Methyl jasmonate promote protostane triterpenes accumulation by up-regulating the expression of squalene epoxidases in Alisma orientale

Methyl jasmonate induces the regulation of protostane triterpene biosynthesis by microRNAs in Alisma orientale

Protostane triterpenes are medicinally important components found in members of the Alismataceae botanical family, notably Alisma orientale. Methyl jasmonate (MeJA) is known to regulate protostane triterpene biosynthesis in A. orientale, but the microRNA (miRNA) mechanism underlying MeJA response to promote triterpene biosynthesis remains unknown. In this study, we conducted miRNA sequencing analysis after MeJA induction in A. orientale to uncover the role of miRNAs in protostane triterpene biosynthesis. We identified 222 known miRNAs and 379 novel miRNAs, including 16 differentially expressed miRNAs (DEMs) between control and MeJA-treated leaf samples. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) enrichment analysis, four DEMs and eight miRNA target genes were significantly enriched in the triterpene biosynthesis pathway. Integrated analysis of the transcriptome and miRNAome revealed a negative expression pattern between miRNAs and their target genes. We then constructed a regulatory network of miRNA-target gene relationships involved in the triterpene biosynthesis pathway. We found miRNAs may be involved in the response of A. orientale to exogenous MeJA by regulating the expression of key biosynthesis enzymes, leading to increased accumulation of medically important protostane triterpenes.

Integrated metabolome and transcriptome analyses revealed key cytochrome P450 genes involved in the biosynthesis of oleanane-type saponins in Hedera helix L

Hedera helix L. is a traditional Chinese medicinal and industrial crop commonly used to treat coughs and upper respiratory tract diseases. Additionally, it can be utilized as insecticidal, mosquito repellent and biopesticide. Its primary components are pentacyclic triterpenoid saponins include oleanolic acid, hederagenin, hederacoside C, etc. Currently, cytochrome P450 (CYP450) has been shown to be closely associated with the structural diversification and functional modification of the triterpenoid. However, the research on H. helix is still shallow, especially the functional characterization of CYP450 gene in the stage of modifying pentacyclic triterpenoid skeleton. This study integrated analyzed transcriptome and the accumulation modes of the main metabolites of H. helix and screened six CYP450 candidate genes. RT-qPCR results showed that candidate genes exhibited tissue specificity and inducible expression specificity. Based on in vitro and in vivo validation, both HhCYP716A409 and HhCYP716S11 showed activity of oxidase in β-amyrin C-28, producing oleanolic acid by participating in the C-28 oxidization of β-amyrin. HhCYP72D57, HhCYP72A1140, and HhCYP72A1141 produced hederagenin by participating in the hydroxylation of oleanolic acid C-23. Additionally, HhCYP72D57, HhCYP72A1139, and HhCYP72A1141 were also involved in the hydroxylation of hederagenin C-16 to produce 16-OH hederagenin. This study confirms the pivotal roles of CYP716 and CYP72 families in oleanane-type triterpenoid biosynthesis and establishes a method to efficiently produce hederacoside C and derivatives, providing a genetic toolkit for metabolic engineering of H. helix to scale saponin production for pharmaceuticals, agrochemicals, or synthetic biology-driven design of novel triterpenoid biopesticides.

Salicylic acid-induced upregulation of AtAACT and AtMVD expression enhances triterpene biosynthesis in Athelia termitophila

Triterpenoids exhibit great potential in the food and pharmaceutical industries and are the predominant secondary metabolites of Athelia termitophila (TMB). AtAACT catalyzes the conversion of acetyl-CoA and acetoacetate in mevalonate biosynthesis, while AtMVD catalyzes the decarboxylation of mevalonate diphosphate, producing key precursors essential for triterpenoid synthesis. To augment the biosynthesis of TMB triterpenes, we cloned the AtAACT and AtMVD genes into plasmids, which were subsequently used to transform Escherichia coli. The resulting bacterial strains were used for sequencing and bioinformatic analyses to elucidate the encoded amino acid sequences. Furthermore, salicylic acid (SA) was employed as an elicitor to enhance triterpene biosynthesis in TMB. The SA treatment was initiated on the 6th day of incubation and maintained continuously across all time points (36, 48, and 60 h and others), achieving a maximal triterpene concentration of 41.83 ± 0.5 mg/100 mL, corresponding to a 26% increase compared to the uninduced group. Comparative transcriptomic analysis showed that the expression of AtAACT and AtMVD was significantly upregulated in the SA-treated group compared to the control. This upregulation underscores the crucial roles of these genes in facilitating triterpene biosynthesis in TMB. Furthermore, qPCR temporal profiling revealed that AtAACT achieved peak transcript levels at 36 h post-induction, whereas AtMVD peaked at 48 h. This study provides an effective strategy to enhance TMB triterpene content and offers new insights into the mechanisms of SA-treated triterpene biosynthesis.

Recent advancements in mogrosides: A review on biological activities, synthetic biology, and applications in the food industry

Mogrosides are low-calorie, biologically active sweeteners that face high production costs due to strict cultivation requirements and the low yield of monk fruit. The rapid advancement in synthetic biology holds the potential to overcome this challenge. This review presents mogrosides exhibiting antioxidant, anti-inflammatory, anti-cancer, anti-diabetic, and liver protective activities, with their efficacy in diabetes treatment surpassing that of Xiaoke pills (a Chinese diabetes medication). It also discusses the latest elucidated biosynthesis pathways of mogrosides, highlighting the challenges and research gaps in this field. The critical and most challenging step in this pathway is the transformation of mogrol into a variety of mogrosides by different UDP-glucosyltransferases (UGTs), primarily hindered by the poor substrate selectivity, product specificity, and low catalytic efficiency of current UGTs. Finally, the applications of mogrosides in the current food industry and the challenges they face are discussed.

Squalene epoxidase (SE) gene related to triterpenoid biosynthesis assists to select elite genotypes in medicinal plant: Cyclocarya paliurus (Batal.) Iljinskaja

Triterpenoids, known for their anti-inflammatory, anticancer, and hypoglycemic properties, are the major bioactive components in Cyclocarya paliurus (Batal.) Iljinskaja. Selecting elite individuals with high triterpenoids content is the basis of C. paliurus industry for medicinal use. In this study, seasonal variation patterns of total triterpenoids and five triterpene monomers accumulation for three groups with different total triterpenoid contents (TTC; H: 59.74-64.03 mg g^-1; M: 47.66-57.08 mg g^-1, and L: 35.26-42.22 mg g^-1) were surveyed. Seasonal expression dynamics of 6 key genes relevant to triterpenoids biosynthesis, including HMGR, DXR, SQS, SE, LUS, and β-AS, were described by quantitative real-time PCR (qRT-PCR) for three groups. The expression levels of HMGR, SE, LUS, and β-AS genes in group H were higher than in groups M and L. In addition, Pearson correlation analysis showed that they were significantly positively correlated with triterpene accumulation, and the expression level of SE gene not only was significantly correlated with downstream genes, but also exhibited a linear relationship with TTC, especially in September. These results suggest that SE gene could serve as an effective make for screening elite individuals with high TTC from the germplasm of C. paliurus for medicinal use. Further testing on randomly selected individuals in next September proved the feasibility and reliability of SE gene in assisted selection. Also, we successfully cloned the full-length cDNA of SE. Thus, our work provides an efficient way to attain superior genotypes to develop medicinal industry of C. paliurus in practice.

Pharmacological Properties and Molecular Targets of Alisol Triterpenoids from Alismatis Rhizoma

More than 100 protostane triterpenoids have been isolated from the dried rhizomes of Alisma species, designated Alismatis rhizoma (AR), commonly used in Asian traditional medicine to treat inflammatory and vascular diseases. The main products are the alisols, with the lead compounds alisol-A/-B and their acetate derivatives being the most abundant products in the plant and the best-known bioactive products. The pharmacological effects of Ali-A, Ali-A 24-acetate, Ali-B, Ali-B 23-acetate, and derivatives have been analyzed to provide an overview of the medicinal properties, signaling pathways, and molecular targets at the origin of those activities. Diverse protein targets have been proposed for these natural products, including the farnesoid X receptor, soluble epoxide hydrolase, and other enzymes (AMPK, HCE-2) and functional proteins (YAP, LXR) at the origin of the anti-atherosclerosis, anti-inflammatory, antioxidant, anti-fibrotic, and anti-proliferative activities. Activities were classified in two groups. The lipid-lowering and anti-atherosclerosis effects benefit from robust in vitro and in vivo data (group 1). The anticancer effects of alisols have been largely reported, but, essentially, studies using tumor cell lines and solid in vivo data are lacking (group 2). The survey shed light on the pharmacological properties of alisol triterpenoids frequently found in traditional phytomedicines.

Metabolite and Gene Expression Analysis Underlying Temporal and Spatial Accumulation of Pentacyclic Triterpenoids in Jujube

Jujube (Ziziphus jujuba Mill.) has attracted increasing attention because of its fruits’ high nutritional and medicinal value, which produce pentacyclic triterpenoids with valuable pharmacological activities beneficial to human health. However, the dynamic accumulation and metabolism pathway of triterpenoids remain unknown in jujube. Here, we performed metabolite assays of triterpenoids and expression analysis of genes involved in the corresponding metabolic processes on cultivated jujube (Z. jujuba cv. Junzao) and one type of wild jujube (Z. jujuba var. spinosa cv. Qingjiansuanzao). Our results showed that the triterpenoids accumulate predominantly in young leaves, annual stems, buds, and white-mature and beginning red stage fruit. Besides, the total triterpenoid content, ceanothic acid, oleanonic acid, and 3-ketoursolic acid were higher in ‘Qingjiansuanzao’ than in ‘Junzao’. Moreover, we found 23 genes involved in terpenoids metabolism were expressed in all organs, and the ZjSQS1, ZjCYP450/1, ZjCYP450/3, ZjOSC1, ZjFPS, and ZjAACT2 gene expression patterns were consistent with metabolites accumulation during fruit development. In addition, 100 μM MeJA induced ZjSQS1, ZjFPS, and ZjHMGR3 expression in leaves and enhanced triterpenoids accumulation. These findings will help understand the unique metabolism of terpenoids and will benefit further utilization and breeding of jujube as both edible fruit and functional food.

Transcriptomic Analysis, Cloning, Characterization, and Expression Analysis of Triterpene Biosynthetic Genes and Triterpene Accumulation in the Hairy Roots of Platycodon grandiflorum Exposed to Methyl Jasmonate

Platycodon grandiflorum is a perennial plant that has been used for medicinal purposes. Specifically, it is widely used in Northern China and Korea for the treatment of various diseases. Terpenoids belong to a group called secondary metabolites and have attracted a wide range of interest. Here, we determined the expressed sequence tag (EST) library of the methyl jasmonate (MeJA)-treated hairy root of P. grandiflorum. In total, 5760 ESTs were obtained, but after deleting the vector sequences and removing poor-quality sequences, a total of 2536 ESTs were attained. Of these, 811 contigs and 1725 singletons were annotated. The data were further analyzed with a focus on the gene families of the terpenoid biosynthetic pathway (TBP). We identified and characterized four TBP genes; among these were three full-length cDNAs encoding PgHMGS, PgMK, and PgMVD, whereas PgHMGR had a partial sequence based on the EST library database. Phylogenetic analysis and a pairwise identity matrix showed that these identified genes were closely related to those of other higher plants. Moreover, the tertiary structure and multiple alignment analysis showed that several distinct conserved motifs were present. Quantitative reverse transcription-polymerase chain reaction results revealed that TBP genes were constitutively expressed in all organs of P. grandiflorum, while the expression of transcript levels of these genes varied distinctly among the organs. Additionally, the total amount of platycosides was highly detected in the root, accumulating in concentrations 7.8 and 2.6 times higher than in the hairy root and stem, respectively, and 1.4 times higher than in the leaf and flower. The highest amount of total phytosterols was found to accumulate in the leaves at 9.3, 9.1, 1.8, and 1.6 times higher than that of the stem, root, hairy root, and flower, respectively. After the hairy root was exposed to the MeJA treatment, the transcript levels of PgHMGS, PgHMGR, PgMK, and PgMVD had significantly increased. The highest level of transcript accumulation occurred at 3 h after initial exposure for most of the genes. Meanwhile, triterpene saponin accumulation increased with the increase in the time of exposure, and at 48 h after initial exposure, the total saponin content was the highest recorded.

Proteomic insights into protostane triterpene biosynthesis regulatory mechanism after MeJA treatment in Alisma orientale (Sam.) Juz

Protostane triterpenes in Alisma orientale (Sam.) Juz. have unique structural features with distinct pharmacological activities. Previously we have demonstrated that protostane triterpene biosynthesis could be regulated by methyl jasmonate (MeJA) induction in A. orientale. Here, proteomic investigation reveals the MeJA mediated regulation of protostane triterpene biosynthesis. In our study, 281 differentially abundant proteins were identified from MeJA-treated compared to control groups, while they were mainly associated with triterpene biosynthesis, α-linolenic acid metabolism, carbohydrate metabolism and response to stress/defense. Key enzymes 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), squalene epoxidase (SE), oxidosqualene cyclase (OSC) and cytochrome P450s which potentially involved in protostane triterpene biosynthesis were significantly enriched in MeJA-treated group. Basic Helix-loop-helix (bHLH), MYB, and GRAS transcription factors were enhanced after MeJA treatment, and they also improved the expressions of key enzymes in Mevalonate pathway and protostane triterpene. Then, MeJA also could increase the expression of α-galactosidase (α-GAL), thereby promoting carbohydrate decomposition, and providing energy and carbon skeletons for protostane triterpene precursor biosynthesis. As well, exogenous MeJA treatment upregulated 13-lipoxygenase (13-LOX), allene oxide synthase (AOS) and allene oxide cyclase (AOC) involved in α-linolenic acid metabolism, leading to the accumulation of endogenous MeJA and activation of the protostane triterpene biosynthesis transduction. Finally, MeJA upregulated stress/defence-related proteins, as to enhance the defence responses activity of plants. These results were further verified by quantitative real-time PCR analysis of 19 selected genes and content analysis of protostane triterpene. The results provide some new insights into the role of MeJA in protostane triterpene biosynthesis.