PatJAZ6 Acts as a Repressor Regulating JA-Induced Biosynthesis of Patchouli Alcohol in Pogostemon Cablin

PatWRKY71 transcription factor regulates patchoulol biosynthesis and plant defense response

Patchoulol, a valuable compound belonging to the sesquiterpenoid family, is the primary component of patchouli oil produced by Pogostemon cablin (P. cablin). It has a variety of pharmacological and biological activities and is widely used in the medical and cosmetic industries. However, despite its significance, there is a lack of research on the transcriptional modulation of patchoulol biosynthesis.Salicylic acid (SA), is a vital plant hormone that serves as a critical signal molecule and plays an essential role in plant growth and defense. However, to date, no studies have explored the modulation of patchoulol biosynthesis by SA. In our study, we discovered that the application of SA can enhance the production of patchoulol. Utilizing transcriptome analysis of SA-treated P. cablin, we identified a crucial downstream transcription factor, PatWRKY71. The transcription level of PatWRKY71 was significantly increased with the use of SA. Furthermore, our research has revealed that PatWRKY71 was capable of binding to the promoter of PatPTS, ultimately leading to an increase in its expression. When PatWRKY71 was silenced by a virus, the expression of both PatWRKY71 and PatPTS was reduced, resulting in the down-regulation of patchoulol production. Through our studies, we discovered that heterologous expression of PatWRKY71 leads to an increase in the sensitivity of Arabidopsis to salt and Cd, as well as an outbreak of reactive oxygen species (ROS). Additionally, we uncovered the regulatory role of PatWRKY71 in both patchoulol biosynthesis and plant defense response. This discovery provided a theoretical basis for the improvement of the content of patchoulol and the resistance of P. cablin through genetic engineering.

PcENO3 interacts with patchoulol synthase to positively affect the enzymatic activity and patchoulol biosynthesis in Pogostemon cablin

Patchouli alcohol, a significant bioactive component of the herbal plant Pogostemon cablin, has considerable medicinal and commercial potential. Several genes and transcription factors involved in the biosynthesis pathway of patchouli alcohol have been identified. However, so far, regulatory factors directly interacting with patchouli synthase (PTS) have not been reported. This study was conducted to analyze the interaction between PcENO3 and PcPTS to explore the molecular regulation effect of PcENO3 on patchouli alcohol biosynthesis. PcENO3, a homologous protein of Arabidopsis ENO3 belonging to the enolase family, was identified and characterized. Subcellular localization experiments in Arabidopsis protoplast cells indicated that the PcENO3 protein was localized in both the cytoplasm and nucleus. The physical interaction between PcENO3 and PcPTS was confirmed through yeast two-hybrid (Y2H), GST pull-down, and bimolecular fluorescence complementation assays. Furthermore, the Y2H assay demonstrated that PcENO3 could also interact with JAZ proteins in the JA pathway. Enzymatic assays showed that the interaction with PcENO3 increased the catalytic activity of patchoulol synthase. Additionally, suppression of PcENO3 expression with VIGS (virus-induced gene silencing) decreased patchouli alcohol content compared to the control. These findings suggest that PcENO3 interacts with patchoulol synthase and modulates patchoulol biosynthesis by enhancing the enzymatic activity of PcPTS.

Comparative physicochemical, hormonal, transcriptomic and proteomic analyses provide new insights into the formation mechanism of two chemotypes of Pogostemon cablin

Patchouli (Pogostemon cablin) is an aromatic plant, and its oil has diverse applications in medicine, food, and cosmetics. Patchouli alcohol is the principal bioactive constituent of its volatile oil. In China, patchouli is typically categorized into two types: patchoulol-type (PA-type) and pogostone-type (PO-type). The study evaluated physiological and biochemical indicators, phytohormone metabolites and conducted transcriptome and proteome analyses on both two chemotypes. The PA-type exhibited higher levels of chlorophyll a, b, and carotenoids than the PO-type. In total, 35 phytohormone metabolites representing cytokinin, abscisic acid, gibberellin, jasmonic acid, and their derivatives were identified using UPLC-MS/MS, 10 of which displayed significant differences, mainly belong to cytokinins and jasmonates. Transcriptome analysis identified 4,799 differentially expressed genes (DEGs), while proteome analysis identified 150 differentially expressed proteins (DEPs). Regarding the transcriptome results, the DEGs of the PO-type showed significant downregulation in the pathways of photosynthesis, photosynthesis-antenna protein, porphyrin and chlorophyll metabolism, carotenoid biosynthesis, sesquiterpene and triterpenoid biosynthesis, and starch and sucrose metabolism, but upregulation in the pathway of zeatin synthesis. A combination of transcriptome and proteome analyses revealed that the DEGs and DEPs of lipoxygenase (LOX2), β-glucosidase, and patchouli synthase (PTS) were collectively downregulated, while the DEGs and DEPs of Zeatin O-xylosyltransferase (ZOX1) and α-amylase (AMY) were jointly upregulated in the PO-type compared to the PA-type. Differential levels of phytohormones, variations in photosynthetic efficiency, and differential expression of genes in the sesquiterpene synthesis pathway may account for the morphological and major active component differences between the two chemotypes of patchouli. The findings of this study offer novel perspectives on the underlying mechanisms contributing to the formation of the two patchouli chemotypes.

An integrated transcriptome and metabolome analysis reveals the gene network regulating flower development in Pogostemon cablin

Pogostemon cablin is a well-known protected species widely used in medicine and spices, however the underlying molecular mechanisms and metabolite dynamics of P. cablin flower development remain unclear due to the difficulty in achieving flowering in this species. A comparison of the transcriptome and widely targeted metabolome during P. cablin flower development was first performed in this study. Results showed that a total of 13,469 differentially expressed unigenes (DEGs) and 371 differentially accumulated metabolites (DAMs) were identified. Transcriptomic analysis revealed that the DEGs were associated with starch and sucrose metabolism, terpenoid biosynthesis and phenylpropanoid biosynthesis. Among these DEGs, 75 MIKC-MADS unigenes were associated with the development of floral organs. Gibberellins (GAs), auxin, and aging signaling might form a cross-regulatory network to regulate flower development in P. cablin. According to the metabolic profile, the predominant DAMs were amino acids, flavonoids, terpenes, phenols, and their derivatives. The accumulation patterns of these predominant DAMs were closely associated with the flower developmental stage. The integration analysis of DEGs and DAMs indicated that phenylpropanoids, flavonoids, and amino acids might be accumulated due to the activation of starch and sucrose metabolism. Our results provide some important insights for elucidating the reproductive process, floral organ, and color formation of P. cablin flowers at the molecular level. These results will improve our understanding of the molecular and genetic mechanisms involved in the floral development of P. cablin.

Integrated mRNA and miRNA Transcriptome Analysis Suggests a Regulatory Network for UV-B-Controlled Terpenoid Synthesis in Fragrant Woodfern (Dryopteris fragrans)

Fragrant woodfern (Dryopteris fragrans) is a medicinal plant rich in terpenoids. Ultraviolet-B (UV–B) light could increase concentration of terpenoids. The aim of this study was to analyze how UV–B regulates the terpenoid synthesis of the molecular regulatory mechanism in fragrant woodfern. In this study, compared with the control group, the content of the terpenes was significantly higher in fragrant woodfern leaves under UV–B treatment for 4 days (d). In order to identify how UV–B regulates the terpenoid metabolic mechanism in fragrant woodfern, we examined the mRNAs and small RNAs in fragrant woodfern leaves under UV–B treatment. mRNA and miRNA–seq identified 4533 DEGs and 17 DEMs in the control group compared with fragrant woodfern leaves under UV–B treatment for 4 d. mRNA–miRNA analysis identified miRNA target gene pairs consisting of 8 DEMs and 115 miRNAs. The target genes were subjected to GO and KEGG analyses. The results showed that the target genes were mainly enriched in diterpene biosynthesis, terpenoid backbone biosynthesis, plant hormone signal transduction, MEP pathway and MVA pathway, in which miR156 and miR160 regulate these pathways by targeting DfSPL and DfARF, respectively. The mRNA and miRNA datasets identified a subset of candidate genes. It provides the theoretical basis that UV–B regulates the terpenoid synthesis of the molecular regulatory mechanism in fragrant woodfern.

Transcriptome analysis of two Pogostemon cablin chemotypes reveals genes related to patchouli alcohol biosynthesis

Pogostemon cablin, a medicinally and economically important perennial herb, is cultivated around the world due to its medicinal and aromatic properties. Different P. cablin cultivars exhibit different morphological traits and patchouli oil components and contents (especially patchouli alcohol (PA) and pogostone (PO)). According to the signature constituent of the leaf, P. cablin was classified into two different chemotypes, including PA-type and PO-type. To better understand the molecular mechanisms of PA biosynthesis, the transcriptomes of Chinese-cultivated P. cablin cv. PA-type “Nanxiang” (NX) and PO-type “Paixiang” (PX) were analyzed and compared with ribonucleic acid sequencing (RNA-Seq) technology. We obtained a total of 36.83 G clean bases from the two chemotypes, compared them with seven databases and revealed 45,394 annotated unigenes. Thirty-six candidate unigenes participating in the biosynthesis of PA were found in the P. cablin transcriptomes. Overall, 8,390 differentially expressed unigenes were identified between the chemotypes, including 2,467 upregulated and 5,923 downregulated unigenes. Furthermore, six and nine differentially expressed genes (DEGs) were mapped to the terpenoid backbone biosynthetic and sesquiterpenoid and triterpenoid biosynthetic pathways, respectively. One key sesquiterpene synthase gene involved in the sesquiterpenoid and triterpenoid biosynthetic pathways, encoding patchoulol synthase variant 1, was significantly upregulated in NX. Additionally, GC-MS analysis of the two chemotypes in this study showed that the content of PA in NX was significantly higher than that of PX, while the content of PO showed the opposite phenotype. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that the DEG expression tendency was consistent with the transcriptome sequencing results. Overall, 23 AP2/ERF, 13 bHLH, 11 MYB, 11 NAC, three Trihelix, 10 WRKY and three bZIP genes that were differentially expressed may act as regulators of terpenoid biosynthesis. Altogether, 8,314 SSRs were recognized within 6,825 unigenes, with a distribution frequency of 18.32%, among which 1,202 unigenes contained more than one SSR. The transcriptomic characteristics of the two P. cablin chemotypes are comprehensively reported in this study, and these results will contribute to a better understanding of the molecular mechanism of PA biosynthesis. Our transcriptome data also provide a valuable genetic resource for further studies on P. cablin.