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Erianin is one of the most representative bibenzyls with significant inhibitory activity against a wide range of tumor cells. However, the low erianin level in natural materials has severely inhibited its further development in health care. Our aim was to uncover the erianin biosynthetic pathway to lay the foundation for promoting its production. Firstly, we screened and obtained two Dendrobium species (Dendrobium thyrsiflorum stems with lower erianin content and D. chrysotoxum stems with higher erianin content), belonging to the same Dendrobium section (Chrysotoxae). A systematic analysis of bibenzyl structure and content in two stems revealed that gigantol might be an erianin biosynthetic intermediate, which was verified by introducing deuterium-labeled gigantol. Chemical structure analyses indicated that gigantol was modified by two kinds of enzymes (hydroxylases and O-methyltransferases), leading to erianin synthesis. Up-regulated hydroxylases and O-methyltransferases (OMTs) were screened out and were performed by molecular docking simulation experiments. We propose a rational biosynthetic pathway from gigantol to erianin, as well as relevant enzymes involved in the process. Our findings should significantly contribute to comprehensive resolution of the erianin biosynthetic pathway, promote its large-scale industrial production as well as contribute to biosynthesis studies of other bibenzyls. [ABSTRACT FROM AUTHOR]

Pyrrole–imidazole alkaloids (PIAs) are a class of marine sponge derived natural products which have complex carbon frameworks and broad bioactivities. In this study, four new alkaloids, stylimassalins A–B (1–2), 3, and 5, together with two known compounds (4 and 6), were isolated from Stylissa massa. Compounds 2, 4, and 6 are the C-2 brominated analogues of 1, 3, and 5, respectively. Their structures display three different scaffolds, of which scaffold 1 (compounds 1,2) is new. A new biosynthetic pathway from oroidin, through spongiacidin, to latonduine and scaffold 1 was proposed by our group, in which the C12-N13-cleavaged compounds of spongiacidin (scaffold 2), dubbed seco-spongiacidins (3 and 4), are recognized as a key bridged scaffold, to afford PIA analogues (1,2 and 5,6). An anti-inflammatory evaluation in a zebrafish inflammation model induced by copper sulphate (CuSO4) demonstrated that stylimassalins A and B (1 and 2) could serve as a promising lead scaffold for treating inflammation. [ABSTRACT FROM AUTHOR]

Terpenoid dimers of the [4+2] type, which are naturally occurring compounds biosynthetically derived from the [4+2] cycloaddition of two precursors, have garnered considerable attention due to their complex molecular structures, diverse biological activities, and intriguing biosynthetic pathways. We have previously summarized the advancements in three types of [4+2] terpenoid dimers. In this review, we will focus on the lesser‐explored class of [4+2] terpenoid dimers which assembled from two electron‐deficient precursors via the unmatched‐electron‐demand Diels‐Alder reaction (UMEDDA). We will summarize their sources, biological activities, proposed biosynthesis, and chemical syntheses. Finally, a summary and outlook for this fascinating class of compounds will be presented. [ABSTRACT FROM AUTHOR]

Hyperforin is the compound responsible for the effectiveness of St. John's wort (Hypericum perforatum) as an antidepressant, but its complete biosynthetic pathway remains unknown. Gene discovery based on co-expression analysis of bulk RNA-sequencing data or genome mining failed to discover the missing steps in hyperforin biosynthesis. In this study, we sequenced the 1.54-Gb tetraploid H. perforatum genome assembled into 32 chromosomes with the scaffold N50 value of 42.44 Mb. By single-cell RNA sequencing, we identified a type of cell, "Hyper cells", wherein hyperforin biosynthesis de novo takes place in both the leaves and flowers. Through pathway reconstitution in yeast and tobacco, we identified and characterized four transmembrane prenyltransferases (HpPT1–4) that are localized at the plastid envelope and complete the hyperforin biosynthetic pathway. The hyperforin polycyclic scaffold is created by a reaction cascade involving an irregular isoprenoid coupling and a tandem cyclization. Our findings reveal how and where hyperforin is biosynthesized, enabling synthetic-biology reconstitution of the complete pathway. Thus, this study not only deepens our comprehension of specialized metabolism at the cellular level but also provides strategic guidance for elucidation of the biosynthetic pathways of other specializied metabolites in plants. This study reports a chromosome-level high-quality genome assembly of the tetraploid H. perforatum and single-cell RNA sequencing-based chaterization of the biosynthesis of the antidepressant hyperforin. A distinct type of cells , 'Hyper cells', is identified, in which hyperforin biosynthesis takes place. Based on expression at the cellular level, four prenyltransferases are characterized, resulting in the entire pathway elucidation and reconstitution in yeast and tobacco. Hyperforin synthase is a unique plant enzyme with an unprecedented cyclase activity through prenylation. [ABSTRACT FROM AUTHOR]

This document is an editorial published in the journal Frontiers in Plant Science. It discusses recent advancements in the understanding of plant secondary metabolites (PSM) and their biosynthesis. The editorial highlights the use of genomics, transcriptomics, and metabolomics technologies in studying PSM biosynthesis. It also emphasizes the importance of sustainable production and utilization of PSM and introduces a research topic on the subject. The document includes summaries of several research articles that explore the identification and characterization of genes involved in PSM biosynthesis and the development of biotechnological techniques to improve PSM yield. [Extracted from the article]

Mollemycin A (MOMA) is a unique glyco-hexadepsipeptide-polyketide that was isolated from a Streptomyces sp. derived from the Australian marine environment. MOMA exhibits remarkable inhibitory activity against both drug-sensitive and multidrug-resistant malaria parasites. Optimizing MOMA through structural modifications or product enhancements is necessary for the development of effective analogues. However, modifying MOMA using chemical approaches is challenging, and the production titer of MOMA in the wild-type strain is low. This study identified and characterized the biosynthetic gene cluster of MOMA for the first time, proposed its complex biosynthetic pathway, and achieved an effective two-pronged enhancement of MOMA production. The fermentation medium was optimized to increase the yield of MOMA from 0.9 mg L−1 to 1.3 mg L− 1, a 44% boost. Additionally, a synergistic mutant strain was developed by deleting the momB3 gene and overexpressing momB2, resulting in a 2.6-fold increase from 1.3 mg L− 1 to 3.4 mg L− 1 . These findings pave the way for investigating the biosynthetic mechanism of MOMA, creating opportunities to produce a wide range of MOMA analogues, and developing an efficient strain for the sustainable and economical production of MOMA and its analogues. [ABSTRACT FROM AUTHOR]

Chemical investigations of the termite-associated Streptomyces tanashiensis BYF-112 resulted in the discovery of four novel alkaloid derivatives: vegfrecines A and B (1 and 2), exfoliazone A (3), and venezueline H (7), in addition to nine known metabolites (4 − 6 , 8 − 13). The structures of these compounds were elucidated through comprehensive spectroscopic analysis and comparison with existing literature data. Antibacterial assays revealed that viridomycin A (11) exhibited potent antibacterial activity against Staphylococcus aureus , with a zone of inhibition (ZOI) of 12.67 mm, in comparison to a ZOI of 17.67 mm for the positive control gentamicin sulfate. Viridomycin A (11) showed moderate activity against Micrococcus tetragenus and Pseudomonas syringae pv. actinidae , with ZOI values of 15.50 and 14.33 mm, respectively, which were inferior to those of gentamicin sulfate (34.67 and 24.00 mm). Viridomycin F (12) also exhibited moderate antibacterial effects against S. aureus , M. tetragenus , and P. syringae pv. actinidae , with ZOI values of 8.33, 16.50, and 10.83 mm, respectively. Cytotoxicity assays demonstrated that viridobruunine A (5), exfoliazone (6), viridomycin A (11), and X-14881E (13) exhibited significant cytotoxicity against human malignant melanoma (A375), ovarian cancer (SKOV-3), and gastric cancer (MGC-803) cell lines, with IC 50 values ranging from 4.61 to 19.28 μmol·L−1. Furthermore, bioinformatic analysis of the complete genome of S. tanashiensis suggested a putative biosynthetic gene cluster (BGC) responsible for the production of compounds 1−12. These findings indicate that the secondary metabolites of insect-associated S. tanashiensis BYF-112 hold promise as potential sources of novel antibacterial and anticancer agents. [ABSTRACT FROM AUTHOR]

In our antioxidant screening of some Vietnamese plant extracts, the CHCl3-soluble fraction from Calotropis gigantea (L.) W.T.Aiton flowers showed moderate DPPH free radical scavenging activity with an IC50 value of 55.8 μg/mL. Thus, a further phytochemical study was carried out to obtain five alkaloids, including a new β-carboline-type alkaloid, caloside H (1). These known compounds were identified as 5-hydroxy-(2-methoxymethyl)pyridine (2), nicotinic acid (3), p-(acetylamino)phenol (4), and thymine (5). These structures were determined based on the NMR spectroscopic analysis. In antioxidant assay, caloside H at concentration of 100 μM showed DPPH radical scavenging capacity with a percentage of inhibition of 40.2%. In addition, a plausible biosynthetic pathway for the formation of caloside H was proposed based on the Schiff base formation and Mannich-like reaction. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Ergothioneine (EGT) is a high-value natural sulfur-containing amino acid and has been shown to possess extremely potent antioxidant and cytoprotective activities. At present, EGT has been widely used in food, functional food, cosmetics, medicine, and other industries, but its low yield is still an urgent problem to overcome. This review briefly introduced the biological activities and functions of EGT, and expounded its specific applications in food, functional food, cosmetic, and medical industries, introduced and compared the main production methods of EGT and respective biosynthetic pathways in different microorganisms. Furthermore, the use of genetic and metabolic engineering methods to improve EGT production was discussed. In addition, the incorporation of some food-derived EGT-producing strains into fermentation process will allow the EGT to act as a new functional factor in the fermented foods. [ABSTRACT FROM AUTHOR]

Steroidal glycoalkaloids (SGAs) are specialized metabolites produced by hundreds of Solanum species, including important vegetable crops such as tomato, potato, and eggplant. Although it has been known that SGAs play important roles in defense in plants and "anti-nutritional" effects (e.g., toxicity and bitterness) to humans, many of these molecules have documented anti-cancer, anti-microbial, anti-inflammatory, anti-viral, and anti-pyretic activities. Among these, α -solasonine and α -solamargine isolated from black nightshade (Solanum nigrum) are reported to have potent anti-tumor, anti-proliferative, and anti-inflammatory activities. Notably, α -solasonine and α -solamargine, along with the core steroidal aglycone solasodine, are the most widespread SGAs produced among the Solanum plants. However, it is still unknown how plants synthesize these bioactive steroidal molecules. Through comparative metabolomic-transcriptome-guided approach, biosynthetic logic, combinatorial expression in Nicotiana benthamiana , and functional recombinant enzyme assays, here we report the discovery of 12 enzymes from S. nigrum that converts the starting cholesterol precursor to solasodine aglycone, and the downstream α -solasonine, α -solamargine, and malonyl-solamargine SGA products. We further identified six enzymes from cultivated eggplant that catalyze the production of α -solasonine, α -solamargine, and malonyl-solamargine SGAs from solasodine aglycone via glycosylation and atypical malonylation decorations. Our work provides the gene tool box and platform for engineering the production of high-value, steroidal bioactive molecules in heterologous hosts using synthetic biology. This study uncovers the biosynthetic pathways of the most widespread SGA scaffold, solasodine, and three main downstream bioactive SGAs (α -solasonine, α -solamargine, and malonyl-solamargine) in Solanum nigrum (black nightshade) and Solanum melongena (eggplant). The genes and enzymes identified in this study will enables sustainable production of high-value, bioactive steroidal molecules using synthetic biology and metabolic engineering. [ABSTRACT FROM AUTHOR]

Hibiscus sabdariffa L. is a widely cultivated herbaceous plant with diverse applications in food, tea, fiber, and medicine. In this study, we present a high-quality genome assembly of H. sabdariffa using more than 33 Gb of high-fidelity (HiFi) long-read sequencing data, corresponding to ∼20× depth of the genome. We obtained 3 genome assemblies of H. sabdariffa : 1 primary and 2 partially haplotype-resolved genome assemblies. These genome assemblies exhibit N50 contig lengths of 26.25, 11.96, and 14.50 Mb, with genome coverage of 141.3, 86.0, and 88.6%, respectively. We also utilized 26 Gb of total RNA sequencing data to predict 154k, 79k, and 87k genes in the respective assemblies. The completeness of the primary genome assembly and its predicted genes was confirmed by the benchmarking universal single-copy ortholog analysis with a completeness rate of 99.3%. Based on our high-quality genomic resources, we constructed genetic networks for phenylpropanoid and flavonoid metabolism and identified candidate biosynthetic genes, which are responsible for producing key intermediates of roselle-specific medicinal natural products. Our comprehensive genomic and functional analysis opens avenues for further exploration and application of valuable natural products in H. sabdariffa. [ABSTRACT FROM AUTHOR]

Orchids, renowned for their exquisite flowers and diverse growth habits, are a family of monocotyledonous plants with a global distribution. With an estimated 25,000-35,000 species worldwide, they demonstrate exceptional adaptability and ecological significance. Thriving in a wide range of environments, from sea level to high elevations, orchids can be found in tropical forests, semiarid regions, coastal areas, tundra, and even beyond the Arctic Circle. Notably, regions like India and Northeast China, particularly Arunachal Pradesh, are hotspots for orchid diversity, contributing significantly to their rich botanical heritage. For centuries, humans have been captivated by orchids' beauty, medicinal properties, and ecological importance. Beyond their essential primary metabolites, orchids produce a diverse array of secondary metabolites. These compounds, synthesized through specialized metabolic pathways, play crucial roles in plant defense, communication, and adaptation to various environmental stresses. This review explores the classification of secondary metabolites in medicinal orchids, including terpenoids, phenols, and nitrogen compounds, highlighting their structural and functional diversity. Their adaptations to abiotic stresses such as salinity, drought, cold, and heavy metals are discussed, emphasizing the important role of secondary metabolites in plant resilience. To cope with these and other stressors, Orchids, in particular, adapt through osmoregulation and secondary metabolite production, utilizing metabolic pathways like the Krebs cycle, the shikimate pathway, and the mevalonate and MEP pathways. This review provides a comprehensive overview of the significance, diversity, classification, adaptive strategies, and sustainable utilization of orchids through secondary metabolites. By understanding these fascinating plants, we can appreciate their ecological value and contribute to their conservation. [ABSTRACT FROM AUTHOR]

Mescaline, among the earliest identified natural hallucinogens, holds great potential in psychotherapy treatment. Nonetheless, despite the existence of a postulated biosynthetic pathway for more than half a century, the specific enzymes involved in this process are yet to be identified. In this study, we investigated the cactus Lophophora williamsii (Peyote), the largest known natural producer of the phenethylamine mescaline. We employed a multi-faceted approach, combining de novo whole-genome and transcriptome sequencing with comprehensive chemical profiling, enzymatic assays, molecular modeling, and pathway engineering for pathway elucidation. We identified four groups of enzymes responsible for the six catalytic steps in the mescaline biosynthetic pathway, and an N -methyltransferase enzyme that N -methylates all phenethylamine intermediates, likely modulating mescaline levels in Peyote. Finally, we reconstructed the mescaline biosynthetic pathway in both Nicotiana benthamiana plants and yeast cells, providing novel insights into several challenges hindering complete heterologous mescaline production. Taken together, our study opens up avenues for exploration of sustainable production approaches and responsible utilization of mescaline, safeguarding this valuable natural resource for future generations. This study elucidates the mescaline biosynthetic pathway in the entheogenic Peyote cactus through genome-based mining of key enzymes and characterization of their functions. Reconstruction of the mescaline biosynthetic pathway in plant and yeast heterologous systems paves the way for sustainable mescaline production and utilization. [ABSTRACT FROM AUTHOR]

Main conclusion: Transcription factors MhMYB1 and MhMYB2 correlate with monoterpenoid biosynthesis pathway in l-menthol chemotype of Mentha haplocalyx Briq, which could affect the contents of (−)-menthol and (−)-menthone. Mentha haplocalyx Briq., a plant with traditional medicinal and edible uses, is renowned for its rich essential oil content. The distinct functional activities and aromatic flavors of mint essential oils arise from various chemotypes. While the biosynthetic pathways of the main monoterpenes in mint are well understood, the regulatory mechanisms governing different chemotypes remain inadequately explored. In this investigation, we identified and cloned two transcription factor genes from the M. haplocalyx MYB family, namely MhMYB1 (PP236792) and MhMYB2 (PP236793), previously identified by our research group. Bioinformatics analysis revealed that MhMYB1 possesses two conserved MYB domains, while MhMYB2 contains a conserved SANT domain. Yeast one-hybrid (Y1H) analysis results demonstrated that both MhMYB1 and MhMYB2 interacted with the promoter regions of MhMD and MhPR, critical enzymes in the monoterpenoid biosynthesis pathway of M. haplocalyx. Subsequent virus-induced gene silencing (VIGS) of MhMYB1 and MhMYB2 led to a significant reduction (P < 0.01) in the relative expression levels of MhMD and MhPR genes in the VIGS groups of M. haplocalyx. In addition, there was a noteworthy decrease (P < 0.05) in the contents of (−)-menthol and (−)-menthone in the essential oil of M. haplocalyx. These findings suggest that MhMYB1 and MhMYB2 transcription factors play a positive regulatory role in (−)-menthol biosynthesis, consequently influencing the essential oil composition in the l-menthol chemotype of M. haplocalyx. This study serves as a pivotal foundation for unraveling the regulatory mechanisms governing monoterpenoid biosynthesis in different chemotypes of M. haplocalyx. [ABSTRACT FROM AUTHOR]

Docosahexaenoic acid（DHA）, an essential polyunsaturated fatty acid in human body, plays a crucial role in maintaining cardiovascular health, combating cancer, and supporting vision and brain function. Traditional methods of extracting DHA from deep-sea fish oil suffer from strong fish odor and complex processing, driving researchers to explore more efficient and environmentally friendly alternatives. Thraustochytrids, with their rapid growth, low heavy metal contamination, and high DHA content, have emerged as potential microorganisms for industrial DHA production. However, several key issues persist in DHA production through Thraustochytrids fermentation, including enhancing fermentation production and reducing costs. This paper aims to comprehensively review the research status of DHA production through Thraustochytrids fermentation, covering strain screening and improvement, DHA biosynthesis pathways, genetic transformation, metabolic engineering, and fermentation control strategies. The paper first summarizes methods for natural screening and mutagenic improvement of wild-type strains to enhance DHA oil production in Thraustochytrids. It then delves into the research progress of DHA biosynthesis pathways in Thraustochytrids, emphasizing the role of key cofactors in DHA production. Additionally, it outlines the current application status of genetic transformation technology for introducing exogenous DNA into Thraustochytrids cells, offering valuable insights for enhancing genetic transformation efficiency and stability. Regarding DHA metabolism regulation, the paper discusses the promoting effect of nitrogen limitation on DHA synthesis and the impact of temperature and oxygen supply on production efficiency. Finally, it summarizes the main challenges and future development trends in leveraging Thraustochytrids for DHA production, aiming to facilitate their widespread application in pharmaceuticals, nutraceuticals, and food industries, and achieve efficient large-scale production. [ABSTRACT FROM AUTHOR]

Main conclusion: The identification of a functional cinnamoyl-CoA reductase enzyme from Cinnamomum cassia involved in trans-cinnamaldehyde biosynthesis offers the potential for enhancing trans-cinnamaldehyde production through genetic engineering. A significant accumulation of trans-cinnamaldehyde has been found in the bark tissues of C. cassia, used in traditional Chinese medicine. trans-Cinnamaldehyde exhibits various pharmacological properties such as anti-inflammatory, analgesic, and protection of the stomach and the digestive tract. However, further elucidation and characterization of the biosynthetic pathway for trans-cinnamaldehyde is required. In this study, we conducted an integrated analysis of trans-cinnamaldehyde accumulation profiles and transcriptomic data from five different C. cassia tissues to identify the genes involved in its biosynthesis. The transcriptome data we obtained included nearly all genes associated with the trans-cinnamaldehyde pathway, with the majority demonstrating high abundance in branch barks and trunk barks. We successfully cloned four C. cassia cinnamoyl-CoA reductases (CcCCRs), a key gene in trans-cinnamaldehyde biosynthesis. We found that the recombinant CcCCR1 protein was the only one that more efficiently converted cinnamoyl-CoA into trans-cinnamaldehyde. CcCCR1 exhibited approximately 14.7-fold higher catalytic efficiency (kcat/Km) compared to the Arabidopsis thaliana cinnamoyl-CoA reductase 1 (AtCCR1); therefore, it can be utilized for engineering higher trans-cinnamaldehyde production as previously reported. Molecular docking studies and mutagenesis experiments also validated the superior catalytic activity of CcCCR1 compared to AtCCR1. These findings provide valuable insights for the functional characterization of enzyme-coding genes and hold potential for future engineering of trans-cinnamaldehyde biosynthetic pathways. [ABSTRACT FROM AUTHOR]

Abstract Biotin, serving as a coenzyme in carboxylation reactions, is a vital nutrient crucial for the natural growth, development, and overall well-being of both humans and animals. Consequently, biotin is widely utilized in various industries, including feed, food, and pharmaceuticals. Despite its potential advantages, the chemical synthesis of biotin for commercial production encounters environmental and safety challenges. The burgeoning field of synthetic biology now allows for the creation of microbial cell factories producing bio-based products, offering a cost-effective alternative to chemical synthesis for biotin production. This review outlines the pathway and regulatory mechanism involved in biotin biosynthesis. Then, the strategies to enhance biotin production through both traditional chemical mutagenesis and advanced metabolic engineering are discussed. Finally, the article explores the limitations and future prospects of microbial biotin production. This comprehensive review not only discusses strategies for biotin enhancement but also provides in-depth insights into systematic metabolic engineering approaches aimed at boosting biotin production.

Crocins are water-soluble apocarotenoids isolated from the flowers of crocus and gardenia. They exhibit various pharmacological effects, including neuroprotection, anti-inflammatory properties, hepatorenal protection, and anticancer activity. They are often used as coloring and seasoning agents. Due to the limited content of crocins in plants and the high cost of chemical synthesis, the supply of crocins is insufficient to meet current demand. The biosynthetic pathways for crocins have been elucidated to date, which allows the heterologous production of these valuable compounds in microorganisms by fermentation. This review article provides a comprehensive overview of the chemistry, pharmacological activity, biosynthetic pathways, and heterologous production of crocins, aiming to lay the foundation for the large-scale production of these valuable natural products by using engineered microbial cell factories.

Abstract Fungal non-ribosomal peptide synthetase (NRPS)-encoding products play a paramount role in new drug discovery. Fusarium, one of the most common filamentous fungi, is well-known for its biosynthetic potential of NRPS-type compounds with diverse structural motifs and various biological properties. With the continuous improvement and extensive application of bioinformatic tools (e.g., anti-SMASH, NCBI, UniProt), more and more biosynthetic gene clusters (BGCs) of secondary metabolites (SMs) have been identified in Fusarium strains. However, the biosynthetic logics of these SMs have not yet been well investigated till now. With the aim to increase our knowledge of the biosynthetic logics of NPRS-encoding products in Fusarium, this review firstly provides an overview of research advances in elucidating their biosynthetic pathways.

Menispermaceae species, as early‐diverging eudicots, can synthesize valuable benzylisoquinoline alkaloids (BIAs) like bisbenzylisoquinoline alkaloids (bisBIAs) and sinomenines with a wide range of structural diversity. However, the evolutionary mechanisms responsible for their chemo‐diversity are not well understood. Here, a chromosome‐level genome assembly of Menispermum dauricum is presented and demonstrated the occurrence of two whole genome duplication (WGD) events that are shared by Ranunculales and specific to Menispermum, providing a model for understanding chromosomal evolution in early‐diverging eudicots. The biosynthetic pathway for diverse BIAs in M. dauricum is reconstructed by analyzing the transcriptome and metabolome. Additionally, five catalytic enzymes – one norcoclaurine synthase (NCS) and four cytochrome P450 monooxygenases (CYP450s) – from M. dauricum are responsible for the formation of the skeleton, hydroxylated modification, and C‐O/C‐C phenol coupling of BIAs. Notably, a novel leaf‐specific MdCYP80G10 enzyme that catalyzes C2′‐C4a phenol coupling of (S)‐reticuline into sinoacutine, the enantiomer of morphinan compounds, with predictable stereospecificity is discovered. Moreover, it is found that Menispermum‐specific CYP80 gene expansion, as well as tissue‐specific expression, has driven BIA diversity in Menispermaceae as compared to other Ranunculales species. This study sheds light on WGD occurrences in early‐diverging eudicots and the evolution of diverse BIA biosynthesis. [ABSTRACT FROM AUTHOR]

Prunella vulgaris is an important material for Chinese medicines with rosmarinic acid (RA) as its index component. Based on the chromosome-level genome assembly we obtained recently, 51 RA biosynthesis-related genes were identified. Sequence feature, gene expression pattern and phylogenetic relationship analyses showed that 17 of them could be involved in RA biosynthesis. In vitro enzymatic assay showed that PvRAS3 catalyzed the condensation of pcoumaroyl-CoA and caffeoyl-CoA with pHPL and DHPL. Its affinity toward pcoumaroyl- CoA was higher than caffeoyl-CoA. PvRAS4 catalyzed the condensation of p-coumaroyl-CoA with pHPL and DHPL. Its affinity toward pcoumaroyl- CoA was lower than PvRAS3. UPLC and LC-MS/MS analyses showed the existence of RA, 4-coumaroyl-3',4'-dihydroxyphenyllactic acid, 4- coumaroyl-4'-hydroxyphenyllactic acid and caffeoyl-4'-hydroxyphenyllactic acid in P. vulgaris. Generation and analysis of pvras3 homozygous mutants showed significant decrease of RA, 4-coumaroyl-3',4'-dihydroxyphenyllactic acid, 4-coumaroyl-4'-hydroxyphenyllactic acid and caffeoyl-4'- hydroxyphenyllactic acid and significant increase of DHPL and pHPL. It suggests that PvRAS3 is the main enzyme catalyzing the condensation of acyl donors and acceptors during RA biosynthesis. The role of PvRAS4 appears minor. The results provide significant information for quality control of P. vulgaris medicinal materials. [ABSTRACT FROM AUTHOR]

Biotin, serving as a coenzyme in carboxylation reactions, is a vital nutrient crucial for the natural growth, development, and overall well-being of both humans and animals. Consequently, biotin is widely utilized in various industries, including feed, food, and pharmaceuticals. Despite its potential advantages, the chemical synthesis of biotin for commercial production encounters environmental and safety challenges. The burgeoning field of synthetic biology now allows for the creation of microbial cell factories producing bio-based products, offering a cost-effective alternative to chemical synthesis for biotin production. This review outlines the pathway and regulatory mechanism involved in biotin biosynthesis. Then, the strategies to enhance biotin production through both traditional chemical mutagenesis and advanced metabolic engineering are discussed. Finally, the article explores the limitations and future prospects of microbial biotin production. This comprehensive review not only discusses strategies for biotin enhancement but also provides in-depth insights into systematic metabolic engineering approaches aimed at boosting biotin production. [ABSTRACT FROM AUTHOR]

Summary: Transient expression in Nicotiana benthamiana offers a robust platform for the rapid production of complex secondary metabolites. It has proven highly effective in helping identify genes associated with pathways responsible for synthesizing various valuable natural compounds. While this approach has seen considerable success, it has yet to be applied to uncovering genes involved in anthocyanin biosynthetic pathways. This is because only a single anthocyanin, delphinidin 3‐O‐rutinoside, can be produced in N. benthamiana by activation of anthocyanin biosynthesis using transcription factors. The production of other anthocyanins would necessitate the suppression of certain endogenous flavonoid biosynthesis genes while transiently expressing others. In this work, we present a series of tools for the reconstitution of anthocyanin biosynthetic pathways in N. benthamiana leaves. These tools include constructs for the expression or silencing of anthocyanin biosynthetic genes and a mutant N. benthamiana line generated using CRISPR. By infiltration of defined sets of constructs, the basic anthocyanins pelargonidin 3‐O‐glucoside, cyanidin 3‐O‐glucoside and delphinidin 3‐O‐glucoside could be obtained in high amounts in a few days. Additionally, co‐infiltration of supplementary pathway genes enabled the synthesis of more complex anthocyanins. These tools should be useful to identify genes involved in the biosynthesis of complex anthocyanins. They also make it possible to produce novel anthocyanins not found in nature. As an example, we reconstituted the pathway for biosynthesis of Arabidopsis anthocyanin A5, a cyanidin derivative and achieved the biosynthesis of the pelargonidin and delphinidin variants of A5, pelargonidin A5 and delphinidin A5. [ABSTRACT FROM AUTHOR]

In recent years, caffeic acid and its derivatives have received increasing attention due to their obvious physiological activities and wide distribution in nature. In this paper, to clarify the status of research on plant-derived caffeic acid and its derivatives, nuclear magnetic resonance spectroscopy data and possible biosynthetic pathways of these compounds were collected from scientific databases (SciFinder, PubMed and China Knowledge). According to different types of substituents, 17 caffeic acid and its derivatives can be divided into the following classes: caffeoyl ester derivatives, caffeyltartaric acid, caffeic acid amide derivatives, caffeoyl shikimic acid, caffeoyl quinic acid, caffeoyl danshens and caffeoyl glycoside. Generalization of their 13C-NMR and 1H-NMR data revealed that acylation with caffeic acid to form esters involves acylation shifts, which increase the chemical shift values of the corresponding carbons and decrease the chemical shift values of the corresponding carbons of caffeoyl. Once the hydroxyl group is ester, the hydrogen signal connected to the same carbon shifts to the low field (1.1~1.6). The biosynthetic pathways were summarized, and it was found that caffeic acid and its derivatives are first synthesized in plants through the shikimic acid pathway, in which phenylalanine is deaminated to cinnamic acid and then transformed into caffeic acid and its derivatives. The purpose of this review is to provide a reference for further research on the rapid structural identification and biofabrication of caffeic acid and its derivatives. [ABSTRACT FROM AUTHOR]

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Benzylisoquinoline alkaloids (BIAs) represent a significant class of secondary metabolites with crucial roles in plant physiology and substantial potential for clinical applications. CYP82 genes are involved in the formation and modification of various BIA skeletons, contributing to the structural diversity of compounds. In this study, Corydalis yanhusuo, a traditional Chinese medicine rich in BIAs, was investigated to identify the catalytic function of CYP82s during BIA formation. Specifically, 20 CyCYP82-encoding genes were cloned, and their functions were identified in vitro. Ten of these CyCYP82s were observed to catalyze hydroxylation, leading to the formation of protopine and benzophenanthridine scaffolds. Furthermore, the correlation between BIA accumulation and the expression of CyCYP82s in different tissues of C. yanhusuo was assessed their. The identification and characterization of CyCYP82s provide novel genetic elements that can advance the synthetic biology of BIA compounds such as protopine and benzophenanthridine, and offer insights into the biosynthesis of BIAs with diverse structures in C. yanhusuo.Key message: CYP82s identified from Corydalis yanhusuo can catalyze the hydroxylation of different substrates. These newly identified CYP82s provide genetic elements for the production of BIAs by synthetic biology. [ABSTRACT FROM AUTHOR]

Ectoine is an important natural secondary metabolite in halophilic microorganisms. It protects cells against environmental stressors, such as salinity, freezing, drying, and high temperatures. Ectoine is widely used in medical, cosmetic, and other industries. Due to the commercial market demand of ectoine, halophilic microorganisms are the primary method for producing ectoine, which is produced using the industrial fermentation process "bacterial milking." The method has some limitations, such as the high salt concentration fermentation, which is highly corrosive to the equipment, and this also increases the difficulty of downstream purification and causes high production costs. The ectoine synthesis gene cluster has been successfully heterologously expressed in industrial microorganisms, and the yield of ectoine was significantly increased and the cost was reduced. This review aims to summarize and update microbial production of ectoine using different microorganisms, environments, and metabolic engineering and fermentation strategies and provides important reference for the development and application of ectoine. [ABSTRACT FROM AUTHOR]

Fungal non-ribosomal peptide synthetase (NRPS)-encoding products play a paramount role in new drug discovery. Fusarium, one of the most common filamentous fungi, is well-known for its biosynthetic potential of NRPS-type compounds with diverse structural motifs and various biological properties. With the continuous improvement and extensive application of bioinformatic tools (e.g., anti-SMASH, NCBI, UniProt), more and more biosynthetic gene clusters (BGCs) of secondary metabolites (SMs) have been identified in Fusarium strains. However, the biosynthetic logics of these SMs have not yet been well investigated till now. With the aim to increase our knowledge of the biosynthetic logics of NPRS-encoding products in Fusarium, this review firstly provides an overview of research advances in elucidating their biosynthetic pathways. [ABSTRACT FROM AUTHOR]

Pyrethrum (Tanacetum cinerariifolium), a perennial herb within the Tanacetum genus, stands as a crucial source of natural insecticides pyrethrins which have been utilized for centuries. This study delves into the historical utilization of pyrethrum and elucidates the biosynthetic pathways of pyrethrum, uncovering the majority of genes responsible for pyrethrin production. Moreover, pyrethrum flowers and stems are rich in sesquiterpene lactones, known for their antifungal attributes, and they release (E)-β-farnesene, an aphid alarm pheromone that lures predators such as ladybirds. These discoveries emphasize pyrethrum's multifaceted chemical defense against various biotic adversaries and its viability as a companion plant in agricultural settings. Farmers have recognized and begun utilizing pyrethrum in this capacity. The paper underscores the need for further research to thoroughly comprehend and exploit pyrethrum defense strategies for sustainable farming practices, underscoring its potential in ecological and agricultural spheres.

Incomplete understanding of the biosynthetic pathway of the anticancer compound Taxol hinders its production by metabolic engineering. Recent reports by Jiang et al. and other groups now describe the missing steps in Taxol biosynthesis, notably including oxetane ring formation. These findings will promote the sustainable production of Taxol through synthetic biology. [ABSTRACT FROM AUTHOR]

Pyrrole–imidazole alkaloids (PIAs) are a class of marine sponge derived natural products which have complex carbon frameworks and broad bioactivities. In this study, four new alkaloids, stylimassalins A–B (1–2), 3, and 5, together with two known compounds (4 and 6), were isolated from Stylissa massa. Compounds 2, 4, and 6 are the C-2 brominated analogues of 1, 3, and 5, respectively. Their structures display three different scaffolds, of which scaffold 1 (compounds 1,2) is new. A new biosynthetic pathway from oroidin, through spongiacidin, to latonduine and scaffold 1 was proposed by our group, in which the C12-N13-cleavaged compounds of spongiacidin (scaffold 2), dubbed seco-spongiacidins (3 and 4), are recognized as a key bridged scaffold, to afford PIA analogues (1,2 and 5,6). An anti-inflammatory evaluation in a zebrafish inflammation model induced by copper sulphate (CuSO4) demonstrated that stylimassalins A and B (1 and 2) could serve as a promising lead scaffold for treating inflammation.

Withania somnifera, a valuable medicinal plant, synthesizes low molecular weight secondary metabolites known as withanolides with beneficial activities towards several diseases. The study of gene expression profiles and the development of EST datasets have developed an understanding of biosynthetic pathways for withanolides to some extent. However, molecular mechanisms regulating this biosynthetic pathway have yet to be studied in detail. In the present study, two transcription factors, WsMYBL1 and WsMYBL2, with contrasting differences in expression in root and leaf tissues, have been used to demonstrate their role in the biosynthesis of withanolides. Using the Virus-Induced Gene Silencing Approach (VIGS), the silencing of both transcription factors modulated plant phenotype and the expression of genes involved in the terpenoid pathway. This led to changes in total and specific withanolide content in the leaf and root tissues of silenced plants compared to the control. In conclusion, our study suggests the role of WsMYBL1 and WsMYBL2 as negative regulators of the withanolides biosynthesis pathway in Withania somnifera. [ABSTRACT FROM AUTHOR]

Bergenin is a typical carbon glycoside and the primary active ingredient in antitussive drugs widely prescribed for central cough inhibition in China. The bergenin extraction industry relies on the medicinal plant species Bergenia purpurascens and Ardisia japonica as their resources. However, the bergenin biosynthetic pathway in plants remains elusive. In this study, we functionally characterized a shikimate dehydrogenase (SDH), two O-methyltransferases (OMTs), and a C-glycosyltransferase (CGT) involved in bergenin synthesis through bioinformatics analysis, heterologous expression, and enzymatic characterization. We found that BpSDH2 catalyzes the two-step dehydrogenation process of shikimic acid to form gallic acid (GA). BpOMT1 and AjOMT1 facilitate the methylation reaction at the 4-OH position of GA, resulting in the formation of 4-O-methyl gallic acid (4-O-Me-GA). AjCGT1 transfers a glucose moiety to C-2 to generate 2-Glucosyl-4-O-methyl gallic acid (2-Glucosyl-4-O-Me-GA). Bergenin production ultimately occurs in acidic conditions or via dehydration catalyzed by plant dehydratases following a ring- closure reaction. This study for the first time uncovered the biosynthetic pathway of bergenin, paving the way to rational production of bergenin in cell factories via synthetic biology strategies. [ABSTRACT FROM AUTHOR]

Heme is an iron-containing porphyrin compound widely used in the fields of healthcare, food, and medicine. Compared to animal blood extraction, it is more advantageous to develop a microbial cell factory to produce heme. However, heme biosynthesis in microorganisms is tightly regulated, and its accumulation is highly cytotoxic. The current review describes the biosynthetic pathway of free heme, its fermentation production using different engineered bacteria constructed by metabolic engineering, and strategies for further improving heme synthesis. Heme synthetic pathway in Bacillus subtilis was modified utilizing genome-editing technology, resulting in significantly improved heme synthesis and secretion abilities. This technique avoided the use of multiple antibiotics and enhanced the genetic stability of strain. Hence, engineered B. subtilis could be an attractive cell factory for heme production. Further studies should be performed to enhance the expression of heme synthetic module and optimize the expression of heme exporter and fermentation processes, such as iron supply. Key points: • Strengthening the heme biosynthetic pathway can significantly increase heme production. • Heme exporter overexpression helps to promote heme secretion, thereby further promoting excessive heme synthesis. • Engineered B. subtilis is an attractive alternative for heme production. [ABSTRACT FROM AUTHOR]

Ergothioneine (ERG), a rare natural sulfur-containing histidine derivative, has been proved to have strong antioxidant property and many biological functions. Therefore, ERG has been received much more attention from researchers and product developers. Currently, ERG has been widely used in food, cosmetics and medical industries. Research shows that ERG only can be synthesized by a few bacteria and fungi. Plants, animals and humans cannot synthesize ERG directly, but it could be obtained by other sources. ERG can be obtained by bioextraction, chemical synthesis, and biosynthesis. However, because of the low yield and poor production efficiency of the traditional methods (bioextraction and chemical synthesis), the large-scale production and application of ERG is limited. Therefore, there is an urgent need for an efficient, economical, safe and reliable ERG synthesis method to meet market needs. With the rapid development of synthetic biology, the use of genetic engineering, protein engineering and metabolic engineering to improve the ability of ERG biosynthesis has gradually become an increasingly favored method. This paper will elaborate the biological characteristics and functions, briefly introduce the biosynthetic pathways of ERG and application prospects of ERG in food, cosmetics and medical industries, compare the main production methods of ERG, and summarize and sort the research progress of adopting various engineering strategies to produce ERG by biosynthesis in recent years, and propose several engineering strategies on how to use genetic engineering, protein engineering and metabolic engineering to increase the yield of ERG, which aims to provide theoretical reference and research ideas for biosynthesis high-yield of ERG. [ABSTRACT FROM AUTHOR]

The Lamiaceae family is renowned for its terpenoid-based medicinal components, but Leonurus , which has traditional medicinal uses, stands out for its alkaloid-rich composition. Leonurine, the principal active compound found in Leonurus , has demonstrated promising effects in reducing blood lipids and treating strokes. However, the biosynthetic pathway of leonurine remains largely unexplored. Here, we present the chromosome-level genome sequence assemblies of Leonurus japonicus , known for its high leonurine production, and Leonurus sibiricus , characterized by very limited leonurine production. By integrating genomics, RNA sequencing, metabolomics, and enzyme activity assay data, we constructed the leonurine biosynthesis pathway and identified the arginine decarboxylase (ADC), uridine diphosphate glucosyltransferase (UGT), and serine carboxypeptidase-like (SCPL) acyltransferase enzymes that catalyze key reactions in this pathway. Further analyses revealed that the UGT–SCPL gene cluster evolved by gene duplication in the ancestor of Leonurus and neofunctionalization of SCPL in L. japonicus , which contributed to the accumulation of leonurine specifically in L. japonicus. Collectively, our comprehensive study illuminates leonurine biosynthesis and its evolution in Leonurus. Leonurine, the principal active compound in Leonurus , has shown significant potential in lowering blood lipids and treating strokes. By employing genome sequencing and multiomics techniques, this study elucidates the genetic basis of leonurine biosynthesis and uncovers the evolutionary history of this potent alkaloid across Lamiales. The findings offer valuable insights into leonurine biosynthesis and its evolutionary trajectory. [ABSTRACT FROM AUTHOR]

Ferula is a genus of flowering plants known for its edible and medicinal properties. Since ancient times, many species of Ferula have been used in traditional medicine to treat various health issues across countries, such as digestive disorders, respiratory problems, and even as a remedy for headaches and toothaches. In addition, they are also used as a flavoring agent in various cuisines. As the main active ingredients in Ferula, sesquiterpenes and their derivatives, especially sesquiterpene coumarins, sesquiterpene phenylpropanoids, and sesquiterpene chromones, have attracted the attention of scientists due to the diversity of their chemical structures, as well as their extensive and promising biological properties, such as antioxidative, anti-inflammatory, antibacterial properties. However, there has not been a comprehensive review of sesquiterpenes and their derivatives from this plant. This review aims to provide an overview of the chemical structures, biosynthetic pathways, and biological properties of sesquiterpenes and sesquiterpene derivatives from Ferula, which may help guide future research directions and possible application methods for this valuable edible and medicinal plant. [ABSTRACT FROM AUTHOR]

Danshen, the dried roots and rhizomes of Salvia miltiorrhiza Bunge (S. miltiorrhiza), is widely used in the treatment of cardiovascular and cerebrovascular diseases. Tanshinones, the bioactive compounds from Danshen, exhibit a wide spectrum of pharmacological properties, suggesting their potential for future therapeutic applications. Tanshinone biosynthesis is a complex process involving at least six P450 enzymes that have been identified and characterized, most of which belong to the CYP76 and CYP71 families. In this study, CYP81C16, a member of the CYP71 clan, was identified in S. miltiorrhiza. An in vitro assay revealed that it could catalyze the hydroxylation of four para -quinone-type tanshinones, namely neocryptotanshinone, deoxyneocryptotanshinone, and danshenxinkuns A and B. SmCYP81C16 emerged as a potential broad-spectrum oxidase targeting the C-18 position of para -quinone-type tanshinones with an impressive relative conversion rate exceeding 90%. Kinetic evaluations and in vivo assays underscored its highest affinity towards neocryptotanshinone among the tested substrates. The overexpression of SmCYP81C16 promoted the accumulation of (iso)tanshinone in hairy root lines. The characterization of SmCYP81C16 in this study accentuates its potential as a pivotal tool in the biotechnological production of tanshinones, either through microbial or plant metabolic engineering. [ABSTRACT FROM AUTHOR]

Holothurians are the dominant megabenthic deposit feeders in the Peru Basin (SE Pacific) and feed to various degrees of selectivity on a heterogenous pool of sedimentary detritus, but drivers of feeding selectivity and diet preferences for most holothurian species are unknown. This study reconstructs the diets of 13 holothurian species of the orders Elasipodida, Holothuriida, and Synallactida. Bulk stable isotope analyses (δ13C, δ15N) of holothurian body wall and gut wall tissues, gut contents, and feces were combined with compound-specific stable isotope analyses of amino acids, phospholipid-derived fatty acids, and neutral-lipid-derived fatty acids in the body wall. We further assessed how holothurians in the Peru Basin partition their resources and calculated how much of the daily particulate organic carbon (POC) flux to the area is ingested by them using information about gut contents of nine species. To assess the dependence of holothurians on fresh phytodetritus, we performed in situ pulse-chase experiments using 13C- and 15N-enriched phytodetritus. By measuring the uptake of this phytodetritus in fatty acids and amino acids and by comparing it with the presence of these compounds in the sediment, we calculated net accumulation and net deficiency for specific fatty acids and amino acids and discussed how climate change might affect the dependence on specific compounds. A Sørensen–Dice coefficient-based cluster analysis using data from trophic levels, levels of heterotrophic re-synthesis of amino acids, feeding selectivity, and food sources/diet suggested two major trophic groups with two optional subgroups each. Species-specific traits of locomotion, tentacle morphology, and gut structure likely allow resource partitioning and differences in selectivity among the holothurians, of which a subpopulation of 65% of all specimens can ingest 4 to 27% of the daily POC flux to the Peru Basin. Holothurians are specifically dependent on the uptake of arachidonic acid from phytodetritus, while most essential amino acids are available in the Peru Basin in sufficient concentrations. [ABSTRACT FROM AUTHOR]

Abstract Menispermaceae species, as early‐diverging eudicots, can synthesize valuable benzylisoquinoline alkaloids (BIAs) like bisbenzylisoquinoline alkaloids (bisBIAs) and sinomenines with a wide range of structural diversity. However, the evolutionary mechanisms responsible for their chemo‐diversity are not well understood. Here, a chromosome‐level genome assembly of Menispermum dauricum is presented and demonstrated the occurrence of two whole genome duplication (WGD) events that are shared by Ranunculales and specific to Menispermum, providing a model for understanding chromosomal evolution in early‐diverging eudicots. The biosynthetic pathway for diverse BIAs in M. dauricum is reconstructed by analyzing the transcriptome and metabolome. Additionally, five catalytic enzymes – one norcoclaurine synthase (NCS) and four cytochrome P450 monooxygenases (CYP450s) – from M. dauricum are responsible for the formation of the skeleton, hydroxylated modification, and C‐O/C‐C phenol coupling of BIAs. Notably, a novel leaf‐specific MdCYP80G10 enzyme that catalyzes C2′‐C4a phenol coupling of (S)‐reticuline into sinoacutine, the enantiomer of morphinan compounds, with predictable stereospecificity is discovered. Moreover, it is found that Menispermum‐specific CYP80 gene expansion, as well as tissue‐specific expression, has driven BIA diversity in Menispermaceae as compared to other Ranunculales species. This study sheds light on WGD occurrences in early‐diverging eudicots and the evolution of diverse BIA biosynthesis.

Abstract Sarcandra glabra (Thunb.) Nakai is a perennial evergreen herb categorised within the Sarcandra Gardner genus under the Chloranthaceae family. Indigenous to tropical and subtropical regions of East Asia and India, this species is extensively distributed across China, particularly in the southern regions (Sichuan, Yunnan, and Jiangxi). In addition to its high ornamental value, S. glabra has a rich history of use in traditional Chinese medicine, evident through its empirical prescriptions for various ailments like pneumonia, dysentery, fractures, bruises, numbness, amenorrhea, rheumatism, and other diseases. Besides, modern pharmacological studies have revealed various biological activities, such as antitumour, anti-bacterial, anti-viral anti-inflammatory and immunomodulatory effects. The diverse chemical constituents of S. glabra have fascinated natural product researchers since the 1900s. To date, over 400 compounds including terpenoids, coumarins, lignans, flavonoids, sterols, anthraquinones, organic acids, and organic esters have been isolated and characterised, some featuring unprecedented structures. This review comprehensively examines the current understanding of S. glabra’s phytochemistry and pharmacology, with emphasis on the chemistry and biosynthesis of its unique chemotaxonomic marker, the lindenane-type sesquiterpenoids. Graphical Abstract

The aroma of horticultural plants is produced by volatile organic compounds (VOCs) in their cells, mainly composed of esters, alcohols, aldehydes, ketones, ethers, terpenoids, alkanes and other substances, which is an important quality index. Horticultural plants are mainly divided into fruit trees, vegetables, flowers and tea. VOCs in different types of horticultural plants vary. This is an important factor leading to the diversity of flavors of horticultural products. The main factors affecting VOCs in horticultural plants include gene expression, cultivation conditions and postharvest treatment. The expression of different genes is an important reason for the VOCs differences between different horticultural plants. Cultivation conditions such as light intensity, cultivation environment, fertilizer application and varieties of grafted stocks directly or indirectly affect the synthesis of VOCs in horticultural plants. Storage temperature and ethylene content after harvest are important factors affecting VOCs. The VOCs synthesis pathways mainly include fatty acid pathway, amino acid pathway, shikimate/phenylpropanoid pathway, terpenoid pathway, lipoxygenase (LOX) pathway and etc. Straight chain aldehydes, alcohols and esters are mainly produced by the lipoxygenase (LOX) pathway and β-oxidation pathway, branched chain aldehydes, alcohols and esters are produced by the amino acid pathway, terpenoids are produced by the terpenoid pathway, and polyphenolic compounds are produced by the shikimic acid/phenylpropanoid pathway. This review summarizes the components of aroma substances, the factors affecting aroma volatilization and the biosynthesis regulation of volatile aroma compounds in horticultural plants. The problems of less studies on physiological function of aroma-related enzymes, genetic control of aroma and its influencing factors, aroma substances and metabolic mechanism of horticultural plants are proposed, and the future research directions are put farward.

De novo nucleotide biosynthetic pathway is a highly conserved and essential biochemical pathway in almost all organisms. Both purine nucleotides and pyrimidine nucleotides are necessary for cell metabolism and proliferation. Thus, the dysregulation of the de novo nucleotide biosynthetic pathway contributes to the development of many human diseases, such as cancer. It has been shown that many enzymes in this pathway are overactivated in different cancers. In this review, we summarize and update the current knowledge on the de novo nucleotide biosynthetic pathway, regulatory mechanisms, its role in tumorigenesis, and potential targeting opportunities.

In recent years, breeding work and planting techniques pursuing high yield and disease resistance, and post-harvest treatments such as low-temperature storage have caused a great decline in tomato flavor quality. How to improve the flavor quality of tomato is an urgent problem to be solved. The flavor quality of tomato mainly involves sweet and sour taste and aroma, which is closely related to sugars, organic acids and volatile flavor substances in the fruit, and losses of volatile flavor substances are the key factor causing the deterioration of tomato flavor quality. In this paper, the flavor composition of tomato, the synthesis pathways of tomato flavor compounds and the factors affecting tomato flavor are systematically reviewed in order to provide theoretical guidance for improving the flavor quality of tomato.