Continuous cropping often exacerbates soil-borne diseases, particularly Fusarium wilt, yet the intricate rhizosphere relationships among phyto-derived metabolites, pathogens, and particular microbial functions remain poorly understood. Here, we observe that citrulline accumulation during continuous cropping is positively correlated with Fusarium wilt severity by enhancing fusaric acid production in Fusarium oxysporum. Metagenomic analyses reveal that citrulline turnover-related functions, represented by functional modules including M00978, are significantly enriched in healthy rhizosphere soils but are notably reduced in Fusarium-conducive soils. The functional genes, arcB and argH, are identified in Pseudomonas putida YDTA3, with arcB being essential for citrulline-degradation via knockout experiments. The inoculation of an arcB-expressing indigenous Escherichia consortium (EO-arcB) in three independent continuous cropping systems of cucurbit crops demonstrates that enhancing and maintaining the soil citrulline-degrading function mitigates soil-borne Fusarium wilt. In summary, this study advances our understanding of rhizosphere interactions underlying Fusarium wilt disease occurrence and offers a promising biocontrol strategy.

Fusarium verticillioides is a common pathogenic fungus of corn since it causes severe yield losses and produces mycotoxins to threaten the health of both humans and livestock. Although extensive research has characterized specific genetic and environmental factors influencing mycotoxin production, a systematic understanding of the temporal transcriptional dynamics governing its developmental progression remains lacking. This study addresses this critical knowledge gap through a time-series transcriptomic analysis of F. verticillioides at four key cultivation stages (3, 5, 7, and 9 days post-inoculation). Transcriptomic analysis identified 1928, 2818, and 1934 differentially expressed genes (DEGs) in the comparisons of FV3 vs. FV5, FV5 vs. FV7, and FV7 vs. FV9, respectively. Gene Ontology enrichment revealed 76, 106, and 56 significantly enriched terms across these comparisons, with "integral component of membrane" consistently being the most enriched cellular component. Pathway analysis demonstrated "amino acid metabolism" and "carbohydrate metabolism" as the most significantly enriched metabolic pathways. Notably, the fumonisin (FUM) and fusaric acid (FA) biosynthetic gene clusters exhibited coordinated peak expression during the early cultivation, followed by progressive decline. Mfuzz clustering further delineated 12 distinct expression trajectories, highlighting the dynamic transcriptional networks underlying fungal adaptation. This work provided the first comprehensive temporal transcriptome of F. verticillioides, establishing a foundational resource for understanding its stage-specific biology and revealing potential time-sensitive targets for future intervention strategies.

Bacteria-Fungi Interactions play a crucial role in soil nutrient cycling and plant disease suppression. Bacillus and Trichoderma exhibit antagonism when inoculated on laboratory media, global soil sample analysis reveals a positive correlation between these two genera in addition to enhanced plant-pathogen Fusarium oxysporum suppression and plant growth promotion. Here, we assess cross-kingdom interactions within artificial model communities of Bacillus velezensis and Trichoderma guizhouense. Transcriptomic profiling revealed that in the presence of fungi, the key stress sigma factor of B. velezensis activates expression of biosynthetic genes for antimicrobial secondary metabolite production. Among these, surfactin induces T22azaphilone production in T. guizhouense that hinders oxidative stress. Both surfactin and T22azaphilone contribute to Bacillus and Trichoderma maintenance in soil in the presence of Fusarium oxysporum. Finally, Fusarium oxysporum-secreted fusaric acid temporarily inhibits B. velezensis growth whereas it is efficiently degraded by T. guizhouense. These metabolite-mediated interactions reveal how competing soil microorganisms could form effective alliances that ultimately enhance plant protection against soil-borne pathogens.

Fusaric acid is a toxic metabolite produced by several Fusarium species, which causes wilt disease in many plants. Among other functions, fusaric acid allows the fungus to outcompete soil bacteria. Understanding mechanisms by which bacteria mitigate the toxic effects of fusaric acid is therefore of interest in terms of controlling Fusarium wilt. The soil bacterium Burkholderia thailandensis encodes a predicted fusaric acid-binding membrane transporter belonging to the FusC2 family. The fusC2 gene is annotated as part of an operon, also encoding an isochorismatase (gene named isoC) and a member of the multiple antibiotic resistance (MarR) family of transcription factors. Isochorismatase converts isochorismate to the antifungal compound 2,3-dihydroxybenzoate. We show here that the transcription factor, which we named FusR2, binds specifically to the promoter of the fusR2-isoC-fusC2 operon and that FusR2 induces marked changes in DNA conformation, as evidenced by hypersensitive DNase I cleavage sites. Fusaric acid induces the expression of fusR2-isoC-fusC2, and it binds directly to FusR2, as shown by thermal shift assays. While the presence of fusaric acid is compatible with DNA binding by FusR2, it eliminates the hypersensitive DNA cleavage. We propose that FusR2 imposes a DNA conformation, which adversely affects the ability of RNA polymerase to bind, whereas fusaric acid binding to FusR2 results in an altered DNA binding mode, in which the RNA polymerase can compete with FusR2 for DNA binding to initiate transcription. By this mechanism, fusaric acid induces the expression of genes encoding both an efflux pump and an enzyme involved in the production of an antifungal metabolite.

Fusaric acid detoxification mediates interspecies interactions for sustainable Fusarium wilt disease management.

The genus Fusarium comprises multiple species recognized as plant pathogens in both annual and perennial crops. Some phytopathogenic species of this genus can be transmitted by insect vectors, which introduce them into woody plant species of ecological and agroeconomic importance. Among these species, Fusarium kuroshium stands out, but studies are limited because it is a quarantine pathogen that requires special biosafety measures for its culture. This fungus produces fusaric acid (FA), a virulence factor that is widespread in Fusarium spp. To gain insight into the role of this phytotoxin in virulence, we exposed leaves of four woody host species (Liquidambar styraciflua, Persea americana, Citrus sinensis, and Populus nigra) of F. kuroshium to FA in vitro. The plant tissue exhibited varying degrees of cell death and physiological alterations, including a reduction in biomass, generation of reactive oxygen species (ROS), elevated electrolyte leakage, and loss of photosynthetic pigments. A chemical analysis demonstrated that the flavonoid and isoflavonoid pathways, in addition to linoleic and linolenic acid metabolism, were markedly affected by FA. Following the quantification of phenolic compounds in leaves, 11 metabolites were identified whose concentrations increased in response to FA stress. The findings of this study indicate that phenolic compounds play a significant role in the response to FA stress. Particularly, scopoletin has a protective effect on leaves of Liquidambar styraciflua.

Chelating agents are metal-sequestering compounds with antibacterial properties suitable for commercial and therapeutic applications. This study investigated the involvement of metal restriction and membrane disruption in the antibacterial mode of action of three chelators. The antibacterial, metal sequestration, and membrane disruptive effects of ethylenediaminetetraacetic acid, diethylenetriamine pentamethylene phosphonic acid, and fusaric acid were examined across five bacterial species. ICP-MS was used to determine the impact on bacterial metal composition, while RT-qPCR of selected genes allowed evaluation of changes in cellular responses to intracellular metal depletion. Mutants defective in metal import and export machinery were also examined to validate processes critical for resistance. Chelator-mediated disruption of membranes was investigated using 1-N-phenylnapthylamine and propidium iodide. Finally, the capacity of two of the chelators to potentiate the activity of ampicillin, chloramphenicol, tetracycline, and three aminoglycosides was assessed in chequerboards. The results show that these chelators restrict access to iron, zinc, manganese, and calcium to varying degrees in these bacterial species, reflecting important differences in envelope architectures and metal handling capabilities. This study shows that all three chelators behave differently in restricting metal access and possess antibacterial properties that often act synergistically in combination, notably with other antimicrobials.

Cyclamen (Cyclamen spp.)is a widelycultivated ornamental plant. Among the soil-borne pathogens affectingcyclamen, Fusarium wilt, caused by Fusarium oxysporum f. sp. cyclaminis, is one of the most significant phytosanitary challenges. This studyaimed to evaluate the antifungal potential of graphene oxide and β-caryophyllene,separately and in combination, applied either by spraying or throughendotherapy (bulb injection), to control Fusarium wilt in cyclamen. The combined application of these antifungal agentsproved more effective, resulting in 40–60% mortality of infectedplants, compared to 100% mortality in the untreated control group.A sorption study of fusaric acid on graphene oxide was also conductedto better understand its antifungal activity, along with an ecotoxicologicalassessment of β-caryophyllene to evaluate its environmentalsafety. Overall, the strong synergistic effect between graphene oxideand β-caryophyllene against Fusarium oxysporum f. sp. cyclaminis highlights their potential usein plant protection and supports the advancement of sustainable agriculturalpractices.

ABSTRACTThe fungi Fusarium guttiforme and Phytophthora palmivora were cultivated in four different media (Potato Dextrose Agar, Czapek, rice, and ISP2) and co‐cultured to stimulate fungal interactions and enhance secondary metabolite production. Promising extracts were fractionated, yielding compounds such as the iron complex of fusaric acid (1), magnesium complex of fusaric acid (2), haematocin (4), fusarinolic acid (7), and cyclonerodiol (8). These compounds exhibited significant papain inhibitory activity, with compounds 2 and 4 showing IC50 values below 20 µM. Notable anti‐Trypanosoma cruzi activity was also observed, particularly for compounds 2 (50% inhibitory concentration [IC50] = 12.19 µM) and 4 (IC50 = 13.32 µM). Additionally, antifungal activity against Candida spp. was detected, with compound 2 and the magnesium complex of 9,10‐dehydrofusaric acid complex (3) showing MICs of 50 µg/mL. This study highlights the potential of fungal co‐cultivation and variation in culture medium as effective strategies for discovering novel bioactive protease inhibitors and antiparasitic agents.

The velvet complex is a master regulator of multiple physiological processes in filamentous fungi. In this study, we characterized the functions of velvet gene FpvelC in Fusarium proliferatum, which was the causative agent of rice spikelet rot disease. Compared with the wild-type Fp9 strain, deletion of FpvelC hindered conidiation, leading to a low level of trehalose content but excessive accumulation of chitin in conidia. Lack of FpvelC resulted in increased sensitivity to oxidative stress and decreased expression of antioxidant genes. Notably, ΔFpvelC exhibited attenuated pathogenicity on rice and maize, failure to produce invasive hyphae, and downregulation of genes encoding xylanases and xyloglucanases during infection processes. Nevertheless, disruption of FpvelC enhanced production of fumonisin B1 (FB1) and fusaric acid concomitantly; transcripts of the clustering genes responsible for the two mycotoxins’ biosynthesis were significantly increased. Additionally, the absence of FpvelC was displayed as more sensitive to rapamycin than the Fp9 strain, accompanied with less intracellular glutamine. Overall, FpvelC played versatile roles in conidiation, response to oxidative stress, pathogenicity and mycotoxins production in F. proliferatum.

Exploring the impact of apocarotenoids on pathogenic Fusarium oxysporum f.sp. lini and endophytic Fo47 strains.

Fusaric acid (FSA) is a mycotoxin produced by pathogenic Fusarium species that inhibits the growth of various beneficial microbes. In this study, we investigated the molecular mechanisms by which Trichoderma harzianum NJAU4742 (Th), a beneficial fungus, responds to FSA-induced stress. Here, by combining a transcriptome analysis, a gene knockout, and physiological data measurements, our study investigated the molecular mechanisms underlying the response of Trichoderma harzianum NJAU4742 (Th) to FSA stress. The results showed that FSA can induce severe oxidative stress in Th, and an aldehyde dehydrogenase (Thaldh3) in Th plays a critical role in alleviating FSA stress. Deleting Thaldh3 significantly decreased the γ-aminobutyrate (GABA) content, causing more severe oxidative damage in Th. Furthermore, we also provide evidence demonstrating that Thaldh3 alleviates FSA stress by enhancing the activities of key enzymes involved in the tricarboxylic acid cycle and ATP content. A pot experiment showed that an enhanced tolerance to FSA increased the Th biomass, strengthening its antagonistic capacity against pathogens and reducing the disease index in tomatoes. In conclusion, these observations provide new insight into the role of beneficial microbes in promoting plant health.

Background/Objectives: Endophytic fungi are valuable sources of bioactive compounds with potential therapeutic applications. This study aimed to evaluate the antifungal activity of secondary metabolites produced by Fusarium sp. isolated from Dizygostemon riparius, with particular focus on the impact of culture medium supplementation with halogenated and metallic additives on metabolite production. Methods: The fungus was cultivated in standard Czapek medium and media supplemented with NH4Br or MnCl2. Methanolic extracts were obtained, fractionated, and chemically characterised via LC-ESI-HRMS. In vitro antifungal assays, including MIC and MFC determinations and biofilm inhibition tests, were performed against Candida albicans strains. In vivo toxicity and efficacy were assessed using Tenebrio molitor larvae. Results: Fifteen metabolites were annotated, including known antifungals such as fusaric acid and cyclosporin A. Fractions EMBr4 and EMC5 demonstrated fungicidal activity with MIC values close to fluconazole and significantly inhibited biofilm formation and maturation. In vivo, these fractions displayed low acute toxicity and improved survival in infected larvae, comparable to fluconazole treatment. Conclusions: The results indicate that culture medium modulation enhances the production of bioactive metabolites by Fusarium sp., leading to extracts with notable antifungal efficacy and safety. EMBr4 and EMC5 are promising candidates for further development as antifungal agents, particularly for targeting biofilm-associated Candida infections. These findings support the potential of endophytic fungi as sources of novel therapeutics and warrant further mechanistic and pharmacological investigations.

Safety evaluation of a food enzyme containing phospholipase activity produced by a strain of Fusariumcommune.

Fusarium wilt, caused by Fusarium oxysporum f. sp. niveum (Fon), poses a significant threat to watermelon production globally. Traditional control methods often rely on chemical fungicides, which pose environmental risks and limited long-term efficacy. This study introduces biogenically-synthesized manganese nanoparticles (MnNPs) as a potent antifungal agent for managing Fusarium wilt. MnNPs were synthesized extracellularly using the culture supernatant of Lysinibacillus sphaericus NOTE11, a Mn-resistant bacterial strain isolated and characterized in this study. Comprehensive physicochemical analyses confirmed their crystalline structure, spherical morphology, and elemental composition. MnNPs demonstrated potent antifungal activity, significantly inhibiting Fon growth, conidiation, and conidial germination in vitro, with 100 µg/mL MnNPs reducing hyphal growth by 21.97% and conidial germination by 80% compared to untreated controls. Disease assays further confirmed that MnNPs significantly reduced Fusarium wilt severity in watermelon (~ 84%) compared with Fon-infected controls, with MnNP-treated infected-plants exhibiting minimal symptoms and reduced invasive fungal biomass in within watermelon tissues. Transcriptomic analysis revealed that MnNPs downregulated genes in the fusaric acid biosynthesis pathway, a key determinant of Fon virulence, disrupting its ability to infect host plants. Additionally, MnNPs modulated rhizosphere metabolites, enriching defense-related compounds, including phenolics, flavonoids, and organic acids. These findings establish MnNPs as a robust and impactful strategy for managing Fusarium wilt. By integrating nanotechnology and plant-rhizopshere interactions, this study provides a novel approach to mitigating soilborne diseases, emphasizing the potential of nano-enabled disease management approaches to enhance crop protection and sustainability in agriculture.

IntroductionThis study investigates the In Vitro antifungal activity of silicon dioxide nanoparticles (SiO2 NPs) against mycotoxigenic Fusarium brachygibbosum species, a fungus posing a significant threat to olive trees in Tunisia.MethodsTwo different doses of SiO2 NPs (100 and 200 mg kg -1 ) were used to evaluate its effect on fungal growth, mycotoxin production, and virulence capability of tested F. brachygibbosum strain.Results and DiscussionWhile mycelial growth was not influenced by SiO2 NPs, a notable increase in macroconidia sporulation was observed at the highest dose tested. Scanning electron microscopy revealed structural alterations in fungal hyphae treated with SiO2 NPs, including hyphal disorganization after the adherence of nanoparticles. Furthermore, SiO2 NPs influenced oxidative stress in Fusarium, with varying effects on hydrogen peroxide levels, total antioxidant activity, and total phenolic compounds, modulating the capability of the fungus to produce mycotoxins. Indeed, fusaric acid and 15-acetyldeoxynivalenol amounts decreased in presence of SiO2, while an increasing level of neosolaniol and diacetoxyscirpenol was observed. Pathogenicity tests on olive and sorghum leaves revealed a reduction of disease severity in SiO2 treated samples compared to untreated controls, showcasing the potential of SiO2 NPs as a sustainable alternative for managing Fusarium infections. These findings underline the potential use of SiO2 NPs as environmentally friendly and effective tool in integrated pest management strategies against F. brachygibbosum as well as other Fusarium species occurring on olive trees. Further research is warranted to optimize their application and understand their interactions with both the pathogen and the host plant.

Fusaric acid as physiological stress trigger in Rumex lunaria

Our previous studies have demonstrated that the phytotoxin fusaric acid (FSA), secreted by several Fusarium species, acts as a key factor in the development of plant diseases; however, the underlying mechanism remains unknown. In this study, we showed that the symptoms of Fusarium wilt in banana seedlings closely resembled those observed in plants grown under potassium (K+) deficiency conditions. Mechanistically, we found that FSA induces the accumulation of intracellular reactive oxygen species (ROS), which in turn inhibits banana K+ in banana roots. This inhibition occurs via S-glutathionylation of the banana AKT1 (MaAKT1) channel, leading to reduced K+ influx and reduced K+ content in banana roots. Through mutagenesis, electrophysiological studies, immunofluorescence staining, and co-immunoprecipitation experiment, we demonstrated that mutation of Cys202, a highly conserved site in the transmembrane segment 5 of MaAKT1, diminished the biochemical interaction of glutathione (GSH) and the channel induced by FSA, and alleviated Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) and FSA-induced yellowing symptom. The evolutionarily conserved function of this site for S-glutathionylation was also observed in Arabidopsis AKT1 (AtAKT1) channel, as mutation of its homologue site in AtAKT1 similarly reduced the GSH-AtAKT1 interaction under FSA stress. Collectively, our results suggest that FSA contributes to disease progression by decreasing K+ absorption through S-glutathionylation of MaAKT1 channel at the conserved Cys202 residue. These findings uncover a previously unrecognized role of FSA in regulating K+ homeostasis in bananas, and provide a foundation for future strategies to treat Fusarium wilt and increase banana production by targeting the conserved S-glutathionylation site in MaAKT1 channel.

Fusarium, a genus of fungi renowned for its plant-pathogenic capabilities, is capable of producing a myriad of structurally diverse secondary metabolites, among which are phytotoxins that play a significant role in the etiology of plant diseases. The particular strain Fusarium oxysporum f. sp. conglutinans (FOC), known as the instigator of Fusarium wilt in cabbage (Brassica oleracea), has been found to secrete an array of toxins and the identities of which have largely remained elusive. In this study, we evaluated the phytotoxicity of crude extracts from the pathogenic FOC strain (FOCr1) and the nonpathogenic F. oxysporum strain (FOcs20) using the cabbage seed phytotoxicity bioassays. Results showed that the crude extract of FOCr1 significantly inhibited seed germination and seedling elongation. Comparative transcriptome analysis and quantitative real-time PCR (qPCR) revealed higher expression levels of a mycotoxin fusaric acid (FA) biosynthetic gene cluster in FOCr1 under host-like conditions (cabbage medium). High-performance liquid chromatography mass spectrometry (HPLC-MS) analysis detected a higher yield FA in the crude extract of FOCr1 but is absent in the FOcs20 strain. Deleting the key gene FUB8 in FOCr1's FA biosynthetic gene cluster delayed wilt symptoms. Moreover, FA treatment was correlated with an uptick in H2O2 levels within seedlings, underscoring its potential as a virulence amplifier. These results suggest that FA acts as a positive virulence factor in FOC.

Circadian clocks are known to modulate host immune responses to pathogen infections, yet their role in influencing pathogen pathogenesis remains unclear. Here, we investigated the role of circadian clocks in regulating the pathogenesis of the fungal pathogen Fusarium oxysporum, which has multiple genes homologous to the Neurospora crassa frq due to gene duplication events, with Fofrq1 being the primary circadian clock gene. The pathogenesis of F. oxysporum in plants is controlled by its circadian clock, with infections causing severe disease symptoms at dawn. Notably, disruption of clock genes dramatically reduces fungal pathogenicity. Circadian clocks regulate the rhythmic expression of several transcription factors, including FoZafA, which enables the pathogen to adapt to zinc starvation within the plant, and FoCzf1, which governs the production of the toxin fusaric acid. Together, our findings highlight the critical roles of circadian clocks in F. oxysporum pathogenicity by regulating zinc starvation response and secondary metabolite production.