Search Results (25)

Microorganisms exert antagonistic effects on pathogens through different mechanisms, thereby achieving biological control of plant diseases. Many Burkholderia strains can produce complex secondary metabolites and substances that have toxic effects on host cells. The phage tail-like bacteriocins (tailocins) is a compound with antibacterial activity. However, its function in B. multivorans has not yet been reported. This article explores the ability of B. multivorans WS-FJ9 to antagonise plant pathogenic fungi and oomycetes, screening the potential tailocins in the strain WS-FJ9 and verifying their function, to reveal its novel antimicrobial mechanisms. We found that WS-FJ9 had strong antagonistic effects on the plant pathogenic fungi Phomopsis macrospore and Sphaeropsis sapinea, and the pathogenic oomycete Phytophthora cinnamomi. The phage tail-like protein Bm_67459 was predicted from the WS-FJ9 strain genome. The Bm_67459 cDNA encoded 111 amino acid sequence, and the relative molecular weight was approximately 11.69 kDa, the theoretical isoelectric point (pI) was 5.49, and it was a hydrophilic protein. Bm_67459 had no transmembrane helix region or signal peptide, and it belonged to the Phage_TAC_7 super family. qRT-PCR results showed that Bm_67459 gene expression was significantly upregulated during contact between WS-FJ9 and P. cinnamomi. The purified Bm_67459 protein significantly inhibited P. cinnamomi mycelial growth at 10 μg·mL⁻¹. In summary, the WS-FJ9 strain had broad-spectrum anti-phytopathogenic activity, and the tailocin Bm_67459 was an important effector against the plant pathogen P. cinnamomi, which helps to reveal the antagonistic mechanism of this strain at the molecular level and provides excellent strain resources for the biological control of plant diseases. Full article

In the present study, an unknown fungal strain was isolated from the fruiting body of a local Dryad’s Saddle mushroom (Polyporaceae). The molecular identification of the isolate was performed by amplification of the ITS1-5.8S-ITS2 region and the strain was identified with 100.00% confidence as Epicoccum nigrum. The morphological characteristics, including the distinctive colony pigmentation, conidiophore structure, and conidial shape, were determined to ensure comprehensive characterization of the fungus. The modeling of the kinetics of the growth process was conducted with the applying the logistic curve model and the reverse autocatalytic growth model, and the concentrations of the compounds in the nutrient medium required for the E. nigrum development were established. Controlled submerged cultivation was carried out for cultural liquid obtaining, which was further used for the evaluation of the biological activities. The untreated cultural liquid demonstrated antimicrobial activity against Sclerotinia sclerotiorum where the minimal inhibitory concentration was 1.25 mg/mL. Antimicrobial activity was also detected toward Botrytis cinerea (2.5 mg/mL) and Aspergillus flavus (2.5 mg/mL). The direct utilization of crude cultural liquid for phytopathogenic control is a sustainable approach that will provide the opportunity for the development of an environmentally friendly manufacturing process. Full article

Background/Objectives: Cork oak forests have been declining due to fungal pathogens such as Diplodia corticola. However, the preventive fungicides against this fungus have restricted use due to the deleterious effects on human health and the environment, prompting the need for sustainable alternatives. Here, we describe the antifungal activity of an aqueous extract of Hedera helix L. leaves (HAE) against D. corticola and the possible mechanism of action. Results/Methods: The chemical analysis revealed compounds like the saponin hederacoside C, quinic acid, 5-O-caffeoylquinic acid, rutin, and glycoside derivatives of quercetin and kaempferol, all of which have been previously reported to possess antimicrobial activity. Remarkable in vitro antifungal activity was observed, reducing radial mycelial growth by 70% after 3 days of inoculation. Saccharomyces cerevisiae mutants, bck1 and mkk1/mkk2, affected the cell wall integrity signaling pathway were more resistant to HAE than the wild-type strain, suggesting that the extract targets kinases of the signaling pathway, which triggers toxicity. The viability under osmotic stress with 0.75 M NaCl was lower in the presence of HAE, suggesting the deficiency of osmotic protection by the cell wall. Conclusions: These results suggest that ivy extracts can be a source of new natural antifungal agents targeting the cell wall, opening the possibility of preventing fungal infections in cork oaks and improving the cork production sector using safer and more sustainable approaches. Full article

The spurge Euphorbia characias is known for its latex, which is rich in antioxidant enzymes and anti-phytopathogen molecules. In this study, we identified a novel polyubiquitin protein in the latex and leaves, leading to the first molecular characterization of its coding gene and expressed protein in E. characias. Using consensus-degenerate hybrid oligonucleotide primers (CODEHOP) and rapid amplification of cDNA ends (5′/3′-RACE), we reconstructed the entire open reading frame (ORF) and noncoding regions. Our analysis revealed that the polyubiquitin gene encodes five tandemly repeated sequences, each coding for a ubiquitin monomer with amino acid variations in four of the five repeats. In silico studies have suggested functional differences among monomers. Gene expression peaked during the summer, correlating with high temperatures and suggesting a role in heat stress response. Western blotting confirmed the presence of polyubiquitin in the latex and leaf tissues, indicating active ubiquitination processes. These findings enhance our understanding of polyubiquitin’s regulatory mechanisms and functions in E. characias, highlighting its unique structural and functional features. Full article

Co-cultivation, coupled with the OSMAC approach, is considered an efficient method for expanding microbial chemical diversity through the activation of cryptic biosynthetic gene clusters (BGCs). As part of our project aiming to discover new fungal metabolites for crop protection, we previously reported five polyketides, the macrolides dendrodolides E (1) and N (2), the azaphilones spiciferinone (3) and 8α-hydroxy-spiciferinone (4), and the bis-naphtho-γ-pyrone cephalochromin (5) from the solid Potato Dextrose Agar (PDA) co-culture of two marine sediment-derived fungi, Plenodomus influorescens and Pyrenochaeta nobilis. However, some of the purified metabolites could not be tested due to their minute quantities. Here we cultivated these fungi (both axenic and co-cultures) in liquid regime using three different media, Potato Dextrose Broth (PDB), Sabouraud Dextrose Broth (SDB), and Czapek-Dox Broth (CDB), with or without shaking. The aim was to determine the most ideal co-cultivation conditions to enhance the titers of the previously isolated compounds and to produce extracts with stronger anti-phytopathogenic activity as a basis for future upscaled fermentation. Comparative metabolomics by UPLC-MS/MS-based molecular networking and manual dereplication was employed for chemical profiling and compound annotations. Liquid co-cultivation in PDB under shaking led to the strongest activity against the phytopathogen Phytophthora infestans. Except for compound 1, all target compounds were detected in the co-culture in PDB. Compounds 2 and 5 were produced in lower titers, whereas the azaphilones (3 and 4) were overexpressed in PDB compared to PDA. Notably, liquid PDB co-cultures contained meroterpenoids and depside clusters that were absent in the solid PDA co-cultures. This study demonstrates the importance of culture regime in BGC regulation and chemical diversity of fungal strains in co-culture studies. Full article

A series of new fluorinated 1-benzylisatins was synthesized in high yields via a simple one-pot procedure in order to explore the possible effect of ortho-fluoro (3a), chloro (3b), or bis-fluoro (3d) substitution on the biological activity of this pharmacophore. Furthermore, the new isatins could be converted into water-soluble isatin-3-hydrazones using their acid-catalyzed reaction with Girard’s reagent P and its dimethyl analog. The cytotoxic action of these substances is associated with the induction of apoptosis caused by mitochondrial membrane dissipation and stimulated reactive oxygen species production in tumor cells. In addition, compounds 3a and 3b exhibit platelet antiaggregation activity at the level of acetylsalicylic acid, and the whole series of fluorine-containing isatins does not adversely affect the hemostasis system as a whole. Among the new water-soluble pyridinium isatin-3-acylhydrazones, compounds 7c and 5c,e exhibit the highest antagonistic effect against phytopathogens of bacterial and fungal origin and can be considered useful leads for combating plant diseases. Full article

The development of effective and ecofriendly agrochemicals, including bactericides, fungicides, insecticides, and nematicides, to control pests and prevent plant diseases remains a key challenge. Nanotechnology has provided opportunities for the use of nanomaterials as components in the development of anti-phytopathogenic agents. Indeed, inorganic-based nanoparticles (INPs) are among the promising ones. They may play an effective role in targeting and killing microbes via diverse mechanisms, such as deposition on the microbe surface, destabilization of cell walls and membranes by released metal ions, and the induction of a toxic mechanism mediated by the production of reactive oxygen species. Considering the lack of new agrochemicals with novel mechanisms of action, it is of particular interest to determine and precisely depict which types of INPs are able to induce antimicrobial activity with no phytotoxicity effects, and which microbe species are affected. Therefore, this review aims to provide an update on the latest advances in research focusing on the study of several types of engineered INPs, that are well characterized (size, shape, composition, and surface features) and show promising reactivity against assorted species (bacteria, fungus, virus). Since effective strategies for plant protection and plant disease management are urgently needed, INPs can be an excellent alternative to chemical agrochemical agents as indicated by the present studies. Full article

Phytopathogens, such as phytopathogenic bacteria, fungi, and nematodes, have caused great losses of crops every year, seriously threatening human health and agricultural production. Moreover, marine-derived fungi are abundant sources of structurally unique and bioactive secondary metabolites that could be potential candidates for anti-phytopathogenic drugs. One new sulfoxide-containing bisabolane sesquiterpenoid aspersydosulfoxide A (1) and nine known analogues (2–10) were isolated from the marine-derived A. sydowii LW09. The absolute configuration of the sulfur stereogenic center in 1 was determined by electronic circular dichroism (ECD) calculations. Compound 5 showed inhibition activity against Pseudomonas syringae, with a minimum inhibitory concentration (MIC) value of 32 μg/mL, whereas, compounds 2, 7, and 8 showed antibacterial activities toward Ralstonia solanacarum, with the same MIC value at 32 μg/mL. Meanwhile, compounds 3, 7, and 8 inhibited the fungal spore germination of Fusarium oxysporum, with the half maximal effective concentration (EC₅₀) values of 54.55, 77.16, and 1.85 μg/mL, respectively, while compounds 2, 3, 7, and 8 inhibited the fungal spore germination of Alternaria alternata, which could be induced by vacuolization of germ tubes, with EC₅₀ values of 34.04, 44.44, 26.02, and 46.15 μg/mL, respectively. In addition, compounds 3, 7, and 8 exhibited nematicidal activities against Meloidogyne incognita second-stage juveniles (J2s). In addition, compound 8 possessed the strongest nematicidal activity of nearly 80% mortality at 60 h with the half lethal concentration (LC₅₀) values of 192.40 μg/mL. Furthermore, compounds 3, 7, and 8 could paralyze the nematodes and then impair their pathogenicity. Full article

A series of oxazinyl flavonoids were synthesized on the basis of flavone. The structures of all target compounds were characterized by ¹H NMR, ¹³C NMR, and HRMS. The effect of the different substituent on the N-position of oxazinyl flavonoids against tobacco mosaic virus (TMV) activities and plant pathogen activities was systematically investigated. In vivo anti-TMV activity showed that most of the compounds showed moderate-to-excellent antiviral activities against TMV at 500 μg/mL. Compounds 6b, 6d, 6j–6k, and 6n–6q showed better antiviral activities than ribavirin (a commercially available antiviral agent) and apigenin. In particular, compounds 6n and 6p even displayed slightly higher activities than ningnanmycin, which were expected to become new antiviral candidates. Antiviral mechanism research by molecular docking exhibited that compounds 6n and 6p could interact with TMV CP and inhibit virus assembly. Then, the antifungal activities of these compounds against six kinds of plant pathogenic fungi were tested, and the results showed that these oxazinyl flavonoids had broad-spectrum fungicidal activities. Compounds 6h exhibited antifungal activity of up to 91% against Physalospora piricola and might become a candidate drug for new fungicides. Full article

The increasing usage of chemical control agents, as well as fungicides to manage plant diseases, causes human and environmental health problems. Macroalgae represent a reservoir for a tremendous variety of secondary metabolites that display a wide range of biological activities. However, their anti-phytopathogenic properties are still being studied. The current study was conducted to investigate whether or not the macroalgae Ulva fasciata extract exhibits antifungal and antiviral activities. In this regard, the organic extracts of U. fasciata were tested for their capabilities against tobacco mosaic virus (TMV) and three molecularly identified fungal isolates, Fusarium verticillioides, Alternaria tenuissima, and Botrytis cinerea with accession numbers OP363619, OP363620, and OP363621, respectively. Among the three tested extract concentrations, 100 µg/mL had the best biological activity against B. cinerea and TMV, with 69.26%and 81.25% inhibition rates, respectively. The HPLC analysis of chemical profiling of the extract showed the presence of a number of phenolic and flavonoid compounds widely known to display many biological activities. In this line, the 4-Hydroxybenzoic acid was the highest phenolic compound (12.3 µg/mL) present in the extract, followed by ferulic acid (9.05 µg/mL). The 7-hydroxyflavone (12.45 µg/mL) was the highest flavonoid in the organic extract of U. faciata followed by rutin, which recorded a concentration of 7.62 µg/ mL. The results of this study show that the U. fasciata extract has antiviral and antifungal properties, which makes it a possible source of natural antimicrobial agents. Full article

The increasing use of chemical control agents and pesticides to prevent plant disease has resulted in several human and environmental health problems. Seaweeds, e.g., Amphiroa anceps extracts, have significant antimicrobial activities against different human pathogens. However, their anti-phytopathogenic activities are still being investigated. In the present investigation, three fungal isolates were isolated from root rot and grey mold symptomatic strawberry plants and were molecularly identified by ITS primers to Fusarium culmorum, Rhizoctonia solani, and Botrytis cinerea with accession numbers MN398396, MN398398, and MN398400, respectively. In addition, the organic extract of the red alga Amphiroa anceps was assessed for its antifungal activity against the three identified fungal isolates and tobacco mosaic virus (TMV) infection. At 100 µg/mL, the A. anceps extract had the best biological activity against R. solani, B. cinerea, and TMV infection, with inhibition rates of 66.67%, 40.61%, and 81.5%, respectively. Contrarily, the A. anceps extract exhibited lower activity against F. culmorum, causing inhibition in the fungal mycelia by only 4.4% at the same concentration. The extract’s HPLC analysis revealed the presence of numerous phenolic compounds, including ellagic acid and gallic acid, which had the highest concentrations of 19.05 and 18.36 µg/mL, respectively. In this line, the phytochemical analysis also showed the presence of flavonoids, with the highest concentration recorded for catechin at 12.45 µg/mL. The obtained results revealed for the first time the effect of the A. anceps extract against the plant fungal and viral pathogens, making the seaweed extract a promising source for natural antimicrobial agents. Full article

Multicomponent materials, where nanosized selenium (Se) is dispersed in polymer matrices, present as polymer nanocomposites (NCs), namely, selenium polymer nanocomposites (SeNCs). Selenium as an inorganic nanofiller in NCs has been extensively studied for its biological activity. More ecologically safe and beneficial approaches to obtain Se-based products are the current challenge. Biopolymers have attained great attention with perspective multifunctional and high-performance NCs exhibiting low environmental impact with unique properties, being abundantly available, renewable, and eco-friendly. Composites based on polysaccharides, including beta-glucans from edible and medicinal mushrooms, are bioactive, biocompatible, biodegradable, and have exhibited innovative potential. We synthesized SeNCs on the basis of the extracellular polysaccharides of several medicinal mushrooms. The influence of bio-composites from mushrooms on potato plant growth and tuber germination were studied in two potato cultivars: Lukyanovsky and Lugovskoi. Bio-composites based on Grifola umbellata demonstrated the strongest positive effect on the number of leaves and plant height in both cultivars, without negative effect on biomass of the vegetative part. Treatment of the potato tubers with SeNC from Gr. umbellata also significantly increased germ length. Potato plants exposed to Se-bio-composite from Ganoderma lucidum SIE1303 experienced an increase in the potato vegetative biomass by up to 55% versus the control. We found earlier that this bio-composite was the most efficient against biofilm formation by the potato ring rot causative agent Clavibacter sepedonicus (Cms). Bio-composites based on Pleurotus ostreatus promoted increase in the potato root biomass in the Lugovskoi cultivar by up to 79% versus the control. The phytostimulating ability of mushroom-based Se-containing bio-composites, together with their anti-phytopathogenic activity, testifies in favor of the bifunctional mode of action of these Se-biopreparations. The application of stimulatory green SeNCs for growth enhancement could be used to increase crop yield. Thus, by combining myco-nanotechnology with the intrinsic biological activity of selenium, an unexpectedly efficient tool for possible applications of SeNCs could be identified. Full article

Six new isocoumarin derivative talaromarins A-F (1–6), along with 17 known analogues (7–23), were isolated from the mangrove-derived fungus Talaromyces flavus (Eurotiales: Trichocomaceae) TGGP35. Their structures were identified by detailed IR, UV, 1D/2D NMR and HR-ESI-MS spectra. The absolute configurations of new compounds were determined by the modified Mosher’s method and a comparison of their CD spectra with dihydroisocoumarins described in the literature. The antioxidant, antibacterial, anti-phytopathogenic and inhibitory activity against α-glucosidase of all the isolated compounds were tested. Compounds 6–11, 17–19 and 21–22 showed similar or better antioxidant activity than the IC₅₀ values ranging from 0.009 to 0.27 mM, compared with the positive control trolox (IC₅₀ = 0.29 mM). Compounds 10, 18, 21 and 23 exhibited strong inhibitory activities against α-glucosidase with IC₅₀ values ranging from 0.10 to 0.62 mM, while the positive control acarbose had an IC₅₀ value of 0.5 mM. All compounds showed no antibacterial or anti-phytopathogenic activity at the concentrations of 50 μg/mL and 1 mg/mL, respectively. These results indicated that isocoumarins will be useful to developing antioxidants and as diabetes control agents. Full article

Phytopathogenic fungi are among the main causes of productivity losses in agriculture. To date, synthetic chemical pesticides, such as hydroxyanilides, anilinopyrimidines and azole derivatives, represent the main treatment tools for crop plant defence. However, the large and uncontrolled use of these substances has evidenced several side effects, namely the resistance to treatments, environmental damage and human health risks. The general trend is to replace chemicals with natural molecules in order to reduce these side effects. Moreover, the valorisation of agri-food industry by-products through biotransformation processes represents a sustainable alternative to chemical synthesis in several sectors. This research is aimed at comparing the anti-phytopathogenic activity of waste bovine and porcine bile with secosteroids obtained by biotransformation of bile acids with Rhodococcus strains. The ultimate goal is to apply these natural products on food crops affected by phytopathogenic fungi. Full article

Microbial co-cultivation is a promising approach for the activation of biosynthetic gene clusters (BGCs) that remain transcriptionally silent under artificial culture conditions. As part of our project aiming at the discovery of marine-derived fungal agrochemicals, we previously used four phytopathogens as model competitors in the co-cultivation of 21 marine fungal strains. Based on comparative untargeted metabolomics analyses and anti-phytopathogenic activities of the co-cultures, we selected the co-culture of marine Cosmospora sp. with the phytopathogen Magnaporthe oryzae for in-depth chemical studies. UPLC-MS/MS-based molecular networking (MN) of the co-culture extract revealed an enhanced diversity of compounds in several molecular families, including isochromanones, specifically induced in the co-culture. Large scale co-cultivation of Cosmospora sp. and M. oryzae resulted in the isolation of five isochromanones from the whole co-culture extract, namely the known soudanones A, E, D (1-3) and their two new derivatives, soudanones H-I (4-5), the known isochromans, pseudoanguillosporins A and B (6, 7), naphtho-γ-pyrones, cephalochromin and ustilaginoidin G (8, 9), and ergosterol (10). Their structures were established by NMR, HR-ESIMS, FT-IR, electronic circular dichroism (ECD) spectroscopy, polarimetry ([α]_D), and Mosher’s ester reaction. Bioactivity assays revealed antimicrobial activity of compounds 2 and 3 against the phytopathogens M. oryzae and Phytophthora infestans, while pseudoanguillosporin A (6) showed the broadest and strongest anti-phytopathogenic activity against Pseudomonas syringae, Xanthomonas campestris, M. oryzae and P. infestans. This is the first study assessing the anti-phytopathogenic activities of soudanones. Full article