Abstract
Metabolites are major contributors to the quality of tea that are regulated by various abiotic stresses. Light intensity and phosphorus (P) supply affect the metabolism of tea plants. However, how these two factors interact and mediate the metabolite levels in tea plants are not fully understood. The present study investigated the consequences of different light intensity and P regimes on the metabolism of carbohydrates, amino acids, and flavonoids in the Fengqing tea cultivar. The leaves and young shoots were subjected to untargeted metabolomics analysis by two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC–TOF/MS), ultra-performance liquid chromatography-quadrupole-TOF/MS (UPLC–Q–TOF/MS), and targeted analysis by high-performance liquid chromatography (HPLC) along with quantification of gene expression by quantitative real time-PCR (qRT–PCR). The results from young shoots showed that amino acids, pentose phosphate, and flavonol glycosides pathways were enhanced in response to decreasing light intensities and P deficiency. The expression of the genes hexokinase 1, ribose 5-phosphate isomerase A (RPIA), glutamate synthetase 1 (GS1), prolyl 4-hydroxylase (P4H), and arginase was induced by P limitation, thereafter affecting carbohydrates and amino acids metabolism, where shading modulated the responses of transcripts and corresponding metabolites caused by P deficiency. P deprivation repressed the expression of Pi transport, stress, sensing, and signaling (SPX2) and induced bidirectional sugar transporter (SWEET3) and amino acid permeases (AAP) which ultimately caused an increase in the amino acids: glutamate (Glu), proline (Pro), and arginine (Arg) under shading but decreased catechins [epicatechingallate (ECG) and Gallic acid, GA] content in young shoots.
Highlights
Tea metabolites are key components of taste, flavor, and health benefits
The dry weights of all tissues were significantly decreased under P deficiency in medium light (ML) (50% of full light) conditions (Table 1; Supplementary Figure 2)
The shading treatment increased the total biomass of young shoots, leaves, and roots in ML compared to full light (FL) and low light (LL) with P sufficient conditions whereas the total biomass in LL was decreased compared to FL and ML under Pdeficient conditions
Summary
Tea metabolites are key components of taste, flavor, and health benefits. These metabolites are largely regulated by various environmental factors such as light intensity and phosphate (Pi) availability during plant growth and development. In agricultural practice, shading is frequently applied in the management of tea gardens as it can improve the quality of green tea by decreasing the ratio of polyphenols to amino acids and reducing the levels of galloylated catechins in tea shoots (Zhang et al, 2021). The understanding of how P and light affects the metabolites of tea plants, and their potential interaction will contribute to balancing the yield and quality of tea in tea production
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