Different Expression Analysis in Fruit Softening and Ethylene Biosynthetic Pathways in Peaches of Different Flesh Textures

The aim of our study was to assess differences in the expression of genes involved in fruit softening and ethylene biosynthetic pathways under different temperature storage conditions. Different peach cultivars of ‘Xiacui' and ‘Yumyeong', which are stonyhard, ‘Yinhualu', which is softmelting, ‘Hujing Milu', which is hard-melting, and ‘Baby Gold 6', which is non-melting at 80% ripening, were collected as test materials. The results showed that only slight ethylene production was detected after harvesting of ‘Yumyeong' and ‘Xiacui' under either a room temperature(25 °C) or low temperature(4 °C). The fruit firmness of stonyhard cultivars was retained at a high level under room temperature over time, whereas a low temperature induced ‘Yumyeong' fruit to soften. Quantitative real-time PCR results indicated that the PpACS1 gene was highly expressed in soft-melting, hard-melting and non-melting cultivars; however, expression was extremely low in stonyhard peaches. PpACS2 or PpACS3, however,was not detected in all five cultivars. Interestingly, cold treatment significantly decreased firmness along with endo-PG expression obviously upregulated in ‘Yumyeong', but not in ‘Xiacui' peaches. In conclusion, this study revealed that fruit softening of peaches with different flesh textures was closely related to ethylene biosynthesis during the storage period, which was controlled via regulating relevant gene expression levels under different storage temperatures.

Comparative Study on the Expression of Genes Involved in Carotenoid and ABA Biosynthetic Pathway in Response to Salt Stress in Tomato

Carotenoid biosynthetic pathway produces not only pigments that protect photosynthetic system against photo-oxidative damage, but also precursors of abscisic acid, the major hormone regulates stress responses. To understand the response of carotenoid biosynthetic pathway to salt stress, the expression of the genes involved in carotenoid and ABA biosynthesis were compared in cultivated tomato Solanum lycopersicon cv. Moneymaker and its relative wild genotype S. pimpinellifolium （PI365967） together with the contents of carotenoids and ABA. The results showed that 11 of the 15 genes investigated were up-regulated and four unaltered in Moneymaker after 5 h of salt stress; whereas only four genes were up-regulated, four unaltered, and seven down-regulated in PI365967 after stress. Further comparison revealed that 11 salinity-induced genes were expressed significantly lower in Moneymaker than in PI365967 under normal condition, and 8 of them were induced to similar levels after salt stress. In consistence, ABA level was doubled in Moneymaker but kept consistent in PI365967 after salt stress, though the contents of neoxanthin, violaxanthin, [3-carotene, lutein, and total carotenoids were kept unchanged in both species. Since it is known that PI365967 is more tolerant to salt stress than Moneymaker, we proposed that the constitutive high level of carotenoid and ABA biosynthetic pathway under normal growth condition could be benefit to PI365967 for establishing the early response to salt stress. In addition, CrtR-bl and CrtR-b2 that encode [3-carotenoid hydroxylases were the only genes in carotenoid biosynthetic pathway that were up-regulated by salt stress in both species. The CrtR-b2 gene was cloned from both species and no essential difference was found in the encoded amino acid sequences. Transformation of CrtR-b2 to tobacco improved the seed germination under salt stress condition, indicating that the hydrolysis of β-carotenoid is the target of transcriptional regulation of the carotenoid biosynthesis in both tomato cultivar and wild relative.

Genome sequencing provides potential strategies for drug discovery and synthesis

Medicinal plants are renowned for their abundant production of secondary metabolites,which exhibit notable pharmacological activities and great potential for drug development.The biosynthesis of secondary metabolites is highly intricate and influenced by various intrinsic and extrinsic factors,resulting in substantial species diversity and content variation.Consequently,precise regulation of secondary metabolite synthesis is of utmost importance.In recent years,genome sequencing has emerged as a valuable tool for investigating the synthesis and regulation of secondary metabolites in medicinal plants,facilitated by the widespread use of high-throughput sequencing technologies.This review highlights the latest advancements in genome sequencing within this field and presents several strategies for studying secondary metabolites.Specifically,the article elucidates how genome sequencing can unravel the pathways for secondary metabolite synthesis in medicinal plants,offering insights into the functions and regulatory mechanisms of participating enzymes.Comparative analyses of plant genomes allow identification of shared pathways of metabolite synthesis among species,thereby providing novel avenues for obtaining cost-effective biosynthetic intermediates.By examining individual genomic variations,genes or gene clusters associated with the synthesis of specific compounds can be discovered,indicating potential targets and directions for drug development and the exploration of alternative compound sources.Moreover,the advent of gene-editing technology has enabled the precise modifications of medicinal plant genomes.Optimization of specific secondary metabolite synthesis pathways becomes thus feasible,enabling the precise editing of target genes to regulate secondary metabolite production within cells.These findings serve as valuable references and lessons for future drug development endeavors,conservation of rare resources,and the exploration of new resources.

Analyzing the Prebiotic Potential of Glucosamine for Targeting the Gut Microbiome Health

Recognizing the composition and modulation of the microbiome, a viable therapeutic tool for multi-targeted therapy is a new strategy that has recently been explored. Glucosamine (GS) is being studied for its prebiotic potential in addition to being the most abundant and naturally occurring amino monosaccharide. The current study focuses on glucosamine’s prebiotic potential by assessing the stability of various GS concentrations (1% - 5%) in the gastrointestinal tract (GIT) and its ability to be fermented by the gut microbiota. The results showed that GS stimulated the most growth in L. acidophilus even after a longer incubation time than B. bifidum and L. acidophilus growth was concentration-dependent, with maximum growth at 3% with a simultaneous decrease in pH (5.6 - 1.7). The decrease in GS concentration with time also represented the growth of bacterial species, demonstrating the species’ utilization of GS. Furthermore, at 3%, GS also represented the prebiotic index of 1.9. In addition, the concentration of GS in various simulated GIT fluids was estimated in both fast and fed conditions to examine GS stability at various levels in the gut. The results showed that GS remained unaffected and non-digestible in all of the simulated GIT fluids (salivary, gastric, intestinal, and colonic), but there was a slight decrease in GS concentration (2.8%) in the fasted state of gastric fluid due to low pH levels (1.6). As a result, the findings are conclusive and suggest that GS possesses prebiotic properties.

Connexin:a potential novel target for protecting the central nervous system?

Connexin subunits are proteins that form gap junction channels, and play an important role in communication between adjacent cells. This review article discusses the function of connexins/hemichannels/gap junctions under physiological conditions, and summarizes the findings re-garding the role of connexins/hemichannels/gap junctions in the physiological and pathological mechanisms underlying central nervous system diseases such as brain ischemia, traumatic brain and spinal cord injury, epilepsy, brain and spinal cord tumor, migraine, neuroautoimmune disease, Alzheimer’s disease, Parkinson’s disease, X-linked Charcot-Marie-Tooth disease, Peli-zaeus-Merzbacher-like disease, spastic paraplegia and maxillofacial dysplasia. Connexins are considered to be a potential novel target for protecting the central nervous system.

Progress on the Chemical Constituents Derived from Glucosinolates in Maca(Lepidium meyenii)

Maca(Lepidium meyenii Walp.),a famous food supplement,has drawn an unprecedented international interest over the last two decades.It was assumed that glucosinolates,macamides,macaenes,and alkaloids are the main bioactive components of Maca before.Recently,a series of novel thiohydantoins which generally exhibit a variety of activities have been isolated from Maca.This review focuses on the progress on the main bioactive components of Maca and their biosynthetic pathway,which indicates that macamides,thiohydantoins,and some alkaloids may originate from glucosinolates.Interestingly,thiohydantoins from Maca are the first type of thiohydantoin derivatives to be found from a natural source and may contribute to some significant effects of Maca.

Three New Heptelidic Acid Derivatives from the Culture of Mushroom Lentinellus ursinus

Three new heptelidic acid derivatives(1-3)including two new dimeric esters and two known heptelidic acid analogues(4 and 5)were isolated from the solid culture of mushroom Lentinellus ursinus.The structures of new compounds were confirmed by the analysis of NMR and HRESIMS spectroscopic data.The biosynthetic origin of compounds 1-5 was postulated.Compounds 1-5 exhibited no antibacterial activity against Staphylococcus aureus and Escherichia coli at the dose of 100 μM.

Multi-omics analysis reveals the evolutionary origin of diterpenoid alkaloid biosynthesis pathways in Aconitum

Diterpenoid alkaloids(DAs) have been often utilized in clinical practice due to their analgesic and anti-infammatory properties. Natural DAs are prevalent in the family Ranunculaceae, notably in the Aconitum genus. Nevertheless, the evolutionary origin of the biosynthesis pathway responsible for DA production remains unknown.In this study, we successfully assembled a highquality, pseudochromosome-level genome of the DA-rich species Aconitum vilmorinianum(A.vilmorinianum)(5.76 Gb). An A. vilmorinianumspecific whole-genome duplication event was discovered using comparative genomic analysis,which may aid in the evolution of the DA biosynthesis pathway. We identified several genes involved in DA biosynthesis via integrated genomic, transcriptomic, and metabolomic analyses. These genes included enzymes encoding target ent-kaurene oxidases and aminotransferases, which facilitated the activation of diterpenes and insertion of nitrogen atoms into diterpene skeletons, thereby mediating the transformation of diterpenes into DAs. The divergence periods of these genes in A. vilmorinianum were further assessed, and it was shown that two major types of genes were involved in the establishment of the DA biosynthesis pathway. Our integrated analysis offers fresh insights into the evolutionary origin of DAs in A.vilmorinianum as well as suggestions for engineering the biosynthetic pathways to obtain desired DAs.

Functional characterization of CYP81C16 involved in the tanshinone biosynthetic pathway in Salvia miltiorrhiza

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.

De novo nucleotide biosynthetic pathway and cancer

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.

Talaroclauxins A and B:Duclauxin-ergosterol and duclauxin-polyketide hybrid metabolites with complicated skeletons from Talaromyces stipitatus

Talaroclauxins A and B(1 and 2),two novel duclauxin hybrids,were obtained from Talaromyces stipitatus,along with three new(3-5)and one known analogue(6).Their structures were determined by NMR spectroscopy,HRESIMS,single-crystal X-ray diffraction,and quantum chemical calculations.Compound 1 is the first example of duclauxin-ergosterol hybrid featuring an unprecedented dodecacyclic ring system formed via a[4+2]cycloaddition,while compound 2,bearing an unusual 6/6/6/5/6/6/6/6 ring system,is a new member of the rare duclauxin-polyketide hybrid class of natural products.Plausible biosynthetic pathways for 1-6 are proposed.Compound 5 displayed moderate neuroprotective effects in glutamate sodium-induced SH-SY5Y cells.

Recent advances in the biosynthesis of coumarin and its derivatives

Coumarin and its derivatives,presenting in many organisms(plants,fungi,and bacteria),are critical metabolites composed of fused benzene andα-pyrone rings.With unique biological and chemical properties,coumarin derivatives possess great technological potential in the agrochemicals,pharmaceuticals,food,and cosmetic industries.The increasing demand for coumarin derivatives accelerates the research in biological and chemical synthesis to provide stable and scalable sources of coumarins.However,the complex structures and unknown pathways have limited the progress in the biosynthesis of coumarin derivatives.Here,we summarize recent developments and provide a detailed analysis of coumarin derivative biosynthetic pathways in different organisms.

Multiomics analyses of two Leonurus species illuminate leonurine biosynthesis and its evolution

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.

Chromosome-level genome of Himalayan yew provides insights into the origin and evolution of the paclitaxel biosynthetic pathway

Taxus,commonly known as yew,is a well-known gymnosperm with great ornamental and medicinal value.In this study,by assembling a chromosome-level genome of the Himalayan yew(Taxus wallichiana)with 10.9 Gb in 12 chromosomes,we revealed that tandem duplication acts as the driving force of gene family evolution in the yew genome,resulting in the main genes for paclitaxel biosynthesis,i.e.those encoding the taxadiene synthase,P450s,and transferases,being clustered on the same chromosome.The tandem duplication may also provide genetic resources for the nature to sculpt the core structure of taxoids at different positions and subsequently establish the complex pathway of paclitaxel by neofunctionalization.Furthermore,we confirmed that there are two genes in the cluster encoding isoenzymes of a known enzyme in the paclitaxel biosynthetic pathway.The reference genome of the Himalayan yew will serve as a platform for decoding the complete biosynthetic pathway of paclitaxel and understanding the chemodi-versity of taxoids in gymnosperms.

Biosynthetic pathway of terpenoid indole alkaloids in Catharanthus roseus

Catharanthus roseus is one of the most extensively investigated medicinal plants, which can produce more than 130 alkaloids, including the powerful antitumor drugs vinblastine and vincristine. Here we review the recent advances in the biosynthetic pathway of terpenoid indole alkaloids （TIAs） in C. roseus, and the identification and characterization of the corresponding enzymes involved in this pathway. Strictosidine is the central intermediate in the biosynthesis of different TIAs, which is formed by the condensation of secologanin and tryptamine. Secologanin is derived from terpenoid （isoprenoid） biosynthetic pathway, while tryptamine is derived from indole biosynthetic pathway. Then various specific end products are produced by different routes during downstream process. Although many genes and corresponding enzymes have been characterized in this pathway, our knowledge on the whole TIA biosynthetic pathway still remains largely unknown up to date. Full elucidation of TIA biosynthetic pathway is an important prerequisite to understand the regulation of the TIA biosynthesis in the medicinal plant and to produce valuable TIAs by synthetic biological technology.

Rhodauricanol A, an analgesic diterpenoid with an unprecedented5/6/5/7 tetracyclic system featuring a unique16-oxa-tetracyclo[11.2.1.0^(1,5).0^(7,13)]hexadecane core from Rhododendron dauricum

A novel diterpenoid with an unprecedented 5/6/5/7 tetracyclic system, rhodauricanol A(1), five new grayanane-derived diterpenoids, dauricanols A-E(2-6), and five known ones(7-11) were isolated from the flowers of Rhododendron dauricum. Rhodauricanol A(1) possesses a unique 5/6/5/7 tetracyclic ring system featuring a 16-oxa-tetracyclo[11.2.1.0^(1,5).0^(7,13)]hexadecane core. Dauricanols A-C(2-4) are the first1,3-dioxolane conjugates of grayanane diterpenoids and 5-hydroxymethylfurfural and vanillin, respectively, and dauricanols D(5) and E(6) represent the first examples of 6-deoxy-1,5-seco-grayanane diterpenoids. Their structures were determined by spectroscopic methods, quantum chemical calculation including ^(13)C NMR-DP4+ analysis and ECD calculation, and single-crystal X-ray diffraction analysis. Plausible biosynthetic pathways for 1-4 were proposed. All the isolates showed significant analgesic activities,and dauricanols B(3) and C(4) showed more potent analgesic activities than the positive control, morphine.

Natural Sesquiterpenoids, Diterpenoids, Sesterterpenoids, and Triterpenoids with Intriguing Structures from 2017 to 2022

This review covers the isolation,structural determination,plausible biosynthetic pathways,and biological activities of 166 natural terpenoids including 57 sesquiterpenoids,65 diterpenoids,15 sesterterpenoids,and 29 triterpenoids from January 2017 to December2022.

Elucidation of the melitidin biosynthesis pathway in pummelo

Specialized plant metabolism is a rich resource of compounds for drug discovery.The acylated flavonoid glycoside melitidin is being developed as an anti-cholesterol statin drug candidate,but its biosynthetic route in plants has not yet been fully characterized.Here,we describe the gene discovery and functional characterization of a new flavonoid gene cluster(UDP-glucuronosyltransferases(Cg UGTs),1,2rhamnosyltransferase(Cg1,2Rha T),acyltransferases(Cg ATs))that is responsible for melitidin biosynthesis in pummelo(Citrus grandis(L.)Osbeck).Population variation analysis indicated that the tailoring of acyltransferases,specific for bitter substrates,mainly determine the natural abundance of melitidin.Moreover,3-hydroxy-3-methylglutaryl-Co A reductase enzyme inhibition assays showed that the product from this metabolic gene cluster,melitidin,may be an effective anti-cholesterol statin drug candidate.Co-expression of these clustered genes in Nicotiana benthamiana resulted in the formation of melitidin,demonstrating the potential for metabolic engineering of melitidin in a heterologous plant system.This study establishes a biosynthetic pathway for melitidin,which provides genetic resources for the breeding and genetic improvement of pummelo aimed at fortifying the content of biologically active metabolites.

Flavidanolides A and B from Isodon flavidus

A phytochemical investigation on Isodon flavidus led to the isolation of flavidanolide A(1),a rearranged diterpenoid featuring a six/seven/five-membered tricyclic skeleton,together with flavidanolide B(2),an uncommon heterodimeric diterpenoid consisting of a norabietane and a seco-isopimarane monomeric units.Their structures were elucidated by extensive spectroscopic data and single-crystal X-ray diffraction analyses.Their plausible biosynthetic routes were also proposed.In the bioassay,flavidanolide B was found to exhibit good inhibitory effect against lipopolysaccharide(LPS)-induced nitric oxide(NO)production in RAW264.7 cells comparable to positive control pyrrolidinedithiocarbamate ammonium(PDTC),which provided evidence for the medicinal value of I.flavidus as a folk medicine for treating inflammatory diseases.

Hawanoids A–E, unprecedented diterpenoids with PAF-induced platelet aggregation inhibitory activities from the deep-sea-derived fungus Paraconiothyrium hawaiiense

Hawanoids A–E(1–5), five highly cyclized diterpenoids were isolated from the deep-sea-derived fungus Paraconiothyrium hawaiiense FS482. Compounds 1 and 2 possessed an unprecedented tetracyclo[6.6.2.0^(2,7).0^(11,15)]cetane carbon skeleton while 3 and 4 possessed an unusual 11,14-macrocyclic ether moiety in phomactin family. Their structures including the stereo-chemistry were determined through spectroscopic analysis, X-ray diffractions and computational calculations. The plausible biosynthetic pathway was proposed based on the predicted biosynthetic gene cluster. All of the isolated compounds exhibited inhibitory activities against PAF-induced platelet aggregation. The molecular docking study was carried out understand the interaction between the PAF receptor and hawanoids with different skeletons.