Jul 2026· International Journal of Molecular Sciences· Vol 27· 0 citations· 56 references
Medicine
TL;DR
This study systematically characterizes the resistance regulatory network of F. graminearum against pydiflumetofen, and provides theoretical guidance for the rational application and sustainable field resistance management of this fungicide.
Abstract
Wheat Fusarium head blight (FHB) is a globally prevalent and destructive fungal disease predominantly caused by Fusarium graminearum. Pydiflumetofen, a novel succinate dehydrogenase inhibitor (SDHI) fungicide, exhibits strong inhibitory activity against F. graminearum; however, the molecular regulatory mechanisms underlying the field-developed resistance in this pathogen remain poorly defined. In the present study, a field-evolved resistant isolate W24-039 and a sensitive isolate W24-016 were subjected to multi-omics analysis. The sequencing results identified compound mutations C89S/A93V in SdhC2, and A21T/S30F in SdhD of the resistant strain, which confer stable fungicide resistance without any detectable fitness costs. Physiological tests revealed that these target mutations sustain the homeostasis of succinate dehydrogenase (SDH) activity and intracellular ATP production. Following pydiflumetofen treatment, the sensitive isolate displayed remarkable declines in SDH activity, intracellular ATP content and deoxynivalenol (DON) biosynthesis, accompanied by markedly elevated cell membrane permeability. Transcriptomic sequencing uncovered 2221 differentially expressed genes (DEGs) in the sensitive strain under fungicide stress, and 2566 DEGs in the resistant isolate under the same conditions. The genes associated with detoxification and drug efflux, including cytochrome P450, glutathione S-transferase (GST), ABC and MFS transporters, were significantly upregulated in the resistant isolate. Metabolomic analysis indicated that differential metabolites were mainly enriched in the tricarboxylic acid (TCA) cycle, amino acid metabolism and membrane lipid biosynthesis pathways. The resistant strain maintained intact TCA cycle operation and accumulated high levels of pivotal metabolites such as phosphatidylcholine, unsaturated fatty acids and reduced glutathione. Integrated multi-omics analysis verified that the ABC transporter and glutathione metabolism pathways serve as core regulatory modules governing fungicide resistance. Collectively, F. graminearum develops resistance via the synergistic effects of SDH compound mutations, enhanced detoxification and efflux, and global metabolic remodeling, demonstrating that target-site mutation alone is not the sole driver of resistance, which is instead controlled by an intricate regulatory network involving multiple coordinated pathways. This study systematically characterizes the resistance regulatory network of F. graminearum against pydiflumetofen, and provides theoretical guidance for the rational application and sustainable field resistance management of this fungicide.
Management of rice bakanae disease (RBD), caused by Fusarium fujikuroi, faces significant challenges arising from the development of fungicide resistance in the pathogen. Pydiflumetofen (Pyd) is a novel succinate dehydrogenase inhibitor (SDHI) and might offer potential in alleviating this crisis. In this study, the establishment of a sensitivity baseline revealed a unimodal distribution (EC50 = 0.0623 ± 0.0108 μg/mL), suggesting that sensitive population is relatively concentrated. To assess the risk of resistance to Pyd in F. fukikoroi, two high resistance mutants (PydHR), six moderate resistant mutants (PydMR), and two low resistance mutants (PydLR) were generated by fungicide mutagenesis. The PydHR mutants exhibited similarities in the mycelial growth rate, sporulation capacity, germination rate of conidium, various osmotic stresses and virulence, indicating that the Pyd resistant (PydR) mutants might form subpopulations with competitive advantages in the field. Analysis of nucleotide sequences of succinate dehydrogenase subunit-coding genes revealed three types of mutations in PydR isolates: FfSdhBH248Y + FfSdhC2A83V, FfSdhC2A83V and FfSdhDD133G. The expression levels of FfSdhA/B/C1/C2/D in resistant double mutations RSS24-13 all exhibited significant up-regulation change, FfSdhC2 was dramatically upregulated by nearly 200-fold. These results indicate that point mutations and FfSdh genes up-regulation expression may be codetermine the Pyd resistance mechanisms in F. fujikuroi. The PydR isolates also exhibited resistance to SDHIs isofetamid and fluopyram, but there was no cross-resistance between benzovindiflupyr and fungicides from other classes. These results indicate that the resistance risk of Pyd is elevated to medium-high, and reasonable monitoring and management of resistance to Pyd should be carried out.
Verticillium dahliae is a destructive soil-borne fungus with a broad host range, and its persistence in soil complicates control. Current measures, mainly resistant cultivars and chemicals, are limited and environmentally risky, promoting biocontrol as a green alternative. Here, we investigated the biocontrol mechanisms of Bacillus velezensis L33a against V. dahliae JR2 in tomato. In vitro assays on PDA plates at 26°C for 9 d showed that L33a inhibited JR2 by 58.6%, caused hyphal malformation and disruption, and its volatile organic compounds suppressed pathogen growth. In pot experiments, tomato roots dipped in JR2 suspension (1 ×10⁶ CFU/mL) for 30 min at 7 d after transplanting and grown for 21 d achieved 60.9% control efficacy. Physiological assays indicated reduced peroxidase and catalase activities, while qPCR revealed that L33a alone upregulated JA signaling (SlJAZ1, SlMYC2, SlPI II) and antioxidant (SlCAT, SlAPX) genes, with further enhancement upon JR2 co-treatment. To track their interactions, we generated GFP-labeled JR2 and RFP-labeled L33a; dual fluorescence labeling showed that L33a endophytically colonized Arabidopsis thaliana roots and competed with JR2 for the same niche, correlating with reduced pathogen colonization. Integrated metabolomic and transcriptomic analysis further revealed that L33a treatment altered pathways related to ABC transporters, amino acid metabolism, cell wall integrity, and energy metabolism in JR2, with tyrosine metabolism significantly enriched at both levels. Collectively, these findings suggest that L33a is a promising biocontrol strain for green management of tomato Verticillium wilt.
Durum wheat is highly susceptible to Fusarium head blight (FHB) caused by the fungal pathogen Fusarium graminearum. Wheat can be protected with the use of environmentally-friendly and sustainable methods involving biological control agents (BCAs) such as yeasts. However, the mechanism underlying the antagonistic effects of yeasts on plant pathogens has not been fully elucidated. Therefore, the aim of this study was to expand the existing knowledge about the mechanisms of action of a Debaryomyces hansenii biopreparation through transcriptome profiling in F. graminearum cells using RNA sequencing (RNA-seq). The changes in the F. graminearum transcriptome resulting from biotic stress induced by the application of D. hansenii cells to durum wheat spikes, and abiotic stress induced by the application of a cell-free supernatant were compared and comprehensively analyzed. Each stressor elicited a completely different transcriptomic response, and differentially expressed genes (DEGs) encoding metabolic pathways essential for pathogen development associated with carbohydrate and amino acid metabolism, pathogenicity factors, effectors, and secondary metabolites. Numerous transporter genes were also identified, which indicates that fungi exhibit complex responses to biotic and abiotic stresses. The study demonstrated that F. graminearum uses various strategies to overcome the biotic stress associated with BCAs, including the upregulation of the brefeldin A resistance gene (FGSG_02870), which encodes an antifungal compound that inhibits the growth of BCA cells. The present findings provide novel insights into the interactions between pathogens and BCAs with specific mechanisms of action at the transcriptome level, thus helping to explain the relative ineffectiveness of BCAs under certain conditions.
Weronika Giedrojć, W. Pluskota, U. Wachowska· Fungal Genetics and Biology· 0 citations
Flacherie is a major bacterial disease compromising silkworm health and cocoon productivity; however, the diversity and genomic features of larva-associated pathogens remain poorly characterized. In the present study, we isolated and characterized a Gram-negative bacterium, designated as Pseudomonas boreofloridensis strain RAC1, from the hemolymph of silkworm larvae with flacherie symptoms. The isolate exhibited clear swimming motility, indicating an active flagellar system. Biochemical profiling using the VITEK-2 platform revealed broad metabolic capabilities, including utilization of multiple organic acids and amino-acids, related enzymatic activities, highlighting its adaptability under nutrient-variable host conditions. Chemotaxonomic analysis using fatty acid methyl ester (FAME) profiling further supported its identity within the genus Pseudomonas. Whole-genome sequencing showed a 4.49 Mb GC-rich genome encoding diverse functional pathways related to central metabolism, aromatic compound degradation, and carbohydrate-active enzymes, suggesting strong ecological flexibility. Importantly, genomic screening identified virulence-associated gene and multiple antimicrobial resistance determinants, dominated by efflux pumps and outer membrane permeability factors. In addition, strain RAC1 contained several mobile genetic elements and three prophage regions, reflecting a highly plastic genome. Pangenome analysis across related Pseudomonas strains indicated an open pangenome, driven largely by accessory and cloud genes. Overall, P. boreofloridensis RAC1 represents a multidrug-resistant and genomically dynamic strain encoding virulence-associated genes and resistance genes. These genomic features suggest adaptive potential in host-associated environments and require further experimental investigation to evaluate its role in silkworm larval disease.
An integrated omics study provides foundational insights into the endophytic potential and genomic distinctiveness of AwOcstreb1, isolated from halophytic rice, and opens new avenues for exploring A. welwitschiae for sustainable agriculture and fungal biology.
Nishat Tamanna, Md Nafis Ul Alam, Arifa Akhter Airin et al.· Microbial Genomics· 0 citations
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