Transcriptomic Analysis of the Regulatory Mechanism of Tea Polyphenol Biosynthesis in Chionanthus retusus and Functional Characterization of CrHSP70-14 in Terms of Its Effect on Tea Polyphenols

Guo, Liyang; Wu, Yuzhu; Li, Jihong; Wang, Haiyan; Niu, Muge; Wang, Mengmeng; Zhao, Shicong; Song, Wenjing; Liu, Jiaxun; Wang, Jingyu; Wang, Jinnan

doi:10.3390/metabo16010026

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Transcriptomic Analysis of the Regulatory Mechanism of Tea Polyphenol Biosynthesis in Chionanthus retusus and Functional Characterization of CrHSP70-14 in Terms of Its Effect on Tea Polyphenols

by

Liyang Guo

^1,2,†

,

Yuzhu Wu

^1,2,†,

Jihong Li

^1,2,

Haiyan Wang

³,

Muge Niu

⁴

,

Mengmeng Wang

^1,2,

Shicong Zhao

^1,2,

Wenjing Song

^1,2,

Jiaxun Liu

^1,2,

Jingyu Wang

^1,2 and

Jinnan Wang

^1,2,*

¹

College of Forestry, Shandong Agricultural University, Tai’an 271018, China

²

State Forestry and Grassland Administration Key Laboratory of Silviculture in Downstream Areas of the Yellow River, Tai’an 271018, China

³

Heze Forestry Technical Service Center, Heze 274099, China

⁴

College of Forestry and Grassland, Nanjing Forestry University, Nanjing 210037, China

^*

Author to whom correspondence should be addressed.

^†

These authors contributed equally to this work.

Metabolites 2026, 16(1), 26; https://doi.org/10.3390/metabo16010026

Submission received: 1 December 2025 / Revised: 16 December 2025 / Accepted: 22 December 2025 / Published: 25 December 2025

(This article belongs to the Special Issue LC-MS/MS Analysis for Plant Secondary Metabolites, 2nd Edition)

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Abstract

Background: Chionanthus retusus Lindl. et Paxt., a deciduous tree of the genus Chionanthus (Oleaceae), represents a significant native species and a widely cultivated ornamental. Its tender leaves can be processed into tea, traditionally consumed in southern China under the common name “Nuomi Cha”. Methods: Our team quantified the tea polyphenol content across 150 individual trees of C. retusus and selected three low-polyphenol (ZB_D_14, AQ_2, AQ_1) and three high-polyphenol (SX_3, SXG_D_8, TS_D_13) lines for transcriptome sequencing of their young leaves. The resulting data were analyzed to screen for candidate genes. Subsequently, transgenic plants were constructed, and their tea polyphenol content was determined. Results: A significant difference in tea polyphenol content was confirmed between the high- and low-polyphenol lines. Weighted Gene Co-expression Network Analysis (WGCNA) pinpointed a key module strongly associated with tea polyphenol synthesis, encompassing 432 DEGs, which were predominantly enriched in pathways like phenylpropanoid biosynthesis. A comparative transcriptomic analysis further yielded 84 DEGs (40 up- and 44 down-regulated). Enrichment analysis showed these were primarily involved in flavonoid and phenylpropanoid biosynthesis pathways. Expression profiling of genes in the tea polyphenol biosynthetic pathway indicated that several key genes (e.g., 4CL, CHS, DFR) were highly expressed in the high-content lines. A gene interaction network related to this synthesis identified 20 hub genes (e.g., CrHSP70-14, CrMYB44, CrbHLH92). Functional validation of four hubs (CrMYB44, CrHSP70-14, CrCDC6B, CrRAE1) via tobacco transient transformation assays demonstrated that all four significantly elevated tea polyphenol levels, with CrHSP70-14 overexpression yielding the highest content. Furthermore, stable CrHSP70-14 overexpression transgenic tobacco lines were generated, exhibiting significantly higher leaf tea polyphenol content versus controls. Conclusions: This study identifies multiple regulatory genes involved in C. retusus tea polyphenol biosynthesis, provides initial mechanistic insights, and establishes a molecular foundation for breeding specialized tea cultivars of this species.

Keywords: Chionanthus retusus; tea polyphenol; regulatory network; CrHSP70-14

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MDPI and ACS Style

Guo, L.; Wu, Y.; Li, J.; Wang, H.; Niu, M.; Wang, M.; Zhao, S.; Song, W.; Liu, J.; Wang, J.; et al. Transcriptomic Analysis of the Regulatory Mechanism of Tea Polyphenol Biosynthesis in Chionanthus retusus and Functional Characterization of CrHSP70-14 in Terms of Its Effect on Tea Polyphenols. Metabolites 2026, 16, 26. https://doi.org/10.3390/metabo16010026

AMA Style

Guo L, Wu Y, Li J, Wang H, Niu M, Wang M, Zhao S, Song W, Liu J, Wang J, et al. Transcriptomic Analysis of the Regulatory Mechanism of Tea Polyphenol Biosynthesis in Chionanthus retusus and Functional Characterization of CrHSP70-14 in Terms of Its Effect on Tea Polyphenols. Metabolites. 2026; 16(1):26. https://doi.org/10.3390/metabo16010026

Chicago/Turabian Style

Guo, Liyang, Yuzhu Wu, Jihong Li, Haiyan Wang, Muge Niu, Mengmeng Wang, Shicong Zhao, Wenjing Song, Jiaxun Liu, Jingyu Wang, and et al. 2026. "Transcriptomic Analysis of the Regulatory Mechanism of Tea Polyphenol Biosynthesis in Chionanthus retusus and Functional Characterization of CrHSP70-14 in Terms of Its Effect on Tea Polyphenols" Metabolites 16, no. 1: 26. https://doi.org/10.3390/metabo16010026

APA Style

Guo, L., Wu, Y., Li, J., Wang, H., Niu, M., Wang, M., Zhao, S., Song, W., Liu, J., Wang, J., & Wang, J. (2026). Transcriptomic Analysis of the Regulatory Mechanism of Tea Polyphenol Biosynthesis in Chionanthus retusus and Functional Characterization of CrHSP70-14 in Terms of Its Effect on Tea Polyphenols. Metabolites, 16(1), 26. https://doi.org/10.3390/metabo16010026

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Transcriptomic Analysis of the Regulatory Mechanism of Tea Polyphenol Biosynthesis in Chionanthus retusus and Functional Characterization of CrHSP70-14 in Terms of Its Effect on Tea Polyphenols

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