Search Results (262)

Root rot, mainly caused by Fusarium oxysporum, is one of the most destructive diseases and leads to significant economic loss of Astragalus membranaceus. To develop an effective strategy for the management of this serious disease, a bacterial strain 2-12 was screened from A. membranaceus rhizosphere soil and identified as Bacillus paralicheniformis based on the phylogenetic analyses of gyrase subunit B gene (gyrB) and RNA polymerase gene (rpoB) sequences. Interestingly, the volatile organic compounds (VOCs) produced by B. paralicheniformis 2-12 exhibited potent antifungal activities against F. oxysporum, as well as fifteen other plant pathogens. Under scanning electron microscopy observation, hyphae treated with the VOCs exhibited abnormal variation such as distortion, twist, and vesiculation, leading to distinctive protoplasm shrinkage. After treatment with B. paralicheniformis 2-12 VOCs, the lesion diameter and disease incidence both reduced significantly compared to control (p < 0.05), thus demonstrating prominent biological efficiency. Moreover, B. paralicheniformis 2-12 VOCs were composed of 17 VOCs, including 9 alkanes, 3 alcohols, 3 acids and esters, 1 aromatic compound, and 1 alkyne compound. A total of 1945 DEGs, including 1001 up-regulated and 944 down-regulated genes, were screened via transcriptome analysis. These DEGs were mainly associated with membranes and membrane parts, amino acid metabolism, and lipid metabolism. The findings in this work strongly suggested that B. paralicheniformis 2-12 VOCs could be applied as a new candidate for the control of A. membranaceus root rot. Full article

The number of fungal infections is steadily increasing, with considerable morbidity and mortality. Additionally, antifungal resistance is a growing concern, highlighting the need to develop new treatment options. One alternative is the use of antimicrobial peptides (AMPs). The aim of this study was to assess the in vitro and in vivo antifungal activity of designed short AMPs, Act-6 and Act 8-20, derived from cecropin transcripts of beetles from the family Scarabaeidae, against eight reference strains of the pathogenic yeasts Candida and Cryptococcus. We also evaluated the effect of these modified AMPs on the biofilm, morphogenesis, and cell morphology of Candida albicans, as well as the in vivo activity via a murine model of disseminated candidiasis. The AMPs herein analyzed exhibit differential antifungal activity against the yeasts assessed, and inhibit biofilm, hyphae, and pseudohyphae formation with morphological alterations in C. albicans. Moreover, the fungal load in mice treated with these AMPs significantly decreased. Altogether, our results suggest that Act-6 and Act 8-20 are promising antifungal molecules to control mycoses. Full article

Nine chaetoglobosins (1–9) including five previously undescribed ones (1–5) were obtained from the culture broth of an endophytic fungus (Chaetomium sp. UJN-EF006) isolated from the leaves of Vaccinium bracteatum. The structures of these fungal metabolites were elucidated by spectroscopic methods including mass spectroscopy, nuclear magnetic resonance, single crystal X-ray crystallography, and electronic circular dichroism. To accelerate the development of novel fungicides, all of the isolated chaetoglobosins were evaluated for their antifungal activity against two crop pathogens, Botrytis cinerea and Sclerotinia sclerotiorum. The assay results revealed that chaetoglobosins 2, 6, 7, and 9 possessed a significant fungicidal effect against B. cinerea, with EC₅₀ values all below 10 μg/mL. Particularly, the most potent compound, 7, was 175- and 96-fold as active as the commercially available fungicides carbendazim (EC₅₀ 70.11 μg/mL) and azoxystrobin (EC₅₀ 39.02 μg/mL), respectively. A further observation under scanning electron microscope indicated that compound 2 could markedly impair the fungal hyphae of B. cinerea. The study demonstrates that the chaetoglobosins had excellent in vitro antifungal activities against B. cinerea. Full article

Sclerotinia sclerotiorum, known as a typical necrotrophic pathogenic fungus, exhibits a complex pathogenic mechanism. Research on S. sclerotiorum has primarily focused on oxalic acid, pathogenicity-related enzymes, and secreted proteins. In this study, we identified a transcription factor, SsSR (S. sclerotiorum Sterol-Related transcription factor), which regulates S. sclerotiorum infection by modulating virulence through ergosterol biosynthesis. We characterized the transcriptional activity of SsSR and its downstream target gene, SsCYP51. SsSR undergoes phosphorylation induced by the host plant, subsequently regulating the expression of SsCYP51. The deletion of SsSR or SsCYP51 does not affect the growth or acid production of S. sclerotiorum, but it leads to a reduction in ergosterol, significantly diminishing virulence and impairing the stress tolerance of the hyphae. In summary, this study identifies a transcription factor, SsSR, that specifically regulates the virulence of S. sclerotiorum. SsSR upregulates the expression of SsCYP51 through phosphorylation during the infection phase, leading to the synthesis of ergosterol, which enhances hyphal stress tolerance and thereby promotes infection. Full article

Pear black spot disease seriously threatens the pear industry. Currently, its control mainly relies on chemical fungicides while biological control using antagonistic microorganisms represents a promising alternative approach. This study identified and characterized Bacillus velezensis TRMB57782 as a biocontrol strain through whole-genome sequencing. AntiSMASH analysis predicted the strain’s potential to produce secondary metabolites such as surfactin, difficidin, and bacilysin. In vitro experiments demonstrated that TRMB57782 inhibited the growth of Alternaria gaisen. In vivo experiments using excised branches and pear fruits at two different stages also showed significant control effects. A preliminary exploration of the metabolic substances of TRMB57782 was carried out. The strain can produce siderophores and three biocontrol enzymes. Crude extracts obtained by the hydrochloric acid precipitation and ammonium sulfate saturation precipitation of the bacterial liquid exhibited significant activity and volatile organic compounds showed biocontrol activity. Meanwhile, the effects of strain TRMB57782 on the hyphae of pathogenic fungi were studied, leading to hyphal atrophy and spore shrinkage. This paper provides an effective biocontrol strategy for fragrant pear black spot disease, reveals the antibacterial mechanism of Bacillus velezensis TRMB57782, and offers a new option for the green control of pear black spot disease. Full article

Fungal diseases severely threaten global agriculture, while conventional chemical fungicides face increasing restrictions due to environmental and safety concerns. In this study, we isolated a soil-derived Bacillus stercoris strain, DXQ-1, exhibiting strong antagonistic activity against plant pathogenic fungi, notably Magnaporthe oryzae, the causal agent of rice blast. Scanning electron microscopy revealed that DXQ-1 disrupts fungal hyphae and inhibits conidial germination, with a 24 h crude broth treatment reducing germination to 83.33% and completely blocking appressoria formation. LC-MS-based metabolomic analysis identified key antifungal components, including lipids (35.83%), organic acid derivatives (22.15%), and small bioactive molecules (e.g., Leu-Pro, LPE 15:0). After optimizing fermentation conditions (LB medium, pH 7.0, 28 °C, 48 h), the broth showed >90% inhibition against M. oryzae and Nigrospora oryzae and retained high thermal (68 °C, 1 h) and UV (4 h) stability. Field trials demonstrated effective disease control and significant promotion of rice growth, increasing plant height (17.7%), fresh weight (53.3%), and dry weight (33.3%). These findings highlight DXQ-1 as a promising biocontrol agent, offering a sustainable and effective alternative for managing fungal diseases in crops. Full article

Dollar spot is one of the world’s most widely distributed turfgrass diseases. The pathogen of the disease has been re-identified as a fungus belonging to the genus Clarireedia in the United States, Japan, and China. Since Clarireedia species vary depending on the response to fungicides, hosts, and distribution ranges, it is necessary to re-identify dollar spot in South Korea for effective turfgrass management. In this study, the amplified nucleotide sequences with primer sets of the internal transcribed spacer (ITS) region, Calmodulin (CaM), and Mini-chromosome maintenance complex component 7 (Mcm7) were analyzed to re-identify Clarireedia spp. isolated from creeping bentgrass and Kentucky bluegrass on golf courses in South Korea. The ITS and CaM regions were analyzed through multiple sequence alignments. The isolates were identified as C. paspali, and Clarireedia sp. When cultured on PDA, three groups formed fast growing, cottony colonies with white aerial hyphae that later collapsed and turned tan to brown. Most isolates formed apothecia, but ascospores were not observed. The apothecia formation of C. paspali has never been reported. All isolates exhibited pathogenicity on creeping bentgrass and Kentucky bluegrass. These results indicated that the pathogens causing dollar spot on creeping bentgrass and Kentucky bluegrass in South Korea might be C. paspali and Clarireedia sp. The present study reports the first re-identification of the turfgrass dollar spot pathogen Sclerotinia homoeocarpa into the genus Clarireedia in South Korea. Full article

Objectives: The oral cavity hosts one of the most complex microbial communities in the body. A disruption of the balance favors the growth of pathogenic species, contributing to oral diseases. The rise in microbial resistance has limited the effectiveness of conventional treatments, shifting the interest to natural product-based alternatives. Given its superior bioavailability and bioactivity in other models, this study investigates the antifungal potential of a novel curcumin derivative, PAC (3,5-bis(4-hydroxy-3-methoxybenzylidene)-N-methyl-4-piperidone), and studies its impact on host–pathogen dynamics and host defense mechanisms. Methods: Candida albicans was used as the model organism. Viability, growth kinetics, and colony formation were evaluated using optical density, agar culture, and MTT assay. Biofilm formation was assessed through electron microscopy and total sugar quantification. The morphological transition from hyphae to the less virulent blastospore was monitored using an optical microscope. The gene expression of adhesion factors and host defense markers was analyzed using RT-PCR. Results: PAC impairs C. albicans viability and reduces virulence by compromising biofilm formation and ensuring phenotypic transition to a blastospore form. Also, PAC controls C. albicans growth via necrosis/ROS pathways. As a result, PAC appears to repress host–pathogen interaction by downregulating SAPs, EAP1, and HWP1 adhesion genes, thus relieving the need to activate gingival epithelial cell defense mechanisms. This is highlighted by recording baseline levels of IL-6, IL-8, and IL-1β cytokines and antimicrobial β-defensin peptides in the presence of less virulent candida forms. Conclusions: PAC effectively reduces C. albicans virulence by limiting biofilm formation and adhesion while minimizing inflammatory responses. These findings support its potential as a promising therapeutic agent for infectious disease control. Full article

To learn about the yeast biodiversity of Hungarian honeys and to isolate osmotolerant yeasts, fifteen different honey varieties, beeswax, and bee bread were purchased, and samples of another, but highly osmotic material, tree sap (cherry, sour cherry, and plum), were collected from the northeastern region of the country. In total, 60 yeast strains were isolated and their taxonomic positions were determined by barcode sequences using ITS1-NL4 primers. The honey products contained mostly Zygosaccharomyces and Starmerella species. In addition, Hanseniaspora uvarum, Rhodotorula mucilaginosa and diobovata, Sporobolomyces roseus, Filobasidium magnum, Naganishia sp., and Aureobasidium pullulans were also present in smaller numbers. In contrast, tree saps contained Metschnikowia and Pichia fermentas cells. Further results suggest that some of the yeasts in honey can only “survive”, while others can propagate at high sugar levels, generally between 600 and 700 mg/g, with a predominance of fructose. Properties important for pathogenicity, such as invasive hyphae production, gelatin melting ability, and growth at 37 °C, were also examined. Hanseniaspora uvarum and Pichia fermentans representatives seemed to be negative for gelatin hydrolysis, while the other strains were able to melt gelatin. Although some of the strains could produce hyphae-like structures at 25 °C, none of them could grow at 37 °C. Full article

Pine needle blight of Pinus massoniana caused by pathogens of the Pestalotiopsis genus is a destructive disease worldwide, especially in young forests. Chemical fungicides accelerate the formation of resistant strains among plant pathogenic fungi, which makes microbial biocontrol particularly important. In this study, we identified Neopestalotiopsis camelliae-oleiferae as a new pathogen of pine needle blight in P. massoniana via pathogen isolation, inoculation, pathogenicity assays, morphology observations, and multilocus phylogenetic analyses of the ITS, TEF1, and TUB2 regions. PSM-6, an endophytic bacterium, was subsequently isolated from pine needles and was shown to have excellent antagonistic activity against N. camelliae-oleiferae in vitro. Based on the morphology, physiology, and molecular analysis, we identified this strain as P. silvicola. The extracellular secondary metabolites of PSM-6 were further proven to cause the shrinkage and collapse of pathogen hyphae. The decreased disease index and mortality indicated that pretreatment with PSM-6 may effectively protect pine seedlings from pathogen infection. In addition, PSM-6 exhibited broad-spectrum antifungal activity in several phytopathogenic fungi, including Fusarium graminearum, Botrytis cinerea, and Verticillium dahliae. These findings establish PSM-6 as a promising biocontrol agent, offering an environmentally friendly alternative to chemical fungicides for managing pine needle blight and other fungal diseases. Full article

Pathogenic fungi that exhibit the ability to alternate between hyphal and yeast morphology in response to environmental stimuli are considered dimorphic. Under saprobic conditions, some fungi exist as filamentous hyphae, producing conidia. When conidia are inhaled by mammals or traumatically inoculated, body temperature (37 °C) triggers dimorphism into yeast cells. This shift promotes fungal dissemination and immune evasion. Some fungal pathogens undergo dimorphism in the contrary way, forming pseudohyphae and hyphae within the host. While temperature is a major driver of dimorphism, other factors, including CO₂ concentration, pH, nitrogen sources, and quorum-sensing molecules, also contribute to morphological shifts. This morphological transition is associated with increased expression of virulence factors that aid in adhesion, colonization, and immune evasion. Candida albicans is a fungus that is commonly found as a commensal on human mucous membranes but has the potential to be an opportunistic fungal pathogen of immunocompromised patients. C. albicans exhibits a dimorphic change from the yeast form to the hyphal form when it becomes established as a pathogen. In contrast, Histoplasma capsulatum is an environmental dimorphic fungus where human infection begins when conidia or hyphal fragments of the fungus are inhaled into the alveoli, where the dimorphic change to yeast occurs, this being the morphology associated with its pathogenic phase. This review examines the main signaling pathways that have been mostly related to fungal dimorphism, using as a basis the information available in the literature on H. capsulatum and C. albicans because these fungi have been widely studied for the morphological transition from hypha to yeast and from yeast to hypha, respectively. In addition, we have included the reported findings of these signaling pathways associated with the dimorphism of other pathogenic fungi, such as Paracoccidioides brasiliensis, Sporothrix schenckii, Cryptococcus neoformans, and Blastomyces dermatitis. Understanding these pathways is essential for advancing therapeutic approaches against systemic fungal infections. Full article

Pear Valsa cankers were found in various Korla fragrant pear orchards in Alaer, Xinjiang. Disease samples underwent tissue isolation, resulting in six isolates. Pathogenicity tests revealed that the XLFL-6 isolate was the most virulent, demonstrating typical Valsa canker symptoms. Research on its biological characteristics indicated that the optimal growth conditions for XLFL-6 were a temperature of 28 °C and a pH of five. Under these conditions, the colonies of XLFL-6 exhibited the largest growth diameter, and adding glucose and peptone separately to the Czapek medium was most conducive to the growth of its mycelium. Based on morphological observations and multigene sequence analyses (ITS+TEF+TUB), the pathogenic fungus was identified as C. pyri. The infection process of C. pyri was elucidated through tissue observations using both light and electron microscopy. The conidia displayed a similar germination pattern on both wounded and intact twigs. However, the infection process was delayed in the case of intact bark. By 8 h post-inoculation, the conidia achieved a germination rate of 15%. Although germination had occurred, the infection process had not yet commenced. In contrast, for wounded bark tissue, it was observed that 24 h post-inoculation, the fungal hyphae from the conidia directly invaded the wounded tissue. These hyphae penetrate the cell walls, proliferate within the host tissue, and spread throughout the phloem and xylem. After 20 d, numerous pycnidia had breached the bark surface, and yellow waxy gums filled with conidia flowed abundantly from the pycnidia ostioles, with the host tissue being nearly totally disintegrated. Regarding enzyme activity, the polygalacturonase (PG) activity, the primary cell wall-degrading enzyme in the treatment group, was seven times greater than that of the control group. The carboxymethyl cellulose (Cx) activity within the treatment group continued to increase. Xylanase activity rose swiftly to its peak between days 1 and 4, then decreased from days 5 to 10, although it remained higher than that of the control group. Overall, this study is the first to provide a detailed report on the characteristics and proliferation of C. pyri and further elucidates its modes and pathways of invasion. Full article

Rice false smut, caused by Ustilaginoidea virens, is one of the three major rice diseases in China. It not only seriously affects the rice yield and quality but also endangers human and animal health. Studying the pathogenic mechanism of U. virens has important theoretical significance and application value for clarifying the infection characteristics of the pathogen and cultivating disease-resistant varieties. Plant pathogenic fungi utilize secreted effectors to suppress plant immune responses, which can function in the apoplast or within host cells and are likely glycosylated. However, the posttranslational regulation of these effectors remains unexplored. Deletion of ΔUvALG led to the cessation of secondary infection hyphae growth and a notable decrease in virulence. We observed that ΔUvALG mutants triggered a significant increase in reactive species production within host cells, akin to ALG mutants, which plays a crucial role in halting the growth of infection hyphae in the mutants. ALG functions by sequestering chitin oligosaccharides to prevent their recognition by the rice chitin elicitor, thereby inhibiting the activation of innate immune responses, including reactive species production. Our findings reveal that ALG3 possesses three N-glycosylation sites, and the simultaneous Alg-mediated N-glycosylation of each site is essential for maintaining protein stability and chitin-binding activity, both of which are critical for its effector function. These outcomes underscore the necessity of the Alg-mediated N-glycosylation of ALG to evade host innate immunity. Full article

Background and Clinical Significance: Since the prevalence of fungal lung infections is increasing, certain agents, such as Cladosporium spp., have emerged as unexpected causes. Cladosporium spp. fungi are ubiquitous in environments such as soil, fruits, and wine corks; they are a part of the normal human skin flora; and they are known respiratory allergens. Case Presentation: A patient with a history of post-COVID-19 syndrome and AIDS presented with lung pathology indicative of an invasive fungal infection. The initial histopathological examination revealed numerous yeast-like cells with narrow-based budding, which led to a mistaken diagnosis of cryptococcosis. However, further detailed examination revealed sparse hyphae in the lung tissue, suggesting a more complex fungal infection. Molecular analyses and sequence BLAST alignment were performed, ultimately identifying the infectious agent as “Cladosporium species novum”, a rare cause of invasive pulmonary cladosporiasis. Conclusions: Invasive pulmonary cladosporiasis is a rare condition, and the morphological features of the fungus alone were insufficient to establish a correct diagnosis. A comprehensive pathohistological and molecular approach with bioinformatics tools is essential for the correct identification of rare and potentially life-threatening fungal pathogens in immunocompromised patients. Full article

The length of incubation period, i.e., the time between first contact of host and pathogen and the appearance of symptoms, varies among diseases and depends on environmental conditions. Cercospora beticola is the most important fungal pathogen in sugar beet production worldwide, as Cercospora leaf spot (CLS) reduces the leaf area contributing to yield formation. Using sugar beet cultivars differing in CLS resistance, a single infection period of C. beticola resulted in minor differences in the incubation period among host genotypes and among individual plants of cultivars, greater differences among leaves within plants, and substantial variation within individual leaves. Under greenhouse conditions not suitable for secondary infections, the first CLS lesions appeared 10 days after inoculation; however, the number of leaf spots and CLS severity further increased significantly for another 7 to 17 days. A geographic information system approach enabled the tracking of colony appearance and growth of all CLSs on inoculated leaves for up to 27 days. Asymptomatic colonization of leaves was associated with thick hyphae which switched to thin hyphae or melanization after lesion appearance. The lifestyle of C. beticola—intercellular tissue colonization, triggering of necrotic host reaction—is discussed considering the experimental results as well as literature resources. Full article