differences between CF and CH treatments.
- Microbes like Variovorax and Pseudomonas strongly correlated with phenylpropane pathway metabolites in CF tea.

## Abstract

Tea quality in greenhouse was certain gap with open air. Metabolites and foliar microorganisms were investigated under seaweed fertiliser (CF) and gibberellin (CH) treatments using sensory evaluation, HPLC, untargeted metabolomics, 16S rDNA, and Internal Transcribed Spacer. CF tea was mellow, less astringent, and of better quality compared to CH. Catechin, −(−)Epicatechin, and Epigallocatechin were notably lower in CF. Differentially accumulated metabolites (DAMs) were notably enriched in Flavonoid and Phenylpropanoid biosynthesis, both involved in Catechin synthesis. DAMs in these pathways appeared down-regulated in CF. The CF improved quality by down-regulating metabolites in Phenylpropanoid biosynthesis in conjunction with microbial community metabolism enriched in amino acid and secondary metabolite biosynthesis. Metabolite- microbial correlation analysis indicated that the highest correlation with phenylpropane pathway metabolites was in bacteria Variovorax and Pseudomonas, and in fungi Filobasidium. The study provides theoretical basis for regulating flavour quality of greenhouse tea.

Unlabelled Image

•CCF exhibited umami, mellow and fragrant and sweet flavour, while CH showed slightly astringent, mellow and thick•Catechin, −(−)Epicatechin, and Epigallocatechin flavour metabolites were notably lower in CF•Phenylpropanoid biosynthesis was identified as a key pathway driving the flavour differences•Strong correlations were observed between signature microorganisms and flavour substances•A greenhouse tea quality improvement measure was proposed

CCF exhibited umami, mellow and fragrant and sweet flavour, while CH showed slightly astringent, mellow and thick

Catechin, −(−)Epicatechin, and Epigallocatechin flavour metabolites were notably lower in CF

Phenylpropanoid biosynthesis was identified as a key pathway driving the flavour differences

Strong correlations were observed between signature microorganisms and flavour substances

A greenhouse tea quality improvement measure was proposed