Search Results (64)

Dryopteris fragrans (L.) Schott synthesizes volatile sesquiterpenes through the mevalonate pathway (MVA), in which 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) serves as the key rate-limiting enzyme. Although HMGR plays a crucial role in terpenoid biosynthesis, its functional characteristics in D. fragrans and its involvement in stress responses remain unclear. This study identified three HMGR genes (DfHMGR1/2/3) from the transcriptome data of D. fragrans. Bioinformatics analysis revealed that the encoded proteins are localized to the endoplasmic reticulum and share high sequence similarity with fern homologs. Under abiotic stress conditions, DfHMGRs exhibited differential expression patterns, with marked upregulation under salt and drought stress. To validate the functions of these genes, we generated transgenic Nicotiana tabacum L. plants overexpressing DfHMGRs. Compared with wild-type controls, the transgenic lines showed enhanced tolerance to drought and heat stress. Promoter analysis identified functional regulatory regions controlling DfHMGR expression, and co-expression network analysis predicted 21 potential transcriptional regulators. This study validates the function of D. fragrans HMGRs in a heterologous system and provides candidate genes for improving stress resistance in plants. Full article

Volatile terpenoids (VTs) are key secondary metabolites that play dual roles as endogenous antioxidants and airborne signals in plants under abiotic stress. Their biosynthesis is orchestrated via the mevalonate (MVA) and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways, with metabolic plasticity regulated by transcription factors, phytohormonal crosstalk, and stress-responsive elements. Recent advances have revealed that VTs such as isoprene, monoterpenes, and sesquiterpenes help mitigate oxidative stress by scavenging reactive oxygen species (ROS) and modulating antioxidant enzyme systems. However, regulatory mechanisms of stress-induced VT emissions remain fragmented and species-dependent. This review synthesizes current knowledge of VT biosynthesis and emission under abiotic stress, highlights their antioxidant functions and regulatory architecture, and underscores their protective roles in redox homeostasis and stress signal transduction. By identifying key metabolic nodes (e.g., TPS, DXS and MYC2) and stress-responsive pathways, we propose potential molecular targets for the development of stress-resilient cultivars. The integration of VT-based traits into breeding strategies and production-oriented metabolic engineering offers promising avenues for improving crop performance, reducing oxidative damage, and supporting sustainable agricultural systems. Full article

The characteristic minty-like aroma of ‘Rucheng Baimaocha’ black tea (RCBT) enhances the tea’s unique flavor profile, driving high demand among consumers. The dynamic changes in key aroma compounds in minty-like RCBT were elucidated by sensory evaluation and gas chromatography olfactometry quadrupole time of flight mass spectrometry (GC × GC-O-Q-TOF-MS). The results indicated that during processing, the aroma of RCBT transitions from a fresh to floral, sweet, and minty-like aroma. Among the 189 identified volatile compounds, alcohols constitute the predominant category (over 50%), with 71 compounds identified as key differential compounds across all stages. Aroma analysis revealed that 28 compounds with odor activity values (OAV) > 1 were the primary contributors during RCBT processing. Notably, minty-like odorants in RCBT were primarily derived from the metabolic pathways of the methylerythritol phosphate (MEP) and mevalonic acid (MVA), lipid oxidation, and phenylalanine. These findings offer theoretical insights for improving unique black tea quality and optimizing processing techniques. Full article

Triterpenoids derived from Sanghuangporus baumii exhibit potent antitumor activity, but their yields under natural conditions are relatively low due to their status as secondary metabolites. In this study, we investigated the effects of Zn²⁺ induction on the growth and triterpenoid biosynthesis of S. baumii. The results showed that 0.5 mM Zn²⁺ significantly enhanced the mycelial growth rate (0.43 ± 0.004 cm/d) and biomass (4.8 ± 0.024 g/L), representing increases of 8.71% and 16.95%, respectively, compared with the Zn0 group. This result was mainly caused by an increase in the soluble sugar content. Furthermore, 5 mM Zn²⁺ induced upregulation of genes in the mevalonate (MVA) pathway, thereby promoting triterpenoid accumulation by 167.86% compared with the Zn0 group. Transcriptome analysis identified SbHMGS as the key gene involved in triterpenoid biosynthesis under Zn²⁺ induction. Heterologous expression of SbHMGS in Saccharomyces cerevisiae confirmed its critical role in triterpenoid production. The triterpenoid (squalene) content of the engineered strain (Sc-HMGS) reached 0.88 mg/g under Zn²⁺ induction, which was 208.6% higher than in the non-induced control strain (Sc-NTC). These findings provide a foundation for optimizing the industrial fermentation condition of S. baumii and S. cerevisiae to enhance triterpenoid yields. Full article

Vibrio natriegens (V. natriegens) is an emerging synthetic biology chassis characterized by rapid growth, and its potential for the synthesis of sesquiterpenes (such as pentalenene) has not been developed. In this study, heterologous pentalenene biosynthesis was successfully established in V. natriegens via metabolic engineering. The optimization of gene dosage and culture conditions led to an increase in pentalenene yield from 0.75 mg/L to 39.4 mg/L, representing the highest titer reported in V. natriegens to date, though still markedly lower than yields achieved in conventional microbial hosts. Transcriptome analysis demonstrated that the exogenous mevalonate (MVA) pathway effectively activated terpenoid precursor synthesis, as evidenced by the up-regulation of key pathway genes. However, the endogenous methylerythritol 4-phosphate (MEP) pathway remained inactive, and genes involved in oxidative phosphorylation, the pentose phosphate pathway, and thiamine biosynthesis were down-regulated, leading to limited availability of ATP, NADPH, and acetyl-CoA. Competition for cofactors, particularly NADPH, further constrained precursor supply and pathway efficiency. This study confirmed the potential of V. natriegens as a pentalenene production platform and revealed its metabolic bottleneck, providing a theoretical basis for subsequent engineering optimization. Full article

Retinoids, including retinol, retinal, and retinoic acid, are a group of vitamin A derivatives with skin-improving effects. Retinoic acid is highly effective for skin anti-aging but can cause irritation, requiring a prescription. Retinol, a less irritating alternative, needs conversion to retinal and then retinoic acid in the skin, whereas direct absorption of retinal enhances efficacy by bypassing this conversion process. This study aimed to produce retinal through precision fermentation using metabolically engineered Saccharomyces cerevisiae. The introduction of heterologous retinal biosynthetic genes and overexpression of the truncated HMG-CoA reductase (tHMG1) and acetyl-CoA acetyltransferase (ERG10) genes in the mevalonate (MVA) pathway increased retinal production up to 10.2 mg/L. At the same time, ethanol was produced as a major byproduct in S. cerevisiae. To address this, a pyruvate decarboxylase (Pdc)-deficient S. cerevisiae strain, incapable of producing ethanol, was employed. Overexpression of ERG10 and tHMG1 in the Pdc-deficient S. cerevisiae harboring the retinal biosynthetic plasmids achieved a retinal production up to 117.4 mg/L in the dodecane layer without ethanol through a two-phase in situ fermentation and extraction. This study demonstrates that eliminating pyruvate decarboxylase activity effectively redirects carbon flux toward retinal biosynthesis in the recombinant S. cerevisiae, offering a promising approach for sustainable retinal production through precision fermentation. Full article

This study investigates the dual role of salicylic acid (SA) in enhancing the production of triterpenes and elucidates its molecular regulatory mechanisms in the fungus Athelia termitophila (TMB), a rich source of bioactive triterpenoids vital to the cosmetics and pharmaceutical industries. Our innovative approach involves the strategic application of SA during the mycelial growth phase, leading to a remarkable 21.87% increase in triterpene yield under optimized conditions of 200 μmol/L SA over 9 days. Pioneering in its methodology, our research employs Spearman correlation analysis to dissect the intricate relationship between triterpene content and gene expression within the mevalonate (MVA) pathway of A. termitophila. This analysis has identified four key genes—Acetyl-Coa Acetyltransferase (AACT), Squalene Epoxidase (SE), Phosphomevalonate Kinase (PMK), and Mevalonate Diphosphate Decarboxylase (MVD)—that are important for triterpene synthesis, providing new insights into the biosynthetic capabilities of A. termitophila. Furthermore, our application of cluster analysis has unveiled unprecedented expression patterns among critical genes, at specific growth intervals. This novel insight into the temporal dynamics of gene transcription during triterpene synthesis provides a comprehensive view of the biosynthetic process, setting the stage for targeted enhancement of triterpene production in A. termitophila. This investigation not only highlights TMB’s potential as a biotechnological source of triterpenes but also provides critical insights into the underlying molecular pathways responsible for triterpene synthesis. Full article

Terpenoids, abundant and structurally diverse secondary metabolites in plants, especially in conifer species, play crucial roles in the plant defense mechanism and plant growth and development. In Pinus massoniana, terpenoids’ biosynthesis relies on both the mevalonate (MVA) pathway and the 2-methyl-D-erythritol-4-phosphate (MEP) pathway, with 1-hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate synthase (HDS) catalyzing the sixth step of the MEP pathway. In this study, we cloned and conducted bioinformatics analysis of the PmHDS gene from P. massoniana. The results showed that PmHDS shares homology with HDS proteins from other species. Analysis of tissue expression patterns indicated that PmHDS exhibits the highest expression level in xylem tissue, followed by stems, with significantly lowest expression in the apical meristem. Treatment with NaCl, abscisic acid (ABA), ethylene (ETH), methyl jasmonate (MeJA), and salicylic acid (SA) upregulated the expression of PmHDS. Furthermore, we successfully cloned the PmHDS promoter (about 2220 bp) and integrated it into a GUS reporter vector, which resulted in GUS activity being observed in various tissues of Arabidopsis thaliana. Overexpression of the PmHDS gene in A. thaliana significantly increased the content of carotenoids, chlorophylls a and b, and related enzyme activities, as well as the levels of terpenoid derivatives such as cytokinin (CTK), gibberellic acid (GA), and ABA, thereby enhancing the resistance to those abiotic stresses. These findings suggest that PmHDS plays an important role in the terpenoid synthesis pathway. This study provides a theoretical basis for understanding the biosynthesis of terpenoids and lays a foundation for future research on the regulation of terpene synthesis and resistance in molecular breeding. Full article

HMGR (3-hydroxy-3-methylglutaryl-CoA reductase) plays a crucial role as the first rate-limiting enzyme in the mevalonate (MVA) pathway, which is the upstream pathway of natural rubber biosynthesis. In this study, we carried out whole-genome identification of Taraxacum kok-saghyz (TKS), a novel rubber-producing alternative plant, and obtained six members of the TkHMGR genes. Bioinformatic analyses were performed including gene structure, protein properties, chromosomal localization, evolutionary relationships, and cis-acting element analyses. The results showed that HMGR genes were highly conserved during evolution with a complete HMG-CoA reductase conserved domain and were closely related to Asteraceae plants during the evolutionary process. The α-helix is the most prominent feature of the secondary structure of the TkHMGR proteins. Collinearity analyses demonstrated that a whole-genome duplication (WGD) event and tandem duplication event play a key role in the expansion of this family and TkHMGR1 and TkHMGR6 have more homologous gene between other species. Cis-acting element analysis revealed that the TkHMGR gene family had a higher number of MYB-related, light-responsive, hormone-responsive elements. In addition, we investigated the expression patterns of family members induced by ethylene (ETH) and methyl jasmonate (MeJA), and their expression levels at different stages of T. kok-saghyz root development. Finally, subcellular localization results showed that six TkHMGR members were all located in the endoplasmic reticulum. In conclusion, the results of our study lay a certain theoretical basis for the subsequent improvement of rubber yield, molecular breeding of rubber-producing plants, and genetic improvement of T. kok-saghyz. Full article

The genus Cinnamomum exhibits a rich variety of chemotypes and is an economically important essential oil (EO)-producing plant belonging to the family Lauraceae. Here, we aimed to explore the potential differences in the terpenoid (the principal components of EOs) biosynthesis pathways of different chemotypes at the molecular level in four Cinnamomum species—C. camphora var. linaloolifera, C. kanehirae, C. longipaniculatum, and C. micranthum. Gas chromatography–mass spectrometry (GC-MS) was employed to elucidate the discrepancies in the chemical profiles and compositions of leaf EO terpenoids among the four Cinnamomum species. The results revealed significant variations in leaf EO yields. The main constituents of the leaf EOs from C. camphora var. linaloolifera and C. kanehirae were the acyclic monoterpene linalool, and those of C. longipaniculatum and C. micranthum were the monoterpene eucalyptol and the sesquiterpene β-caryophyllene, respectively. Furthermore, a comparative transcriptome analysis of the leaves from the four Cinnamomum species revealed that differentially expressed genes (DEGs) were significantly enriched in terpene-related entries. Specifically, 42 and 24 DEGs were significantly enriched to the mevalonate (MVA)/2-methylerythritol 4-phosphate (MEP) pathways and terpene synthase (TPS) activity, respectively. Most genes encoding proteins involved in the terpenoid precursor MVA and MEP pathways exhibited differential expression across the four species, which correlated with the distinct terpenoid profiles observed in their leaf EOs. Four acyclic monoterpene linalool synthase genes—Maker00024100, Maker00014813, Maker00014818, and Maker00018424—were highly expressed in C. camphora var. linaloolifera and C. kanehirae. A monoterpene eucalyptol synthesis gene, Maker00001509, was highly expressed in C. longipaniculatum, and a sesquiterpene β-stigmasterol synthesis gene, Maker00005791, was highly expressed in C. micranthum. These expression levels were subsequently validated through quantitative real-time polymerase chain reaction (qRT-PCR). In conclusion, the combined results of the GC-MS and transcriptome analyses revealed a strong correlation between the metabolite content of the EOs and gene expression. This research contributes to a better understanding of the differences in terpene accumulation in various chemotypes of Cinnamomum at the molecular and mechanistic levels, laying a solid foundation for the cultivation of an ideal Cinnamomum variety. Full article

Potato tubers are reproductive and storage organs, enabling their survival. Unraveling the molecular mechanisms that regulate tuberization is crucial for understanding how potatorespond to environmental stress situations and for potato breeding. Previously, we did a transcriptomic analysis of potato microtuberization without light. This showed that important cellular processes like ribosomal proteins, cell cycle, carbon metabolism, oxidative stress, fatty acids, and phytosterols (PS) biosynthesis were closely connected in a protein–protein interaction (PPI) network. Research on PS function during potato tuberization has been scarce. PS plays a critical role in regulating membrane permeability and fluidity, and they are biosynthetic precursors of brassinosteroids (BRs) in plants, which are critical in regulating gene expression, cell division, differentiation, and reproductive biology. Within a PPI network, we found a module of 15 genes involved in the PS biosynthetic process. Darkness, as expected, activated the mevalonate (MVA) pathway. There was a tight interaction between three coding gene products for HMGR3, MVD2, and FPS1, and the gene products that synthetize PS, including CAS1, SMO1, BETAHSD, CPI1, CYP51, FACKEL, HYDRA1, SMT2, SMO2, STE1, and SSR1. Quantitative real-time polymerase chain reaction (qRT-PCR) confirmed the expression analysis of ten specific genes involved in the biosynthesis of PS. This manuscript discusses the potential role of genes involved in PS biosynthesis during microtuber development. Full article

Light is one of the most important factors regulating plant gene expression patterns, metabolism, physiology, growth, and development. To explore how light may induce or alter transcript splicing, we conducted RNA-Seq-based transcriptome analyses by comparing the samples harvested as etiolated seedlings grown under continuous dark conditions vs. the light-treated green seedlings. The study aims to reveal differentially regulated protein-coding genes and novel long noncoding RNAs (lncRNAs), their light-induced alternative splicing, and their association with biological pathways. We identified 14,766 differentially expressed genes, of which 4369 genes showed alternative splicing. We observed that genes mapped to the plastid-localized methyl-erythritol-phosphate (MEP) pathway were light-upregulated compared to the cytosolic mevalonate (MVA) pathway genes. Many of these genes also undergo splicing. These pathways provide crucial metabolite precursors for the biosynthesis of secondary metabolic compounds needed for chloroplast biogenesis, the establishment of a successful photosynthetic apparatus, and photomorphogenesis. In the chromosome-wide survey of the light-induced transcriptome, we observed intron retention as the most predominant splicing event. In addition, we identified 1709 novel lncRNA transcripts in our transcriptome data. This study provides insights on light-regulated gene expression and alternative splicing in rice. Full article

Dendrobium species, which are perennial herbs widely distributed in tropical and subtropical regions, are notable for their therapeutic properties attributed to various bioactive compounds, including dendrobine-type sesquiterpenoid alkaloids (DTSAs). The objective of this review article is to provide a comprehensive overview of recent advances in the biosynthesis of DTSAs, including their extraction from Dendrobium species and endophytes, elucidation of associated genes through genomic and transcriptomic sequencing in both Dendrobium spp. and endophytes, exploration of the biosynthetic pathways of DTSAs, and drawing conclusions and outlining future perspectives in this field. Alkaloids, predominantly nitrogen-containing compounds found in medicinal orchids, include over 140 types discovered across more than 50 species. DTSAs, identified in 37 picrotoxane alkaloids, have a distinctive five-membered nitrogen heterocyclic ring. This review highlights endophytic fungi as alternative sources of DTSAs, emphasizing their potential in pharmaceutical applications when plant-derived compounds are scarce or complex. Genomic and transcriptomic sequencing of Dendrobium spp. and their endophytes has identified key genes involved in DTSAs biosynthesis, elucidating pathways such as the mevalonate (MVA) and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways. Genes encoding enzymes, such as acetyl-CoA C-acetyltransferase and diphosphomevalonate decarboxylase, are positively associated with dendrobine production. Despite significant advancements, the complexity of terpenoid biosynthesis in different subcellular compartments remains a challenge. Future research should focus on leveraging high-quality genomic data and omics technologies to further understand and manipulate the biosynthetic pathways of DTSAs and enhance their medicinal use. Full article

The sterol regulatory element-binding protein (SREBP) pathway is an integral cellular mechanism that regulates lipid homeostasis, in which transcriptional activator SREBPs regulate the expression of various genes. In the carotenogenic yeast Xanthophyllomyces dendrorhous, Sre1 (the yeast SREBP homolog) regulates lipid biosynthesis and carotenogenesis, among other processes. Despite the characterization of several components of the SREBP pathway across various eukaryotes, the specific elements of this pathway in X. dendrorhous remain largely unknown. This study aimed to explore the potential regulatory mechanisms of the SREBP pathway in X. dendrorhous using the strain CBS.cyp61^- as a model, which is known to have Sre1 in its active state under standard culture conditions, resulting in a carotenoid-overproducing phenotype. This strain was subjected to random mutagenesis with N-methyl-N’-nitro-N-nitrosoguanidine (NTG), followed by a screening methodology that focused on identifying mutants with altered Sre1 activation phenotypes. Single-nucleotide polymorphism (SNP) analysis of 20 selected mutants detected 5439 single-nucleotide variants (SNVs), narrowing them down to 1327 SNPs of interest after a series of filters. Classification based on SNP impact identified 116 candidate genes, including 49 genes with high impact and 68 genes with deleterious moderate-impact mutations. BLAST, InterProScan, and gene ontology enrichment analyses highlighted 25 genes as potential participants in regulating Sre1 in X. dendrorhous. The key findings of this study include the identification of genes potentially encoding proteins involved in protein import/export to the nucleus, sterol biosynthesis, the ubiquitin–proteasome system, protein regulatory activities such as deacetylases, a subset of kinases and proteases, as well as transcription factors that could be influential in SREBP regulation. These findings are expected to significantly contribute to the current understanding of the intricate regulation of the transcription factor Sre1 in X. dendrorhous, providing valuable groundwork for future research and potential biotechnological applications. Full article

Ophibolin A, a fungal sesterterpene, exerts a pivotal influence in a diverse array of biological processes, encompassing herbicidal, bactericidal, fungicidal, and cytotoxic activities. Sixty genes associated with sesterterpene compound biosynthesis were obtained from Bipolaris eleusines via transcriptome sequencing, and those closely linked to ophiobolin A biosynthesis were subsequently filtered. A gene encoding 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) that catalyzes the first committed step of ophiobolin biosynthesis in the mevalonic acid (MVA) pathway was isolated and characterized using RACE (Rapid Amplification of cDNA Ends) technology from ophiobolin A-producing fungus, B. eleusines. The full-length cDNA of the B. eleusines HMGR gene (BeHMGR) was 3906 bp and contained a 3474 bp open reading frame (ORF) encoding 1157 amino acids. Sequence analysis revealed that deduced BeHMGR had high homology to the known HMGRs from Pyrenophora tritici-repentis and Leptosphaeria maculans. It had a calculated molecular mass of about 124.65 kDa and an isoelectric point (pI) of 6.90. It contained two putative HMG-CoA-binding motifs and two NADP(H)-binding motifs. Induced expression analysis of the BeHMGR gene by methyl jasmonate treatment using quantitative fluorescence PCR showed that it significantly elevated after 3 h of methyl jasmonate treatment, peaked at 6 h, and then gradually decreased. This demonstrates that BeHMGR gene expression is induced by methyl jasmonate. Full article