Distinguishing between Wheat Grains Infested by Four Fusarium Species by Measuring with a Low-Cost Electronic Nose.

An electronic device based on the detection of volatile substances was developed in response to the need to distinguish between fungal infestations in food and was applied to wheat grains. The most common pathogens belong to the fungi of the genus Fusarium: F. avenaceum, F. langsethiae, F. poae, and F. sporotrichioides. The electronic nose prototype is a low-cost device based on commercially available TGS series sensors from Figaro Corp. Two types of gas sensors that respond to the perturbation are used to collect signals useful for discriminating between the samples under study. First, an electronic nose detects the transient response of the sensors to a change in operating conditions from clean air to the presence of the gas being measured. A simple gas chamber was used to create a sudden change in gas composition near the sensors. An inexpensive pneumatic system consisting of a pump and a carbon filter was used to supply the system with clean air. It was also used to clean the sensors between measurement cycles. The second function of the electronic nose is to detect the response of the sensor to temperature disturbances of the sensor heater in the presence of the gas to be measured. It has been shown that features extracted from the transient response of the sensor to perturbations by modulating the temperature of the sensor heater resulted in better classification performance than when the machine learning model was built from features extracted from the response of the sensor in the gas adsorption phase. By combining features from both phases of the sensor response, a further improvement in classification performance was achieved. The E-nose enabled the differentiation of F. poae from the other fungal species tested with excellent performance. The overall classification rate using the Support Vector Machine model reached 70 per cent between the four fungal categories tested.

A novel hypovirulence-associated Hadaka virus 1 (HadV1-LA6) in Fusarium oxysporum f. sp. cubense.

Fusarium oxysporum f. sp. cubense (Foc) poses a significant threat to banana crops as a lethal fungal pathogen. The global spread of Foc underscores the formidable challenges associated with traditional management methods in combating this pathogen. This study delves into the hypovirulence-associated mycovirus in Foc. From Foc strain LA6, we isolated and characterized a novel member of the Hadakaviridae family, named Hadaka virus 1 strain LA6 (HadV1-LA6). HadV1-LA6 comprises 10 genomic RNA segments, with RNA1 to RNA7 sharing 80.9%-95.0% amino acid sequence identity with known HadV1-7n, while RNA8 to RNA10 display significantly lower identity. HadV1-LA6 demonstrates horizontal transmission capabilities in an all-or-none fashion between different Foc strains via coculturing. Phenotypic comparisons highlight that HadV1-LA6 significantly reduces the growth rates of its host fungus under cell wall stress and oxidative stress conditions. Importantly, HadV1-LA6 attenuates Foc's virulence in detached leaves and banana plants. This study represents the first introduction of a novel hypovirulence-associated Hadaka virus 1 in Foc.IMPORTANCEFusarium wilt of banana (FWB) is a severe fungal disease caused by soil-borne Fusarium oxysporum f. sp. cubense (Foc). Among various strategies, biocontrol emerges as a safe, ecologically friendly, and cost-effective approach to managing FWB. In this study, we focus on exploring the potential of a novel hypovirulent member of hadakavirid, HadV1-LA6. Previous reports suggest that HadV1 shows no apparent effect on the host. However, through phenotypic assessments, we demonstrate that HadV1-LA6 significantly impedes the growth rates of its host fungus under stress conditions. More importantly, HadV1-LA6 exhibits a remarkable capacity to attenuate Foc's virulence in detached leaves and banana plants. Furthermore, HadV1-LA6 could be horizontally transmitted between different Foc strains, presenting a promising resource for revealing the molecular mechanism of the interaction between Hadaka virus 1 and its host.

Outcomes in solid organ transplant recipients receiving organs from a donor with Fusarium solani species complex meningitis.

BACKGROUND: Five organs (heart, right lung, liver, right, and left kidneys) from a deceased patient were transplanted into five recipients in four US states; the deceased patient was identified as part of a healthcare-associated fungal meningitis outbreak among patients who underwent epidural anesthesia in Matamoros, Mexico. METHODS: After transplant surgeries occurred, Fusarium solani species complex, a fungal pathogen with a high case-mortality rate, was identified in cerebrospinal fluid from the organ donor by metagenomic next-generation sequencing (mNGS) and fungal-specific polymerase chain reaction and in plasma by mNGS. RESULTS: Four of five transplant recipients received recommended voriconazole prophylaxis; four were monitored weekly by serum (1-3)-ß-d-glucan testing. All five were monitored for signs of infection for at least 3 months following transplantation. The liver recipient had graft failure, which was attributed to an etiology unrelated to fungal infection. No fungal DNA was identified in sections of the explanted liver, suggesting that F. solani species complex did not contribute to graft failure. The remaining recipients experienced no signs or symptoms suggestive of fusariosis. CONCLUSION: Antifungal prophylaxis may be useful in preventing donor-derived infections in recipients of organs from donors that are found to have Fusarium meningitis.

First report of sweet cherry root rot caused by Fusarium solani in China.

Sweet cherry (Prunus avium L.) has become an economically important fruit in China. And its cultivation area has significantly expanded over the last three decades (Wang et al. 2020; Zhao et al. 2023). In July 2023, wilting of cherry trees was observed in a cherry plantation in Wenchuan County (31°51'N, 103°56'E, altitude: 1,510 m) in Sichuan Province and approximately 27% of the trees showed symptoms of root rot including soft roots, dark brown to black lesions, yellowing and wilted leaves, and a distinct yellow-brown core discoloration of the inner root core when cut in cross-section. To isolate the causal pathogens, six infected sweet cherry plants with rootstock 'Daqingye' from Cerasus pseudocerasus were randomly selected from the orchard and then the intertwined diseased and healthy roots (5mm× 5mm × 2mm) were washed with sterile water to remove surface soil. The root samples were surface sterilized with 75% ethanol for 30 seconds and NaClO for 30 seconds and washed three times with distilled water. The disinfected tissues were placed on potato dextrose agar (PDA) and incubated at 27°C in darkness for 5 days (Zhao et al. 2024). A total of nine fungal isolates with similar morphological characteristics were obtained. The colony obtained through single-spore purification displays a red reverse side and a concentric ring pattern on the front, with a sparse surface. Macroconidia were relatively slender with a curve, like sickle shape, 0 to 3 septate measuring (25.8 to 46.1) µm× (4.2 to 7.5) µm, respectively (n=20). The morphological characteristics were consistent with the description of Fusarium spp. (Li et al. 2021). Among these isolates, only HB5 was selected for additional molecular identification. Three target genes, including the internal transcribed spacer (ITS), partial translation elongation factor 1-alpha (TEF), and RNA polymerase second largest subunit (RPB2) were amplified using the primers ITS1/ITS4, TEF1-728/FTEF1-re, and fRPB2-5F/fRPB2-7r, respectively (Groenewald et al. 2013; Carbone and Kohn 1999; Reeb et al. 2004). Sequences of HB5 was deposited in GenBank (ITS, PP388208; TEF, PP580036; RPB2, PP580035). A BLAST search revealed high similarity to those of F. solani sequences with 99%, 100% and 100% respectively (MN013858.1, JF740846.1, OR371902.1), and a multilocus phylogenetic tree was generated to represent the molecular identification results. Pathogenicity studies were conducted on the rootstocks from 'Daqingye' of Cerasus pseudocerasus in 1 liter plastic flowerpots. The seedlings were incubated in a constant temperature incubator at 25°C with a humidity level of 65% for two weeks. Following the growth of green leaves, 200ml (1x106 spores/ml) of spore suspensions were poured into pots. After 4 weeks of inoculation, the same symptoms of the inoculated plants were observed consistent with those shown in the field , while control plants were inoculated with distill water with asymptomatic. The inoculated pathogen was confirmed both morphologically and molecularly as described earlier, thereby fulfilling Koch's postulates. It has been reported that Fusarium solani has been reported to cause root rot in various plants in China, including Actinidia sppt, Zanthoxylum bungeanum, Fragaria×ananassa Duch (Song et al.2022; Li et al. 2023; Zhao et al. 2024). To our knowledge, this is the first report of Fusarium solani causing root rot in sweet cherry (Prunus avium). We here also report the severity and outbreak of this disease, which has been found in other regions in recent years and may become prevalent. Further research on disease management strategies is urgently needed to protect sweet cherry production.

Fusarium mycotoxins: The major food contaminants.

Mycotoxins, which are secondary metabolites produced by toxicogenic fungi, are natural food toxins that cause acute and chronic adverse reactions in humans and animals. The genus Fusarium is one of three major genera of mycotoxin-producing fungi. Trichothecenes, fumonisins, and zearalenone are the major Fusarium mycotoxins that occur worldwide. Fusarium mycotoxins have the potential to infiltrate the human food chain via contamination during crop production and food processing, eventually threatening human health. The occurrence and development of Fusarium mycotoxin contamination will change with climate change, especially with variations in temperature, precipitation, and carbon dioxide concentration. To address these challenges, researchers have built a series of effective models to forecast the occurrence of Fusarium mycotoxins and provide guidance for crop production. Fusarium mycotoxins frequently exist in food products at extremely low levels, thus necessitating the development of highly sensitive and reliable detection techniques. Numerous successful detection methods have been developed to meet the requirements of various situations, and an increasing number of methods are moving toward high-throughput features. Although Fusarium mycotoxins cannot be completely eliminated, numerous agronomic, chemical, physical, and biological methods can lower Fusarium mycotoxin contamination to safe levels during the preharvest and postharvest stages. These theoretical innovations and technological advances have the potential to facilitate the development of comprehensive strategies for effectively managing Fusarium mycotoxin contamination in the future.

Development and application of multiplex PCR for the rapid identification of four Fusarium spp. associated with Fusarium crown rot in wheat.

Fusarium crown rot (FCR), caused by Fusarium spp., is a devastating disease in wheat growing areas. Previous studies have shown that FCR is caused by co-infection of F. graminearum, F. pseudograminearum, F. proliferatum and F. verticillioides in Hubei Province, China. In this study, a method was developed to simultaneously detected DNAs of F. graminearum, F. pseudograminearum, F. proliferatum and F. verticillioides that can efficiently differentiate them. Whole genome sequence comparison of these four Fusarium spp. was performed and a 20 bp sequence was designed as an universal upstream primer. Specific downstream primers of each pathogen was also designed, which resulted in a 206, 482, 680, and 963 bp amplicon for each pathogen, respectively. Multiplex PCR specifically identified F. graminearum, F. pseudograminearum, F. proliferatum and F. verticillioides but not from other 46 pathogens, and the detection limit of target pathogens is about 100 pg/µl. Moreover, we accurately determined the FCR pathogen species in wheat samples using the optimized multiplex PCR method. These results demonstrate that the multiplex PCR method established in this study can efficiently and rapidly identify F. graminearum, F. pseudograminearum, F. proliferatum, and F. verticillioides, which should provide technical support for timely and targeted prevention and control of FCR.

Isolation and characterization of native antagonistic rhizobacteria against Fusarium wilt of chilli to promote plant growth.

In the eastern coastal regions of Odisha, wilt caused by Fusarium oxysporum f. sp.capsici is an extremely damaging disease in chilli. This disease is very difficult to manage with chemical fungicides since it is soil-borne in nature. The natural rhizosphere soil of the chilli plant was used to isolate and test bacterial antagonists for their effectiveness and ability to promote plant growth. Out of the fifty-five isolates isolated from the rhizosphere of healthy chilli plants, five isolates, namely Iso 01, Iso 17, Iso 23, Iso 24, and Iso 32, showed their highly antagonistic activity against F. oxysporum f. sp. capsici under in vitro. In a dual culture, Iso 32 (73.3%) and Iso 24 (71.5%) caused the highest level of pathogen inhibition. In greenhouse trials, artificially inoculated chilli plants treated with Iso 32 (8.8%) and Iso 24 (10.2%) had decreased percent disease incidence (PDI), with percent disease reduction over control of 85.6% and 83.3%, respectively. Iso 32 and Iso 24 treated chilli seeds have shown higher seed vigor index of 973.7 and 948.8, respectively, as compared to untreated control 636.5. Furthermore, both the isolates significantly increased plant height as well as the fresh and dry weight of chilli plants under the rolled paper towel method. Morphological, biochemical, and molecular characterization identified Bacillus amyloliquefaciens (MH491049) as the key antagonist. This study demonstrates that rhizobacteria, specifically Iso 32 and Iso 24, can effectively protect chilli plants against Fusarium wilt while promoting overall plant development. These findings hold promise for sustainable and eco-friendly management of Fusarium wilt in chilli cultivation.

Cold atmospheric plasma inactivates Aspergillus flavus and Fusarium keratoplasticum biofilms and conidia in vitro.

Introduction. Aspergillus flavus and Fusarium keratoplasticum are common causative pathogens of fungal keratitis (FK), a severe corneal disease associated with significant morbidity and vision loss. Escalating incidence of antifungal resistance to available antifungal drugs poses a major challenge to FK treatment. Cold atmospheric plasma (CAP) is a pioneering nonpharmacologic antimicrobial intervention that has demonstrated potential as a broad-spectrum antifungal treatment.Gap statement. Previous research highlights biofilm-associated resistance as a critical barrier to effective FK treatment. Although CAP has shown promise against various fungal infections, its efficacy against biofilm and conidial forms of FK pathogens remains inadequately explored.Aim. This study aims to investigate the antifungal efficacy of CAP against clinical fungal keratitis isolates of A. flavus and F. keratoplasticum in vitro.Methodology. Power parameters (22-27 kVpp, 300-400 Hz and 20-80 mA) of a dielectric barrier discharge CAP device were optimized for inactivation of A. flavus biofilms. Optimal applied voltage and total current were applied to F. keratoplasticum biofilms and conidial suspensions of A. flavus and F. keratoplasticum. The antifungal effect of CAP treatment was investigated by evaluating fungal viability through means of metabolic activity, c.f.u. enumeration (c.f.u. ml-1) and biofilm formation.Results. For both fungal species, CAP exhibited strong time-dependent inactivation, achieving greater than 80 % reduction in metabolic activity and c.f.u. ml-1 within 300 s or less, and complete inhibition after 600 s of treatment.Conclusion. Our findings indicate that CAP is a promising broad-spectrum antifungal intervention. CAP treatment effectively reduces fungal viability in both biofilm and conidial suspension cultures of A. flavus and F. keratoplasticum, suggesting its potential as an alternative treatment strategy for fungal keratitis.

Current therapy and advancements in the treatment of equine fungal keratitis.

Equine fungal keratitis represents a substantial portion of keratitis cases in horses, with fungal involvement identified in approximately half of all infectious keratitis cases. Despite its prevalence, more comprehensive retrospective analyses are needed to better understand this condition. Outcomes vary, with approximately two-thirds of cases achieving complete healing with retained vision, although enucleation is often necessary. Predominant pathogens include Aspergillus and Fusarium, with yeast reported in a minority of cases. Resistance to common antifungal agents among filamentous fungi poses a significant challenge. Advances in diagnostics, including repeat culture and antifungal susceptibility testing, as well as the incorporation of PCR technology, hold promise for improving detection and guiding treatment decisions. Newer antifungals, combination therapies, and innovative modalities such as photodynamic therapy offer hope for improved outcomes. Continued research efforts are essential to further elucidate the epidemiology, pathogenesis, and optimal management strategies for this condition.

Biostimulant and antagonistic potential of endophytic fungi against fusarium wilt pathogen of tomato Fusarium oxysporum f. sp. lycopersici.

Endophytic fungal-based biopesticides are sustainable and ecologically-friendly biocontrol agents of several pests and diseases. However, their potential in managing tomato fusarium wilt disease (FWD) remains unexploited. This study therefore evaluated effectiveness of nine fungal isolates against tomato fusarium wilt pathogen, Fusarium oxysporum f. sp. lycopersici (FOL) in vitro using dual culture and co-culture assays. The efficacy of three potent endophytes that inhibited the pathogen in vitro was assessed against FWD incidence, severity, and ability to enhance growth and yield of tomatoes in planta. The ability of endophytically-colonized tomato (Solanum lycopersicum L.) plants to systemically defend themselves upon exposure to FOL were also assessed through defence genes expression using qPCR. In vitro assays showed that endophytes inhibited and suppressed FOL mycelial growth better than entomopathogenic fungi (EPF). Endophytes Trichoderma asperellum M2RT4, Hypocrea lixii F3ST1, Trichoderma harzianum KF2R41, and Trichoderma atroviride ICIPE 710 had the highest (68.84-99.61%) suppression and FOL radial growth inhibition rates compared to EPF which exhibited lowest (27.05-40.63%) inhibition rates. Endophytes T. asperellum M2RT4, H. lixii F3ST1 and T. harzianum KF2R41 colonized all tomato plant parts. During the in planta experiment, endophytically-colonized and FOL-infected tomato plants showed significant reduction of FWD incidence and severity compared to non-inoculated plants. In addition, these endophytes contributed to improved growth promotion parameters and yield. Moreover, there was significantly higher expression of tomato defence genes in T. asperellum M2RT4 colonized than in un-inoculated tomato plants. These findings demonstrated that H. lixii F3ST1 and T. asperellum M2RT4 are effective biocontrol agents against FWD and could sustainably mitigate tomato yield losses associated with fusarium wilt.

Field isolates of Beauveria bassiana exhibit biological heterogeneity in multitrophic interactions of agricultural importance.

Beauveria bassiana (Bb) is a widespread entomopathogenic fungus widely used in agriculture for crop protection. Other than pest control, fungi belonging to the B. bassiana complex represent an important microbial resource in agroecosystems, considering their multiple interactions with other microorganisms as antagonists of phytopathogens, or with plants as endophytic colonizers and growth promoters. Here, we characterised field collected or commercial isolates of B. bassiana relative to the environmental factors that affect their growth. We further compared the metabolome, the entomopathogenic potential and biocontrol activity of the tested isolates respectively on the insect pest Spodoptera littoralis or against the fungal plant pathogen Fusarium oxysporum. Our analysis revealed that the B. bassiana complex is characterised by a high level of inter-isolate heterogeneity in terms of nutritional requirements, establishment of intra- or inter-kingdom interactions, and the nature of metabolites produced. Interestingly, certain B. bassiana isolates demonstrated a preference for low nutrient plant-derived media, which hints at their adaptation towards an endophytic lifestyle over a saprophytic one. In addition, there was a noticeable variation among different B. bassiana isolates in their capacity to kill S. littoralis larvae in a contact infection test, but not in an intrahaemocoelic injection experiment, suggesting a unique level of adaptability specific to the host. On the other hand, most B. bassiana isolates exhibited similar biocontrol efficacy against the soil-dwelling ascomycete F. oxysporum f. sp. lycopersici, a pathogen responsible for vascular wilt disease in tomato plants, effectively averting wilting. Overall, we show that the effectiveness of B. bassiana isolates can greatly vary, emphasising the importance of isolate selection and nutritional adaptability consideration for their use in sustainable agriculture.

Molecular Identification and Pathogenicity of Fusarium Species Associated with Wood Canker, Root and Basal Rot in Turkish Grapevine Nurseries.

Fusarium species are agriculturally important fungi with a broad host range and can be found as endophytic, pathogenic, or opportunistic parasites in many crop plants. This study aimed to identify Fusarium species in bare-rooted, dormant plants in Turkish grapevine nurseries using molecular identification methods and assess their pathogenicity. Asymptomatic dormant plants were sampled from grapevine nurseries (43) in different regions of the country, and fungi were isolated from plant roots and internal basal tissues. The Fusarium strains were identified by performing gene sequencing (TEF1-α, RPB2) and phylogenetic analyses. Pathogenicity tests were carried out by inoculating mycelial agar pieces of strains onto the stem or conidial suspensions into the rhizosphere of vines (1103 Paulsen rootstock). Laboratory tests revealed that Fusarium species were highly prevalent in Turkish grapevine nurseries (41 out of 43). Gene sequencing and phylogenetic analyses unraveled that 12 Fusarium species (F. annulatum, F. brachygibbosum, F. clavum, F. curvatum, F. falciforme, F. fredkrugeri, F. glycines, F. nanum, F. nematophilum, F. nirenbergiae, F. solani, and Fusarium spp.) existed in the ready-to-sale plants. Some of these species (F. annulatum, F. curvatum and F. nirenbergiae) consistently caused wood necrosis of seedling stems, rotting of the basal zone and roots, and reduced root biomass. Although the other nine species also caused some root rot and root reduction, their virulence was not as severe as the pathogenic ones, and they were considered opportunistic parasites or endophytic species. This study suggests that Fusarium species might play an important role in root-basal rot, wood canker symptoms, and young vine decline in Turkish grapevine nurseries and that these species need to be considered for healthy seedling production.

Identification of Food Spoilage Fungi Using MALDI-TOF MS: Spectral Database Development and Application to Species Complex.

Fungi, including filamentous fungi and yeasts, are major contributors to global food losses and waste due to their ability to colonize a very large diversity of food raw materials and processed foods throughout the food chain. In addition, numerous fungal species are mycotoxin producers and can also be responsible for opportunistic infections. In recent years, MALDI-TOF MS has emerged as a valuable, rapid and reliable asset for fungal identification in order to ensure food safety and quality. In this context, this study aimed at expanding the VITEK® MS database with food-relevant fungal species and evaluate its performance, with a specific emphasis on species differentiation within species complexes. To this end, a total of 380 yeast and mold strains belonging to 51 genera and 133 species were added into the spectral database including species from five species complexes corresponding to Colletotrichum acutatum, Colletotrichum gloeosporioides, Fusarium dimerum, Mucor circinelloides complexes and Aspergillus series nigri. Database performances were evaluated by cross-validation and external validation using 78 fungal isolates with 96.55% and 90.48% correct identification, respectively. This study also showed the capacity of MALDI-TOF MS to differentiate closely related species within species complexes and further demonstrated the potential of this technique for the routine identification of fungi in an industrial context.

Phytotoxic Strains of Fusarium commune Isolated from Truffles.

Most Fusarium species are known as endophytes and/or phytopathogens of higher plants and have a worldwide distribution. Recently, information discovered with molecular tools has been also published about the presence of these fungi in the microbiome of truffle fruiting bodies. In the present work, we isolated and identified three Fusarium strains from truffle fruiting bodies. All isolates were assigned to the same species, F. commune, and the strains were deposited in the All-Russian Collection of Microorganisms under accession numbers VKM F-5020, VKM F-5021, and VKM F-5022. To check the possible effects of the isolated strains on the plants, the isolates were used to infect sterile seedlings of Sarepta mustard (Brassica juncea L.). This model infection led to a moderate suppression of the photosynthetic apparatus activity and plant growth. Here, we present characteristics of the F. commune isolates: description of the conidial morphology, pigmentation, and composition of the mycelium fatty acids. Overall, this is the first description of the Fusarium cultures isolated from truffle fruiting bodies. Possible symbiosis of the F. commune strains with truffles and their involvement in the cooperative fatty acid production are proposed.

The Non-Histone Protein FgNhp6 Is Involved in the Regulation of the Development, DON Biosynthesis, and Virulence of Fusarium graminearum.

Fusarium graminearum is the primary causative agent of Fusarium head blight (FHB), a devastating disease affecting cereals globally. The high-mobility group (HMG) of non-histone proteins constitutes vital architectural elements within chromatin, playing diverse roles in various biological processes in eukaryotic cells. Nonetheless, the specific functions of HMG proteins in F. graminearum have yet to be elucidated. Here, we identified 10 HMG proteins in F. graminearum and extensively characterized the biological roles of one HMGB protein, FgNhp6. We constructed the FgNhp6 deletion mutant and its complementary strains. With these strains, we confirmed the nuclear localization of FgNhp6 and discovered that the absence of FgNhp6 led to reduced radial growth accompanied by severe pigmentation defects, a significant reduction in conidial production, and a failure to produce perithecia. The ∆FgNhp6 mutant exhibited a markedly reduced pathogenicity on wheat coleoptiles and spikes, coupled with a significant increase in deoxynivalenol production. An RNA sequencing (RNA-seq) analysis indicated that FgNhp6 deletion influenced a wide array of metabolic pathways, particularly affecting several secondary metabolic pathways, such as sterol biosynthesis and aurofusarin biosynthesis. The findings of this study highlight the essential role of FgNhp6 in the regulation of the asexual and sexual reproduction, deoxynivalenol (DON) production, and pathogenicity of F. graminearum.

Pathogenicity Differentiation of Fusarium spp. Causing Fusarium Basal Rot and Wilt Disease in Allium spp.

Here, 12 Fusarium strains, previously described as F. oxysporum f. sp. cepae (Foc), were examined via multi-locus sequencing of calmodulin (cmdA), RNA polymerase II second largest subunit (rpb2), and translation elongation factor 1-alpha (tef1), to verify the taxonomic position of Foc in the newly established epitype of F. oxysporum. The strains in this study were divided into two clades: F. nirenbergiae and Fusarium sp. To further determine the host specifications of the strains, inoculation tests were performed on onion bulbs and Welsh onion seedlings as potential hosts. Four strains (AC145, AP117, Ru-13, and TA) isolated from diseased onions commonly possessed the secreted in xylem (SIX)-3, 5, 7, 9, 10, 12, and 14 genes and were pathogenic and highly aggressive to onion bulbs, whereas all strains except for one strain (AF97) caused significant inhibition of Welsh onion growth. The inoculation test also revealed that the strains harboring the SIX9 gene were highly aggressive to both onion and Welsh onion and the gene was expressed during infection of both onions and Welsh onions, suggesting the important role of the SIX9 gene in pathogenicity. This study provides insights into the evolutionary pathogenicity differentiation of Fusarium strains causing Fusarium basal rot and wilt diseases in Allium species.

First Report on Mycotoxin Contamination of Hops (Humulus lupulus L.).

The presence of mycotoxins and other toxic metabolites in hops (Humulus lupulus L.) was assessed for the first time. In total, 62 hop samples were sampled in craft breweries, and analyzed by a multi-toxin LS-MS/MS method. The study collected samples from craft breweries in all of the Croatian counties and statistically compared the results. Based on previous reports on Alternaria spp. and Fusarium spp. contamination of hops, the study confirmed the contamination of hops with these toxins. Alternaria toxins, particularly tenuazonic acid, were found in all tested samples, while Fusarium toxins, including deoxynivalenol, were present in 98% of samples. However, no Aspergillus or Penicillium metabolites were detected, indicating proper storage conditions. In addition to the Alternaria and Fusarium toxins, abscisic acid, a drought stress indicator in hops, was also detected, as well as several unspecific metabolites. The findings suggest the need for monitoring, risk assessment, and potential regulation of Alternaria and Fusarium toxins in hops to ensure the safety of hop usage in the brewing and pharmaceutical industries. Also, four local wild varieties were tested, with similar results to the commercial varieties for toxin contamination, but the statistically significant regional differences in toxin occurrence highlight the importance and need for targeted monitoring.

Disruption of Cell Membranes and Redox Homeostasis as an Antibacterial Mechanism of Dielectric Barrier Discharge Plasma against Fusarium oxysporum.

Direct barrier discharge (DBD) plasma is a potential antibacterial strategy for controlling Fusarium oxysporum (F. oxysporum) in the food industry. The aim of this study was to investigate the inhibitory effect and mechanism of action of DBD plasma on F. oxysporum. The result of the antibacterial effect curve shows that DBD plasma has a good inactivation effect on F. oxysporum. The DBD plasma treatment severely disrupted the cell membrane structure and resulted in the leakage of intracellular components. In addition, flow cytometry was used to observe intracellular reactive oxygen species (ROS) levels and mitochondrial membrane potential, and it was found that, after plasma treatment, intracellular ROS accumulation and mitochondrial damage were accompanied by a decrease in antioxidant enzyme activity. The results of free fatty acid metabolism indicate that the saturated fatty acid content increased and unsaturated fatty acid content decreased. Overall, the DBD plasma treatment led to the oxidation of unsaturated fatty acids, which altered the cell membrane fatty acid content, thereby inducing cell membrane damage. Meanwhile, DBD plasma-induced ROS penetrated the cell membrane and accumulated intracellularly, leading to the collapse of the antioxidant system and ultimately causing cell death. This study reveals the bactericidal effect and mechanism of the DBD treatment on F. oxysporum, which provides a possible strategy for the control of F. oxysporum.

Transcription factor FoAce2 regulates virulence, vegetative growth, conidiation, and cell wall homeostasis in Fusarium oxysporum f. sp. cubense.

Fusarium wilt of banana, caused by the fungus Fusarium oxysporum f. sp. cubense (Foc), is a serious fungal disease that affects banana plants globally. To explore the virulence mechanisms of this pathogen, we created a null mutation of the transcription factor gene FoAce2 (encoding F. oxysporum angiotensin converting enzyme 2). Deletion of FoAce2 resulted in slower growth, decreased aerial mycelia and conidiation, and a significant decrease in fungal virulence against banana hosts relative to those of the wild-type (WT) fungus. Additionally, transmission electron microscopy showed that the cell wall was thicker in the FoAce2 deletion mutants. Consistent with this finding, the cell wall glucose level was decreased in the ΔFoAce2 mutants compared with that in the WT and complemented strain, ΔFoAce2-C1. Complementation with the WT FoAce2 gene fully reversed the mutant phenotypes. Analysis of the transcriptome of ΔFoAce2 and the WT strain showed alterations in the expression levels of many genes associated with virulence and growth. Thus, FoAce2 appears to be essential for Foc virulence, cell wall homeostasis, conidiation, and vegetative growth.

A cyclic lipopeptide from Fusarium graminearum targets plant membranes to promote virulence.

Microbial plant pathogens deploy amphipathic cyclic lipopeptides to reduce surface tension in their environment. While plants can detect these molecules to activate cellular stress responses, the role of these lipopeptides or associated host responses in pathogenesis are not fully clear. The gramillin cyclic lipopeptide is produced by the Fusarium graminearum fungus and is a virulence factor and toxin in maize. Here, we show that gramillin promotes virulence and necrosis in both monocots and dicots by disrupting ion balance across membranes. Gramillin is a cation-conducting ionophore and causes plasma membrane depolarization. This disruption triggers cellular signaling, including a burst of reactive oxygen species (ROS), transcriptional reprogramming, and callose production. Gramillin-induced ROS depends on expression of host ILK1 and RBOHD genes, which promote fungal induction of virulence genes during infection and host susceptibility. We conclude that gramillin's ionophore activity targets plant membranes to coordinate attack by the F. graminearum fungus.