Combined Analysis of Volatile Terpenoid Metabolism and Transcriptome Reveals Transcription Factors Related to Terpene Synthase in Two Cultivars of Dendrobium officinale Flowers

Abstract

Dendrobium officinale is a kind of traditional Chinese herbal medicine. Its flowers could be used as health care tea for its aroma flavor and medicinal value. Most recent studies demonstrated that terpenoids are the main components of the aromatic compounds in the flowers, but the biosynthesis of terpenoids is poorly understood in D. officinale. In the experiment, the flowers from two cultivars of D. officinale with different smells were collected. The transcriptome analysis and combined volatile terpenoids determination were performed to identify the genes related to the biosynthesis of the terpenoids. The results showed that the different products of volatile terpenoids are α-thujene, linalool, α-terpineol, α-phellandrene, γ-muurolene, α-patchoulene, and δ-elemene in two cultivar flowers. The transcriptome analysis detected 25,484 genes in the flowers. And 18,650 differentially expressed genes were identified between the two cultivars. Of these genes, 253 genes were mapped to the terpenoid metabolism pathway. Among these genes, 13 terpene synthase (TPS) genes may have correlations with AP2/ERF, WRKY, MYB, bHLH, and bZIP transcription factors by weighted gene co-expression network analysis (WGCNA). The transcription factors have regulatory effects on TPS genes. These results may provide ideas for the terpenoid biosynthesis and regulatory network of D. officinale flowers.

Transcriptomic Characterization of Nitrate-Enhanced Stevioside Glycoside Synthesis in Stevia (Stevia rebaudiana) Bertoni

“…Accordingly, the similar expression patterns of specific SG synthesis-related genes from RNA-Seq and qRT-PCR results confirmed the validity of our transcriptome analysis results (Figure 7). These transcriptomic analyses suggested the key genes, TFs and pathways in regulating specific metabolism, most of which have been previously reported in terpenoid-enriched plants including Finger Citron [42], Ferula assafoetida [43], Dendrobium officinale [44], as well as stevia [17,45]. The KEGG results clearly indicated that NO 3 − mostly upregulates the pathways relating to secondary metabolism, with "diterpenoid biosynthesis" being the most significant for SGs.…”

An Integrated Analysis of Metabolomics and Transcriptomics Reveals Significant Differences in Floral Scents and Related Gene Expression between Two Varieties of Dendrobium loddigesii

“…In the research, among the top ten volatile metabolites with the highest level in high-scented D. loddigesii (TH), 3-carene (11.87%) had the highest relative content with sweet smell. 3-Carene was a kind of monoterpene, which was identified widely in aromatic constituents of Dendrobium species, such as D. chrysotoxum, D. hancockii, and D. officinale [16,24]. Therefore, we inferred that 3-carene was the base content of floral scent in these Dendrobium species, and it was also the basic constituent of high-scented D. loddigesii aromatic scent.…”

“…Terpenes were the dominant components of floral scent in D. chrysotoxum, 15 terpenes were identified as scent components in its flowers [9]. Similarly, the aromatic composition of D. hancockii and D. officinale was mainly terpenes [16]. In the research, among the top ten volatile metabolites with the highest level in high-scented D. loddigesii (TH), 3-carene (11.87%) had the highest relative content with sweet smell.…”

“…The genetic and molecular mechanisms responsible for the floral scent in Dendrobium species are poorly revealed. Thanks to the rapid developments of molecular biology and high-throughput sequencing technologies, recent research studies on floral scent have elucidated several biosynthetic pathways of fragrance compounds and some structural genes encoding key enzymes in D. officinal [16,17]. Nonetheless, there are few studies on the molecular mechanism of synthesis of D. loddigesii's aromatic ingredients.…”

Research Advances in Multi-Omics on the Traditional Chinese Herb Dendrobium officinale

“…The combination of metabolomic and transcriptomic analysis has also widely been used to analyze various physiological processes in D. officinale , such as flower development ( He et al, 2020 ), cold acclimation ( Wu et al, 2016 ), stem color ( Zhan et al, 2020 ), salt stress ( Zhang et al, 2021 ), and flower volatile terpenoids ( Li N. et al, 2021 ). Some key factors have been identified to explain why the metabolites were changed, including the key enzymes in the biosynthetic pathway and potential transcription factors ( Li N. et al, 2021 ). For example, the increase in content of delphinidin and quercetin derivatives was responsible for the purple stem of D. officinale and F3H and leucoanthocyanidin dioxygenase ( LDOX ) genes were found to be highly expressed ( Zhan et al, 2020 ).…”