Search Results (467)

This study aimed to separate and characterize compounds from Aspergillus tubingensis ZMGR14. The antifungal activities of monomer compounds and the ethyl acetate (EtOAc) layer from the fermented liquor of A. tubingensis were isolated, purified and structurally identified. The EtOAc layer from the fermented liquor showed significant antifungal activity against Fusarium oxysporum and Alternaria alternata with IC₅₀ values of 273.8 and 330.7 μg·mL⁻¹, respectively. The EtOAc extract was further purified by column chromatography and recrystallization to yield six compounds. Antifungal trials showed that Cyclo-(L-Pro-D-Leu) (5) exhibited the highest inhibition against A. alternata and F. oxysporum, with an IC₅₀ value of 48.1 and 232.7 μM, respectively, and cyclo-(L-Pro-L-Leu) (6) displayed moderate antifungal activity against Alternaria solani, with an IC₅₀ value of 493.4 μM. The results suggest that the EtOAc extract of ZMGR14 and its bioactive compounds hold promise as environmentally friendly microbial fungicides. Full article

Broccoli (Brassica oleracea var. italica) by-products represent an abundant and underutilized source of bioactive compounds with potential applications in sustainable food systems. This study aimed to characterize the microbiota associated with different plant fractions (leaves, stems, and heads) of broccoli (Parthenon and Tritón cultivars) and to evaluate the antioxidant and antimicrobial properties of their extracts, using cauliflower as a reference. Microbial counts and fungal identification (ITS sequencing) were performed, while phytochemical profiles were analyzed by HPLC-ESI-QTOF. Antioxidant activity was assessed using DPPH and ABTS assays, and antimicrobial activity under in vitro conditions was evaluated against selected foodborne bacteria and phytopathogenic fungi. Broccoli by-products, particularly leaves, showed lower microbial loads in certain cultivars and were rich in phenolic compounds and glucosinolates; however, higher phenolic content did not always correlate with greater antioxidant activity, highlighting the importance of compound composition. All extracts showed strong antibacterial activity at higher concentrations, especially against Listeria spp. Notably, antifungal activity was selective but relevant, with consistent inhibition observed against Alternaria alternata, while Penicillium purpurogenum and Botrytis cinerea exhibited higher resistance. Overall, these findings highlight the potential of broccoli by-products as sustainable sources of natural bioactive compounds for food applications, particularly in the development of preservation strategies and postharvest treatments. Further studies focusing on individual compounds and their specific biological activities are needed to better understand the mechanisms underlying these effects and to support their application in real food systems. Full article

Alternaria blight, caused by fungi of the genus Alternaria, is one of the most common and damaging diseases affecting tomatoes, leading to significant yield losses. The intensive use of chemical fungicides faces the problems of pathogen resistance development and negative environmental impacts. This study investigated the possibility of using RNA interference technology based on exogenous double-stranded RNAs (dsRNAs) to protect tomatoes against the causal agent of early blight (EB), Alternaria alternata. Key genes of the pathogen A. alternata were selected as targets: Alt-a1 (a major allergen and virulence factor), TEF1a (translation elongation factor 1-alpha) and β-Tub (β-tubulin). Specific dsRNAs were synthesized in vitro and applied to tomato plants (Solanum lycopersicum L. cv. Micro-Tom) simultaneously with inoculation of A. alternata strain C7.24-T2-L-F1 spores. Visual assessment, measurement of chlorophyll A and B, and real-time quantitative PCR analysis showed that treatment with dsRNAs targeting the Alt-a1, TEF1a and β-Tub genes significantly suppressed infection development, reducing the amount of pathogen DNA in plant tissues by 7 to 27 times depending on the dsRNA type. The most effective was dsRNA to the Alt-a1 gene. Thus, the obtained results demonstrate the promise of spray-induced gene silencing (SIGS) as a strategy for protecting tomato plants against the pathogen A. alternata. Full article

Endophytic fungi are promising sources of novel antiviral compounds, and the crude extract from Alternaria alternata PO4PR2 has previously shown anti-HIV-1 activity. This study evaluated its efficacy against integrase strand-transfer inhibitor (INSTI)-resistant HIV-1 and its mechanism of action. Key resistance mutations (Y143H, G118R, N155H, and R263K) were introduced into the HIV-1 pNL4.3 clone via site-directed mutagenesis and confirmed through Sanger sequencing. Viral infectivity was assessed in TZM-bl cells, while cytotoxicity was measured using an MTT assay. Antiviral activity was determined through a luciferase-based assay, and integration inhibition was evaluated using integrase activity assays and Alu-gag nested PCR. The extract demonstrated potent inhibition of resistant mutants, with low IC₅₀ values (0.02971–0.1652 μg/mL), and showed minimal cytotoxicity (CC₅₀ = 300 μg/mL), maintaining over 80% cell viability. It inhibited integrase activity by 67%, specifically targeting the strand-transfer step, and significantly reduced integrated viral DNA. Molecular docking of 14 compounds identified coumarin derivatives as key bioactive metabolites, exhibiting mutation-tolerant binding within the integrase catalytic pocket. Overall, these findings highlight PO4PR2 as a promising source of compounds for developing new therapies targeting drug-resistant HIV-1 integrase. Full article

Despite its rich bioactive composition, orange peel dust (OPD), a fine industrial by-product generated during citrus processing in the filter tea industry, has not received much attention as a valuable matrix. Using antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and reducing power (RP)), α-amylase inhibitory activity, antimicrobial potential, and sugar composition as function-oriented indicators, this study aimed to compare four green extraction technologies: subcritical water extraction (SWE), pressurized ethanol extraction (PEE), ultrasound-assisted extraction (UAE), and sequential supercritical CO₂–UAE (Sc-CO₂–UAE) applied to OPD derived from Citrus sinensis L. Among thermally driven techniques, PEE at 220 °C had the highest radical-scavenging activity, while UAE showed the broadest antifungal activity against Fusarium spp. and Alternaria alternata, along with selective antibacterial activity against Bacillus cereus. Sequential Sc-CO₂ pretreatment at 300 bar followed by UAE resulted in the highest α-amylase inhibitory activity. Sugar analysis indicated that thermal conditions enhanced carbohydrate hydrolysis, while UAE and Sc-CO₂-UAE maintained structural sugars under mild conditions. All green extraction approaches outperformed conventional maceration. These findings validate OPD as a valuable industrial by-product suitable for sustainable valorization, supporting circular economy concepts in the citrus processing sector. Full article

Alternariol (AOH) and alternariol monomethyl ether (AME) are major mycotoxins produced primarily by Alternaria alternata on cereal grains and fruits. A. alternata is a causative pathogen of strawberry black spot disease. However, little is known about the characteristics of A. alternata, which was isolated from strawberry products. In the present study, we evaluated the influence of temperature, pH, and relative humidity (RH) on the growth of A. alternata OM1 and its production of AOH and AME on different media including strawberry puree agar medium (SPAM) after its isolation from strawberry jam. The fungal strain showed the highest growth rate at 25 °C under pH 6.5 and RH 97%, while the highest amounts of AOH and AME were produced by the strain at 25 °C under pH 4.5 and RH 97%. Additionally, the strain did not produce AOH and AME on SPAM at 25 °C under RH 92% until 7 days. Moreover, RT-qPCR analysis exhibited that relative expression levels of 2 AOH or AME biosynthetic genes (pksI and omtI) in A. alternata OM1 were up-regulated in YES medium, while they were not in MEB medium. Our results demonstrated that the three key environmental parameters had a significant influence on the growth of A. alternata OM1 and its production of AOH and AME. These findings suggest that storage of strawberries below 25 °C under RH 92% could prevent the production of AOH and AME by A. alternata OM1 on them. Full article

Background/Objectives: Endophytic fungi represent an alternative source for resveratrol (RES) production. The present study aims to utilize mycoendophytic-derived resveratrol as a reducing agent for the synthesis of silver nanoparticles (AgNPs), in addition to further assay the cytotoxic activity of a RES-conjugated nanocarrier system toward human epidermoid carcinoma A-431 cells. Methods: Alternaria alternata AUMC 16209 was isolated from the stem of grapevine Vitis vinifera L. cultivar prime. Strain identification was achieved through morphological and molecular characterization using ITS sequencing. A. alternata AUMC 16209 exhibited RES production capability upon cultivation on PDB medium for seven days with a total of 8.25 mg/L as determined by HPLC. The crude RES was purified using flash chromatography followed by structure elucidation through ¹H and ¹³C NMR analyses. The purified RES was used for green synthesis of nanoparticles, acting as a reducing agent for silver ions. Results: Stable RES-AgNPs were fabricated at particle sizes ranging from 25 to 47 nm. RES-AgNPs observed a plasmon resonance absorption band at 415 nm with a negative zeta potential value of −38.5 mV. The crystalline structure of RES-AgNPs was addressed through X-ray diffraction analysis. FT-IR spectroscopy confirms the involvement of the functional –OH group and the aromatic C=C bond in the reduction and stabilization process. RES-AgNPs was more efficient to inhibit the cellular proliferation of human epidermoid carcinoma A-431 cells compared to RES alone. Conclusions: This report introduces for the first time an endophytic A. alternata as a sustainable source for RES production and emphasizes its potential for green synthesis of stable AgNPs with promising cytotoxic activity. Full article

This study evaluates a SiO₂ nanoparticle (SiO₂NPs)/Paraloid B-72 nanocomposite as a restorative and antifungal treatment for deteriorated sandstone at the Ptolemaic Temple of Isis, located within a densely populated residential area. The temple stones exhibit structural damage, soiling, and severe microbiological deterioration. Fungal isolates from the sandstone were cultured on PDA medium and identified by ITS region DNA sequencing as Alternaria alternata, Penicillium chrysogenum, and Aspergillus niger. The SiO₂NPs and their Paraloid B-72 nanocomposites were synthesized and characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Stone samples, examined before and after treatment via SEM-EDX, TEM, and XRD, were used to assess both conservation performance and compatibility. Laboratory antifungal tests showed that SiO₂NPs at 300 ppm exhibited the greatest inhibition of mycelial growth, reaching 91.59% for P. chrysogenum, 90.77% for A. niger, and 85.2% for A. alternata. Mechanical testing demonstrated that treatment with the SiO₂NPs/Paraloid B-72 nanocomposite enhanced stone strength, increasing compressive strength from 26.5 MPa to 27.4 MPa. SEM images confirmed excellent, homogeneous dispersion of the nanocomposite on stone grains, forming a coherent coating without pore occlusion. Overall, the SiO₂NPs/Paraloid B-72 formulation improved sandstone surface properties while substantially improving short-term mechanical performance and antifungal efficacy, indicating promise for enhancing restoration procedures when combined with established conservation protocols for sandstone architectural heritage. Full article

Alternaria brown spot, caused by the tangerine pathotype of Alternaria alternata, is a destructive fungal disease affecting citrus production worldwide. Nucleotide-binding site-leucine-rich repeat (NBS-LRR) genes constitute a major class of plant immune receptors; however, their genome-wide characteristics and potential association with Alternaria brown spot resistance loci in citrus remain poorly understood. In this study, we performed a comprehensive genome-wide identification and comparative analysis of NBS-LRR genes across representative citrus species. A total of 417 and 326 NBS-LRR genes were identified in Citrus reticulata and Citrus clementina, respectively, and were classified into NL, CNL, TNL, and RNL subfamilies based on domain architecture. Phylogenetic reconstruction, gene structure analysis, conserved motif composition, chromosomal distribution, synteny relationships, and promoter cis-element profiling collectively revealed considerable structural variation and lineage-specific expansion of the NBS-LRR gene family in citrus genomes. By integrating previously reported quantitative trait locus (QTL) data for Alternaria brown spot, we identified several NBS-LRR genes located within a resistance-associated genomic interval on chromosome 3. Among these, a candidate gene, designated LRR2, exhibited differential transcriptional responses upon pathogen inoculation and displayed distinct sequence variations between citrus genotypes. Structural modeling and molecular docking analyses suggested potential binding interfaces between LRR2 and multiple host-selective toxins, although the biological relevance of these interactions requires further experimental validation. Subcellular localization assays in Nicotiana benthamiana showed that LRR2 is distributed in both the nucleus and cytoplasm. Notably, transient overexpression of LRR2 triggered hypersensitive response-like cell death and H₂O₂ accumulation. Collectively, this study provides a comprehensive overview of the citrus NBS-LRR gene family and presents a multifaceted characterization of a QTL-anchored candidate gene. These findings establish a genomic and molecular framework for further functional investigations of citrus–Alternaria interactions. Full article

Drunken horse grass (Achnatherum inebrians) plays a vital role in ecological restoration and grassland sustainability in Northwest China, but its ecological functions are increasingly threatened by emerging fungal diseases. In 2024, a leaf spot disease characterized by brown lesions with yellow halos was observed on drunken horse grass in Gansu Province, China. The causal pathogens were identified as Alternaria alternata and Alternaria infectoria based on morphological characterization, pathogenicity tests, and multi-locus phylogenetic analysis (ITS, TEF, GPD, RPB2, Alt a 1, endoPG, and OPA10-2). Preliminary fungicide sensitivity assays revealed that tetramycin and difenoconazole had the strongest inhibitory effects against mycelial growth in vitro. The EC₅₀ values for tetramycin were 0.0755 mg/L (A. alternata) and 0.2175 mg/L (A. infectoria), while for difenoconazole, they were 0.1023 mg/L (A. alternata) and 0.0599 mg/L (A. infectoria). To our knowledge, this is the first report of Alternaria species infecting the host plant, drunken horse grass, providing an essential basis for the effective management of this disease and the protection of grassland ecosystems. Full article

A three-year experiment was conducted over the years 2020–2022 to determine the spectrum of microscopic fungi colonizing the grain of two fungicide-treated cultivars of spring barley and the profiles of mycotoxins identified in grain. In comparison with the unprotected control, fungicide treatment significantly increased grain yield by an average of approximately 10% in cv. Atrika and approximately 20% in cv. Vermont. The most abundantly isolated species were Alternaria alternata and Bipolaris sorokiniana. Fungi of the genus Fusarium were also widely represented, accounting for 7% to 27% of all isolates, depending on the year. Each year, 45 secondary fungal metabolites produced mainly by Fusarium and Alternaria species were identified. Fungicide protection did not reduce the overall concentration of Fusarium toxins and even caused a slight increase, while contributing to a decrease in the levels of nivalenol-3-glucoside, nivalenol, and deoxynivalenol. Concurrently, the concentrations of group A trichothecenes and moniliformin increased. The grain of spring barley cv. Vermont contained higher levels of the major Fusarium toxins than the grain of cv. Atrika. Non-parametric Friedman ANOVA revealed significant differences between years for eight mycotoxin concentrations. These results confirm the complex effects of chemical protection on the composition of grain microflora and mycotoxin profiles, indicating the need for further research into interactions between cultivars, environmental conditions, and integrated plant protection strategies in the production of food and feed cereals to improve food safety. Full article

Tomato fruit rot severely impacts yield and quality, causing economic losses. This study aimed to identify the pathogenic fungi associated with post-harvest tomato fruit rot and characterize the transcriptomic responses of tomatoes. Pathogens were isolated from diseased tomato fruit tissues and identified using morphology, phylogenetic analysis, and in vitro pathogenicity tests. The genome of Cladosporium oxysporum Co-1 was assembled and annotated. RNA-seq analysis was used to profile transcriptional changes in tomatoes infected with C. oxysporum Co-1, with RT-qPCR validating the RNA-seq data and spectrophotometric assays analyzing the host physiological responses. Three pathogenic fungi were isolated. Colonies of C. oxysporum exhibited a near-circular shape, with colonies transitioning from an olive-green center to gray-green at the edges, and based on ITS, β-tubulin, and EF-1α gene sequences, this isolate exhibited 99% identity with C. oxysporum. The other two fungal isolates were identified as Alternaria alternata and Fusarium incarnatum, respectively, based on morphological and multi-locus sequence analysis. All three strains induced fruit rot and browning in tomatoes, confirming their pathogenicity. The genome size of C. oxysporum Co-1 was 34,515,558 bp, comprising 52 scaffolds with a GC content of 52.82%, and encoding 10,081 protein-coding genes. RNA-seq analysis showed dynamic gene expression changes in tomatoes infected with strain A, with differentially expressed genes enriched in pathogenicity-related pathways. Spectrophotometric assays revealed that peroxidase and superoxide dismutase activities decreased initially followed by an increase post-inoculation with C. oxysporum, indicating that tomatoes defend against pathogen infection through the antioxidant enzyme system. These findings revealed the pathogenic fungi were associated with post-harvest tomato rot disease, provided genomic resources for C. oxysporum, and provided insight into the host’s response to this strain. Full article

Pomegranate heart rot (black heart) was observed in several pomegranate-growing areas of Algeria. From 2022 to 2025, surveys were conducted across 15 provinces (20 localities), and a total of 85 fruits (symptomatic and asymptomatic) were collected. Fruits were cut transversely to assess internal symptoms, ranging from early aril browning to dry black rot. Thirty Alternaria isolates were obtained and grouped into four morphotypes based on colony and conidial morphological traits. A subset of 18 isolates was analysed by multilocus phylogeny (ITS, EF-1α, GAPDH and OPA10-2); all analysed isolates clustered within the Alternaria alternata species complex, in the clade including the ex-type strain CBS 916.96. Fruit pathogenicity tests with Algerian isolate GA reproduced typical internal heart rot symptoms, and the pathogen was consistently re-isolated from symptomatic tissues. In fruit inoculations with isolate GA, cultivars differed in susceptibility, with mean disease severities of 94%, 62% and 9.5% in ‘Taferrante’, ‘Ikhessène’ and ‘Kares’, respectively, expressed as the percentage of the fruit section presenting rot symptoms. Detached leaf assays indicated isolate-dependent differences in aggressiveness, and ‘Kares’ showed the lowest susceptibility. Overall, the results confirm that A. alternata is the causal agent of pomegranate heart rot in Algeria and provide baseline information for disease diagnosis and management. Full article

Endophytic fungi widely colonize plant tissues without causing severe disease, protect hosts from pathogenic microorganisms, and represent a key potential resource for novel biocontrol agents. To explore the biocontrol potential of endophytic Epichloë fungi and their correlation with alkaloids, 12 Epichloë strains were isolated from six different geographic sites of Festuca sinensis, Achnatherum inebrians, and Hordeum brevisubulatum. The antifungal activity of these strains was evaluated against five phytopathogenic fungi (Alternaria alternata, Bipolaris sorokiniana, Curvularia lunata, Fusarium avenaceum, and Drechslera erythrospila) using dual-culture assays, which measured the inhibition of both colony growth and spore germination. Concurrently, the concentrations of ergonovine and ergine were quantified in the liquid cultures of each Epichloë strain. The results showed that 12 Epichloë strains had varying degrees of inhibitory effects on the colony growth and spore germination of five pathogenic fungi. Among these, strain F2 had the highest inhibition rate on the spore germination of B. sorokiniana (87.73%), while strain H3 had the lowest inhibition rate on F. avenaceum (7.89%). The concentrations of ergonovine and ergine were positively correlated with the inhibition rate of pathogenic fungi, but the degree of these correlations varied among different pathogenic fungi. This study provides further evidence for Epichloë-mediated pathogen inhibition and establishes a basis for their development as biocontrol agents in agricultural systems. Full article

Postharvest fungal decay is a primary cause of losses in blueberries, motivating the development of sustainable alternatives to conventional fungicides. This study aimed to develop and evaluate antifungal active films based on polylactic acid (PLA) enriched with citronella essential oil to control phytopathogenic fungi associated with blueberry spoilage. PLA films containing 7.5, 10, and 12.5% (w/w) citronella essential oil were produced by solvent casting and characterized for water vapor transmission rate and nanomechanical properties. The antifungal effect was tested in vitro against Epicoccum nigrum, Alternaria alternata, and Cladosporium herbarum. Active films exhibited concentration-dependent antifungal activity, with C. herbarum being the most sensitive fungus. The incorporation of citronella essential oil did not significantly alter the water vapor barrier properties of PLA, while mechanical analysis revealed a reduction in elastic modulus only at the highest concentration. The antifungal mechanism was elucidated using scanning electron microscopy, fatty acid profiling, absorbance at 260 nm, and conductivity measurements. The results indicate that the released citronella essential oil induced membrane disruption and morphological damage in fungal hyphae, with species-specific responses. Overall, PLA–citronella essential oil films represent a promising biodegradable packaging solution to control postharvest blueberry losses. Full article