Search Results (66)

Harmful algal blooms pose a persistent threat to the integrity of freshwater ecosystems and public health. However, there are no selective chemical control agents available to suppress cyanobacterial growth without damaging beneficial phytoplankton. In this study, ten structurally diverse monoterpenes were assessed in vitro for their differential activity against the potent toxin-producing cyanobacterium Microcystis aeruginosa and the ecologically valuable microalga Chlorella sorokiniana using disc diffusion (DDM) and minimum inhibitory concentration (MIC) assays. Inhibition zones against M. aeruginosa ranged from 6.9 to 43.6 mm, with thymol recording the largest zone (43.6 mm). MIC values ranged from 0.25 to >1 mg/mL for both organisms, and selectivity indices identified camphor and carvone as the most cyanobacterium-preferential compounds, while carene and α-pinene showed the inverse selectivity pattern. Molecular docking against six AlphaFold2-predicted target proteins, photosynthetic complexes, Adenosine Triphosphate (ATP) synthase subunits, and superoxide dismutase (SOD) from both organisms, revealed binding affinities between −3.9 and −6.2 kcal/mol. Phenolic monoterpenes consistently engaged active-site glutamate and aspartate residues via hydrogen bonds and Pi–Anion interactions, most strikingly in the M. aeruginosa ATP synthase, whereas the M. aeruginosa SOD represented the least amenable target for all compounds. Computational ADMET profiling confirmed favorable pharmacokinetic properties and low predicted toxicity for the full panel. Full article

Background: Hemolysis and eryptosis of red blood cells (RBCs) contribute to chemotherapy-induced anemia, a marker of poor prognosis. Geraniol (GER) is an anticancer acyclic monoterpene alcohol found in several plant extracts, but a dearth of evidence exists regarding the potential toxicity of GER in RBCs. Methods: Hemolysis and eryptosis were evaluated using colorimetric and fluorescence-assisted cell-sorting methods, respectively. Phosphatidylserine (PS) exposure, loss of volume, and intracellular Ca²⁺ were measured by annexin-V-FITC, forward scatter (FSC), and Fluo4/AM staining. Cells were also examined by electron microscopy to identify membrane blebbing and by the Westergren method to assess erythrocyte sedimentation rate (ESR). Results: In a concentration-responsive fashion, GER induced hemolysis and PS exposure in addition to elevated ESR. GER-induced cell death was characterized by reduced FSC, membrane blebs, and increased Fluo4 fluorescence. Ca²⁺ deprivation prevented eryptosis, whereas concurrent Ca²⁺ deprivation and membrane depolarization prevented hemolysis, eryptosis, and cell shrinkage. Furthermore, whereas inhibition of cyclooxygenase (COX), casein kinase 1α (CK1α), or Rac1 GTPase ameliorated eryptosis and hemolysis, the latter was only prevented by caspase, nitric oxide synthase, or serine palmitoyltransferase inhibition. Exclusive reversal of eryptosis was rather only achieved in the presence of either caffeine or adenine. Conclusions: GER is a novel stimulator of hemolysis and eryptosis, an activity mediated through membrane hyperpolarization following Ca²⁺ elevation. In parallel, GER seems to involve the COX/CK1α/Rac1 GTPase axis to trigger its cytotoxic effects. Targeting the identified mechanisms in combination therapy may attenuate the off-target toxicity of GER and enhance its specificity to cancer cells. Full article

Geranyl diphosphate synthase (GPPS) is a key enzyme in the plant isoprenoid metabolic pathway and regulates the biosynthesis of volatile monoterpenes. It plays an important role in the biosynthesis of floral volatile terpenoids (FVTs) and inter-cultivar variation in snapdragon. Despite its importance in floral scent formation, the GPPS/GGPPS gene family in snapdragon (Antirrhinum majus L.) has not been systematically characterized. In this study, nine GPPS/GGPPS family members were identified at genome-wide level. These include six AmGPPS and three AmGGPPS genes. Phylogenetic analysis grouped them into distinct subfamilies. We further analyzed their chromosomal locations, gene structures, conserved protein motifs, and promoter cis-acting elements. These results revealed both conservation and functional divergence within the gene family. To explore their functional roles, we compared gene expression profiles at the full flowering stage. This comparison was performed between strongly scented cultivar (Am3) and the weakly scented cultivar (Am5). Among all candidates, AmGPPS6 showed the most significant differential expression. Further, functional validation was conducted using transient overexpression and virus-induced gene silencing (VIGS). Overexpression of AmGPPS6 significantly increased terpenoid production. Total floral volatile terpenoids (FVTs) increased by 1.4 fold. Both monoterpene and sesquiterpene emissions were enhanced. In contrast, silencing of AmGPPS6 markedly reduced the emission of key monoterpenes such as ocimene and its isomers. Sequence analysis showed that AmGPPS6 shares 67.04% identity with canonical GPPS small subunit (GPPS.SSU). However, it lacks the conserved catalytic DDx2-D motif. This suggests that AmGGPPS2 is not catalytically active. Instead, it likely functions through heterodimer with AmGGPPS2. This interaction is supported by coordinated transcriptional expression patterns. Additionally, natural sequence polymorphisms were identified in GPPS.SSU. These variations, rather than those in GPPS.LSU, appear to drive differences in monoterpense emission between cultivars. In conclusion, AmGPPS6 in a key regulator of floral scent biosynthesis in snapdragon. This study provides new insights into functional roles of GPPS/GGPPS genes. It also offers valuable gene targets for the molecular breeding of aromatic traits in ornamental plants. Full article

Myrtaceae is one of the largest families of flowering plants and is well known for its prolific terpene production. To investigate the genetic basis underlying this high-level terpene output, we conducted comparative genomic analyses of genes of the entire terpene biosynthetic pathways in selected Myrtaceae species and representative species from three other families within the order Myrtales. Our analyses revealed that genes encoding enzymes in the upstream terpene biosynthetic pathways are generally conserved in copy number across Myrtales. Similarly, isoprenyl diphosphate synthases, which are positioned centrally and responsible for producing the direct precursors of major terpene classes, also exhibit conserved gene numbers among these species. In contrast, substantial differences were observed in the number of terpene synthase (TPS) genes, which function downstream and directly catalyze terpene formation. Myrtaceae species possess markedly more TPS genes than species from other Myrtales families. This expansion is primarily attributable to increased gene numbers in the TPS-a, TPS-b, TPS-g, and TPS-e/f subfamilies, with the first three subfamilies largely associated with sesquiterpene and monoterpene biosynthesis. Further analyses indicate that the enlarged TPS-a and TPS-g subfamilies resulted at the origination of Myrtaceae-specific groups, whereas TPS-b exhibited Myrtaceae-specific expansion. In Eucalyptus grandis, tandem duplication makes a larger contribution to the expansion of TPS-a, TPS-b and TPS-g subfamilies than interchromosomal duplication. The majority of these TPS genes exhibit moderate to high levels of expression in leaves, consistent with their role in elevated terpene production in leaves of E. grandis. Collectively, our findings are consistent with the hypothesis that the novel terpene-producing capacity of Myrtaceae is driven primarily by Myrtaceae-specific origination and/or expansion of downstream TPS genes rather than changes in upstream pathway gene copy numbers. Full article

Terpenes are diverse plant metabolites with essential ecological and physiological functions, yet their biosynthetic regulation in lettuce (Lactuca sativa L.) remains poorly understood. By integrating volatile profiling, genome-wide identification, and biochemical characterization of terpene synthase (TPS) genes, we elucidated how methyl jasmonate (MJ) induces terpene formation in lettuce seedlings. Headspace analysis of 10-day-old seedlings revealed that while mock-treated tissues emitted no detectable volatiles, MJ elicitation triggered the de novo production of a terpene blend dominated by (E)-β-ocimene (9.3–14.6%), (E)-β-caryophyllene (37.2–46.9%), and caryophyllene oxide (26.2–41.4%). A genome-wide search identified 54 putative LsTPS genes, often clustered with prenyl transferases or cytochrome P450 genes. Gene expression assays revealed 17 MJ-responsive LsTPS genes; among them, LsTPS21, LsTPS23, LsTPS28, LsTPS51, and LsTPS52 showed strong (>200-fold) induction, with LsTPS52 exceeding a 20,000-fold increase. Functional characterization of six recombinant enzymes demonstrated diverse substrate specificities: LsTPS8 as an α-copaene synthase, LsTPS16 as a linalool synthase, LsTPS24 as an (E)-nerolidol synthase, LsTPS21 and LsTPS23 as (E)-β-ocimene synthases, and LsTPS10 as an (E)-β-caryophyllene synthase. Phylogenetic analyses confirmed conserved domains characteristic of the TPS-a and TPS-b subfamilies. This study presents the first comprehensive framework for MJ-induced terpene biosynthesis in lettuce, offering new insights into Asteraceae terpenoid metabolism. Full article

Background: Asarum heterotropoides, a prominent medicinal plant in China, is well known for producing an abundance of monoterpenes and sesquiterpenes, which constitute the primary components of its essential oil and serve as the principal active compounds of the species. However, the biosynthetic pathways for these terpenoids remain largely unelucidated. Methods: Gas chromatography–mass spectrometry analysis, in vitro enzyme assay, subcellular localization experiment and molecular docking were used to characterize the function of terpene synthase from A. heterotropoides. Results: In this study, we isolated and characterized two monoterpene synthases and one sesquiterpene synthase from A. heterotropoides. These enzymes exhibit promiscuous activities, accepting geranyl pyrophosphate and farnesyl pyrophosphate as substrates to yield a variety of monoterpene and sesquiterpene products in in vitro enzymatic assays. All three enzymes possess a conserved RRx8W motif, a hallmark typically associated with TPS-b and TPS-d monoterpene synthases involved in cyclic monoterpene formation. However, these two monoterpene synthases yield linear instead of cyclic products. The sesquiterpene synthase (AhTPS3) is a second example of TPS-a terpene synthase harboring such motif. Conclusions: Our findings significantly expand our understanding of terpene biosynthesis, especially the role of RRx8W motif. Full article

Cinnamomum burmanni (Nees & T. Nees) Blume, a member of the Lauraceae family, exhibits adaptability to diverse environmental conditions by synthesizing a diverse array of specialized secondary metabolites, including terpenoids and cinnamaldehyde. Nevertheless, the molecular mechanisms underlying the chemical diversity in the leaves of C. burmanni and their remarkable adaptation to subtropical and tropical forests in South China have not been thoroughly investigated. This research integrates transcriptomic and proteomic analyses across five chemotypes of C. burmanni, namely, the borneol-type (BORCB), cinnamaldehyde-type (PROCB), eucalyptol-type (EUCCB), phytol-type (PHYCB), and chlorophyllinol-type (CARCB), by means of the Nanopore and Nano UPLC-MS/MS sequencing data. The findings indicate that PROCB demonstrates an up-regulation of the phenylpropanoid pathway (such as PAL, C4H, PR proteins), which is associated with biotic stress defense. In contrast, the terpenoid-dominated chemotypes (BORCB, EUCCB, PHYCB) prioritize the biosynthesis of monoterpenes and diterpenes as well as redox homeostasis. Protein–protein interaction networks highlight functional specialization; BORCB up-regulates the expression of enzymes GGPPS and TPS2, which are involved in monoterpene production; PHYCB enhances the activity of diterpene synthases (CPS, KSL) and chloroplast retrograde signaling; EUCCB activates SOD/GST to mitigate oxidative stress. PROCB induced defense hubs (NPR1, WRKY33) mediated by salicylic acid and pathogenesis-related proteins. The study establishes a comprehensive multi-omics resource for a gene–protein–metabolite framework, elucidating the mechanisms of stress resilience of C. burmanni in South China. Full article

Monoterpenoids serve as essential components of plant essential oils and play significant roles in plant growth, development, and insect resistance. Artemisia annua, an important medicinal plant, produces abundant terpenoids. While previous research on A. annua has predominantly focused on artemisinin biosynthesis and its regulation, studies on other terpenoids in this plant have significantly lagged behind. To comprehensively investigate monoterpene biosynthesis in A. annua, we analyzed monoterpenes across its different tissues using optimized extraction and chromatographic conditions developed to enhance sensitivity and resolution in our GC-MS-based analytical method. In A. annua, 31 monoterpenoid compounds were identified. Subsequently, eight candidate monoterpene synthases (mTPS) were characterized in Escherichia coli, confirming their catalytic activity in converting geranyl pyrophosphate (GPP) into distinct monoterpene products. Subcellular localization revealed these TPSs in chloroplasts, consistent with the widely reported chloroplast localization of TPS enzymes. These enzymes were functionally defined as monoterpenoid synthases, collectively responsible for synthesizing 18 monoterpenoid metabolites. Notably, AaTPS13, AaTPS19, and AaTPS20 exhibited substantial product promiscuity. Critically, the AaTPS19 was identified as the first known terpene synthase producing 2-pinanol. These findings systematically elucidate the biosynthesis of monoterpenoids in A. annua and provide key enzymatic elements for metabolic engineering and synthetic biology applications in monoterpenoid production. Full article

Flower fragrance is a crucial ornamental and economic trait of Dendrobium chrysotoxum, and the most abundant and diverse aroma-active compounds are terpenes. Terpene synthase (TPS) is the ultimate enzyme for the biosynthesis of various types of terpenes, and TPS genes were identified as the key regulators governing the spatiotemporal release of volatile terpene compounds. Until recently, the TPS gene family in D. chrysotoxum has remained largely unexplored. Our study characterizes the TPS genes in D. chrysotoxum and identifies 37 DcTPS gene family members. It helped identify the DcTPS genes, gene characteristics, the phylogeny relationship, conserved motif location, gene exon/intron structure, cis-elements in the promoter regions, protein–protein interaction (PPI) network, tissue specific expression and verification of the expression across different flowering stages and floral organs. Three highly expressed DcTPS genes were cloned, and their functions were verified using a transient expressed in tobacco leaves. Further functional verification showed that the proteins encoded by these genes were enzymes involved in monoterpene synthesis, and they were all involved in the synthesis of linalool. This study comprehensively expatiates on the TPS gene family members in D. chrysotoxum for the first time. These data will help us gain a deeper understanding of both the molecular mechanisms and the effects of the TPS genes. Furthermore, the discovery that three TPS-b genes (DcTPS 02, 10, 32) specifically drive linalool-based scent in D. chrysotoxum, will provide new insights for expanding the TPS-b subfamily in orchids and identifying the linalool synthases contributing to orchid fragrance. Full article

Terpenoids have significant biological activity and good clinical efficacy and are important for defence and physiological regulation in plants. Andrographolide and similar labdane-related diterpenoids have been isolated and characterized as the main medicinal constituents of drugs from Andrographis paniculata. To better study the diversity of terpenoids of A. paniculata, a total of 39 ApTPSs were screened, and 27 full-length genes encoding ApTPSs were obtained. The results showed that ApTPS4 could convert GGPP to ent-CPP and that ApTPS5 could convert ent-CPP to kaurene. This study first identified six sesquiterpene synthases with biological activity and also indicated the presence of sesquiterpenes with multiple skeletons in A. paniculata. The increase in the number of ent-copalyl diphosphate synthases and the loss of biological function by most sesquiterpene synthases and monoterpene synthases may explain why diterpenoids are the main specific metabolites in A. paniculata compared with the metabolites produced by AtTPSs found in the Arabidopsis thaliana genome. As revealed by site-directed mutagenesis, 533Val of ApTPS16 is an important site for maintaining the single main product capability, and 534Tyr of ApTPS17 may also be more important. The ApTPS17 Y534V mutation caused it to lose its main biological function. This study characterized a novel ent-copalyl diphosphate synthase and six sesquiterpene synthases. This provided evidence for the existence of other terpenoids and revealed the diversity of chemical components, providing a reference for future pharmacological research for A. paniculata. Full article

Neo-allo-ocimene is a monoterpene which could be applied in pesticides, fragrances, and sustainable polymers. In this study, we mined a terpene synthase, AgTPS40, from the transcriptome of celery leaf tissues. Through sequence and phylogenetic analysis, AgTPS40 was characterized as a monoterpene synthase. The AgTPS40 gene was introduced into a heterologous mevalonate pathway hosted in Escherichia coli to enable terpene production. Gas chromatography–mass spectrometry analysis confirmed that AgTPS40 catalyzes the formation of neo-allo-ocimene, marking the first reported identification of a neo-allo-ocimene synthase. Subsequently, we optimized the fermentation conditions and achieved a yield of 933.35 mg/L in a 1 L shake flask, which represents the highest reported titer of neo-allo-ocimene to date. These results reveal the molecular basis of neo-allo-ocimene synthesis in celery and provide a sustainable way to obtain this compound. Full article

Atractylodes chinensis (DC.) Koidz. is an aromatic and medicinal plant in East Asia. The primary bioactive compounds in this species are sesquiterpenes, particularly β-eudesmol, hinesol, and atractylon. Cultivation techniques require improvement to meet the medicinal demands of this species. In this study, gas chromatography–mass spectrometry analysis of an A. chinensis germplasm showed its essential oil contained various sesquiterpenes, including a high relative ratio of β-eudesmol. Full-length transcriptome profiling of A. chinensis revealed 26 genes related to terpenoid biosynthesis. These genes belonged to 13 gene families, including five in the isopentenyl pyrophosphate synthase gene family and four in the terpene synthase gene family. The functions of the four terpene synthase genes were proposed based on gene expression patterns and phylogenetic relationships: one was thought to encode monoterpene synthase and three to encode sesquiterpene synthase. Based on the results, the central biosynthesis pathways of the major sesquiterpenes in the A. chinensis rhizome were proposed, and three sesquiterpene synthase genes were identified as expressed in the rhizome for the first time. AcHMGR, AcFPPS, and the three sesquiterpene synthase genes were proposed as potential targets for molecular breeding in A. chinensis to enhance its sesquiterpene content. Full article

Terpenes are critical components of the floral fragrance component in Dendrobium chrysotoxum, synthesized by terpene synthase (TPS). Analysis of the D. chrysotoxum genome and transcriptional data revealed that the gene DcTPSb1 was significantly up-regulated during flowering periods, showing a strong correlation with the accumulation of aromatic monoterpenes in the floral components of Dendrobium chrysotoxum. Consequently, the DcTPSb1 gene was selected for further analysis. DcTPSb1 exhibited elevated expression levels in flowers among four organs (roots, stems, leaves, flowers) of D. chrysotoxum, with the highest expression observed during the blooming phase, which aligned with the accumulation of volatile terpenes during flowering. DcTPSb1, located in the chloroplasts, was identified as a member of the TPS-b subfamily associated with monoterpenes synthesis, showing close phylogenetic relationships with homologous proteins in related plant species. An analysis of the promoter region of DcTPSb1 indicated that it may be regulated by methyl jasmonate (MeJA) responsiveness. Functionally, DcTPSb1 was shown to catalyze the conversion of geranyl diphosphate (GPP) to linalool, ocimene, and (-)-α-pinitol in vitro. Overexpression of DcTPSb1 in tobacco resulted in a significant increase in terpenoid release during the blooming stage; however, the up-regulated substances did not include their catalytic products. The classification of DcTPSb1 as a terpene synthase capable of producing multiple products provides valuable insights into the complex biosynthesis of terpenes in orchids. These findings enhance our understanding of the functional diversity of DcTPSb1 and the processes involved in terpene biosynthesis in orchids. Full article

The root of Paeonia lactiflora pall. is a significant component of traditional Chinese medicine, with terpenoids and their glycosides, such as paeoniflorins, serving as key active ingredients known for their anti-inflammatory, hepatoprotective, and analgesic properties. By generating a transcriptome and functionally characterizing 32 terpene synthases (TPSs) from P. lactiflora, we successfully constructed 24 pESC-Trp-PlTPS expression vectors. Through expression in Saccharomyces cerevisiae engineered strains, we identified four mono-TPSs and five sesqui-TPSs that produce 18 compounds, including eight monoterpenes and ten sesquiterpenes in vitro. This includes a bifunctional enzyme (PlTPS22). Additionally, PlTPS21 was characterized as a pinene synthase with α-pinene as its main product. The expression pattern of PlTPS21 aligns closely with the accumulation patterns of paeoniflorins and α-pinene in the plant, suggesting that PlTPS21 is a key enzyme in the biosynthesis of paeoniflorin. Full article

Lauraceae, an important family of Angiospermae, comprises over 2500 species widely distributed in tropical and subtropical evergreen broad-leaved forests. This family is renowned for its rich resource of terpenoids, particularly monoterpenes, sesquiterpenes, and diterpenes. These compounds not only impart specific scents to Lauraceae species but also play crucial roles in plant growth, development, and environmental adaptation. These compounds also possess extensive bioactivities, such as antioxidant, antibacterial, anti-inflammatory, and neuroprotective effects, making them valuable in the fields of perfumery, cosmetics, food, and medicine, and thus holding significant economic value. Recent advancements in high-throughput technologies, especially genomics, transcriptomics, and metabolomics, have significantly advanced our knowledge of the chemical constituents and biosynthetic pathways of terpenoids in Lauraceae species. Such progress has also shed light on the diversity and functionality of the terpene synthases (TPSs) gene family, a key enzyme involved in terpenoid biosynthesis. This paper reviews the latest research findings on the biosynthetic pathways of terpenoids and their key enzyme-encoding gene families in Lauraceae plants. We also analyze the evolutionary patterns of TPS gene family members of four Lauraceae species at the whole-genome level and summarize their mechanisms of action in secondary metabolite synthesis. Furthermore, this paper highlights the current research challenges and proposes prospects, such as the complexity of gene families, the uncertainties in functional predictions, and unclear regulatory mechanisms. Our objective is to provide scientific foundations for the in-depth analysis of terpenoid biosynthesis mechanisms and the development and utilization of natural products in Lauraceae plants. Full article