Search Results (931)

Pyricularia oryzae Triticum lineage (PoTl), the fungal pathogen responsible for wheat blast disease, has demonstrated increased fitness, stable resistance to quinone outside inhibitor (QoI) fungicides, and no associated fitness cost in the absence of fungicide selection pressure. In this study, we assessed whether the fitness-related epidemiological traits and competitive abilities of QoI-resistant (R) PoTl isolates increased or remained unchanged under continuous QoI applications across multiple disease infection cycles in wheat plants, compared to untreated plants. Approximately 48 h before inoculating each group of QoI-R or sensitive (S) PoTl isolates, wheat plants were treated with 10 μg mL⁻¹ azoxystrobin. The EC₅₀, incubation and latent periods, as well as the germination capacity of the QoI-R isolates inoculated on wheat leaves treated with 10 μg mL⁻¹ azoxystrobin, remained unchanged throughout five successive infection cycles. However, continuous azoxystrobin applications throughout successive disease cycles increased head blast severity by 1.33-fold and conidial production on wheat leaves by 36.8-fold in QoI-resistant (QoI-R) PoTl isolates compared with untreated plants. Conidia germination and germ tube development by QoI-R isolates on the abaxial surface of wheat leaves and/or head rachis treated with 10 μg mL⁻¹ azoxystrobin, six hours after inoculation (h.a.i), were observed using a scanning electron microscope (SEM). These findings demonstrate that repeated azoxystrobin exposure enhances fitness-related epidemiological traits of QoI-R PoTl isolates. Consequently, alternative evolutionarily informed disease management strategies, including fungicide rotation, multisite fungicides, and integrated disease management, are urgently needed. Full article

Aspergillus fumigatus is the predominant pathogenic fungus responsible for aspergillosis. In recent years, the global detection rate of azole-resistant A. fumigatus has continuously increased, and the extensive application of agricultural azole fungicides has been recognized as a crucial driving factor for the emergence and spread of resistance mutations in environmental A. fumigatus. Previous investigations conducted by our research team in karst vegetable fields of Guizhou Province revealed that the triazole resistance rate of local A. fumigatus was only 0.49%, which was markedly lower than those reported in most previous studies in China and outside of China. To supplement the prevalence data of azole resistance across different habitats in this region, a total of 191 environmental A. fumigatus strains were isolated from nine tea plantations across Guizhou. In this study, two clinically prevalent azole drugs, itraconazole and voriconazole, were used for antifungal susceptibility testing, and the triazole target gene cyp51A of all isolates was sequenced and analyzed. Antifungal susceptibility results demonstrated that the MIC ranges of the tea plantation A. fumigatus population were 0.015–0.5 μg/mL for itraconazole and 0.031–0.25 μg/mL for voriconazole, with no evidence of triazole resistance. Genetic analysis identified ten different gene mutations among 29 isolates, all of which were classified as non-resistance-associated mutations. Among these mutations, four were synonymous mutations, including 267G→A, 540G→A, 1074A→G, and 1362T→C, while six were non-synonymous mutations, including 137T→A, 514A→G, 743A→C, 744T→A, 765C→G, and 1279G→A. These non-synonymous mutations resulted in five amino acid substitutions in 25 strains, namely F46Y, M172V, N248T/K, D255E, and E427K. The N248T/K mutation exhibited the highest mutational frequency of 0.1309 (25/191) and was distributed across all nine sampling sites. Correlation analyses indicated that no significant correlations were observed between all detected variant loci and MICs of isolates to itraconazole and voriconazole. Phylogenetic analysis revealed that the six sequence types of cyp51A in Guizhou tea plantations were broadly intermixed with those from other parts of China and outside of China. We discussed the implications of these results in the management of antifungal resistance. Full article

Alternaria alternata often causes preharvest potato early blight and postharvest tuber rot, which can result in substantial yield losses. Demethylation inhibitors (DMIs) are widely used to control Alternaria diseases. However, the underlying resistance risk remains poorly understood. In this study, 114 A. alternata isolates from five major potato-producing regions in Shandong, China, were evaluated for sensitivity to four DMIs (mefentrifluconazole, prothioconazole, tebuconazole, and difenoconazole). The mean EC₅₀ values were 0.622, 6.053, 4.763, and 0.651 mg·L⁻¹, respectively. The Shapiro–Wilk test confirmed unimodal sensitivity distributions, allowing these mean EC₅₀ values to serve as baseline sensitivities. Two-year, two-location field trials demonstrated good control efficacy for all fungicides, with mefentrifluconazole exhibiting the highest efficacy. Three resistant mutants produced by artificial selection in the laboratory exhibited 3.78-, 28.06-, and 15.73-fold higher EC₅₀ values and showed fitness costs, including reduced or comparable mycelial growth, sporulation, and spore germination, pathogenicity similar to that of the parental strain, and lower temperature adaptability. By establishing the first baseline sensitivity of A. alternata from potato to these four DMI fungicides and assessing the resistance risk of mefentrifluconazole, this study provides a basis for rational fungicide application, resistance management, and future field resistance monitoring. Full article

Pepper (Capsicum annuum L.) is a major vegetable cultivated for seasoning in Korea. Peppers are typically grown as seedlings and transplanted into fields. Infection with Rhizoctonia solani immediately before transplantation can cause significant damage and loss during cultivation. The effectiveness of chemical fungicides is becoming increasingly limited owing to pesticide resistance, emphasizing the need for sustainable agricultural practices. This study aimed to identify a novel biocontrol agent by investigating tidal flat microorganisms capable of controlling damping-off disease in pepper caused by Rhizoctonia solani. Furthermore, we studied the inhibitory effects of different Bacillus species on the mycelial growth of R. solani AG-4 (KACC 40141) for the biological control of damping-off disease. Of the 116 bacterial strains from the tidal flats tested, five (including Bacillus sp. JB005) showed strong inhibitory activity in dual-culture assays against R. solani AG-4. These strains also demonstrated siderophore production, suggesting their potential to suppress damping-off in pepper. We screened useful agricultural traits (e.g., biofilm formation, IAA production, and phosphate solubilizing activity); the most promising strains were used for greenhouse experiments. The results indicated that Bacillus sp. JB005 strongly inhibited damping-off in pepper, suggesting that Bacillus sp. JB005 could serve as a biocontrol agent against R. solani infections. Full article

Staphylococcus pseudintermedius (SP), including multidrug-resistant SP (MDR-SP), and Malassezia pachydermatis (MP) are major canine cutaneous pathogens. Chlorhexidine-based shampoos, alone or containing azoles, are commonly used in veterinary dermatology; however, comparative data on commercially available products are limited. This study evaluated the in vitro antimicrobial activity of seven chlorhexidine-based shampoos against 30 clinical MDR-SP isolates and 30 clinical MP isolates. Six two-fold dilutions (1:16,000–1:512,000) of KetoChlor^®, BioHex^®, MAX Chlorhexidine 4%, Douxo S3™ Pyo, TrizCHLOR^®4, Malaseb^®, and MiconaHex+Triz^® were tested using a broth microdilution assay. Minimum inhibitory, bactericidal, and fungicidal concentrations (MIC, MBC, and MFC) were determined. Malaseb^® and MiconaHex+Triz^® exhibited the lowest MIC and MBC/MFC values, although the observed differences represented a single two-fold dilution step, with MIC values of 1:128,000 against both MDR-SP and MP, and MBC/MFC values of 1:32,000 and 1:128,000, respectively. The remaining shampoos demonstrated bactericidal activity (MIC = 1:32,000/1:64,000; MBC = 1:16,000), while some exhibited MIC and MFC values of 1:64,000 against MP. MIC and MFC endpoints were not reached for a limited number of MP isolates. Overall, all shampoo formulations demonstrated substantial antimicrobial activity across the tested dilution range. Further clinical studies are needed to determine whether these in vitro differences translate into meaningful in vivo efficacy. Full article

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. Full article

Potato late blight, Phytophthora infestans, remains a major global threat to potato production due to the rapid genetic change, long-distance dispersal and fungicide resistance. To clarify the genetic structure and phenotypic characteristics of P. infestans populations in southwestern China during 2019–2025, this study analyzed 241 isolates collected from Sichuan, Chongqing, Guizhou, Yunnan and Hubei. The isolates were characterized using 14 SSR markers, together with mating-type determination, metalaxyl sensitivity assays, mitochondrial haplotype identification and virulence profiling. A total of 70 alleles and 118 multilocus genotypes were detected, with certain genotypes (SW-40, SW-48 and SW-81) broadly distributed across regions, while the simultaneous presence of numerous low-frequency genotypes reflected high overall genetic diversity. Population genetic analyses revealed weak regional differentiation and strong genetic connectivity, with most genetic variation occurring within regional populations, where self-fertile isolates, metalaxyl-resistant phenotypes and mitochondrial haplotype Ia were predominant. Cluster and principal component analyses separated the isolates into three major genetic groups, with the largest group containing most isolates and showing close genetic similarity to the Blue_13 reference genotype. These findings indicate that southwestern China harbors a highly diverse and admixed P. infestans population, likely driven by frequent pathogen movement among potato-growing regions. Full article

The growing demand for sustainable crop protection has intensified interest in biological control agents. This study characterized a Trichoderma asperellum strain (IDE-10) to assess its suitability for integrated pest and disease management. Key ecophysiological traits, including temperature, pH, and ultraviolet (UV) tolerance, were evaluated, along with compatibility with commonly used fungicides and insecticides. The strain exhibited optimal growth at 28.28 °C and sustained high growth rates up to 35 °C, with a maximum threshold of 39.21 °C, indicating strong adaptation to warm climates. Sporulation was enhanced between 25 and 35 °C, with no growth at 5 °C, and soil viability remained stable from 7 to 21 °C. The IDE-10 strain demonstrated broad pH tolerance (3–7) and high resistance to UV-A and UV-B radiation, distinguishing it from commercial strains. Insecticides had no significant adverse effects, while fungicide compatibility varied, with IDE-10 being compatible with metalaxyl- and copper-based formulations. These findings highlight the robustness and adaptability of T. asperellum IDE-10, supporting its potential as a biocontrol agent for sustainable crop protection strategies, particularly in Mediterranean agricultural systems. Full article

Bipolaris oryzae was recently identified as a new species causing eyespot disease of banana in China. Propiconazole, flusilazole and tebuconazole, belonging to demethylation inhibitor (DMI) fungicides, are commonly used for controlling this disease in China. In this study, the propiconazole, flusilazole and tebuconazole sensitivity of 108 B. oryzae isolates collected from banana leaf samples in different locations of Hainan Island, China, in 2021–2023 was determined by mycelial growth inhibition, and the control efficacy of the three DMI fungicides against B. oryzae was assayed in pot experiments. The sensitivity frequency distributions of 108 B. oryzae isolates to propiconazole, flusilazole and tebuconazole indicated the emergence of subpopulations with reduced sensitivity, with EC₅₀ values ranging from 0.029 to 3.495 μg/mL, 0.008 to 3.665 μg/mL, and 0.022 to 8.288 μg/mL, with means and standard errors of 0.826 ± 0.059 μg/mL, 0.204 ± 0.036 μg/mL and 0.952 ± 0.113 μg/mL, respectively. However, the sensitivity distributions of 82.41%, 82.41%, and 80.56% of B. oryzae isolates at the main peak, respectively, to the three fungicides fitted to a normal distribution. Thus, the mean EC₅₀ values of 0.594 ± 0.032 μg/mL, 0.118 ± 0.007 μg/mL and 0.574 ± 0.033 μg/mL of these isolates could be used as the baseline for testing the sensitivity of B. oryzae to propiconazole, flusilazole and tebuconazole, respectively. No significant sensitivity differences to each fungicide among different geographical populations were observed, but a statistically significant and positive association in sensitivity between all three fungicides existed. Seven unstably inherited DMI-resistant isolates all exhibited lower fitness levels than those of the sensitive isolates, suggesting a low risk of resistance to the three DMI fungicides in B. oryzae. Three fungicides applied separately exhibited 100% protective control efficacy against B. oryzae and less than 40% curative control efficacy in pot experiments. Therefore, propiconazole, flusilazole and tebuconazole should be used as protective rather than curative fungicides. These results provide essential information on the evolution of DMI resistance in B. oryzae in Hainan Island, China, and may serve as a reference point in the management of B. oryzae and future DMI resistance monitoring programs. Full article

Background/Objectives: The study addresses the global health challenge posed by multidrug-resistant (MDR) pathogens, highlighting the urgent need for alternative antimicrobial solutions. This study investigated the in vitro antimicrobial and antibiofilm potential of endophytic mediated-synthesized silver nanoparticles (AgNPs). Methods: An endophytic bacterium was isolated from the medicinal plant Commiphora gileadensis in Saudi Arabia and identified as Bacillus subtilis CG1 through 16S rRNA gene sequencing. The bacterium was utilized for the green synthesis of AgNPs, as confirmed by Ultraviolet-visible (UV–Vis) spectroscopy. AgNPs characterization was done using Fourier-transform infrared (FTIR) spectroscopy, Transmission and scanning electron microscopy (TEM and SEM), energy-dispersive X-ray spectroscopy (EDX), and dynamic light scattering (DLS). The antimicrobial efficacy of the fabricated AgNPs was tested against eight clinically relevant pathogens using standard in vitro assays such as the agar disk diffusion method, minimum inhibitory concentration (MIC), minimum bactericidal and fungicidal concentrations (MBC and MFC). Additionally, AgNPs were tested for antibiofilm activity against P. aeruginosa and S. epidermidis. Tested pathogens included Methicillin-Resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Candida auris, Candida albicans, and Candida tropicalis. The antibiofilm efficacy was tested using the Crystal violet assay. Results: UV–Vis spectroscopy confirmed AgNP formation with a characteristic absorption peak at 412 nm. FTIR analysis identified the presence of hydroxyl, nitrile, and alkyne functional groups, which are involved in nanoparticle reduction and stabilization. TEM and SEM revealed predominantly spherical AgNPs with sizes ranging from 17 to 72 nm, while EDX confirmed silver as the major elemental component. DLS analysis showed a Z-average particle size of 113.9 ± 67.75 nm and a zeta potential of −24.2 mV. The synthesized AgNPs exhibited concentration-dependent antimicrobial activity, producing inhibition zones of 10–20 mm at 240 µg/mL. MIC values ranged from 6.25 to 25 µg/mL, whereas MBC and MFC values ranged from 6.25 to 50 µg/mL and 25 to 100 µg/mL, respectively. Moreover, bacterial growth kinetics analysis demonstrated a concentration-dependent inhibition of growth by AgNPs at MIC and sub-MIC concentrations. Additionally, AgNPs demonstrated significant antibiofilm activity against P. aeruginosa and S. epidermidis.Conclusions: Overall, B. subtilis CG1-mediated AgNPs exhibited promising physicochemical properties and antimicrobial and antibiofilm activities, suggesting their potential as alternatives for combating resistant and biofilm-associated infections. Full article

This study investigated the effects of repeated dielectric barrier discharge (DBD) plasma applications on the morphological and physiological characteristics of pathogenic Alternaria and Fusarium species. Fungi, including both culture collection strains and environmental isolates, were exposed to sublethal doses of DBD plasma. The results demonstrated that the plasma exposure time required to achieve 90% cell mortality varied significantly among microorganisms, ranging from 2 min and 39 s for Fusarium culmorum DSM 1094 to 5 min and 19 s for Alternaria alternata DSM 62010. Tolerance to oxidative stress, assessed by determining the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of hydrogen peroxide, generally decreased following repeated plasma exposure. Notably, F. tricinctum Ft11S–23 exhibited increased resistance to hydrogen peroxide, with MIC values doubling after fifteen plasma treatments. The MFC also increased significantly, rising from 25.5 mM to 102.0 mM. Furthermore, repeated DBD plasma applications resulted in reduced tolerance of fungi to at least one of the tested fungicides; however, exceptions were observed, including increased tolerance of F. culmorum to specific fungicides. The capacity for biofilm formation was modulated by plasma treatment, with some species exhibiting reduced biofilm formation while others demonstrated increased capacity, depending on the specific pathogen and frequency of plasma exposure. Full article

Following the application of biotic and abiotic systemic resistance inducers, which are enzymes related to plant defense, different responses are observed after infection with pathogens. Research into alternative methods using resistance inducers is a promising tool in the search for products with high potential for pathogen control. The application of the inducers acibenzolar-S-methyl, citrus biomass, K phosphite, silicate clay, and Ca and Mg silicate with or without the fungicide carbendazim showed greater potential to reduce anthracnose caused by Colletotrichum truncatum in lima bean plants, resulting in a reduced area under the disease progress curve and disease index. Disease progression promoted changes in enzymatic activity, where the application of acibenzolar-S-methyl, citrus biomass, K phosphite, silicate clay, and Ca and Mg silicate with or without the fungicide carbendazim resulted in the highest enzymatic activities and gas exchange rates compared to the other inducers. The use of biotic (citrus biomass) and abiotic (acibenzolar-S-methyl, K phosphite, silicate clay, and Ca and Mg silicate) inducers showed the highest potential to control anthracnose in the lima bean variety UFPB04. However, the resistance inducers promoted different plant responses when combined with fungicides and when applied in plants cultivated in different regions. Full article

Rice (Oryza sativa L.) is one of the world’s major staple foods. However, its production is severely constrained by rice blast disease, caused by Magnaporthe oryzae, which leads to substantial yield losses. Conventional management relies on fungicides and chemical treatments; however, these methods raise concerns regarding the development of pathogen resistance and potential environmental impacts. This study evaluated carrageenan from Hypnea musciformis, collected from the coast of Saint Martin (92°19′21.28″ E and 20°37′38.12″ N), located in the Bay of Bengal, Bangladesh, as a natural plant growth promoter as well as a biocontrol agent. Carrageenan was characterized by high sulfate (19–35%) and galactose (12–18%) contents, with FT-IR confirming characteristic κ-carrageenan functional groups. Application of 15% carrageenan significantly increased the germination of seed (27%), seedling vigor (93%), shoot and root lengths (54% and 47%), and biomass compared with untreated controls. Carrageenan markedly suppressed M. oryzae, inhibiting mycelial growth (83%), reducing conidiogenesis and conidial germination, and decreasing lesion length in detached leaves and potted plants. Treated rice seedlings exhibited improved soluble sugars, photosynthetic pigments, proline, phenolic and flavonoid contents, and enhanced antioxidant enzyme activities such as CAT (catalase) and POD (peroxidase), while lowering oxidative stress markers such as H₂O₂ and MDA (malondialdehyde). These results demonstrate that carrageenan from H. musciformis enhances rice growth and elicits defense responses against rice blast, offering a sustainable and environmentally friendly alternative to chemical-based fungicides for integrated M. oryzae management. Full article

The rise in antimicrobial resistance and the resilience of microbial biofilms demand innovative strategies that combine, for instance, membrane-active agents with marketed drugs. Arginine-based surfactants are promising alternatives to conventional quaternary ammonium compounds, but comparative data on their antimicrobial, antibiofilm and modulatory activities remain limited. Five arginine-derived surfactants, the single-chain Nα-lauroyl-L-arginine methyl ester (LAM) and ethyl ester (LAE), together with their double-chain homologues LANHC₃, LANHC₅ and LANHC₈ were evaluated against Gram-positive and Gram-negative bacteria and four Candida spp. Minimum inhibitory (MIC) and lethal (MLC) concentrations were determined by broth microdilution method. Antibiofilm activity was assessed through minimum biofilm inhibitory (MBIC) and eradication (MBEC) concentrations. Checkerboard assays were used to evaluate the synergism between the surfactants and conventional therapeutic antibacterial and antifungal agents. LANHC₃ and LANHC₈ exhibited uniform antibacterial MICs of 19.53 µg/mL, while LAM and LANHC₅ showed MICs of 19.53 µg/mL for most strains, with Enterococcus faecalis requiring 39.06 µg/mL. LANHC₃ was the most potent surfactant over Candida spp. With MICs of 9.76 µg/mL for all species, and similarly to LAM, both were fungicidal at 39.06 µg/mL. LAM and LANHC₃ also showed the lowest MBIC and MBEC values, inhibiting the Candida biofilm formation at 39.06 µg/mL and eradicating mature biofilms at 78.12 µg/mL, while the other surfactants required higher concentrations to disrupt the microbial biofilms. Synergic or additive interactions were found between the surfactants and selected β-lactam and macrolide antibiotics, as well as azole antifungals, with no antagonism observed. LAM and particularly LANHC₃ combined broad-spectrum antimicrobial activity, relevant antibiofilm effects and the ability to potentiate the activity of conventional agents, supporting their choice as alternative or complementary antimicrobial adjuvants over resistant microorganisms and their biofilms. Full article

Ginseng Alternaria leaf and stem blight (GALSB), caused by Alternaria alternata, poses a severe threat to ginseng cultivation. Although azoxystrobin is a cornerstone fungicide for GALSB management, the emergence of widespread adaptive resistance has severely curtailed its field efficacy. This study integrated molecular, transcriptomic, and genetic approaches to unravel the underlying resistance mechanisms. Targeted gene sequencing and molecular docking revealed that resistant strains harbor a conserved G143A point mutation in the AaCyt b protein. This mutation weakens the azoxystrobin–AaCyt b protein binding affinity by decreasing the binding energy from −8.31 to −7.08 kcal/mol. Additionally, comparative transcriptomics and RT-qPCR demonstrated pronounced upregulation of the alternative oxidase gene (AaAOX) and core energy metabolism pathways in resistant strain TYC8-2, with AaAOX expression increasing 4.45–6.91-fold. Fungicidal inhibition of AOX via salicylhydroxamic acid (SHAM) restored fungal sensitivity, increasing azoxystrobin sensitivity by 11.66-fold. Crucially, genetic knockout of AaAOX enhanced sensitivity by approximately 2.7 × 10⁴-fold. Phenotypic assays further established AaAOX as a multifunctional regulator; the AaAOX mutant exhibited attenuated virulence on ginseng leaves and increased sensitivity to oxidative and osmotic stresses (NaCl, H₂O₂, NaAc). We conclude that the G143A mutation in AaCyt b and the transcriptional overexpression of AaAOX act independently to drive azoxystrobin resistance in A. alternata. These findings provide comprehensive mechanistic insights to guide resistance monitoring, optimize fungicide applications, and develop precision strategies for GALSB management. Full article