Biosynthesis and the Transcriptional Regulation of Terpenoids in Tea Plants (Camellia sinensis)

Abstract

Terpenes, especially volatile terpenes, are important components of tea aroma due to their unique scents. They are also widely used in the cosmetic and medical industries. In addition, terpene emission can be induced by herbivory, wounding, light, low temperature, and other stress conditions, leading to plant defense responses and plant–plant interactions. The transcriptional levels of important core genes (including HMGR, DXS, and TPS) involved in terpenoid biosynthesis are up- or downregulated by the MYB, MYC, NAC, ERF, WRKY, and bHLH transcription factors. These regulators can bind to corresponding cis-elements in the promoter regions of the corresponding genes, and some of them interact with other transcription factors to form a complex. Recently, several key terpene synthesis genes and important transcription factors involved in terpene biosynthesis have been isolated and functionally identified from tea plants. In this work, we focus on the research progress on the transcriptional regulation of terpenes in tea plants (Camellia sinensis) and thoroughly detail the biosynthesis of terpene compounds, the terpene biosynthesis-related genes, the transcription factors involved in terpene biosynthesis, and their importance. Furthermore, we review the potential strategies used in studying the specific transcriptional regulation functions of candidate transcription factors that have been discriminated to date.

Multiomics Analysis Reveals the Genetic Basis of Volatile Terpenoid Formation in Oolong Tea

“…Our results showed that all three high-aroma oolong tea cultivars had a high abundance of cadinane sesquiterpenoids, which are mainly found in plants and fungi and widely used in essential oils in the perfume industry and also have various pharmacological activities, such as antibacterial, anti-inflammatory, and hypoglycemic. , Many terpenoids have been reported as aroma compounds essential to tea flavor, such as δ-cadinene and α-cadinol (cadinane sesquiterpenoids), α-farnesene, linalool, and nerolidol . In previous studies, nerolidol and linalool have received significant attention as major floral aroma compounds in oolong tea, but cadinane sesquiterpenoids have not been taken into serious consideration. − Our results showed eight cadinane sesquiterpenoids with significantly higher contents in three high-aroma oolong teas, suggesting that they may belong to a class of key volatile compounds related to aroma formation in oolong tea.…”

“…43,44 Many terpenoids have been reported as aroma compounds essential to tea flavor, such as δ-cadinene and α-cadinol (cadinane sesquiterpenoids), α-farnesene, linalool, and nerolidol. 45 In previous studies, nerolidol and linalool have received significant attention as major floral aroma compounds in oolong tea, but cadinane sesquiterpenoids have not been taken into serious consideration. 45−48 Our results showed eight cadinane sesquiterpenoids with significantly higher contents in three high-aroma oolong teas, suggesting that they may belong to a class of key volatile compounds related to aroma formation in oolong tea.…”

Integrated transcriptomics and metabolomics analysis provides insights into aromatic volatiles formation in Cinnamomum cassia bark at different harvesting times

“…TPSs play important roles in controlling the biosynthesis of the diverse terpenoids in plants [39]. It has been proven that the tremendous diversity of volatile terpenoids is mainly attributable to the catalytic versatility of TPSs, many of which use only GPP, FPP, and GGPP as substrates to generate multiple volatile products from prenyl diphosphate precursors [18]. In recent decades, an increasing number of individual volatile TPS genes have been identified and characterized in plants [23,40].…”

“…Key candidate genes associated with the biosynthesis of phenylpropanoids and flavonoids in C. cassia were identified from three tissue types: bark, leaves, and branches [16]. The mevalonic acid (MVA) and methylerythritol phosphate (MEP) pathways are two alternative, compartmentally separated pathways in terpenoid biosynthesis [17,18]. The MEP pathway mainly produces mono-and diterpenes, whereas the MVA pathway is associated with the formation of sesquiterpenes, triterpenes, and sterols [19].…”

Chemically Mediated Plant–Plant Interactions: Allelopathy and Allelobiosis

“…Terpenoids constitute the second-largest group of allelochemicals, characterized by poor water solubility, making it challenging for rainwater to leach them into the soil [ 229 ]. The precursors of terpenoids are synthesized through two pathways: the MVA pathway that occurs in the cytoplasm and the methylerythritol phosphate (MEP) pathway that takes place in the plastids.…”