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Journal of Fungi

MDPI AG

Preprints posted in the last 30 days, ranked by how well they match Journal of Fungi's content profile, based on 31 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

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Evaluating β-glucanases as cell wall-permeabilising agents against Phytophthora agathidicida oospores

Pierson, E.; Mainwaring, J. C.; Patrick, W. M.; Gerth, M. L.

2026-05-12 biochemistry 10.64898/2026.05.08.723360 medRxiv
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The persistence of specialised survival spores produced by microbial pathogens represents a primary bottleneck in the management of plant diseases. In oomycetes, these spores (known as oospores) are largely impervious to chemical control, allowing them to persist in soil and initiate new infection cycles over many years. A prominent example is the soil-borne pathogen Phytophthora agathidicida, the causal agent of kauri dieback disease, where long-lived oospores hinder conservation efforts in native forests. The resilience of oospores is attributed to their thick wall composed of complex {beta}-glucan layers that render the oospores impermeable to most conventional biocides. Here we have investigated an enzyme-based approach for weakening the oospore cell wall. We searched enzyme databases to select {beta}-glucanases targeting a variety of linkages found in Phytophthora oospore walls. Eight of these {beta}-glucanases were successfully purified and tested for their digestive activity against intact oospores in vitro using a phenol-sulfuric acid assay. We showed that combining these enzymes was crucial to achieve significant digestion through synergies and additive effects. The optimal combination, comprising 1,3-, 1,6-, and 1,3(4)-{beta}-glucanases, was evaluated for its ability to permeabilise oospores to five biocides typically effective only on other, more sensitive lifecycle stages of the pathogen. Using a live/dead fluorescence assay, we observed that the effects of the membrane-targeting biocides were potentiated in oospores that were pre-treated with the {beta}-glucanase mixture. Our results highlight enzymatic cell wall permeabilisation as a promising strategy toward improved management of oospore persistence in kauri forest soils and against broader oomycete threats. KeypointsO_LIOur phenol-sulfuric acid assay can be used to screen for oospore-degrading enzymes. C_LIO_LISynergistic enzyme combinations are essential for effective oospore wall digestion. C_LIO_LIEnzyme pre-treatment sensitises oospores to membrane-targeting biocides. C_LI

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C. albicans ergosterol modulates the antifungal response of human neutrophils by masking β-glucan

Jiang, H.; Nobbs, A.; Leaves, I.; Gow, N. A. R.; Diezmann, S.; Amulic, B.

2026-05-18 microbiology 10.64898/2026.05.18.721578 medRxiv
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IntroductionErgosterol-targeting azoles are widely used in the treatment of Candida albicans infection. In addition to direct antifungal activity, azoles are known to enhance neutrophil-mediated killing of C. albicans, but the underlying mechanisms remain unclear, particularly whether ergosterol depletion directly modulates host immune responses. Gap StatementIt remains unknown whether reduced ergosterol levels alone, independent of broader disruption to sterol biosynthesis and fungal morphogenesis, influence neutrophil antifungal activity. AimThis study aimed to determine how genetic disruption of late-stage ergosterol biosynthesis affects neutrophil-mediated responses to C. albicans. MethodologyDoxycycline-repressible GRACE mutants targeting late-stage ergosterol biosynthesis genes (ERG4, ERG5, ERG3 and ERG28) were co-incubated with primary human neutrophils. Fungal survival, oxidative burst, phagocytosis, neutrophil extracellular trap (NET) formation and cell wall composition were assessed. ResultsAll ergosterol-deficient strains induced elevated neutrophil reactive oxygen species (ROS) production; however, only ERG4 depletion was associated with enhanced fungal clearance. This phenotype correlated with increased phagocytosis and reduced NET formation. Cell wall analysis revealed no changes in total chitin or mannan content but demonstrated significantly increased surface exposure of {beta}-1,3-glucan in ERG4-depleted cells. ConclusionThese findings indicate that disruption of late-stage ergosterol biosynthesis, particularly via ERG4, enhances neutrophil antifungal responses and is associated with increased {beta}-glucan exposure. This study highlights a potential role for ergosterol in immune evasion and suggests that targeting terminal steps of the pathway may improve host-mediated clearance of C. albicans.

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Candida glabrata YPK2 is a multidrug susceptibility locus

Simonicova, L.; Conway, T. P.; Brakhage, A. A.; Krueger, T.; Moye-Rowley, W. S.

2026-05-20 molecular biology 10.64898/2026.05.15.725557 medRxiv
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The biological conservation between fungi and mammals due to a common ancestor has made development of selective antifungal drugs a difficult challenge. Further complicating this situation is the selection of antifungal drug-resistant organisms during drug treatment. The pathogenic yeast Nakaseomyces glabratus (called here Candida glabrata) presents an especially challenging organism due to its tendency to frequently lose susceptibility to the major antifungal drug class the azoles. Additionally, C. glabrata develops resistance to echinocandin drugs, a second, more recently described antifungal agent at 10 times the rate of other organisms. Previous work has established that the sterol responsive transcriptional regulator Upc2A is a key determinant of azole susceptibility in C. glabrata and plays a role in echinocandin resistance. We used a biochemical approach to identify proteins that co-purified with Upc2A and identified the Ypk2 AGC kinase as an interacting protein. Strains lacking YPK2 exhibited increased susceptibility to fluconazole and the echinocandin caspofungin. A ypk2{Delta} strain failed to normally induce transcription of several ERG genes but exhibited normal induction of the CDR1 ATP-binding cassette transporter gene. Isogenic ypk2{Delta} strains were also highly susceptible to the three major classes of antifungal drugs, indicating that this kinase behaves as a multidrug susceptibility factor. RNA-seq analyses indicated that the transcriptional response to exposure is different for each drug and each response is differentially altered upon loss of Ypk2. Our data indicate that Ypk2 plays an important role in coordinating gene expression that impacts susceptibility to all major antifungal drug classes.

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First occurrence of Corynespora cassiicola infecting chia plant in Bangladesh and its sensitivity to selected fungicides

Badhon, A. K.; Gupta, D. R.; Paul, S. K.; Ali, J.; Rahman, M. M.; Islam, T.

2026-05-06 molecular biology 10.64898/2026.05.01.722373 medRxiv
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Chia (Salvia hispanica L.) is an emerging crop in Bangladesh valued for its medicinal properties and economic significance. In March 2024, target spot-like symptoms were observed in an experimental chia field (24.75{degrees} N, 90.50{degrees} E) at Bangladesh Agricultural University in Mymensingh, Bangladesh with disease incidence ranging from 23% to 47% across approximately 0.25 ha. Initially appearing as brick-red spots, these symptoms developed into target-shaped concentric rings, affecting leaves, stems, and inflorescences. A total of 24 fungal isolates were recovered from infected tissue; two representative isolates (BGECh-3 and BGECh-4) were randomly selected for details characterization. Pathogen identity was established through morphological traits, multilocus phylogenetic analysis of internal transcribed spacer (ITS) and elongation factor 1-alpha (EF-1) genes sequence, and pathogenicity confirmation through Kochs postulates, collectively identifying the causal agent as Corynespora cassiicola. The isolates demonstrated a broad host range, successfully infecting brinjal, chili, bottle gourd, country bean, tomato, and soybean. In vitro fungicide sensitivity assays with seven commercial fungicides showed that both isolates were highly sensitive to Goldzim (50% carbendazim), which completely inhibited mycelial growth at 10 {micro}g mL-{superscript 1}. Conza (10% Hexaconazole) and Amister top (18.2% azoxystrobin + 11.4% difenoconazole) reduced growth by up to 85% and 67%, respectively at equal concentration. Other fungicides showed comparatively lower efficacy even at higher concentrations. This study represents the first report of target spot disease of chia caused by C. cassiicola in Bangladesh and provides insights for effective disease management strategies.

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Effects of Chitosan as a Permeabilizing Agent in Different Yeast Species. Studying Enzymes in situ.

Araiza-Villanueva, M.; Sanchez, N. S.; Calahorra, M.; Padilla-Garfias, F.; Pena, A.

2026-05-07 microbiology 10.64898/2026.05.06.723273 medRxiv
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Chitosan is an oligosaccharide derived from chitin that is protonated at acidic pH to form a polycation. Its positive charge promotes the interaction with negatively charged components of the yeast cell surface, which has been associated with increased cell permeability and growth inhibition. In this study, we investigated the interaction of chitosan with the cell surface and its permeabilizing capacity in three yeast species displaying distinct susceptibility profiles, Saccharomyces cerevisiae, Candida albicans and Debaryomyces hansenii. We evaluated the correlation between differential susceptibility and chitosan association at the cell surface, as well as cell permeabilization, by integrating growth analyses with surface-binding assays, including FITC-conjugated chitosan to monitor surface association and cellular integration over time, and ultrastructural examination by transmission electron microscopy (TEM). Our results showed that chitosan exhibited varying effects on the growth and permeability of each yeast strain, with D. hansenii being the most susceptible. Furthermore, we observed the incorporation of chitosan onto the cell surface and confirmed its role as a permeabilizing agent. Finally, we used chitosan-induced permeabilization as a method to measure the activity of selected enzymes in situ, demonstrating its potential for studying metabolic functions in permeabilized yeast cells. Overall, our findings establish chitosan as a strain-dependent antifungal agent and a useful tool for functional biochemical analyses in yeast.

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The HOG MAPK - Transcription Factor CsAtf1 - CsErg5B Regulatory Module Mediates Conidial Germination and Fludioxonil Sensitivity in Colletotrichum siamense

Lin, Y.; Wang, K.; Guan, X.; Song, M.; Han, Z.; Liu, W.; Wu, W.; Zhang, Y.; Miao, W.; Lin, C.

2026-05-22 microbiology 10.64898/2026.05.18.725934 medRxiv
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Colletotrichum siamense is a predominant causal agent of anthracnose in rubber tree and numerous economically important crops, causing severe yield losses worldwide. Conidial germination represents a critical early step for successful infection, while the high-osmolarity glycerol (HOG) MAPK pathway and ergosterol biosynthesis individually govern fungal development, stress adaptation and fungicide responses. However, the molecular crosstalk between these two modules remains largely elusive in phytopathogenic fungi. Here, we identified CsErg5B, a sterol C-22 desaturase homolog, as a direct target of the HOG- regulated transcription factor CsAtf1 in C. siamense. CsErg5B was indispensable for ergosterol biosynthesis, conidial germination, appressorium formation, and full virulence. The {Delta}CsErg5B mutant showed increased conidiation but severely impaired germination, and exhibited elevated resistance to fludioxonil while hypersensitivity to azole fungicides. Epistasis analysis using the {Delta}CsErg5B/{Delta}CsCyp51G1 double mutant - where CsCyp51G1 serves as another downstream target of CsAtf1 - revealed that CsErg5B functions as the predominant downstream effector of CsAtf1 in modulating conidial development and fludioxonil sensitivity. Furthermore, overexpression of CsErg5B significantly rescued the defects in conidial germination and fludioxonil sensitivity in both {Delta}CsAtf1 and {Delta}CsPbs2 mutants. Taken together, our findings uncover a HOG MAPK - CsAtf1 - CsErg5B regulatory axis that connects HOG MAPK signaling to ergosterol homeostasis, thereby governing conidial germination and fungicide sensitivity in C. siamense. This study provides novel insights into the regulatory network underlying fungal development and fungicide response, and offers promising molecular targets for the integrated management of plant anthracnose.

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Characterization of a Novel Pseudomonad with Biocontrol Activity Against Aphanomyces euteiches

Kirk, A.; Workman, S. D.; Tiefenbach, A. M.; Hemmingsen, S. M.; Yost, C. K.

2026-05-19 microbiology 10.64898/2026.05.18.726007 medRxiv
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Aphanomyces euteiches, the causative agent of Aphanomyces root rot (ARR), is of major concern for pea and other legume crops globally. This oomycete pathogen causes substantial decreases in crop yields, is unaffected by most fungicides, and persists in the soil for many years via its resilient oospores. Given the significance of pea crops in sustainable agriculture, namely the ability to fix nitrogen and act as a sustainable protein source, solutions to ARR are of high importance. We used RNA-seq in a novel strain of Pseudomonas donghuensis to identify two biosynthetic gene clusters under GacA/S control that are involved in producing bioactive molecules capable of inhibiting A. euteiches. Based on similarity to other reported clusters in Pseudomonas, the first is predicted to encode for a pseudoiodinine compound, while the second is predicted to produce the siderophore 7-hydroxytropolone. Individual knockouts of each cluster showed loss of inhibitory action of P. donghuensis NRC29 against A, euteiches in vivo. This is the first report highlighting the potential of P. donghuensis and the products of the two identified biosynthetic pathways as biocontrol agents for A. euteiches. Further investigations into the efficacy of P. donghuensis NRC29 and its metabolites in inhibiting A. euteiches in field trials will be of high value in developing sustainable strategies for ARR mitigation. ImportanceModern fungicidal treatments for control of root rot in pulse crops are ineffective for control of A. euteiches, leaving limited strategies for management of A. euteiches infected fields. We describe a novel P. donghuensis strain with potential for biocontrol against this persistent pathogen. Given the economic value of peas and other pulses globally, further work into harnessing the bioactive metabolites produced by this strain into a practical in-field treatment will be valuable.

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On the evolution, function and cellular fate of Neurospora crassa ACW-1 and NCW-3, proteins with different cell wall interaction mechanism

Ramirez-Pelayo, A. S.; Callejas-Negrete, O. A.; Amaya-Delgado, L.; Verdin, J.

2026-05-10 microbiology 10.64898/2026.05.09.718313 medRxiv
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The fungal cell wall is populated by proteins (CWPs), mostly uncharacterized, that show an atypical evolutionary behavior. Most CWPs are glycosylphosphatidylinositol(GPI)-proteins, followed by proteins with internal repeats (PIR), and non-covalently attached proteins that harbor carbohydrate binding domains (CBM). Several structural CWPs are initially bound to the same wall carbohydrates, but either covalently or non-covalently. However, it is not clear whether they work in the same way and if they are subjected to the same evolutionary constraints. In Neurospora crassa, CWPs ACW-1 (NCU08936) and NCW-3 (NCU07817) bind to {beta}-1,3-glucans through a GPI anchor or a predicted CBM-52 domain, respectively. Here, the evolutionary trajectories and functional roles of both CWPs were analyzed. Both proteins localized primarily to distal septa and hyphal wall surfaces. Morphological characterization and stress cell wall assays suggested that both proteins contribute to cell wall integrity, but NCW-3 likely plays a more prominent role. ACW-1 and NCW-3 homologues were predominantly identified in Ascomycota. ACW-1 displayed a broader distribution than NCW-3, whose homologues were largely restricted to Sordariales. Despite these differences, both protein families exhibited similar moderate global conservation and signatures of purifying selection within shared taxa. Nevertheless, a divergence gradient was identified within ACW-1, related to its tandem leucine-rich repeat (LRR) regions. A similar local accumulation of evolutionary change was not observed within NCW-3. These findings suggested that distinct CWP architectures can accommodate different patterns of sequence diversification despite sharing similar global evolutionary change.

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Studying Effects of PDA Media Strengths on the Growth of Colletotrichum sublineola Using MPLEx-Based Integrative Proteomics and Metabolomics Analyses

Dawar, P.; Farago, D.; Zemaitis, K. J.; Thomas, A.; Lalli, P. M.; Clendinen, C. S.; Paurus, V. L.; Law, T. F.; Bredeweg, E. L.; Fulcher, J. M.; Dangl, J. L.; Liu, Q.; Pasa-Tolic, L.

2026-05-17 molecular biology 10.64898/2026.05.15.724728 medRxiv
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Colletotrichum sublineola (Cs), the hemibiotrophic fungus that causes sorghum anthracnose, impacts sorghum grain and biomass crop production worldwide. Although nutrient availability is known to influence development in filamentous fungi, including Colletotrichum species, how in vitro nutrient limitation reprograms the Cs cellular state remains unclear. We cultured Cs on full-strength, half-strength, and one-tenth-strength potato dextrose agar (PDA) to define responses across a nutrient gradient. Nutrient limitation induced a pronounced high-sporulation phenotype, with one-tenth-strength PDA producing the strongest conidiation response, followed by half-strength PDA. To study the underlying molecular programs in each condition, we employed a multiplexed metabolite, protein, and lipid extraction (MPLEx) protocol for global proteomics and metabolomics. Global proteomics resulted in 4,590 protein identifications, including 204 unique to one-tenth-strength PDA. Among them are proteins linked to sporulation, vesicular transport, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, and common in fungal extracellular membrane (CFEM)-domain proteins. Differential abundance and pathway analyses revealed a broad reduction of central carbon and energy metabolism, including glycolysis/gluconeogenesis, pentose phosphate, pyruvate metabolism, and glyoxylate pathways, together with increased ribosome-related processes, cAMP signaling, and cell-surface remodeling in one-tenth-strength PDA conditions. In addition, correlative metabolomics supported selective metabolic depletion and resource reallocation toward stress adaptation, membrane remodeling, and conidiation, supporting proteomics findings. Together, these data support a starvation-adapted Cs developmental state associated with enhanced sporulation, cellular pathway reprogramming, and potential virulence linked preparedness under nutrient-limited growth conditions in vitro. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/724728v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@f6ceb2org.highwire.dtl.DTLVardef@17c4836org.highwire.dtl.DTLVardef@68e995org.highwire.dtl.DTLVardef@1bf3983_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Putative Herbicolin A, an antifungal lipopeptide produced by Pantoea agglomerans APC 4211 is a promising biocontrol agent against food spoilage fungi

Kamilari, E.; O'Connor, P.; Reen, F. J.; Das, P.; Aiswariya Deliephan, A.; Hill, D.; Fursenko, O.; Wiese, J.; Moore, A. S. N.; Hill, C.; Stanton, C.; Ross, R. P.

2026-05-21 microbiology 10.64898/2026.05.21.726617 medRxiv
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Fungal contamination of food with yeast and moulds is associated with major economic losses due to spoilage and also poses health risks in the form of mycotoxin production. The strain Pantoea agglomerans APC 4211 isolated from leaves of Ilex aquifolium (holly tree) has broad spectrum antifungal activity against a variety of food spoilage fungi. Genomic analysis of the strain confirmed the presence of biosynthetic gene clusters potentially encoding for the enzymatic machinery required for the production of the antifungal lipopeptide herbicolin A. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis of the cell-free supernatant (CFS) confirmed the presence of molecular masses corresponding to herbicolin A (1300.8 Da), and herbicolin B (1138 Da). Purified herbicolin A has desirable properties for biotechnological applications, including potent antifungal activity against a range of spoilage fungi, thermal stability and resistance to proteases. Herbicolin A has low cytotoxicity against epithelial cell lines and has minimum inhibitory concentrations (MICs) lower than those of some commercial antifungal drugs (0.2 - 2.5 {micro}g/ml). In a model dairy system (10% skim milk), herbicolin A demonstrated excellent solubility and stability, effectively eliminating Aspergillus niger and Penicillium notatum at a concentration of 5 {micro}g/mL. In conclusion, herbicolin A is a potent, naturally occurring antifungal agent with the potential to be applied as a biopreservative in food systems, providing a safe, clean-label, and efficient compound for synthetic preservatives replacement. HighlightsO_LIHerbicolin A has a strong potential as a natural preservative for food protection C_LIO_LIHerbicolin A shows lower MICs than several antifungal agents C_LIO_LIHerbicolin A is stable under heat and resistant to proteolytic degradation C_LIO_LIHerbicolin A has strong solubility and stability in a model dairy system C_LIO_LIHerbicolin A indicates low cytotoxicity against epithelial cell lines C_LI Data summaryThe authors confirm all supporting data, code and protocols have been provided within the article or through supplementary data files.

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Longitudinal performance of the ENLIST ENL Severity Scale in individuals with severe erythema nodosum leprosum: responsiveness, trajectories and clinical features - a secondary analysis of the Methotrexate and Prednisolone study - MaPs in ENL

de Barros, B.; Hamza, A.; Getachew, A.; Medhi, M.; Sultana, F.; Acharya, B.; Pai, V.; Wakade, A.; Bhame, B.; Hagge, D.; Napit, I.; Shah, M.; Maximus, N.; Darlong, J.; Listiawan, M. Y.; Doni, S.; Nicholls, P.; Genser, B.; Lambert, S. M.; Lockwood, D. N. J.; Walker, S. L.

2026-06-01 infectious diseases 10.64898/2026.05.26.26354110 medRxiv
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Background Erythema nodosum leprosum (ENL) is a severe inflammatory complication of lepromatous leprosy characterised by recurrent inflammatory episodes often requiring prolonged immunosuppression. The severity of ENL can be quantified using the validated and reliable ENLIST ENL Severity Scale (EESS). The longitudinal course of ENL and how it is captured using standardised severity measures has not been well described. We prospectively evaluated the changes in ENL severity over time using the EESS in a randomised clinical trial. Methods We conducted a post-hoc analysis of participants enrolled in the Methotrexate and Prednisolone Study in ENL, an international multicentre randomised controlled trial conducted in Ethiopia, India, Indonesia, and Nepal. Adults with severe ENL (EESS score [&ge;]9) were followed for 60 weeks with repeated EESS assessments. Longitudinal trajectories were analysed using mixed-effects regression models. Item-level analyses characterised the clinical phenotype captured by the scale. Associations between EESS score, prednisolone exposure, and dermatology-specific health-related quality of life measured using the Dermatology Life Quality Index (DLQI) were examined. Findings A total of 135 participants contributed 1,958 EESS assessments. Mean EESS declined rapidly during the first four weeks of treatment (-2.10 points/week; 95% CI -2.36 to -1.84; p<0.001), increased modestly during reduction in corticosteroid dose (weeks 4-20), and gradually declined thereafter. Severe ENL (EESS score [&ge;]9) occurred in 20.6% of visits and was characterised primarily by pain and cutaneous inflammatory manifestations. Participants who required additional prednisolone had persistently higher EESS scores and showed limited improvement compared with those who did not receive additional prednisolone. Longitudinal EESS scores were strongly correlated with the DLQI score (Spearmans {rho}=0.75; p<0.001). Conclusion The EESS captures clinically meaningful changes in ENL severity, aligns with treatment decisions, and reflects patient-reported severity over time. These findings support the use of the EESS as a robust tool for monitoring ENL severity in both clinical research and routine care.

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Dynamic Regulation of Atg4 Protease and Autophagy by Dithiothreitol and Iron in Alternaria alternata

Lu, H.-Y.; Choo, C. Y. L.; Wu, P.-C.; Chung, K.-R.

2026-05-06 microbiology 10.64898/2026.05.04.722700 medRxiv
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Autophagy is a critical cellular process regulated by Atg proteins, yet its modulation by redox-active compounds and iron remains incompletely understood. Here, we investigated the effects of dithiothreitol (DTT) and iron on autophagy and on AaAtg4 protease activity in the plant-pathogenic fungus Alternaria alternata. Using GFP-tagged AaAtg8, fluorescence microscopy and proteolysis assays revealed that DTT markedly enhanced autophagic vacuole formation and GFP release, indicating increased autophagic flux. Western blot analyses confirmed that DTT promoted AaAtg8 lipidation, while co-treatment with hydrogen peroxide (H2O2) suppressed this modification. AaAtg4 was constitutively active and could process AaAtg8 regardless of DTT supplementation, whereas moderate DTT concentrations elevated AaAtg4 protein abundance and phosphorylation. Bimolecular fluorescence complementation assays demonstrated that DTT, but not iron, facilitated AaAtg4-AaAtg8 interactions and vacuolar localization, whereas H2O2 counteracted these effects. Notably, combined DTT and H2O2 sustained autophagy at a low but stable level, suggesting a redox balance in autophagic regulation. Iron supplementation selectively destabilized AaAtg8 and modulated AaAtg4 phosphorylation in a concentration-dependent manner, without altering autophagy or protease activity. Collectively, these findings demonstrate that DTT enhances autophagy primarily by promoting AaAtg8 lipidation, AaAtg4 phosphorylation, and AaAtg4-AaAtg8 complex formation, while exerting minimal influence on AaAtg4 protease activity. In contrast, ion regulates autophagy flux through its effects on AaAtg4 phosphorylation and AaAtg8 stability, without significantly altering AaAtg4 protease activity, AaAtg8 lipidation, or AaAtg4-AaAtg8 interactions. Together, this work underscores the intricate interplay between redox signaling, nutrient cues, and autophagy regulation in A. alternata. IMPORTANCEThis study provides critical new insights into how redox-active compounds and iron modulate autophagy in the plant-pathogenic fungus Alternaria alternata, a pathogen of agricultural relevance. By dissecting the distinct roles of DTT, hydrogen peroxide, and iron in regulating AaAtg8 lipidation, AaAtg4 phosphorylation, and AaAtg4-AaAtg8 interactions, our findings reveal that autophagy is not simply a constitutive process but is finely tuned by redox balance and nutrient cues. This work advances the fundamental understanding of autophagy regulation in filamentous fungi, highlights the interplay between oxidative stress and protease activity, and establishes a framework for exploring how environmental factors shape fungal pathogenicity. Ultimately, these insights may inform novel strategies to mitigate crop fungal diseases by targeting autophagic pathways.

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Metabarcode and transcriptome datasets of Pinus sylvestris to assess fungal phyllosphere and disease dynamics.

Moore, B.; Perry, A.; Kaur, S.; Crampton, B.; Gurung, A.; Beaton, J.; Smith, V. A.; Morris, J.; Hedley, P. E.; Nemeth, K.; Barber, H.; Cavers, S.; Jones, S.

2026-05-18 bioinformatics 10.64898/2026.05.14.725107 medRxiv
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Understanding how host-microbiome interactions influence tree disease is critical for understanding forest resilience. Here, we present foliar microbiome ITS2 metabarcoding transcriptomic datasets from Pinus sylvestris to investigate susceptibility to Dothistroma needle blight (DNB), a globally important foliar disease caused by Dothistroma septosporum. We hypothesised that host genotype shapes foliar microbial communities and their interactions, thereby influencing disease outcomes. Samples were collected from a progeny-provenance field trial in the south of Scotland representing a broad spectrum of disease susceptibilities. The dataset comprises ITS2 metabarcoding samples from 200 genotypes across three timepoints and RNAseq samples from 48 genotypes across two timepoints. Sampling captured key stages of pathogen exposure and disease progression. Both standardised and bespoke protocols were used for nucleotide extraction, sequencing, and quality control, including multiple negative and positive controls. These datasets, available in the European Nucleotide Archive (project accession PRJEB88228), enable analysis of temporal dynamics in foliar fungal communities, host-microbiome transcriptional responses, and genotype-dependent variation in disease susceptibility.

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Rapid and Specific Identification of Emerging Trichophyton mentagrophytes Genotype VII Using an In-House Developed and Validated Real-Time PCR Assay

Zhao, J.; Todd, G.; Zhu, Y. C.; Chaturvedi, S.

2026-05-21 microbiology 10.64898/2026.05.20.726730 medRxiv
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Trichophyton mentagrophytes genotype VII (TmVII) is an emerging sexually transmitted dermatophyte that causes skin infections characterized by inflammatory, erythematous-squamous, painful, and persistent lesions. This genotype is part of the T. interdigitale/T. mentagrophytes Species Complex (TiTmSC), which comprises 28 genotypes. To enable rapid and specific differentiation of TmVII from other genotypes, a real-time polymerase chain reaction (rt-PCR) assay was developed targeting three unique single-nucleotide polymorphisms in the ITS1 region of TmVII. Assay specificity was further improved by introducing an additional mismatch at the 3 ends of both forward and reverse primers. The rt-PCR assay demonstrated high sensitivity, with a detection limit of 0.0002 ng of TmVII genomic DNA. The assay was highly specific, with no cross-reactivity observed with either closely or distantly related fungal pathogens when a cycle threshold (Ct) cutoff of 37 was applied. Among 497 mold isolates tested, 47 were confirmed as TmVII by rt-PCR, and the results were fully concordant with conventional ITS-PCR/Sanger sequencing. The rt-PCR assay demonstrated high sensitivity, specificity, reproducibility, and speed, with a turnaround time of one day after DNA extraction, compared with seven to ten days for Sanger sequencing. The first rapid molecular assay developed using TaqMan chemistry for TmVII identification is expected to enhance patient care and support infection control measures.

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Danish profile of soft rot Pectobacteriaceae; A three-year field sampling study proving several clonal clades of soft rot isolates across diverse locations implicating a common origin

Pedersen, J. S.; Junco, L. M. F.; Streubel, A.; Jensen, B.; Kot, W.; Roy, C.; Carstens, A. B.; Hansen, L. H.; Hille, F.; Franz, C. M. A. P.; Rothgardt, M. M.; Nielsen, T. K.

2026-05-15 microbiology 10.64898/2026.05.11.724364 medRxiv
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Soft rot Pectobacteriaceae (SRP) are among the most economically important plant pathogenic bacteria and are especially known to be problematic in potato production. The epidemiology of disease transmission has been investigated for almost a century, and several aspects have been highlighted as plausible infection routes. However, it is generally accepted that the major source of disease is the latently infected mother tuber, but several parameters are still influencing disease prevalence including contaminated equipment, soil water status as well as temperature. Management of the disease is limited to hygiene practices, dry storage and seed certification systems but several studies have also proven biocontrol agents such as bacteriophages (phages) as promising tools. Despite the severity of SRP on potato production, little is known about the genetic diversity of SRPs in Denmark, and since only few isolates are available, the possibility to design a broadly effective phage cocktail is limited. Here we describe a three-year field study utilizing an agri-citizen science approach where Danish farmers provided symptomatic potato plants or tubers, together with metadata such as date, location, potato variety and origin. By using whole genome sequencing (Illumina and Nanopore) together with metadata we were able to investigate and monitor the epidemiological disease spread across the country using 103 complete genomes, sampled across all three years. In this study we provide epidemiological evidence of disease origins and a suite of phages that could be used as a biocontrol tool for early disease intervention. Our results revealed several clonal clades across diverse locations (SNPs < 20) which strongly indicate common origin. A total of 17 Pectobacterium phages were tested and did target > 80% of clonal clades. Based on the clonality across the soft rot isolates we propose the possibility to set in early on using phages targeting strains relevant for soft rot development, with the possibility of a surveillance program together with customizing the phage preference.

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Pigeon-Guano-Contaminated Environments in Blantyre, Southern Malawi, are Reservoirs of Medically Important Fungi

Merico, B. J.; Chigwechokha, P.; Alubino, P.; Bandawe, G. P.

2026-05-30 occupational and environmental health 10.64898/2026.05.26.26354139 medRxiv
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Close to 50% of all bird species are reservoirs of potentially pathogenic fungi, including those listed as priority by the World Health Organization. In Malawi, data on diversity, pathogenic potential, and ecological avian sources of medically important yeast are scarce. A cross-sectional study using a descriptive approach was conducted in Blantyre, Southern Malawi, to characterise medically important yeasts recovered from environments contaminated with excreta/guano from synanthropic pigeons. A total of 20 samples were collected from 4 peri-urban areas, which yielded 71 yeast isolates. To assess the pathogenic potential of the environmental isolates, we compared their phenotypic virulence traits with those of 21 clinical yeast isolates collected from referral hospital laboratories. Pichia kudriavzevii (39%) and Candida orthopsilosis (30%) were the commonly isolated species in the pigeon-guano-contaminated environments. Candida parapsilosis sensu stricto (29%) and Candida albicans (24%) constituted most of the clinical yeast isolates. Half of the species isolated in the pigeon-guano-contaminated environments were also identified among the clinical isolates. A majority of the environmental isolates showed virulence traits similar to or stronger than clinical isolates. The findings underscore the critical need for integrated surveillance under the One Health framework, especially in bird-inhabited spaces close to human settlements.

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Compatibility and Multi-Season Field Evaluation of Trichoderma koningiopsis Integrated with Fungicides for Soybean Charcoal Rot Management

Bleckwedel, J.; Nieva, R. E.; Gonzalez, V.; Ploper, L. D.; Reznikov, S.

2026-05-13 plant biology 10.64898/2026.05.11.724353 medRxiv
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Soybean (Glycine max [L.] Merr.) productivity is frequently compromised by soil-borne pathogens. Macrophomina phaseolina (Mp), the causal agent of charcoal rot, can produce important soybean yield losses especially when hot and dry weather prevails. Integrating biological control agents with chemical seed treatments represents a promising strategy for improving disease management. This study aimed to (i) assess the in vitro compatibility of Trichoderma koningiopsis with commercial fungicide seed treatments, and (ii) evaluate the field performance of T. koningiopsis, alone or combined with compatible fungicides, across three soybean growing seasons. Compatibility assays revealed fungicide-specific effects, with Acronis(R) classified as non-fungitoxic and Topseed Extra as moderately fungitoxic. Across field seasons, Mp inoculation reduced seedling emergence, while several seed treatments improved emergence compared to the inoculated control, however, treatment effects varied markedly among years. Disease severity did not differ significantly among treatments in any season, and yield responses were strongly modified by environmental conditions rather than treatment effects. Temperature-response assays showed that T. koningiopsis exhibited optimal growth between 28 to 30{degrees}C and complete inhibition above 40{degrees}C, indicating high thermal sensitivity. The results demonstrate that T. koningiopsis can be integrated with compatible fungicides and may enhance early stand establishment under favorable conditions, but its field performance is strongly limited by high temperatures. These findings highlight the importance of environmental conditions when biological seed treatments are used.

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Simulated Microgravity Induces Cultivar-Specific Changes Affecting Salmonella enterica Ingression Independent of Stomatal Physiology

Wiest, T. A.; Bais, H.

2026-05-15 plant biology 10.64898/2026.05.13.724889 medRxiv
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Advances in NASAs astrobiology program have demonstrated the feasibility of cultivating plants in space and in analog extraterrestrial habitats. In addition to abiotic stressors, plants grown in terrestrial and space-like environments are challenged by both phytopathogens and opportunistic human pathogens, with implications for plant productivity and human health. The persistence of human-associated pathogens in spacecraft and space stations raises significant concerns regarding food safety. The molecular, biochemical, and signaling mechanisms governing stomatal development and function under microgravity remain poorly understood. We employed an experimental system incorporating human pathogen Salmonella enterica and lettuce microgreens exposed to simulated microgravity through two-dimensional clinorotation to investigate plant innate immunity and stomatal development and function. We further evaluated four lettuce cultivars to determine whether genetic variation impacts these factors under simulated microgravity conditions. Our findings indicate that simulated microgravity significantly influences stomatal development and function, as evidenced by an increase in stomatal density and variable changes to stomatal aperture. Notably, cultivar-dependent variation in stomatal traits and responses to Salmonella enterica was observed under microgravity conditions. Although increased stomatal density was hypothesized to enhance pathogen ingression, internalization was more strongly predicted by cultivar selection and simulated microgravity; simulated microgravity increased ingression, with red pigmented cultivars having less pathogen than green cultivars. These results suggest that targeted selection of cultivars with favorable physiological traits may improve food safety and the viability of crop production systems in space environments. They also suggest that development and function of stomata may change in spaceflight conditions.

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A genomic and proteomic characterization of mannan-degradable Bacillus sp. TTS1, isolated from Tomakomai Forest in Hokkaido

Mitsumasu, S.; Kasuga, Y.; Nagano, T.; Kumar, V.; Hasegawa, Y.; Maeda, T.; Takasuka, T. E.

2026-05-19 microbiology 10.64898/2026.05.18.725066 medRxiv
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A challenge in using plant biomass is its highly recalcitrant nature, which makes it economically infeasible to utilize. In natural environments, various microbes, including bacteria and fungi, are reported to decompose plant cell wall materials such as cellulose and hemicellulose, and there may be undescribed microbes that contribute to the degradation of plant biomass. We focused on isolating novel plant biomass-degrading bacteria and screened more than 100 isolates from the Tomakomai experimental forest in Hokkaido, Japan. Among them, one novel Bacillus species was chosen for whole-genome sequencing. Comparative genomics and a carbon source utilization assay indicated that the isolate belongs to a subspecies of Bacillus subtilis, which we named B. sp. TTS1. Glucose, cellobiose, xylose, xylan, mannose, or mannan was used as the sole carbon source in the minimum medium, and the growth of this bacterium was determined. Furthermore, a proteomic analysis of B. sp. TTS1 was performed using culture supernatants from various polysaccharide-containing media. In the present study, several key enzymes involved in plant biomass degradation were identified, namely {beta}-1,4-mannanase and xylanase, and they were highly enriched in all tested polysaccharides.

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The impact of long-read sequencing on fungal genome assemblies: progress and disparity

Kroll, E.; Zoclanclounon, Y. A. B.; Urban, M.; Hill, R.; Hammond-Kosack, K. E.

2026-05-14 genomics 10.64898/2026.05.12.724544 medRxiv
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Fungal genomics has expanded rapidly over the past 30 years, and recently the pace and breath has further quickened for many taxa, although many taxonomic gaps persist. With three decades of rapid growth, fungal genomics now merits a re-examination of its history, progress, and unresolved taxonomic gaps. Here, we review the development of fungal genomics from early efforts such as the Fungal Genome Initiative to current progress driven by third-generation long-read sequencing. We have compiled and summarised publicly available fungal genomes to highlight trends in assembly quality, adoption of long-read technologies, and taxonomic representation. Notably, substantial phylogenetic gaps remain, particularly outside Dikarya, and significant challenges persist for unculturable taxa. This review identifies priorities for the fungal community, including: (1) coordinated efforts to close major taxonomic gaps across the fungal tree of life; (2) improved repository metrics to facilitate identification of high-quality assemblies; and (3) improved and standardised genome annotation which is lacking for most assemblies. Together, these steps will support the development of reliable genomic resources that capture the full breadth of diversity across the fungal kingdom, generating foundational data for comparative genomics, evolutionary biology, functional studies, genetic studies and applied research.