bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2025.10.16.682737

Dissecting allele-specific fungicide resistance mechanisms by heterologous expression of the demethylase inhibitor target gene Cyp51 in a phytopathogen model

Zulak, K. G.·Chang, S.·Tan, K.-C.·Turo, C. J.·Oliver, R. P.·Lopez-Ruiz, F. J.
View original source ↗Export metadata ↓

Abstract

BACKGROUNDFungicide resistance is a major concern both in agriculture and clinical disease control. Whilst several mechanisms of resistance have been elucidated, assigning phenotype to genotype is often difficult and reliant on correlations. Resistance to demethylase inhibitor (DMI) fungicides was recently reported in the economically important filamentous fungal barley (Hordeum vulgare) pathogen Pyrenophora teres f. teres (Ptt) in Australia. The target of DMI fungicides is encoded by the Cyp51 gene family; single allele of Cyp51B and two copies of the Cyp51A gene1. Five Cyp51A alleles (W1-A1, 9193-A1, KO103-A1, W1-A2 and 9193-A2) were identified in Ptt with KO103-A1 containing the mutation F489L (F495L) which correlates with resistance to various DMIs.1 RESULTSWe replaced the coding region of the native Cyp51B gene of the filamentous fungal Dothideomycete wheat pathogen Parastagonospora nodorum with each of the five Ptt Cyp51A alleles to compare the phenotypic effects of each allele in isolation. The native Cyp51B of P. nodorum could be functionally replaced by Cyp51-A1 but not Cyp51-A2. Transformants carrying KO103-A1 exhibited significantly higher gene expression than 9193-A1 and W1-A1, suggesting the mechanism of gene regulation lies within the coding sequence and is conserved between Ptt and P. nodorum. The EC50 values of the KO103-A1 transformants were significantly higher than any other transformants or wild type isolates for metconazole, prochloraz and tebuconazole but lower for epoxiconazole. CONCLUSIONThis system permits the functional characterisation of fungicide target genes in an isogenic background that mimics the physiological environment of plant pathogens. We suggest the system will prove useful in dissecting the impact of genetic mutations on a spectrum of fungicides and permit the design of fungal strains for screening active ingredients that may control strains resistant to existing fungicides.

Explore related subjects

microbiologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Zulak, K. G., Chang, S., Tan, K.-C., Turo, C. J., Oliver, R. P., Lopez-Ruiz, F. J.. 2025-10-16. Dissecting allele-specific fungicide resistance mechanisms by heterologous expression of the demethylase inhibitor target gene Cyp51 in a phytopathogen model. https://doi.org/10.1101/2025.10.16.682737

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

A population-scale landscape of the subgingival microbiome reveals divergent routes to periodontal dysbiosis

Periodontitis is an archetypical mucosal inflammatory disease in which microbiome dysbiosis at the tooth-epithelial interface interacts with host genetic and behavioral risk factors to drive immune-mediated tissue destruction. Although subgingival microbiome compositional shifts are thought to parallel disease severity, microbiome variation at the population-level and its relationship to periodontal clinical phenotypes and disease-modifying factors remain poorly defined. Here, we use unsupervised manifold learning to map the compositional landscape of the subgingival microbiome in 1,355 adults spanning periodontal health to severe periodontitis. We identified eight latent microbiome states organized along a branching continuum from eubiosis to dysbiosis. An intermediate microbial configuration marked ecological destabilization and bifurcation into two distinct periodontitis-associated dysbiotic trajectories, distinguished by links to gingival inflammation and smoking. Although the microbiome trajectories broadly tracked periodontal destruction, a minority of individuals showed discordant microbiome-clinical phenotypes, with some individuals with periodontitis retaining otherwise eubiotic microbiomes enriched for low-abundance pathobionts, while some cases of health or mild disease had highly dysbiotic communities, suggesting distinct host susceptibility. Together, these findings define a population-scale ecological landscape of the subgingival microbiome, reveal divergent trajectories to periodontal dysbiosis, and highlight heterogeneity in the relationship between microbial community structure and clinical disease expression.

microbiology↗
bioRxiv2026

The iron-binding siderophore enterobactin is required for the response of multi-drug resistant Klebsiella pneumoniae to zinc limitation

To persist during infection Klebsiella pneumoniae must overcome nutrient iron and zinc limitation imposed by the host immune system through a process called nutritional immunity. Secreted small molecule siderophores are a major virulence determinant of Klebsiella pneumoniae pathogenesis and are presumed to overcome nutritional immunity by binding iron for bacterial acquisition. In this work, we set out to identify how a multi-drug resistant K. pneumoniae grows in zinc limited environments. Using unbiased transcriptomics, proteomics, and an arrayed transposon screen, we identified that synthesis and uptake of the siderophore enterobactin is required to allow for growth in low zinc conditions. Iron-specific chelators did not replicate this phenotype and addition of supplemental iron through heme in growth media could not complement severe growth defects of enterobactin mutant K. pneumoniae experiencing zinc limitation. Finally, zinc starvation induced enterobactin production independent of the canonical zinc uptake regulator (Zur) transcription factor suggesting an unidentified regulatory mechanism by which Gram-negative pathogens may respond to zinc stress. Together, these studies expand the role of enterobactin beyond iron regulation and highlight a previously unreported link between iron and zinc homeostasis in Klebsiella pneumoniae.

microbiology↗
bioRxiv2026

A microbiota-derived protease links phage susceptibility to host epithelial responses

Bacteriophages are major ecological drivers of gut microbial ecology, yet whether bacterial mechanisms that determine phage susceptibility have consequences for the mammalian host remains poorly understood. Here, we identify dipeptidyl peptidase 11 (Dpp11a), the predominant active serine protease of the prevalent gut commensal Phocaeicola vulgatus, as an unexpected bacterial defence factor. Dpp11a protects against environmental proteases and confers resistance to bacteriophage infection. Metatranscriptomic analyses further reveal increased expression of both dpp11a and P. vulgatus-associated phage transcripts in ulcerative colitis stool samples, indicating that both components of this interaction are transcriptionally active in disease-associated human microbiomes. Using the microfluidic gut-on-a-chip co-culture model HuMiX, we show that the absence of Dpp11 is accompanied by altered epithelial tight-junction remodelling during phage-bacterial infection. Together, our findings reveal that the consequences of bacterial phage defence can extend beyond phage-bacterium interactions to the mammalian epithelium.

microbiology↗