Search Results (660)

The most common reason for a decrease in the quantity and quality of produced crops is microbial diseases. The aims of this study were to evaluate the antagonistic activity of Streptomyces sp. CACIS-1.16CA against plant pathogenic fungi and to assess its bioactive metabolites to inhibit fungal conidial germination. Antagonistic evaluations of fungal phytopathogens were performed using dual and multiple confrontation assays. Additionally, the inhibitory effect of the bioactive extract (BE) containing secondary metabolites produced by the CACIS-1.16CA strain on the germination of conidia from some fungi was tested. The results indicate that Streptomyces sp. CACIS-16CA inhibited the growth of all tested pathogens (16 strains) with percentages of inhibition (PIs) ranging from 43.3% to 72%, while S. lydicus inhibited 13 of the 16 fungi, with PI values from 35.6% to 68.5%. Moreover, CACIS-1.16CA exerted superior PI values (significant differences at p < 0.05) than S. lydicus against the damping-off fungi consortia with Phytophthora capsici, Fusarium oxysporum, and Rhizoctonia solani. Otherwise, an inhibitory effect was observed on the germination of conidial cells due to the interaction with the BE in Alternaria sp., Botrytis cinerea, and Colletotrichum spp. In conclusion, Streptomyces sp. CACIS-1.16CA may serve as an effective and natural alternative for managing several fungal plant diseases. Full article

Fungicide treatment is one of the most common methods for controlling fungal plant diseases. However, many phytopathogenic fungi develop resistance to fungicides. Addressing this agriculturally important issue requires comprehensive investigations into fungicide resistance. Our study aims to assess the degree and prevalence of resistance to carbendazim—one of the most widely used fungicides—in populations of Microdochium nivale, the causal agent of the deleterious plant disease pink snow mold; to explore possible relationships between carbendazim resistance and physiological and genetic traits; and to gain insight into the molecular basis of carbendazim resistance in this species. We showed that carbendazim resistance is widespread in the analyzed M. nivale populations, and that the application of carbendazim increases the proportion of resistant strains. Nevertheless, carbendazim-resistant strains are present at high relative abundance in populations that have never been exposed to fungicides. Carbendazim resistance in M. nivale is strongly associated with sequence variations in the β-tubulin gene, resulting in amino acid sequence variability that leads to differential affinity for carbendazim. Additionally, we propose a metabarcoding-based approach employing a genetic marker linked to a specific phenotypic trait to assess the ratio of genotypes with contrasting properties within a particular fungal species in environmental communities. Full article

Chinese pine, Pinus tabuliformis, is one of the most important garden plants in northern China, and the planting of this species is of great significance for the improvement of the ecological environment. In this study, different fungi were isolated and purified from diseased Pinus tabuliformis samples collected in Xi’an city, Shaanxi Province. Of these fungal isolates, only one (isolate AP-3) was pathogenic to the healthy host plant. The pathogenic isolate was identified as Fusarium acuminatum by morphological characteristics and ITS and TEF-1α sequence analyses. The optimal growth conditions for this isolate were further analyzed as follows: Optimal temperature of 25 °C, pH of 11, soluble starch and sodium nitrate as the most preferred carbon and nitrogen sources, respectively. By combining Oxford Nanopore Technologies (ONT) long-read sequencing with Illumina short-read sequencing technologies, we obtained a 41.50 Mb genome assembly for AP-3, with 47.97% GC content and 3.04% repeats. This consisted of 14 contigs with an N50 of 4.64 Mb and a maximum length of 6.45 Mb. The BUSCO completeness of the genome assembly was 98.94% at the fungal level and 97.83% at the Ascomycota level. The genome assembly contained 13,408 protein-coding genes, including 421 carbohydrate-active enzymes (CAZys), 120 cytochrome P450 enzymes (CYPs), 3185 pathogen-host interaction (PHI) genes, and 694 candidate secreted proteins. To our knowledge, this is the first report of F. acuminatum causing needle blight of P. tabuliformis. This study not only uncovered the pathogen responsible for needle blight of P. tabuliformis, but also provided a systematic analysis of its biological characteristics. These findings provide an important theoretical basis for disease control in P. tabuliformis and pave the way for further research into the fungal pathogenicity mechanisms and management strategies. Full article

Plant viruses have been traditionally considered pathogens restricted to plant hosts. However, recent studies have shown that some plant viruses can infect and replicate in filamentous fungi and oomycetes, suggesting that their host range is broader than previously thought, and that their ecological interactions are more complex. In this study, we investigated the ability of the well-characterized positive-sense RNA plant virus Tobacco mosaic virus (TMV) to replicate in four major phytopathogenic fungi from different taxonomic groups: Botrytis cinerea, Fusarium oxysporum f. sp. lycopersici, Verticillium dahliae, and Monilinia fructicola. Using a recombinant TMV-based vector expressing a green fluorescent protein (TMV-GFP-1056) as reporter, we demonstrated that TMV can enter, replicate, and persist within the mycelia of B. cinerea and V. dahliae—at least through the first subculture. However, it cannot replicate in F. oxysporum f. sp. lycopersici and M. fructicola. RNA interference (RNAi) is a conserved eukaryotic epigenetic mechanism that provides an efficient defence against viruses. We explored the role of RNAi in the interaction between TMV and the mycelia of V. dahliae and B. cinerea. Our results revealed a strong induction of the Dicer-like 1 and Argonaute 1 genes, which are key compounds of the RNA silencing pathway. This RNAi-based response impaired TMV-GFP replication in both fungi. Notably, despite viral replication and RNAi activation, the virulence of V. dahliae and B. cinerea on their respective host plants remained unaffected. These findings reinforce the emerging recognition of cross-kingdom virus transmission and interactions, which likely play a crucial role in pathogen ecology and viral evolution. Understanding these virus–fungus interactions not only sheds light on RNAi interference silencing mechanisms but also suggests that plant viruses like TMV could serve as simple and effective tools for functional genomic studies in fungi, such as in V. dahliae and B. cinerea. Full article

Tree plantations can help reverse the negative impacts of deforestation and land degradation worldwide, and soil microbial communities play key roles in tree growth and productivity. We studied microbial communities in the bulk soil of five native species monoculture plantations in the Republic of Panamá to assess how bacteria and fungi were affected by soil chemistry and plant identity after seven years of tree growth. Relative to the other species, Terminalia amazonia accumulated over three times the aboveground biomass and had lower mortality. Soil nutrients, especially phosphorus, were low, and we found no differences in soil chemistry across the five plantation types. Similarly, there was no difference in alpha diversity of the soil microbial communities across plantation types, and the bacterial communities showed no compositional variation or enrichment of any individual taxa. However, soil fungal communities differed in T. amazonia plantations as compared to the others, exhibiting enrichment or absence of specific taxa of arbuscular mycorrhizal fungi and putative phytopathogens. Our results suggest that T. amazonia may associate with certain microbial taxa that help it overcome low nutrient availability in these habitats. Consideration of plant–soil–microbe interactions in restoration efforts may facilitate tree growth and help to promote climate resilient forested areas. Full article

Myxobacteria, a group of swarming, predatory soil bacteria, are of interest because of their biocontrol potential. In this study, the inhibitory effects of 13 strains of myxobacteria were examined against four different phytopathogenic fungi, as follows: two isolates of Rhizoctonia solani from different AG groups and one isolate each from Sclerotinia sclerotiorum and the oomycete Pythium ultimum. Inhibition levels varied among phytopathogens, with slow-growers being more susceptible than fast-growers. Myxococcus xanthus BS 248, M. flavus ATCC 29617, and M. coralloides BS249 were the most inhibitory strains tested. non-contact and contact inhibition on agar media between phytopathogens and myxobacteria were visually discernible. This distinction potentially reflects the activity of low-molecular-weight metabolites and high-molecular-weight lytic enzymes, respectively. In a pot soil study, the inhibitory effect of a mixture of two strains of myxobacteria against two strains of R. solani was apparent from the reduced disease in cucumber seedlings compared to controls without myxobacteria. This is the first report of an in vivo inhibitory effect of myxobacteria against Rhizoctonia. The survival of M. xanthus BS248 in sterile soil amended with rabbit manure (1:1) increased up to five weeks compared to one week in soil without the manure, suggesting that organic amendment could enrich myxobacteria in soil. Full article

Phytopathogenic fungi secrete numerous effector proteins to disrupt plant defenses. At present, their sequence–structure–function relationships remain poorly understood owing to their diversity. Comprehensive understanding of conserved effectors is necessary to elucidate the molecular relationship between fungi and plants. To fill this research gap, we investigated the Colletotrichum higginsianum effector candidate (ChEC)-88 specifically expressed during infection. Notably, similar to the biotrophy-associated secreted protein 3 (BAS3) from Pyricularia oryzae, ChEC88 inhibited plant cell death caused by necrosis- and ethylene-inducing peptide 1-like protein (NLP1). Nuclear magnetic resonance analysis results revealed that ChEC88 adopted a novel pseudo two-fold symmetrical three-dimensional structure. Homology modeling suggested that BAS3 exhibited a ChEC88-like conformation despite sharing less than 50% sequence identity. Through PSI-BLAST searches, we found that ChEC88 homologs were conserved in various hemibiotrophic phytopathogenic fungi, including Colletotrichum, P. oryzae, and Fusarium species. Functional assays demonstrated that all of the representative homologs suppressed NLP1-induced plant cell death. Mutation experiments identified the residues critical for ChEC88 function. Overall, our findings suggest that hemibiotrophic phytopathogenic fungi share a conserved immune-suppression strategy mediated by ChEC88-like proteins and that such effectors possibly originated from a common ancestral lineage of phytopathogenic fungi. Full article

A wide range of microorganisms, including endophytes, frequently interact with forest trees. The role of endophytes in industrial conifers has not been fully investigated. The Yezo spruce Picea jezoensis is widely used for logging in Russia and Japan. In this work, the endophytic communities of bacteria and fungi in healthy needles, branches, and fresh wood of P. jezoensis from Primorsky Territory were analyzed using metagenomic analysis. The results indicate that the diversity of endophytic communities in P. jezoensis is predominantly influenced by the specific tree parts (for both bacteria and fungi) and by different tree specimens (for fungi). The most abundant bacterial classes were Alphaproteobacteria, Gammaproteobacteria and Actinobacteria. Functional analysis of KEGG orthologs (KOs) in endophytic bacterial community using PICRUSt2 and the PLaBAse PGPT ontology revealed that 59.5% of the 8653 KOs were associated with plant growth-promoting traits (PGPTs), mainly, colonization, stress protection, bio-fertilization, bio-remediation, vitamin production, and competition. Metagenomic analysis identified a high abundance of the genera Pseudomonas and Methylobacterium-Methylorubrum in P. jezoensis, which are known for their potential growth-promoting activity in other coniferous species. The dominant fungal classes in P. jezoensis were Dothideomycetes, Sordariomycetes, and Eurotiomycetes. Notably, the genus Penicillium showed a pronounced increase in relative abundance within the fresh wood and needles of Yezo spruce, while Aspergillus displayed elevated abundance specifically in the fresh wood. It is known that some of these fungi exhibit antagonistic activity against phytopathogenic fungi. Thus, our study describes endophytic communities of the Yezo spruce and provides a basis for the production of biologicals with potential applications in forestry and agriculture. Full article

This study investigated the diversity and distribution of phytopathogenic fungi associated with goosegrass (Eleusine indica), an aggressive weed in agriculture, and bioprospected fungi isolates with potential for biological control of this species. Samples showing disease symptoms were collected from Goias, Minas Gerais, and São Paulo (Brazilian states), resulting in 88 isolates, of which 50 were phytopathogenic to E. indica. A total of 26 isolates were considered more aggressive based on visual analysis and were preliminarily identified at the genus level, with an emphasis on Bipolaris, Fusarium, Curvularia, Exserohilum, and Alternaria. The influence of climatic factors, such as sunny days (UV radiation), temperature, and precipitation on fungal occurrence was analyzed. These climatic factors are critical to the presence of fungi, providing insights into their potential as biological control agents and guiding future surveys of specific genera. The number of sunny days during surveys influenced the occurrence of fungi associated with E. indica, depending on the genera of the fungi. In addition, precipitation was also a determining factor for a higher incidence of fungal isolates during periods of increased rainfall, suggesting a positive relationship between relative humidity and the dispersal or infection of phytopathogenic fungi. New tests will be conducted to confirm the potential of the identified plant phytopathogenic fungi as biological control agents against E. indica. Full article

One of the important traits of many plant growth-promoting rhizobacteria (PGPR) is the biocontrol of phytopathogens. Some PGPR metabolize phytohormone abscisic acid (ABA); however, the role of this trait in plant–microbe interactions is scarcely understood. Phytopathogenic fungi produce ABA and use this property as a negative regulator of plant resistance. Therefore, interactions between ABA-producing necrotrophic phytopathogen Botrytis sp. BA3 with ABA-metabolizing rhizobacterium Rhodococcus sp. P1Y were studied in a batch culture and in gnotobiotic hydroponics with sunflower seedlings. Rhizobacterium P1Y possessed no antifungal activity against BA3 and metabolized ABA, which was synthesized by BA3 in vitro and in associations with sunflower plants infected with this fungus. Inoculation with BA3 and the application of exogenous ABA increased the root ABA concentration and inhibited root and shoot growth, suggesting the involvement of this phytohormone in the pathogenesis process. Strain P1Y eliminated negative effects of BA3 and exogenous ABA on root ABA concentration and plant growth. Both microorganisms significantly modulated the hormonal status of plants, affecting indole-3-acetic, salicylic, jasmonic and gibberellic acids, as well as cytokinins concentrations in sunflower roots and/or shoots. The hormonal effects were complex and could be due to the production of phytohormones by microorganisms, changes in ABA concentrations and multiple levels of crosstalk in hormone networks regulating plant defense. The results suggest the counteraction of rhizobacteria to ABA-producing phytopathogenic fungi through the metabolism of fungal ABA. This expands our understanding of the mechanisms related to the biocontrol of phytopathogens by PGPR. Full article

One of the most important features of Metschnikowia pulcherrima is its strong antimicrobial activity against phytopathogens, which makes it a suitable candidate for use in biocontrol during crop cultivation. However, the mechanisms of its antimicrobial activity are not currently well understood. In this study, we used metabolomic methods to investigate the possible mechanisms of antimicrobial activity by M. pulcherrima against phytopathogenic fungi. First, we tested the antimicrobial activity of five selected isolates against eleven phytopathogenic molds. Based on the results, selected yeast–pathogen co-cultures were cultivated on liquid and solid media. The supernatants from the liquid co-cultures were analyzed using the UHPLC-QToF-UHRMS and MS/MS methods. Co-culture growth on solid agar media was examined using the LARAPPI/CI MSI method. The yeast exhibited strong antagonism toward the mold phytopathogens. The LARAPPI/CI MSI method revealed the presence of various compounds with potential antifungal activity. The complex UHPLC-QToF-UHRMS analysis confirmed that the metabolic response of M. pulcherrima depends on specific yeast–pathogen interactions. Full article

Oregano (Origanum vulgare) cultivation is of great economic importance in Peru. Tacna stands out as its main producer. However, the presence of phytopathogenic fungi represents a challenge for its production. This study aimed to characterize both the morphological and molecular levels of the causal agent of crown and root rot in a crop field in the Camilaca district, Candarave, Tacna. To this end, systematic sampling was carried out using the five-gold method, collecting plants with typical symptoms. Fungi were isolated from diseased roots and characterized using macroscopic and microscopic morphological analysis as well as sequencing and multilocus phylogenetic analysis (ITS, 28S, HIS3, TEF1, TUB2). In addition, pathogenicity tests were performed on healthy plants to confirm the infectivity of the isolates. The results demonstrated that root rot was caused by a complex of phytopathogenic fungi through phylogenetic analysis of Dactylonectria torresensis, Fusarium oxysporum, F. iranicum, and F. redolens. These findings represent the first report of these species as causal agents of oregano root rot in Peru, highlighting the need for integrated management strategies that reduce the economic impact of these diseases and contribute to the sustainability of the crop in key producing regions such as Tacna. Full article

The scientific community’s interest in natural compounds with antiviral properties has considerably increased after the emergence of the severe acute respiratory syndrome coronavirus (SARS-CoV-2), especially for their potential use in the treatment of the COVID-19 infection. From this perspective, bovine coronavirus (BCoV), member of the genus β-CoV, represents a valuable virus model to study human β-CoVs, bypassing the risks of handling highly pathogenic and contagious viruses. Pimarane diterpenes are a significant group of secondary metabolites produced by phytopathogenic fungi, including several Diplodia species. Among the members of this class of natural products, sphaeropsidin A (SphA) and its analog sphaeropsidin B (SphB) are well known for their bioactivities, such as antimicrobial, insecticidal, herbicidal, and anticancer. In this study, the antiviral effects of SphA and SphB were evaluated for the first time on bovine (MDBK) cells infected with BCoV. Our findings showed that both sphaeropsidins significantly increased cell viability in infected cells. These substances also caused substantial declines in the virus yield and in the levels of the viral spike S protein. Interestingly, during the treatment, a cellular defense mechanism was detected in the downregulation of the aryl hydrocarbon receptor (AhR) signaling, which is affected by BCoV infection. We also observed that the presence of SphA and SphB determined the deacidification of the lysosomal environment in infected cells, which may be related to their antiviral activities. In addition, in silico investigations have been performed to elucidate the molecular mechanism governing the recognition of bovine AhR (bAhR) by Sphs. Molecular docking studies revealed significant insights into the structural determinants driving the bAhR binding by the examined compounds. Hence, in vitro and in silico results demonstrated that SphA and SphB are promising drug candidates for the development of efficient therapies able to fight a β-CoV-like BCoV during infection. Full article

Indane and phenylpropyl derivatives are interesting precursors for the synthesis of bioactive compounds, including those with antifungal or anti-inflammatory properties. In light of the increasing interest in the biocatalytic potential of marine-derived fungi, a study was conducted in which the substrates indene (1), indanone (2), 5-chloroindanone (2a), 1-phenylpropyl acetate (3), and 1-(4′-chlorophenyl)propyl acetate (3a) were biotransformed by the marine sediment-derived fungal strains Purpureocillium lilacinum BC17-2 and Emericellopsis maritima BC17. Fermentations led to the isolation of sixteen derivatives, which exhibited noteworthy stereoselectivities. The absolute configurations of the optically active indane and phenylpropyl derivatives isolated were determined through electronic circular dichroism and optical rotation dispersion computational calculations. Furthermore, given the known biocatalytic potential of the phytopathogenic fungus Botrytis cinerea to modify the structures of certain antifungal phenylpropyl derivatives, substrates 3 and 3a were also subjected to biotransformation by the strain B. cinerea UCA992. The antifungal activities of the biotransformation products (R)-5, (S)-6, syn-(1S,2R)-7, anti-(1R,2R)-7, (R)-8, (R)-9, threo-(1R,2R)-11, and erythro-(1R,2S)-11 were evaluated against B. cinerea UCA992 using a resazurin-based microdilution method. Full article

The potential of Trichoderma fungi as biocontrol agents has not yet been fully explored, as there is a large repertoire of inter- and intra-species variation in their phytopathogenic antagonistic effects due to different adaptations of individual Trichoderma strains. In the present study, we investigated the biocontrol efficacy of eight native isolates of Trichoderma spp. against the soilborne phytopathogens Sclerotinia sclerotiorum and Rhizoctonia solani and a representative of the Mucoromycota, Phycomyces blakesleeanus. An in vitro dual culture test showed a complete (100%) inhibition of S. sclerotiorum and P. blakesleeanus by each tested Trichoderma strain and a high (80–100%) inhibition of R. solani. The crude chloroform extracts, whose peptide contents were confirmed by thin-layer chromatography, caused a concentration-dependent reduction in the growth of the target fungi, with inhibition comparable to the effect of the peptaibol standard alamethicin. Despite the differences between fungi from the phyla Basidiomycota, Ascomycota, and Mucoromycota, their inhibition by alamethicin followed the same dose–response dependence. The growth inhibition of P. blakesleeanus induced by Trichoderma extracts was characterized by a significantly increased activity of antioxidative defense enzymes. Both variants of biocontrol agents, the native strains of Trichoderma spp. and their extracts, are efficient in controlling fungal growth and should be considered for the development of new potent bioformulations applicable in agriculture. Full article