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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 32 papers previously published here. The average preprint has a 0.03% match score for this journal, so anything above that is already an above-average fit.

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High-throughput functional genomics and transcriptomics reveal molecular mechanisms regulating the synergistic fungicidal activity of copper and zinc

Kerkaert, J. D.; Carvalho, R.; Schnirman, R. E.; Wu, C. X. Y.; Reyes-Chavez, B.; Zhang, Y.; Koker, M. K. A.; Smieska, L. M.; Huberman, L. B.

2026-10-05 microbiology 10.64898/2026.10.02.756351 medRxiv
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Fungal diseases cause devastating crop infestations and millions of deaths annually. To improve disease treatment development, we must understand the biological processes these treatments target and the fungal cellular responses they elicit. Current methods to identify genetic responses of fungi to antifungal drugs and fungicides typically involve laborious molecular genetics experiments or transcriptomics. We utilized high-throughput screens in the basidiomycete yeast Rhodotorula (Rhodosporidium) toruloides to rapidly identify genes associated with the fungal response to a copper-zinc fungicide developed by VM Agritech and compared identified genes to those transcriptionally activated in response to the fungicide in R. toruloides and the filamentous ascomycete Neurospora crassa. These 'omics technologies combined with molecular genetics and biochemical analyses showed copper and zinc synergize to inhibit fungal growth due, at least in part, to an increase in cellular zinc concentrations when copper is present. Intriguingly, although we identified genes involved in the copper-zinc fungicide response using both high-throughput screens and transcriptomics, there was little overlap in genes identified through the two methods. Our findings demonstrate the power of combining functional genomics and transcriptomics approaches in identifying a more comprehensive map of the genetic mechanisms necessary for responding to fungicides.

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From acidic extreme environments to agriculture: a multi-stress-tolerant Talaromyces pseudofuniculosus enhances soybean growth under abiotic stress

Staiano, I.; Castaldi, s.; Masi, M.; Salvatore, M. M.; de Tommasis, G.; Gentile, M. C.; Andolfi, A.; Cimmino, A.; Isticato, R.

2026-10-06 microbiology 10.64898/2026.10.06.756979 medRxiv
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Extremophilic fungi are a relatively unexplored source of stress-resilient microbes for sustainable agriculture. Here, we describe Talaromyces pseudofuniculosus FAR, isolated from the highly acidic site of Piccolo Inferno in southern Italy and identified by ITS and {beta}-tubulin (BenA) sequencing. Despite its origin from an extreme environment, T. pseudofuniculosus FRA remained fully functional under non-stress conditions and displayed tolerance to salinity and heavy metals while maintaining key plant growth-promoting traits, including phosphate solubilization, auxin-related compound production and hydrolytic activities. In soybean (Glycine max L.), the live fungus promoted plant growth under both non-stress conditions and agriculturally relevant salinity and copper stress, and successfully colonized the roots. A cell-free extracellular extract (exCFS) promoted early seedling development in vitro, but its effects were not sustained in pot experiments. GC-MS analysis provided a qualitative characterization of the extracellular metabolite profile and revealed condition-dependent differences between control, NaCl and CuSO4; growth conditions, indicating environment-dependent modulation of fungal metabolism. Overall, these findings highlight the physiological and metabolic plasticity of T. pseudofuniculosus FRA and support its potential as a fungal biostimulant for saline- and metal-impacted agricultural soils.

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Novel human long noncoding RNA responses to Candida auris and its cell-wall components in peripheral blood mononuclear cells

Sarker, M. T.; Bisha, B.

2026-09-24 bioinformatics 10.64898/2026.09.21.753102 medRxiv
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Candida auris is an emerging multidrug-resistant fungal pathogen. However, little is known about the role of long noncoding RNAs (lncRNAs) in the human immune response to this fungus. We reanalyzed RNA-sequencing data from peripheral blood mononuclear cells obtained from three healthy donors. The cells were exposed to live C. auris, purified mannan, purified {beta} glucan, or RPMI control for 4 h and 24 h. We identified 607 putative novel polyadenylated lncRNA loci that were absent from GENCODE Release 48. Of the 449 novel loci tested for differential expression, 102 responded to at least one stimulus. Novel-lncRNA responses were limited at 4 h but increased markedly at 24 h. At 24 h, 78 novel lncRNAs responded to live C. auris, 34 to mannan, and 11 to {beta}-glucan. Many of these responses were specific to a particular stimulus. Among the 102 responsive lncRNAs, 94 were significantly co-expressed with protein coding genes. The coding-gene partners of the most highly connected lncRNAs were associated with innate immunity, defense responses, lysosomal functions, and signaling pathways. Temporal analysis identified 19 novel lncRNAs whose responses changed between 4 and 24 h. Fourteen were also differentially expressed and were selected for further analysis. Combining temporal response, co-expression, and genomic proximity identified 4 candidate cis-associated pairs: MSTRG.32011-TLR2, MSTRG.5763-DUSP5, MSTRG.25627-HCK, and MSTRG.18159 ITGB3.These findings reveal a predominantly late and stimulus-specific novel-lncRNA response to C. auris and provide prioritized candidates for experimental validation.

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Occurrence, incidence, and severity of Alternaria leaf spot of cotton (Gossypium hirsutum L.) in major cotton-growing districts of the Lake Zone, Tanzania

EUSTACE, S. M. M.; Mwaipopo, B. V.; Madege, R. R.

2026-09-24 plant biology 10.64898/2026.09.24.754005 medRxiv
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Background: Alternaria leaf spot (ALS), caused by fungi in the genus Alternaria (family Pleosporaceae), is a significant fungal disease that affects cotton production in the Lake Zone of Tanzania, the country's main cotton-producing region. The disease reduces photosynthetic capacity, boll retention, and fiber quality, leading to substantial yield losses in affected fields. Despite its increasing prevalence, systematic baseline epidemiological data remain scarce. Objective: This study aimed to determine the occurrence, incidence, and severity of Alternaria leaf spot across the major cotton-growing districts of the Lake Zone, Tanzania. Methods: Field surveys were conducted during the 2024-2025 growing season in the districts of Bariadi, Bunda, Chato, and Magu; 20 representative cotton fields were systematically assessed using a diagonal sampling approach. Disease incidence, prevalence, and severity were recorded for 1,000 cotton plants. Fungal isolates recovered from symptomatic leaves were sent to the laboratory for isolation and morphological identification. Results: Field prevalence was 100%, and the overall mean incidence was 64.4%, with significant inter-district variation: Bariadi (77.6%), Bunda (68.8%), Chato (60.0%), and Magu (52.4%). Mean DSI ranged from 44.0% (Magu) to 70.1% (Bariadi), indicating moderate-to-severe infection. Disease incidence and Disease severity (DSI) were strongly correlated when uninfected plants were included (r = 0.942, P < 0.001). However, this relationship weakened substantially and became non-significant when restricted to infected plants only (r = 0.396, P = 0.084). This suggests that higher incidence reflected more plants becoming infected rather than greater severity among already infected plants. Morphological characterization identified all 40 isolates as belonging to the genus Alternaria. Conclusion: These findings provide the first systematic epidemiological baseline for Alternaria leaf spot across the major cotton-growing districts of Tanzania's Lake Zone. Disease incidence and severity varied significantly across districts, underscoring the need for tailored disease management strategies. This study recommends ongoing surveillance and integrated disease management to safeguard cotton productivity among smallholder farmers in the region.

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Mapping virulence-associated protein interaction networks reveals regulators of thermotolerance in Cryptococcus neoformans

da Silva, M.; Sa, M.; Roux-Dalvai, F.; Droit, A.; Geddes-McAlister, J.

2026-09-26 microbiology 10.64898/2026.09.25.754343 medRxiv
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Protein-protein interactions (PPIs) influence critical biological processes in pathogenic microorganisms, such as the human fungal pathogen, Cryptococcus neoformans. Fungal thermotolerance and stress response pathways are key virulence determinants that directly impact pathogen adaptation and survival and the infection process. To establish a comprehensive baseline of PPIs in C. neoformans and explore these interactions to infer functional roles for uncharacterized proteins, we applied size exclusion chromatography coupled with mass spectrometry to the secreted and cellular proteomes of the fungi. As a result, 216 and 1699 unique proteins were identified across 24 secretome and proteome fractions, respectively. The predicted secretome networks included expected proteins associated with vesicles and virulence, indicating a role in extracellular defense. Whereas the cryptococcal proteome highlighted interactions among proteins with defined roles in fungal virulence for protein stability and thermotolerance, including two previously uncharacterized proteins, CNAG_00287 and CNAG_05199, putatively involved in complex formation with heat-shock proteins (HSP). Based on sequence and structure homology, we propose that CNAG_00287 is a tetratricopeptide repeat-containing co-chaperone that modulates Hsp 70 activity and CNAG_05199 functions as a Hsp70. We validated the thermotolerance role of CNAG_00287 in heat-related stress, as its absence significantly impaired fungal growth in nutrient-limited media at 37 {degrees}C. Together, this work resolves virulence-associated PPIs within C. neoformans and reveals new molecular regulators of thermotolerance that underpin fungal pathogenicity.

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Rapid whole genome- and annotation-based multilocus sequence typing of the fungal pathogen Histoplasma capsulatum

van Vliet, A. H. M.

2026-09-30 genomics 10.64898/2026.09.27.754713 medRxiv
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Introduction. Histoplasma capsulatum is an important fungal pathogen of humans, especially in immunocompromised patients, and the World Health Organisation has listed Histoplasma as a High Priority fungal pathogen. The taxonomy of the genus Histoplasma is still under development, but its only species H. capsulatum has at least of seven lineages, and a range of sublineages. Gap Statement. Allelic multilocus sequence typing (MLST) has been very successfully applied for typing and epidemiology of pathogenic bacteria, but its adoption for fungal pathogens is more limited. Genome sequence-based MLST approaches promise much a higher resolution for comparative phylogenetics, but there are only a small number of genome assemblies available for H. capsulatum. Aim. To develop and validate genome-based MLST typing for H. capsulatum. Methodology. A total of 406 genome assemblies were generated from publicly available Illumina short-read sequencing samples. Selected genome assemblies were subsequently used to generate MLST schemes with chewBBACA, based on whole genome sequences (wgMLST), NCBI-obtained annotations (annMLST) and annotations obtained with Funannotate (fanMLST), and used for lineage identification, and comparative analyses of population structure. Results. Genome assemblies were successfully generated for 406 H. capsulatum samples, with BUSCO completeness scores of over 98%. A subset of 60 genome assemblies was used to generate and validate MLST schemes based on the 60 genome assemblies, 5 genome annotations obtained from Genbank, and 13 genome annotations generated using Funannotate, resulting in schemes with > 8,000 markers. Each of the MLST schemes allowed reproducible separation of all 7 lineages and 6 H. capsulatum Suramericanum sublineages, without the need for high-performance clusters or powerful computing equipment. Comparison of the different schemes using tanglegrams and scatter plots showed good reproducibility (r2 values of 0.8-1.0). Comparison of total sizes of genome assemblies showed significant lineage-dependent size differences, with the Suramericanum, LAmB, India, Capsulatum and Mississippiense lineages averaging a total genome size of 30-33 million bp, and the Africa and Ohiense lineages averaging at 39 million bp. Conclusion. Genome sequence- and especially genome annotation-based MLST analyses are a promising approach that can be adapted as a rapid, high-throughput method for genomic clustering and epidemiological tracing of pathogenic fungi.

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Positive and negative effects of CaMCA1 deletion on stress sensitivity and virulence

Wilkinson, D.

2026-09-23 microbiology 10.64898/2026.09.23.753419 medRxiv
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Metacaspases are cysteine proteases and are found in every group of organisms except animals. They are structural orthologs of caspases, which orchestrate apoptosis in animals. Caspases, metacaspases, paracaspases and orthocaspases are class C14 proteases with a similar active site (the hemoglobinase fold) and a catalytic cysteine residue. However, metacaspases cleave after arginine and lysine instead of aspartate and some researchers point out that a name ending with caspase is unsuitable. Also, most metacaspases are activated by calcium, they do not target the same proteins as caspases and they cut multiply instead of once. The Candida albicans metacaspase Mca1p mediates cell death in response to various stresses but also has pro-life functions. Many plant and protist metacaspases lack cell death roles and are involved in development, differentiation and immunity. This article highlights an interesting phenomenon, whereby the promotion of stress sensitivity and reduction of virulence, by Mca1p in C. albicans cells from exponential culture are abolished and reversed, respectively in cells from stationary-phase culture. This hints at the proteases's dual nature and at the conditions that might initiate a switch between pro-life and pro-death functions.

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PDF2.2 links constitutive defensin expression to disease resistance in Arabidopsis

Singh, S.

2026-10-09 plant biology 10.64898/2026.10.04.756585 medRxiv
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Background: Plant defensins are small cysteine-rich antimicrobial peptides. In Arabidopsis thaliana, the inducible Class I gene AtPDF1.2a is widely used as a transcriptional marker of jasmonate/ethylene immunity, whereas the constitutively expressed Class II members have received less functional attention. AtPDF2.2 was compared with AtPDF1.2a during infection of Arabidopsis by the vascular fungal pathogen Verticillium longisporum, the necrotrophic fungus Sclerotinia sclerotiorum and the bacterium Pseudomonas syringae pv. tomato DC3000. Results: Profiling of the AtPDF family showed that AtPDF2.2, together with the Class II genes AtPDF2.3 and AtPDF2.5, was significantly reduced during V. longisporum infection, whereas AtPDF1.2a was induced. A promoter-reporter line showed a corresponding decrease in AtPDF2.2 promoter activity during V. longisporum infection, strongest in infected roots. KD-pdf2.2 plants contained more V. longisporum DNA, whereas OE-PDF2.2 plants contained less. The same reciprocal disease pattern was observed during S. sclerotiorum and Pst DC3000 infection. Histochemical Prom::AtPDF2.2::GUS reporter signal decreased during S. sclerotiorum infection but increased following Pst DC3000 infection. Basal AtPDF2.2 expression was lower in JA and ET-signaling mutants and higher in the SA-deficient sid2 background, while the analyzed promoter lacked the GCC-box that mediates inducible AtPDF1.2a regulation. AtPDF1.2a overexpression reduced symptoms across the three pathosystems, but loss of AtPDF1.2a increased disease only during V. longisporum infection under the conditions tested and did not alter Pst DC3000 DNA abundance. AtPDF2.2 overexpression was not associated with reduced vegetative growth under the conditions tested, whereas AtPDF1.2a overexpression reduced rosette size and leaf number. Conclusions: AtPDF2.2 is a constitutively expressed Class II defensin whose expression level is associated with disease outcome across two fungal pathogens and a bacterium. Its promoter shows tissue-dependent regulation during V. longisporum infection, while histochemical reporter signal decreases during S. sclerotiorum infection and increases during Pst DC3000 infection. This regulatory behavior differs from that of the inducible reference gene AtPDF1.2a. The reciprocal disease phenotypes of the AtPDF2.2 transgenic backgrounds support a protective association that may involve direct antimicrobial activity, modulation of host responses or both. The absence of reduced vegetative growth in OE-PDF2.2 under the conditions tested supports further evaluation of PDF2-type genes in Brassica.

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Species Distribution, Antifungal Susceptibility, and Machine Learning-Based Prediction of Optimal Therapies Against Candida Species

Paik, P.; tilak, R.; Tiwari, P.; Rai, A. k.; Gupta, M. K.; Varnika, S.

2026-10-08 microbiology 10.64898/2026.10.06.757060 medRxiv
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Invasive candidiasis has become more common in recent decades, particularly within ICUs. Identifying specific Candida spp., and testing their sensitivity to antifungal drugs is crucial for effective treatment that helps healthcare providers to detect potential treatment challenges early. This study aimed to identify Candida spp. at their spp. level present in blood, assess their susceptibility to antifungal agents, and apply a random forest classifier to predict the best antifungal drug for a given species. The isolates were classified at the species complex level through MALDI-TOF MS. The strains' susceptibility to antifungal agents such as AMB, FLZ, VOZ, ITZ, POZ, CAS, MFN, and ANF was assessed using CLSI guidelines. Out of the 354 Candida spp. isolated from blood, C. utilis was found to be the predominant species, followed by C. tropicalis, and C. albicans. This study demonstrated that MFN and ANF exhibited high potency, with an impressive MIC90 of 0.12 {micro}g/mL against all isolates, surpassing CAS, which had a slightly higher overall MIC90 of 0.25 {micro}g/mL. FLZ exhibited the highest MIC90 value among the azoles at 16 {micro}g/mL, while VOZ, ITZ, and POZ all had MIC90 values of 0.5 {micro}g/mL. AMB MIC90 values were 2 {micro}g/mL against all isolated Candida species. The Random Forest AI/ML model showed perfect overall prediction, with the actual and predicted best antifungal drugs matching for all fungal species. This study is particularly essential because rare Candida spp. becoming more common and exhibiting higher MICs to AMB and FLZ and required suitable remedies for controlling the infection.

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Consolidating species boundaries in the Fusarium oxysporum species complex based on genomic evidence

Bell, J.; van Os, J.; Thines, M.; Moreira Costa, M.; Collemare, J.; Groenewald, J. Z.; Mishra, B.; Ulaszewski, B.; Crous, P. W.; Seidl, M. F.

2026-10-01 evolutionary biology 10.64898/2026.09.25.754427 medRxiv
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The Fusarium oxysporum species complex (FOSC) comprises numerous plant pathogens infecting crops such as tomato, lettuce, melon, and banana. Despite its economic and ecological importance and decades of research, the species names linked to different phylogenetic lineages within this species complex remain largely controversial. Earlier taxonomic frameworks relied on a limited number of marker genes, variable taxon sampling and inconsistent species definitions, leading to a fragmented and unstable taxonomy. To address these challenges, we here analysed nearly 2,500 conserved marker genes from 660 genomes, including genome assemblies from 22 ex-type strains that were sequenced using long-read sequencing technology, representing nearly half of the 51 currently described species within FOSC. Maximum likelihood- and coalescence-based analyses of the full phylogenomic data matrix as well as subsets yielded a robust phylogeny of FOSC, which was furthermore corroborated by whole genome comparisons. Many previously described species are redundant, while two novel lineages remain undescribed. Direct comparisons to traditional marker gene-based approaches demonstrate their inadequacy for species delimitation in FOSC. We show that our phylogenomic framework can guide the detection of novel marker genes able to distinguish the major lineages within FOSC, which will be essential for taxon delineation and classification in future studies. Thus, our phylogenomic analyses provide a stable cornerstone for revising FOSC taxonomy and offers a critical resource for the broader research community.

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Mutation in Ralstonia pseudosolanacearum F1C1 cytochrome p450 homologue impairs virulence through root but not through shoot of tomato plants

Dutta, L.; Kabyashree, K.; Giri, S. J.; Bansal, K.; Chakraborty, D.; Begum, S.; Kalita, S.; Jain, M.; Bhuyan, S.; Kushwah, S.; Kumar, A.; Jha, G.; Patil, P. B.; Ray, S. K.

2026-10-11 pathology 10.64898/2026.10.09.757812 medRxiv
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Ralstonia pseudosolanacearum causes a lethal bacterial wilt disease in many plants. The pathogen enters through roots and systemically colonizes the xylem tissue, resulting in wilting and eventual death of the host. Using transposon mutagenesis followed by screening in tomato seedlings, we identified a mutant exhibiting virulence deficiency by root inoculation, but not by leaf inoculation. The mutation was recreated in the wild-type genome via natural transformation to prove the linkage of virulence deficiency with the transposon insertion. Whole genome sequencing revealed that the transposon insertion was in a cyp450 homologue, encoding cytochrome P450 monooxygenase. Two independent targeted mutations were generated in the cyp450 gene, and both the mutants recapitulated the root-specific virulence deficiency. The mutants rarely cause disease in mature plants following soil drenching but remained fully virulent upon petiole pricking inoculation. Complementation with the full length cyp450 gene amplified from the wild-type strain F1C1 restored virulence in the mutant. Compared to the wild-type F1C1, the cyp450 mutants exhibited greater sensitivity to tomato root extracts. HR-LCMS of tomato root extracts revealed the occurrence of several antimicrobial compounds. Cytochrome P450 enzymes are known to mediate the degradation or biosynthesis of diverse metabolites in bacteria. Considering the virulence difference due to the mode of inoculation, our findings indicate that cyp450 contributes to tissue-specific adaptation of the pathogen during infection has opened an avenue for integrating tissue metabolomics with bacterial wilt susceptibility research.

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An expanded microsporidia species attribute database documents the extensive ecological and phenotypic diversity of these parasites

Chen, C.; Alassal, A.; Reinke, A. W.

2026-09-24 microbiology 10.64898/2026.09.21.753277 medRxiv
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Microsporidia are a group of parasites that exhibit vast morphological, ecological, and genetic diversity. To catalog this diversity, we previously generated a database of attributes for microsporidia species. Here we expand this database to include species described since 2021, previously missed descriptions, and provisional species defined by clustering GenBank 18S rRNA sequences, resulting in 1,795 species. Using these data, we describe when and where microsporidia have been reported, their hosts and host habitats, the tissues they infect, and their spore morphology. A phylogeny of 18S sequence clusters shows that closely related microsporidia tend to infect closely related hosts, such that sequence identity is predictive of host taxonomy. Clustering also reveals previously unappreciated genetic diversity within some named species, in particular the human pathogen Vittaforma corneae, suggesting that these may comprise multiple species. We have also generated a web portal through which new species information can be submitted, which will facilitate regular updates. This database provides a resource for systematic analysis of microsporidia properties and a reference for taxonomic descriptions.

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Interference competition influences virulence in Metarhizium coinfections

Ghani, N.; Oeguet, C.; Kimenyi, N.; Kilker, S.; Rafaluk, C.

2026-10-07 evolutionary biology 10.64898/2026.10.02.756158 medRxiv
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Coinfections are common in a nature and often involve competition among coinfecting parasites to extract resources from the host. As a consequence of this competition, parasites can face trade-offs between investing in competition with other parasites and exploiting the host for their own growth and transmission. Such within-host interactions among parasites can either increase or decrease virulence depending on how they alter parasite density, resource use, and host damage. We tested the inhibitory effect of different species of the entomopathogenic fungus Metarhizium on one another in vitro and the impact of coinfection on virulence towards Tribolium castaneum. We found that Metarhizium pemphigi is able to inhibit all other isolates of Metarhizium tested, whereas Metarhizium pingshaense was relatively resistant to inhibition by other Metarhizium strains. Virulence towards the host, Tribolium castaneum, differed very little among isolates tested. We did, however, observe differences between virulence in single and coinfections in two cases. Where there were virulence differences, these were both consistent with in vitro inhibition patterns and interestingly resulted in reduced virulence in coinfection. This is inconsistent with broader patterns of virulence in coinfection, where virulence seems to be driven by the more virulent parasite. It is, however, consistent with data from other systems where there is evidence of interference competition. Our data thus support the idea that, in contrast to other forms of between parasite interaction, interference competition results in reduced virulence in coinfection.

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Monothiol glutaredoxin DaGrxB couples iron homeostasis with redox balance to orchestrate development and virulence in the peach shoot blight fungus Diaporthe amygdali

Yang, L.; Liu, X.; Xiong, L.; Zhang, Y.; Jing, Y.; Shi, H.; Pan, Z.; Cao, S.; Li, L.; Liang, Y.; Ji, Z.

2026-10-02 pathology 10.64898/2026.09.28.755239 medRxiv
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Peach shoot blight (PSB), caused by Diaporthe amygdali, is one of the most devastating fungal diseases affecting peach production worldwide. Glutaredoxins (Grxs) are ubiquitous redox-regulatory proteins involved in antioxidant defense and iron metabolism, yet their functions in phytopathogenic fungi remain largely unknown. Here, we identified four Grxs (DaGrxA-DaGrxD) in D. amygdali. Among them, DaGrxB, a monothiol glutaredoxin, is the sole member essential for vegetative growth, asexual reproduction and virulence. DaGrxB interacts with iron-regulatory transcription factors DaHapX and DaSreA and modulates their activities via iron-dependent nucleocytoplasmic shuttling, coordinating iron acquisition and storage gene expression. During infection, D. amygdali encounters a biphasic iron environment: an inherently iron-limited host environment at early stages (1-2 dpi) followed by host-mediated iron excess (3-4 dpi), and DaGrxB is essential for navigating this transition. Consistently, deletion of either DaHAPX or DaSREA significantly reduced virulence, confirming that iron homeostasis is a critical determinant of D. amygdali virulence. Notably, deletion of DaGRXB disrupts Fe-S cluster biosynthesis, causing mitochondrial Fe2+ accumulation, impaired aconitase activity, and reduced ATP production, which triggers constitutive activation of the GSH-dependent antioxidant system, with elevated GSH/GSSG ratios, increased GR and GST activities, and reduced H2O2 levels. Exogenous GSH and H2O2 depletion both reduced virulence, suggesting that disturbed redox balance directly contributes to attenuated virulence. Additionally, the Trx domain assists the Grx domain in nucleocytoplasmic translocation through intramolecular interactions. Finally, LDH-delivered dsRNA targeting DaGRXB effectively controls PSB. Collectively, these findings reveal how a monothiol glutaredoxin integrates iron homeostasis, redox balance and virulence in a plant pathogen, providing a foundation for RNAi-based disease management.

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Rice blast fungus hijacks a rice RALF peptide to initiate infection

Fukada, F.; Fujii, S.; Konishi, N.; Furuta, T.; Hino, Y.; Sebastian, A.; Shimizu, M.; Harada, Y.; Arazoe, T.; Galis, I.; Asuke, S.; Decker, F.-F.; Guo, T.; Ono, N.; Nishimura, H.; Cao, W.; Kloos, M.; Minato, H.; Suzuki, D.; Wang, P.; Kawano, Y.

2026-10-01 plant biology 10.64898/2026.09.30.754903 medRxiv
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Plant-derived peptides regulate immunity and host-microbe interactions, but whether fungal pathogens exploit endogenous plant peptides for infection-site selection remains largely unknown. Rapid alkalinization factors (RALFs) are a family of plant peptide hormones that contribute to plant development, reproduction, stress responses, and cell-wall organization. Here, we show that OsRALF7, which is an immune-activating peptide in rice (Oryza sativa), is co-opted by the rice blast fungus Magnaporthe oryzae as a host-derived cue for appressorium formation, specialized infection structures required for host penetration. While synthetic OsRALF7 peptide induced defense responses in rice suspension cells, the same peptide induced appressorium formation in M. oryzae. OsRALF7-induced appressorium formation was associated with activation of the cAMP/PKA and Pmk1 MAPK pathways and required a hydrophobic surface. M. oryzae inoculated onto Osralf7 knockout plants formed fewer appressoria, and the positioning of these appressoria relative to the boundaries between two adjacent plant epidermal cells was altered. These findings suggest that OsRALF7 provides positional information for infection initiation for M. oryzae. OsRALF7 localized to the plasma membrane and cell wall in rice, and its appressorium-inducing activity required a conserved YISY motif and cysteine residues. This activity was not conserved in Colletotrichum higginsianum, as RALF23 from Arabidopsis thaliana did not induce appressorium formation but instead showed antifungal activity. Together, these findings uncover a dual function of endogenous plant immune-modulating RALF peptides at the plant-pathogen interface, where they can be exploited by M. oryzae as a host-derived cue for infection initiation while also retaining antifungal activity against other fungal species.

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Towards operational epidemiology of Pyricularia oryzae in sports turf: contribution of a multi-matrix molecular monitoring strategy at stadium scale

Saadi, S.; Gruet, C.; Adreit, H.; Poncelet, N.; Di Mattia, J.; Courot, O.; Tharreau, D.

2026-10-01 plant biology 10.64898/2026.09.30.755619 medRxiv
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Gray leaf spot can cause severe turfgrass damage, particularly in intensively managed sports fields, while disease management remains challenging due to the rapid development of symptoms under favorable environmental conditions. Early detection of Pyricularia oryzae could therefore provide valuable information for anticipating disease development and supporting management decisions. This study aimed to develop a digital PCR (dPCR) molecular tool to support the monitoring and management of gray leaf spot disease in stadium turfgrass. The assay showed high sensitivity, consistently detecting P. oryzae when infected tissue represented only 0.05% of a mixture with healthy turfgrass, and enabled pathogen detection before symptom appearance under both controlled and field conditions. Different matrices were also investigated across 15 stadiums to identify the most relevant material for disease monitoring. Roots showed the highest prevalence of P. oryzae detection, including during asymptomatic periods, highlighting their potential as a relevant matrix for pathogen surveillance. In a stadium monitored several months after a gray leaf spot outbreak, P. oryzae DNA was still detected in roots from 27 of the 32 sampled zones despite the absence of visible symptoms. Overall, these results demonstrate the potential of dPCR for the early detection and monitoring of P. oryzae in stadium turfgrass, particularly through root sampling during periods when environmental conditions are not favorable for gray leaf spot development, and a spatio-temporal surveillance at stadium scale.

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Dynamics of cutaneous infection of a Bacillus cereus biovar anthracis strain

Rougeaux, C.; Garnier, A.

2026-09-28 microbiology 10.64898/2026.09.28.754931 medRxiv
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Bacillus cereus biovar anthracis (Bcbva) strains, which cause fatal anthrax-like disease, have been isolated from animals in Central and West Africa. Like B. anthracis, Bcbva produces a poly-{gamma}-D-glutamic acid (PDGA) capsule, as well as edema factor (EF), lethal factor (LF) and protective antigen (PA). Bcbva also possesses a hyaluronic acid capsule that is not expressed by B. anthracis. The pathogenesis of Bcbva has recently been characterized in inhalational infection models, in rabbits and guinea pigs. Here, we characterized the ki-netics of Bcbva infection and toxin production in a murine model of cutaneous infection using the Bcbva CA strain isolated in Cameroon. We found that spore germination oc-curred rapidly at the inoculation site, followed by bacterial dissemination to the draining cervical lymph nodes. Germination was associated with rapid production and diffusion of LF and EF. Bacteria rapidly disseminated to lymphoid organs and other compartments, with distal germination observed 18 hours post-infection. Infected mice developed septi-cemia within 24 hours, accompanied by high circulating LF levels and signs of cardiac and renal injury. These findings may contribute to the fulminant course of Bcbva infection observed in animals and highlight its potential risk to humans.

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Distinct metabolic states of yeast and pseudohyphae differentially prime innate immune responsiveness

Kato, H.; NandyMazumdar, M.; Rahmani, Z.; Kukhta, T.; Wolford, C.; Vallabhajoysul, S.; Miyagi, M.; Kajiwara, S.; Zhang, M.

2026-10-08 microbiology 10.64898/2026.10.08.757614 medRxiv
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Pseudohyphal growth in skin-associated fungi is often considered a morphological response to environmental stress, but whether it represents a coordinated metabolic state that influences host immunity remains unclear. Using Malassezia furfur, we combined synchronized morphogenesis, temporal metabolomics, stable-isotope tracing, targeted metabolite measurements, transcriptional profiling, and functional immune assays to compare yeast and pseudohyphal states. Yeast cells maintained an active tryptophan-aldehyde metabolic program that partitioned carbon between oxidative and reductive branches associated with redox balance and methylation potential. Pseudohyphal cells attenuated this program and instead underwent sequential metabolic remodeling, characterized by early changes in one-carbon and amino acid metabolism followed by sulfur-pathway remodeling and increased glutathione biosynthesis. These distinct fungal states generated extracellular environments that altered THP-1 innate immune responsiveness without directly inducing canonical macrophage polarization. Yeast-conditioned cells responded preferentially to tissue-repair signals, whereas pseudohypha-conditioned cells displayed enhanced responses to inflammatory stimuli. Individual metabolites did not reproduce these effects, suggesting that immune conditioning depends on the integrated extracellular milieu. Together, these findings identify pseudohyphal growth as an organized adaptive metabolic state and establish a framework linking fungal morphogenetic potential to context-dependent host immune responses.

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Distinct infection and colonization strategies in cowpea leaves by three Colletotrichum species recently reported in Nigeria

Dada, A. O.; Dania, V. O.; Oyatomi, O. A.; Abberton, M. T.; Ortega-Beltran, A.

2026-10-02 plant biology 10.64898/2026.10.01.755927 medRxiv
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Cowpea, a crop of great importance in several regions in West Africa, faces many biotic and abiotic challenges. Several species of the genus Colletotrichum cause cowpea anthracnose disease (CAD), a major constraint to cowpea production severely affecting foliage and yield. Three Colletotrichum species: C. cliviicola, C. truncatum, and C. chrysophilum recently reported as causal agents of CAD in Nigeria were investigated in their infective processes and pathogenicity on cowpea leaves using histopathological and microscopic examination of stained leaf tissues. Inoculated leaves were examined at intervals to monitor fungal establishment, colonization, and reproductive development within host tissues. The three species completed the infection cycle, progressing from conidial germination and host penetration to tissue colonization, and sporulation. However, differences in both infective ability and pathogenicity were observed in representative isolates of each species. C. truncatum isolate was the most virulent, had extensive branching hyphae, produced severe tissue necrosis, abundant acervuli, and prominent seta formation. C. cliviicola also had substantial colonization and sporulation ability with dense conidial masses and mature acervuli. In contrast, C. chrysophilum had moderate infectivity with less extensive reproductive structures and tissue degradation. Here we provide the first histopathological report of infection and pathogenic development of these three species recently reported as causal agents of CAD

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Genitourinary Brucellosis in an Endemic Region: Clinical Spectrum, Diagnostic Pitfalls and Treatment Outcomes of a 13-Year Retrospective Cohort

Savas, L.; Pekok, A. U.; Pekok, B. S.; Eser, Z. S.

2026-09-24 infectious diseases 10.64898/2026.09.22.26363646 medRxiv
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Aim: Brucellosis remains endemic throughout the Mediterranean basin, the Middle East and Central Asia. Genitourinary involvement is an uncommon but clinically consequential focal complication that closely mimics urological emergencies and may precipitate unnecessary surgery. Contemporary data describing its frequency, laboratory signature and treatment outcomes in endemic settings remain limited. Material-Methods: We retrospectively screened all adults ([&ge;]18 years) with confirmed brucellosis managed at a tertiary infectious diseases unit between January 2008 and December 2020. Genitourinary involvement was defined as epididymo-orchitis, orchitis, epididymitis and/or brucellar pyelonephritis. Clinical, laboratory, ultrasonographic, therapeutic and outcome variables were abstracted using a standardised form. Proportions are reported with Wilson score 95% confidence intervals (CI). Reporting followed the STROBE statement. Result: Genitourinary involvement was identified in 18 of 125 patients with brucellosis (14.4%; 95% CI 9.3-21.6); 16 (88.9%) were men and the mean age was 35.2 years (range 22-62). Scrotal disease dominated the male presentation: epididymo-orchitis in 10 of 16 men (62.5%; 95% CI 38.6-81.5), orchitis in 4 (25.0%) and epididymitis in 2 (12.5%). Both women presented with pyelonephritis, one of whom developed a tubo-ovarian abscess requiring drainage. Constitutional features were near-universal (fatigue 100%, night sweats 88.9%, fever 77.8%). Leukocyte counts remained within the reference interval in every patient (mean 5,680/mm3), whereas erythrocyte sedimentation rate (mean 32 mm/h) and C-reactive protein (mean 24.2 mg/L) were only mildly to moderately raised. The Coombs anti-Brucella test was positive in 18 of 18 patients (100%) and the standard agglutination test in 17 of 18 (94.4%), whereas blood culture yielded Brucella melitensis in only 1 of 18 (5.6%). Concomitant extragenitourinary focal disease was present in 8 patients. All patients received doxycycline plus rifampicin; none required modification of the regimen or orchiectomy, and no treatment failure occurred (0 of 18; 95% CI 0-17.6). Median follow-up was 12 weeks (range 6-52) and no relapse was documented within this interval. Conclusions: In endemic regions, genitourinary brucellosis should be suspected in any patient with acute scrotal or flank symptoms accompanied by constitutional complaints, even when the leukocyte count is normal and acute-phase reactants are only marginally elevated. Coombs anti-Brucella serology rather than blood culture is the diagnostic cornerstone, and prompt doxycycline-rifampicin therapy averts surgical intervention.