It is demonstrated that equisetin is the active antifungal metabolite produced by F. incarnatum Y2, with potent in vitro activity against major wheat root and crown rot pathogens.
Abstract
Background/Objectives: Wheat root and crown rot, caused by Fusarium pseudograminearum, Fusarium graminearum, and Bipolaris sorokiniana, are devastating soil-borne diseases that cause substantial yield losses worldwide. Endophytic fungi are promising sources of bioactive metabolites for agricultural applications. This study aimed to isolate and characterize an endophytic fungus with antifungal activity against major wheat pathogens, identify its active compound, and investigate the underlying transcriptional response. Methods: An endophytic strain Y2 was isolated from Hedyotis diffusa leaves and identified through morphological and phylogenetic analysis based on TEF-1α and RPB2 sequences. Pathogenicity of strain Y2 was evaluated on wheat stem bases. The bioactive compound was purified by HPLC and identified by HR-ESI-MS and NMR. Antifungal activity was assessed using dual-culture and microbroth dilution assays. Transcriptomic analysis (RNA-seq) was performed on F. pseudograminearum treated with equisetin, with qRT-PCR validation of seven representative differentially expressed genes. Results: Strain Y2 was identified as Fusarium incarnatum or a closely related member of the F. incarnatum–equiseti species complex (FIESC) and confirmed to be non-pathogenic to wheat. The purified bioactive compound was characterized as equisetin, which exhibited significant antifungal activity with MIC values of 16, 32, and 64 μg/mL against F. pseudograminearum, B. sorokiniana, and F. graminearum, respectively. Transcriptomic analysis revealed that equisetin treatment induced a polarized transcriptional response in F. pseudograminearum, characterized by strong upregulation of ribosome and translation-related genes and widespread downregulation of other metabolic pathways, particularly nitrogen metabolism. qRT-PCR validation of seven representative genes confirmed the reliability of the RNA-seq data. Conclusions: Our findings demonstrate that equisetin is the active antifungal metabolite produced by F. incarnatum Y2, with potent in vitro activity against major wheat root and crown rot pathogens. The transcriptomic data provide insights into the potential mechanism of action, while the non-pathogenic nature of strain Y2 supports its biosafety. Although these results highlight equisetin as a promising lead compound for antifungal development, further in planta efficacy and safety studies are required before it can be considered for practical biocontrol.
India contributes 26% of global banana production, yet cultivation is severely threatened by Fusarium wilt (Fusarium oxysporum f. sp. cubense, Foc), necessitating sustainable, eco-friendly management strategies. This study evaluated the biocontrol potential of endophytic bacteria isolated from Foc-resistant and -susceptible banana cultivars. Isolates from the pseudostem, corm, and root of the resistant cultivar showed significantly greater inhibitory activity than those from the susceptible cultivar, underscoring the role of host genotype in shaping functionally competent endophytic communities. Among all isolates, Bacillus sp. from the corm of cv. Rose (AB) showed the highest mycelial inhibition of Foc (70.37–76.54%) in vitro. GC-MS-based metabolite profiling revealed a chemically diverse array of secondary metabolites, fatty acid esters, steroids, terpenoids, siloxanes, and nitrogenous compounds. Corm-associated endophytes exhibited membrane-disruptive and cytotoxic activity, while root-associated endophytes contributed protective, defense-modulatory effects. Halomonas sp. RoRo2 and B. subtilis RoC1 showed the highest inhibition in both agar-well and in planta assays, with unsaturated fatty acids and organic acid derivatives implicated as key antifungal effectors acting through multiple biochemical pathways. These findings identify metabolically versatile endophytes as promising candidates for developing efficient, environmentally compatible bioinoculants as sustainable alternatives to chemical control of Fusarium wilt in banana.
D. P. Mohite, Kavino Mathiyazhagan, Nakkeeran Sevugapperumal et al.· Pathogens· 0 citations
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.
Weronika Giedrojć, W. Pluskota, U. Wachowska· Fungal Genetics and Biology· 0 citations
Sweetpotato black rot, caused by Ceratocystis fimbriata, is a major postharvest disease that leads to substantial storage losses worldwide. In this study, a salt-tolerant rhizobacterial strain, Bacillus albus SSR3, was isolated from the rhizosphere of sweetpotato grown in saline-alkali soil, with broad-spectrum antagonistic activity against postharvest fungal pathogens. LC-MS/MS analysis revealed diverse bioactive metabolites associated with its antifungal activity. Integrated transcriptomic and metabolomic analyses showed that SSR3 bioactive metabolites extensively reprogrammed fungal metabolism, particularly pathways involved in carbohydrate and amino acid metabolism, antioxidant defense, and energy production. These alterations were accompanied by disruption of cell wall and membrane integrity, excessive reactive oxygen species accumulation, and mitochondrial dysfunction, ultimately inhibiting fungal growth. Here, we also found that SSR3 bioactive metabolites effectively inhibited aflatoxin B1 production by Aspergillus flavus and deoxynivalenol accumulation in Fusarium graminearum. In vivo assays further demonstrated that SSR3 bioactive metabolites significantly reduced sweetpotato black rot severity and effectively limited fungal colonization and mycotoxin contamination in stored agricultural commodities. Collectively, our findings demonstrate that B. albus SSR3 suppresses postharvest fungal pathogens through coordinated metabolic reprogramming, oxidative stress induction, and cellular integrity disruption, highlighting its potential as a sustainable biocontrol agent for postharvest disease management.
Feng-Qin Song, Qing-Ru Geng, Bing-Qian Hu et al.· Journal of food microbiology· 0 citations
Secondary metabolites are promising alternatives due to their diverse biological activities, including antimicrobial and antiviral effects. Wild plants, particularly Solanum elaeagnifolium Cav (Silverleaf Nightshade), harbor endophytic microorganisms that represent an untapped source of such bioactive compounds. In the present study, four bacterial endophytes were isolated from the leaves of Solanum elaeagnifolium Cav (LS1, LS2, LS3, and LS4), and their extracts (S1, S2, S3, and S4) were prepared. Extract S4 showed both qualitative and quantitative inhibitory activity against a broad range of standard and multidrug-resistant (MDR) pathogens, including Gram-positive and Gram-negative pathogens. Moreover, it showed significant antiviral effects against Adenovirus serotype 7 and Herpes Simplex Viruses 1 and 2. The endophytic bacterium LS4 was identified microscopically, biochemically, and via whole-genome sequencing as Bacillus spizizenii CCASU-2025-89. Cytotoxic assessment of S4 revealed a CC50 of 80.71 μg/mL and a safe concentration of 6.23 μg/mL. Whole-genome analysis revealed conserved biosynthetic gene clusters of antimicrobial peptides including bacilysin, subtilin, mycosubtilin, bacillaene, bacillibactin, subtilosin A, and Pulcherriminic acid. Overall, this study demonstrates that endophytic bacterium Bacillus spizizenii from Solanum elaeagnifolium represents a promising resource for developing new antimicrobial and antiviral therapeutics.
Merihan S. Sabra, Lina Jamil M. Abdel-Hafez, Amr S. Bishr et al.· Frontiers in Cellular and In...· 0 citations
Fusarium wilt of Phalaenopsis spp., caused by Fusarium species, is a major soil-borne disease that severely threatens the yield and ornamental quality of Phalaenopsis. Endophytic fungi can serve as natural biocontrol agents against soil-borne pathogens and have potential applications in biological control. In this study, a pathogenic isolate, HT-1, was obtained from Fusarium-wilted Phalaenopsis plants, and its pathogenicity was confirmed through inoculation assays on detached leaves and intact plants. Morphological observations, together with internal transcribed spacer (ITS) and translation elongation factor 1-α (TEF-1α) sequence analyses, identified HT-1 as Fusarium proliferatum. Seven endophytic fungi with strong antagonism against F. proliferatum were screened using a dual-culture assay. All seven isolates consistently inhibited five representative plant pathogens in vitro, showing broad-spectrum and promising biocontrol potential. Detached leaf inoculation assays showed that both Trichoderma virens and Trichoderma asperellum significantly reduced lesion area and disease severity caused by F. proliferatum, indicating potential application in disease management. In summary, this study identified seven endophytic fungi from Phalaenopsis with broad-spectrum antagonistic potential against multiple plant pathogenic fungi. Meanwhile, the protective effects of T. virens and T. asperellum against F. proliferatum were preliminarily evaluated using detached leaves. These findings provide theoretical reference and fungal resources for screening candidate biocontrol strains against Phalaenopsis Fusarium wilt and related plant diseases, and lay a foundation for future studies on biocontrol mechanisms, whole-plant efficacy verification, and practical application.
: Clove ( Syzygium aromaticum ), a member of the Myrtaceae family, is widely distributed throughout tropical regions from Indonesia to China. This research aimed to investigate the antifungal effects and mechanisms of clove essential oil (CEO) against Fusarium oxysporum , the causal agent of root rot disease in Pseudostellaria heterophylla and other crops. The inhibitory effects of CEO on mycelial growth, spore germination and ergosterol biosynthesis of F. oxysporum were assessed through in vitro assays. The mechanism was initially investigated by analyzing the primary components of CEO using gas chromatography-mass spectrometry (GC-MS) and performing molecular docking studies with the target enzyme. Results showed that CEO inhibited mycelial radial growth in a dose-dependent manner, with inhibition rates ranging from 16.61% to 100%. The median effective concentration (EC 50 ) value was determined to be 131.7 µ L/L (R 2 = 0.985). Spore germination decreased significantly by 61.6% at 300 µ L/L ( p < 0.05), resulting in shortened germ tubes and noticeable morphological changes. CEO inhibited ergosterol biosynthesis in a concentration-dependent manner, disrupting membrane integrity. The inhibition rate can reach 34.6% at 150 µ L/L ( p < 0.05). GC-MS analysis identified 24 compounds, with phenylpropanoids representing 92.44% of compounds. Within this category, eugenol and eugenyl acetate were the predominant components, representing 72.51% and 19.66%, respectively. The molecular docking results showed that eugenyl acetate exhibits a strong binding affinity for ERG3 and CYP51, with binding free energies of − 6.615 and − 6.336 kcal/mol, respectively. This research identifies eugenyl acetate as a key component contributing to the antifungal effect through molecular docking, and reveals a dual-action antifungal mechanism of CEO against F. oxysporum . These findings suggest that CEO has potential natural antifungal agent for controlling soil-borne diseases by disrupting membranes through ergosterol inhibition.
Hualin Hu, Cai-Wei Wang, Jian Fan et al.· Phyton· 0 citations
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