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PubMed2025

Transcriptome and metabolome profiling of the medicinal plant Dictamnus dasycarpus reveal key genes involved in quinoline alkaloids biosynthesis and limonoids biosynthesis.

BACKGROUND: As a member of Rutaceae family, Dictamnus dasycarpus Turcz. represents a prominent medicinal plant and economically valuable crop in traditional Chinese medicine, and is renowned for its therapeutic efficacy in treating dermatological conditions. The pharmacological activity of this species primarily stems from quinoline alkaloids and limonoids, which predominantly accumulate in the taproots. These bioactive compounds serve as critical determinants of both medicinal quality and crop yield. Nevertheless, the molecular mechanisms governing their dynamic accumulation patterns in D. dasycarpus taproots remain uncertain, and the fundamental biochemical basis underlying this process has yet to be elucidated. RESULTS: Metabolomic and transcriptomic analyses were carried out to investigate metabolites and gene expression during the development of D. dasycarpus taproots. The differentially accumulated secondary metabolites (DAMs) mainly included quinoline alkaloids and limonoids, and the accumulation of total alkaloids and total limonoids primarily occurred during 2- and 4-year-old. The differentially expressed genes (DEGs) are related to Glycolysis/Gluconeogenesis, Phenylalanine, tyrosine and tryptophan biosynthesis, Tryptophan metabolism, Terpenoid backbone biosynthesis, Sesquiterpenoid and triterpenoid biosynthesis, which had a close relationship with the accumulation of quinoline alkaloids and limonoids. Furthermore, we identified that some CYP450s, acetyltransferase, isomerase, 2-ODDs and others may play an important role in the process of producing quinoline alkaloids and limonoids. CONCLUSION: These results elucidated the molecular mechanisms and metabolic changes underlying the dynamic accumulation process occurring in the taproots of D. dasycarpus. These findings provide a theoretical basis for the planting and harvesting of D. dasycarpus.

Limonins↗
PubMed2026

A chromosome-scale genome of Capsicum pubescens provides insights into candidate terpene-associated gene clusters and pan variation of terpene synthases.

A chromosome-scale genome of Capsicum pubescens and comparative pan-TPS analysis support structural characterization and gene-level prioritization of a chromosome-9 terpene-associated candidate locus in this accession. Capsicum pubescens is one of the five domesticated Capsicum species, mainly cultivated in mid- to high-elevation regions of the Americas. Despite its distinctive morphology and fruit traits, genomic resources for C. pubescens remain less developed than those for the widely cultivated C. annuum. Here, we assembled a chromosome-scale reference genome for accession HNUCP0001, spanning 3.70 Gb with a scaffold N50 of 278.01 Mb. Comparative genomics revealed 679 significantly expanded gene families enriched in sesquiterpenoid and triterpenoid biosynthesis. Genome-wide biosynthetic gene-cluster mining identified multiple terpene-associated candidate loci, which were subsequently prioritized using genome-derived structural criteria and Capsicum pubescens-specific expression evidence. Subsequently, we curated the terpene synthase (TPS) repertoire and, across 16 Capsicum genomes, resolved 36 TPS orthogroups with pronounced presence/absence variation, highlighting dynamic lineage-specific diversification. Together, these analyses establish HNUCP0001 as an accession-specific genomic resource and provide a comparative framework for prioritizing terpene-associated TPS genes and candidate BGCs in Capsicum. These candidate loci, together with accession-level transcriptomic and metabolomic evidence, offer testable hypotheses for future functional studies of specialized terpenoid metabolism in C. pubescens.

Alkyl and Aryl Transferases↗
PubMed2026

Cucurbitacins in Plant-Insect Interactions: Biosynthesis, Regulation, Ecological Functions, and Prospects for Crop Protection.

Cucurbitacins are highly oxygenated tetracyclic triterpenoids characterized by intense bitterness, substantial structural diversity, and important consequences for plant-herbivore interactions. Although best known from Cucurbitaceae, cucurbitacins and related cucurbitane-type metabolites also occur in phylogenetically distant herbaceous and woody plants. Genetic and biochemical studies have validated several core biosynthetic steps, including cucurbitadienol formation by oxidosqualene cyclases and subsequent modification by cytochrome P450 monooxygenases, acyltransferases, and glycosyltransferases. Tissue-preferential basic helix-loop-helix transcription factors constitute the best-characterized regulatory layer, whereas the evidence supporting accessory regulators, transporters, and environmental responses varies from functional validation to transcriptomic or genomic prediction. From the plant perspective, cucurbitacins deter feeding or impair performance in many generalist and non-adapted herbivores. By contrast, their use as host-recognition cues and feeding stimulants by specialist diabroticite beetles reflects evolved herbivore adaptations involving perception, tolerance, metabolism, or sequestration rather than a second defensive function of the plant trait. Herbivore-induced cucurbitacin accumulation has been demonstrated in particular systems, although its regulatory mechanisms and ecological generality remain unresolved. Unlike previous reviews centered primarily on cucurbitacin chemistry, pharmacological activity, or individual biosynthetic pathways, this review integrates evidence-graded pathway reconstruction and molecular regulation with taxonomic distribution, insect adaptation, domestication, and agroecological consequences. Mechanistically, this review traces how scaffold formation, oxidative tailoring, conjugation, tissue-specific regulation, and transport give rise to contrasting ecological outcomes through herbivore-specific perception, tolerance, metabolism, and sequestration. We conclude that uniformly increasing or eliminating cucurbitacins is unlikely to provide broadly effective crop resistance because either direction may favor a different herbivore group. Future priorities include functional validation of candidate genes, spatially resolved metabolite analysis, comparative investigation of non-cucurbit lineages, and field evaluation involving generalist and specialist herbivores, crop quality, and non-target organisms. These advances will support context-specific fruit-quality improvement, behavioral pest control, and integrated pest management strategies rather than cucurbitacin manipulation as a stand-alone resistance approach.

agroecology↗
PubMed2026

Functional characterization of SHC-like triterpene cyclase genes in azole response and virulence-related traits of Aspergillus fumigatus.

Aspergillus fumigatus is a major opportunistic fungal pathogen, and increasing azole resistance poses a challenge for aspergillosis treatment. Squalene is an upstream precursor of ergosterol biosynthesis and may also be utilized by SHC-like triterpene cyclases, suggesting a potential link between squalene-associated metabolism, membrane adaptation, and azole response. However, the roles of SHC-like triterpene cyclase genes in A. fumigatus remain unclear. Here, we characterized three candidates, shc1, shc2, and shc3, using comparative bioinformatic analysis, gene deletion, phenotypic assays, azole susceptibility testing, transcriptomics, and host-interaction models. Sequence, genomic-context, phylogenetic, and structural analyses suggested divergence among the three candidates. Individual shc deletion caused limited effects on vegetative growth, whereas loss of shc1 mildly reduced susceptibility to voriconazole and posaconazole, as reflected by twofold MIC increases and lower inhibition rates. Transcriptomic analysis revealed distinct remodeling patterns, with Δshc3 showing the broadest transcriptional changes despite no detectable MIC shift. Targeted metabolite profiling and PI uptake analysis further supported an association between shc deletion, sterol/hopane-type triterpenoid balance, and membrane-associated properties. shc deletion also altered epithelial cell interaction phenotypes, while Δshc1 showed reduced lethality in Galleria mellonella. In clinical isolates, elevated shc transcription was associated with azole-resistant backgrounds. These findings suggest functional diversification among SHC-like triterpene cyclase genes and indicate that shc1 may contribute to azole-associated adaptation and virulence-related traits in A. fumigatus.

Aspergillus fumigatus↗
PubMed1975

Effect of sterol replacement in vivo on the fatty acid composition of Tetrahymena.

The addition of ergosterol to cultures of Tetrahymena pyriformis results in (a) the accumulation of the sterol by the cells; (b) the inhibition of the synthesis of the pentacyclic triterpenoid alcohol, tetrahymanol; (c) the replacement of tetrahymanol by ergosterol in the ciliate membranes. The dry weight and lipid content of sterol-supplemented ciliates did not differ from the controls. Examination of the lipid classes revealed no change in composition except for a higher content of ergosterol in supplemented cells than tetrahymanol in control cultures. The relative proportions of triglycerides, the major classes of polar lipids, 1-alkyl phospholipids and phosphonolipids, appeared unaltered. A complex array of fatty acids is found in this ciliate. Several acids not reported previously in this organism were isolated and identified, and the novel fatty acid 18:2 delta 6, 11, was found in substantial amounts. Ergosterol supplementation altered the proportions of the fatty acids, although not all lipid classes were affected to the same extent. The changes noted were of three general types: (a) a shortening of the fatty acyl chain length in the acids of the normal series; (b) a lowering in the degree of unsaturation; (c) a discrimination between two isomers of lionoleate, 18:2 delta 6, 11 and 18:2 delta 9, 12. The former is elevated in the presence of ergosterol while the latter is depressed. Each class of polar lipids has a distinctive fatty acid composition. Among the glycerophospholipids, cardiolipin and phosphatidylcholine were least affected, while the mixture of 1-alkyl-2-acyl-sn-glycero-3-(2-aminoethyl)-phosphonate and 1,2-diacyl-sn-glycero-3-(2-aminoethyl)-phosphonate was most markedly altered. Sphingolipid fatty acid composition was influenced by ergosterol supplementation. Two changes were noted: (a) a reduction in the length of the hydrocarbon chain; (b) an increase in the proportion of alpha-hydroxy acids. The impact of ergosterol on the fatty acid composition of the polar lipids may be on fatty acid biosynthesis, on incorporation of fatty acids, or on the turnover rates of the fatty acyl groups. Ergosterol is concentrated in the ciliary (limiting) membrane, as are the polar lipids most affected. This localization allows the speculation that the change in fatty acid composition may be related to the maintenance of optimal membrane properties upon the introduction of the sterol.

Animals↗