Jul 2026· Journal of Agricultural and Food Chemistry· Vol 74, pp. 22758-22770· 0 citations· 46 references
Medicine
TL;DR
Transient overexpression and virus-induced gene silencing in tea plants demonstrated that CsbHLH18 positively regulates theanine biosynthesis by activating CsTSI transcription, elucidate a previously uncharacterized molecular mechanism underlying theanine biosynthesis and provide theoretical insights into molecular breeding and cultivation of high-quality tea varieties.
Abstract
Theanine, a unique nonproteinogenic natural amino acid predominantly accumulated in tea plants (Camellia sinensis), is a key determinant of tea flavor and quality, with broad applications. Theanine synthase (CsTSI) is a key enzyme in theanine biosynthesis. However, the transcriptional regulation of CsTSI, particularly by bHLH transcription factors, remains largely unexplored. Through coexpression network screening and tissue-specific qPCR, we identified CsbHLH18 as a putative regulator of CsTSI. Yeast one-hybrid (Y1H) and dual-luciferase reporter assays confirmed the direct interaction between CsbHLH18 and the CsTSI promoter. An electrophoretic mobility shift assay (EMSA) further identified the specific binding motif of CsbHLH18 as "CAAATG". Transient overexpression and virus-induced gene silencing (VIGS) in tea plants demonstrated that CsbHLH18 positively regulates theanine biosynthesis by activating CsTSI transcription. These findings elucidate a previously uncharacterized molecular mechanism underlying theanine biosynthesis and provide theoretical insights into molecular breeding and cultivation of high-quality tea varieties.
This study assembled a high-quality chromosome-level B. semperflorens genome and elucidates a key molecular module in low temperature-induced anthocyanin biosynthesis regulatory pathway, laying a theoretical and data foundation for future studies on leaf color improvement and stress resistance breeding in Begonia.
A MeJA-responsive DoMYB41-DoMYC2 cascade that iteratively activates DoTIP1–1 expression and promotes the biosynthesis of GMs, thereby enhancing salinity tolerance in D. officinale is uncovered and provides genetic targets for salinity tolerance in breeding programs for this horticultural orchid.
Geraniol is a key floral aroma compound in tea and preferentially accumulates in young leaves for premium tea production, yet the molecular basis underlying its leaf position–dependent distribution remains unclear. Here, metabolomic profiling across successive leaf positions uncovered geranyl monophosphate (GP) abundance significantly positively correlated with geraniol accumulation. Functional analyses combining in vitro enzyme assays and metabolic profiling of transgenic tea plants identified CsNudix1-cyto as a key hydrolase responsible for GP accumulation, and geraniol production. Integrative transcriptome analyses and molecular validation revealed that CsMYB88 and CsMYB200 directly activate both CsNudix1-cyto and CsTPS1, thereby promoting geraniol biosynthesis in young leaves. Intriguingly, CsMYB200 activates the CsMYB88 promoter, forming a MYB cascade amplifying downstream geraniol biosynthetic genes. Furthermore, bisulfite sequencing demonstrated developmental stage–specific hypermethylation of a CpG island in the CsMYB200 promoter in mature leaves, which is associated with coordinated repression of CsMYB200, CsMYB88, CsNudix1-cyto, and CsTPS1, and decline in geraniol accumulation. Together, these findings establish a Nudix/TPS-mediated biosynthetic pathway controlled by a MYB transcriptional cascade and epigenetic regulation, providing a mechanistic framework for leaf position–dependent aroma formation in tea plants.
Ge-Fei Tu, Long Cheng, Li Huang et al.· Horticulture Research· 0 citations
A preliminary elucidation of the molecular mechanism by which upstream transcriptional regulation of the AmFLS gene controls flavonol biosynthesis in JHK is provided, offering a theoretical basis for further elucidating the regulatory network of flavonol metabolism in JHK and accelerating its industrial development.
Da-Yun Wang, Hongtao Chu, Zhong Liu et al.· Plants· 0 citations
The bHLH family is considered as the second largest class of transcription factors in plants, playing important roles in various biological processes, particularly in color regulation. Previous research indicated that bHLH family genes were significantly involved in screening for genes associated with color variation in chili fruits. Further analysis of the predicted bHLH family genes revealed a high correlation between CabHLH118 and delphinidin, and subsequent assays showed that CabHLH118 was localized in the nucleus, possessed transcriptional activation activity, but lacked self-activation activity in yeast. Silencing or transient overexpression of CabHLH118 in pepper CS03 fruits resulted in significant phenotypic changes, accompanied by a marked decrease or increase in anthocyanin accumulation, respectively. Consistently, the expression of CabHLH118 was significantly down- or up-regulated, and the structural genes in anthocyanin biosynthesis pathway showed corresponding changes. Yeast one-hybrid (Y1H) and dual-luciferase assay demonstrated that CabHLH118 can bind to the upstream promoter of CaF3'H and promote anthocyanin formation. Furthermore, CabHLH118 may respond to blue light to enhance anthocyanin biosynthesis, although the underlying mechanism requires further verification. Collectively, these findings contribute to the understanding of anthocyanin regulation in Solanaceae plants.
Yun-Rong Mo, Hao-Ran Zhang, Qiao-Ling Deng et al.· Plant physiology and biochem...· 0 citations
Caffeine biosynthesis in tea plants (Camellia sinensis) is dynamically regulated by environmental cues; however, the mechanisms linking early drought signals to caffeine accumulation remain unclear. Here, we show that acute PEG-induced osmotic stress induces rapid caffeine accumulation, accompanied by transcriptional activation of the key biosynthetic gene CsTCS1. Through integrative analyses, including GWAS and co-expression network modeling, we identified a CsBPC6-CsNACX2-CsTCS1 module as a central regulatory hub. Mechanistically, CsNACX2 directly binds the promoter of the caffeine synthase gene CsTCS1, activating its transcription and promoting caffeine accumulation. Moreover, the drought-responsive transcription factor CsBPC6 acts upstream to transactivate CsNACX2. Functional validation using gene silencing and transient overexpression assays confirmed that the CsBPC6-CsNACX2-CsTCS1 module positively regulates caffeine biosynthesis under PEG-induced drought conditions. Collectively, our findings uncover a previously uncharacterized drought-responsive transcriptional module governing caffeine biosynthesis, providing new mechanistic insights into how environmental cues regulate secondary metabolism in tea plants.
Shiyu Zhang, Zhouzhuoer Chen, Xin-Zhuan Yao et al.· Plant, Cell and Environment· 0 citations
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