Search Results (375)

Fusarium solani is an emerging pathogen responsible for Fusarium-related diseases in durian trees in Thailand. Several chemical fungicides and biocontrol agents are ineffective in controlling these diseases, which affects durian trees and reduces yields. This study aimed to identify soil-derived bacteria with biocontrol activity against F. solani that surpasses traditional biocontrol bacteria. The characteristics and biocontrol efficacy of effective isolates were analyzed. Four isolates from 107 bacterial isolates were identified as effective biocontrol agents against F. solani. Isolate S301 exhibited the highest inhibition at 74.31%, exceeding that of the traditional biocontrol bacterium Bacillus subtilis. These isolates antagonized F. solani by producing siderophores, fungal cell wall lytic enzymes, and hydrogen cyanide, and by promoting plant growth. Molecular and phylogenetic analyses identified the four isolates as members of the Bacillus genus, specifically B. safensis, B. thuringiensis, B. subtilis, and B. cereus. The application of B. safensis strain S101 and B. subtilis strain S301 showed potential to reduce fungal disease symptoms on Monthong durian leaves. These findings are the first to demonstrate the potential of B. safensis and B. subtilis as promising bacterial biocontrol agents for managing F. solani-related diseases in durian trees in Thailand. Full article

Buds are a critical stage in the annual growth–dormancy cycle of perennial woody plants and are essential for survival and biomass accumulation. To safeguard these structures, trees employ both physical and chemical protection. Although Populus buds are known to contain rich phytochemistry, population-level variation remains largely unexplored. Here, we characterized bud phytochemistry across a population of Populus trichocarpa natural variants using gas chromatography–mass spectrometry and examined the antifungal properties of bud extracts. In the reference genotype Nisqually-1, a total of 32 lipophilic metabolites were detected, belonging to four chemical groups: terpenoids, phenylpropanoids, linear hydrocarbons, and others. Analysis of 49 additional P. trichocarpa natural variants revealed both shared features and substantial variation. All lines contained metabolites from the phenylpropanoid, linear hydrocarbon and terpenoid classes, which consistently dominated the profiles. However, quantitative differences in individual metabolites and relative class abundances distinguished the lines, allowing them to be grouped into three chemotypic clusters. To assess potential biological implications of phytochemical variance, we tested antifungal activity of bud extracts against the pathogenic fungus Fusarium oxysporum. Extracts from all 50 lines significantly inhibited fungal growth compared with controls. Correlation analyses between metabolite abundance and inhibition strength identified candidate metabolites that were most strongly associated with antifungal activity. Together, these findings reveal both conserved and variable components of bud phytochemistry in P. trichocarpa. The observed chemical diversity and consistent antifungal effects suggest that bud metabolites contribute to defense and may reflect adaptation across natural populations. Full article

Pathogen manipulation of host behavior is a widespread evolutionary strategy to enhance its transmission, yet whether different pathogens elicit distinct behavioral and molecular responses in the same host remains poorly understood. We performed parallel behavioral assays and comparative transcriptomic analyses on third-instar Lymantria dispar larvae infected with Lymantria dispar multiple nucleopolyhedrovirus (LdMNPV, virus), Staphylococcus aureus (bacterium) and Metarhizium anisopliae (fungus). Climbing height was recorded over 72 h post-infection, and gene expression pattern was profiled using RNA-seq at 72 h. Only LdMNPV infection induced significant, sustained upward climbing behavior among the three pathogen infection groups. All three pathogens activated Toll and IMD immune pathways, but LdMNPV triggered substantially broader transcriptomic reprogramming. Notably, the virus specifically upregulated multiple energy metabolism pathways (nicotinate/nicotinamide metabolism, pyruvate metabolism, TCA cycle and oxidative phosphorylation) and the neuroactive ligand-receptor interaction pathway—a pattern absent in bacterial and fungal infections. LdMNPV drove tree-top disease through a virus-specific, multi-system manipulation strategy that couples metabolic activation with neural signaling modulation. This comparative study reveals fundamental differences in behavioral manipulation across pathogen kingdoms and provides candidate pathways for functional validation. Full article

Horse chestnut (Aesculus hippocastanum L.) is a widely planted ornamental and urban tree valued for its aesthetic and ecological functions. In recent years, declining health of horse chestnut in urban environments has been increasingly reported, often associated with a complex of biotic and abiotic stressors. During a health survey of A. hippocastanum trees growing along an urban road corridor in Warsaw, Poland, extensive bark necrosis and branch dieback were observed. The aim of this study was to identify the causal agent of these symptoms using morphological, cultural, molecular (ITS rDNA), and pathogenicity tests under controlled conditions. Fungal isolates were obtained from necrotic tissues and were consistently identified as Kalmusia variispora based on ITS sequence analysis (99.0–99.6% similarity to GenBank references) and characteristic morphology. Pathogenicity tests fulfilled Koch’s postulates, reproducing necrotic lesions and cambial damage similar to those observed in the field. To our knowledge, this is the first documented report worldwide of K. variispora infecting A. hippocastanum. The findings expand the known host range of this opportunistic Didymosphaeriaceae species and highlight its potential role in bark and wood disease complexes of urban trees. Further research is needed to assess its distribution, genetic diversity, and epidemiological significance in urban forest ecosystems. Full article

The necrotrophic pathogen Sclerotinia sclerotiorum compromises the physiological and anatomical integrity of cotton, leading to substantial economic losses due to rapid tissue necrosis, stem blight, boll rot, and leaf wilting. In this context, the use of endophytic microorganisms emerges as a promising strategy for the biocontrol of white mold. This study tested the hypothesis that endophytic fungal strains isolated from the roots of Butia purpurascens, a palm tree endemic to the Cerrado biome, could mitigate disease symptoms in Gossypium hirsutum L. To evaluate this, cotton plants were subjected to biotic stress imposed by S. sclerotiorum to assess the effectiveness of seven fungal strains in attenuating disease. The impact of the pathogen was monitored through growth variables, gas exchange, leaf temperature, chlorophyll a fluorescence, antioxidant enzyme activity, proline and malondialdehyde (MDA) levels, and the incidence of rot in petioles, leaves, and flower buds. Overall, inoculation with endophytic fungi significantly alleviated the effects of the phytopathogen, promoting vegetative growth and optimizing physiological performance. Treated plants exhibited alleviated stress in primary photochemistry, reduced non-photochemical energy dissipation, and stable carbon fixation. Additionally, efficient modulation of the antioxidant system and preservation of anatomical structures were observed, minimizing the severe symptoms of white mold. Notably, the non-pathogenic strains BP10EF (Gibberella moniliformis), BP16EF (Penicillium purpurogenum), and BP33EF (Hamigera insecticola) acted as potent physiological modulators, yielding responses similar to those of healthy plants. These results highlight the biotechnological potential of these endophytic strains, which can be explored as both growth promoters and resistance inducers in cotton against white mold. Full article

Plant fungal diseases, such as apple tree canker caused by Valsa mali, have caused severe losses in agricultural production. Traditional chemical fungicides induce drug resistance in pathogens and cause environmental pollution. Therefore, it is of substantial importance to screen efficient and environmentally friendly bacterial strains as potential biocontrol agents. The tea rhizosphere harbors abundant microbial resources, and previous research has identified microorganisms with antifungal activity existing in this environment. Therefore, in this study, we isolated antagonistic bacteria with broad-spectrum biocontrol potential from tea rhizosphere soil. In this study, a strain with strong antagonistic activity against V. mali was isolated from tea rhizosphere soil. Based on morphological characteristics, 16S rRNA gene sequencing, and whole-genome analysis, the isolated strain was identified as Bacillus velezensis and designated as LW-66. This strain demonstrated broad-spectrum antifungal activity against various plant pathogenic fungi, including Valsa mali, Fusarium graminearum, Bipolaris sorokinianum, Alternaria solani, and Exserohilum turcicum. The active extract of B. velezensis maintained strong stability across a wide range of temperatures (25–90 °C) and pH values (2–8), with stability decreasing only when the temperature reached 100 °C or pH ≥ 10. In a preventive assay using detached apple branches inoculated with V. mali, the control efficacy of LW-66 against apple tree canker reached more than 90%. Additionally, in a therapeutic assay using V. mali-infected potted apple seedlings, the LW-66 bone-glue bacterial agent achieved a survival rate of up to 90%. Whole-genome analysis revealed that the genome of LW-66 contains 13 predicted secondary metabolite biosynthetic gene clusters, seven of which showed high homology (≥92% similarity) with known antimicrobial gene clusters, including surfactin, bacillaene, macrolactin H, fengycin, difficidin, bacillibactin, and bacilysin. These gene clusters may be connected to the broad-spectrum antifungal activity of B. velezensis, as well as its ability to disrupt hyphal morphology. The volatile organic compounds produced by LW-66 inhibited V. mali growth by 91.70%. Collectively, these findings demonstrate that B. velezensis LW-66 has a wide antimicrobial range and strong antagonistic effects against multiple plant pathogenic fungi. Therefore, B. velezensis shows promise as a biocontrol agent for managing fungal diseases in plants, providing a basis for developing LW-66-derived biocontrol products aimed at controlling diseases such as apple tree canker. Full article

High-density apple (Malus domestica Borkh.) orchards yield fruits as early as three years after planting but nutrient inputs and availability are paramount to a successful orchard; sustainable practices that balance tree growth and production with environmental concerns are not widely available. In this three-year study, we implemented a split-plot design in three orchards across the Mid-Atlantic region of the USA to evaluate integrated soil management approaches that combine locally sourced carbon-based organic mulch with fertilizers on rhizosphere microbes and tree growth. Bacterial and fungal communities were sampled at the end of the first and third growing seasons in addition to soil and tree-related physicochemical properties. Mulch treatment showed the most significant effect on both the bacterial and fungal groups. Most of these changes reflect the increase in soil organic matter and the increase in carbon cycling. Sequence variants belonging to Flavobacteria and Cytophaga were enriched by the mulch application. A key result from this project is the suppression of the relative abundance of potential soil-borne plant fungal pathogens in all orchards in all years. Additionally, arbuscular mycorrhizal fungi were enriched under the mulch treatment. Microbial shifts accompanying the mulch treatments supported higher trunk cross-sectional areas by the third sampling year that increased by 33.5%. Fertilizer treatments had less pronounced effects on microbial communities. These results highlight the potential for using sustainable, integrated nutrient management strategies to promote healthy orchard soils and support vigorous tree growth while reducing fungal pathogens. Our work will contribute to regional and location-specific fertilizer recommendations for apple producers. Full article

The Numidian cypress (Cupressus sempervirens var. numidica, C. numidica hereafter) is a rare, almost unknown, endemic taxon of Tunisia whose conservation has long been hampered by human activities, taxonomic uncertainty and limited ecological knowledge, with only 64.33 ha of its populations remaining. Although recent genetic studies have confirmed its native status and long-term isolation, detailed information on its distribution, population structure and threats remain lacking. This study provides the first comprehensive assessment of C. numidica across its remaining range. Field surveys revealed that the species persists in only three small, fragmented forests, Bou Abdallah, Sidi Amer, and Dir Satour, covering a total of 64.33 ha. Soil analysis revealed some differences among sites, with Bou Abdallah showing higher clay content and Dir Satou exhibiting the highest levels of nitrogen, organic carbon, Olsen P, and available Mn and Mo. Climatic analyses indicate a semi-arid Mediterranean environment with pronounced summer droughts and a clear warming trend. Trees showed widespread damages, due to intensive grazing, tree cutting, crown dieback (drought), and pest and pathogen attacks. Natural regeneration was limited, and the condition of affected trees ranged from moderate to severe, with Bou Abdallah showing the highest levels of degradation. Notably, the severe fungal pathogen Seiridium cardinale, causal agent of cypress canker, was detected on C. numidica for the first time, highlighting an urgent conservation concern. Our results point to a staged conservation approach over time. In the immediate term (within 1 year), urgent monitoring and management of S. cardinale is needed. In the short term, efforts should focus on protecting carefully selected areas, about 5–10 regeneration microsites per forest, from grazing to support natural regeneration, reduce ongoing soil degradation, and establish clonal and seed-production plantations along with long-term seed storage. In the long term, the survival of C. numidica will only be possible with the active involvement of local communities, through awareness campaigns, adapting traditional practices such as gdel, and developing small-scale ecotourism that provides sustainable livelihoods while reinforcing support for conservation. Full article

The global rise in antimicrobial resistance has spurred increased interest in alternative antimicrobial agents, particularly essential oils (EOs). These oils are complex mixtures of volatile compounds that exhibit documented biological activity. This study evaluated antimicrobial and antibiofilm effects of selected EOs against clinically relevant bacterial and fungal pathogens. Antimicrobial activity against planktonic cells was assessed using disc diffusion assays with DMSO-diluted EO solutions against Escherichia coli (E.coli), Staphylococcus aureus (S.aureus), Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. Antibiofilm activity of E. coli and S. aureus was examined using ethanol-based EO formulations, with biofilm viability quantified by colony forming unit (CFU) enumeration. Cinnamon (Cinnamomum verum) oil showed the strongest and most consistent activity, inhibiting planktonic and biofilm models. Tea tree (Melaleuca alternifolia), lemongrass (Cymbopogon citratus), rosemary (Rosmarinus officinalis), rose (Rosa damascena), and jasmine (Jasminum officinale) oils showed significant planktonic antimicrobial effects, while jasmine oil (Jasminum officinale) demonstrated pronounced antibiofilm activity against S. aureus, including strong biofilm eradication in several replicates. In contrast, chamomile (Matricaria chamomilla) and sandalwood (Santalum austocaledonicum) oils showed limited or no activity. These findings highlight differences between planktonic and biofilm responses, emphasizing the importance of incorporating biofilm models into antimicrobial evaluation. Overall, Cinnamomum verum and Jasminum officinale oils may serve as complementary antimicrobial agents, warranting further investigation. Full article

Detection of brown spot needle blight (BSNB) disease caused by the fungal pathogen Lecanosticta acicola (Thum.) Syd. has increased significantly at commercial loblolly pine (Pinus taeda L.) plantations across the southeastern United States in recent years. Historically, it has been a serious problem in longleaf pine (Pinus palustris Mill) during the grass stage of seedlings, when the environment is more conducive to fungal infection. However, since 2016, confirmed cases of the disease on loblolly pines have increased in several states, including AL, AR, FL, GA, LA, MS, SC, TN, and TX. We investigated the distribution pattern of confirmed cases of BSNB on loblolly pine between 2016 and 2023, identified site-specific factors, and evaluated the historical standardized precipitation index (SPI) value record over the past four decades. Our results showed that extended periods of above-normal SPI values are associated with BSNB spatial distribution patterns, particularly where the disease has been widely reported in AL, AR, LA, and MS. We observed significant reduction in tree height and dbh in severely infected versus healthy trees at the six study sites evaluated in 2023. Excessive rainfall and prolonged water saturation associated with historical 5-Year SPI values suggest that vulnerable loblolly pine seedlings (depending on genetic family) are more likely to be predisposed to L. acicola infection due to persistent stress from reduced soil nutrient flux and other physiological processes of the host. Understanding the effect of precipitation patterns on cases of BSNB is an important step toward preventing or minimizing the future impact of the disease on commercial plantations in the Southeast. Full article

Woody tissue diseases of avocado (Persea americana Mill. var. Hass) pose a major phytosanitary threat due to their chronic progression, late symptom expression, and severe impact on tree stability and productivity. Although white rot has traditionally been attributed to saprobic basidiomycetes, increasing evidence suggests corticioid fungi may act as facultative pathogens in agricultural systems. This study examined corticioid basidiomycetes associated with white rot in stems and branches of avocado in Michoacán, Mexico. Field surveys revealed consistent symptoms of structural weakening, branch dieback, and wood decay. Fungal isolates obtained from symptomatic tissues and sporomes were characterized morphologically and identified through ITS-based phylogenetic analyses. Representative isolates of Grammothele spp. and Dentocorticium portoricense were evaluated in pathogenicity assays under controlled conditions. All isolates reproduced field symptoms, confirming pathogenicity, though aggressiveness varied. D. portoricense exhibited the highest incidence, severity, and AUDPC values, indicating greater virulence, while Grammothele isolates showed slower, moderate progression. Phylogenetic analyses provided robust support for D. portoricense, whereas Grammothele was resolved at genus level. Integration of field, pathogenicity, and molecular data demonstrates corticioid fungi are not merely secondary saprotrophs but relevant pathogens in avocado white rot. These findings highlight the need to include corticioid fungi in diagnostic, monitoring, and management strategies for trunk and branch diseases. Full article

Pomegranate dieback is a disease whose etiology remains only partially understood. In this study, surveys were carried out in orchards located in the Apulia, Basilicata, and Veneto regions from 2016 to 2020 with the objective to identify pathogens involved in pomegranate dieback. Six fungal species were isolated from symptomatic trees and identified through morphological and molecular analyses. In addition to the known pomegranate pathogens Neofusicoccum parvum, Diaporthe eres and D. foeniculina, new fungal species, including Neopestalotiopsis rosae, Sporothrix stenoceras, and one belonging to the Xenoacremonium genus, were identified. This study represents the first report of their association with pomegranate plants exhibiting dieback symptoms. When artificially inoculated on pomegranate trees, these fungi caused wood browning, proving their pathogenicity. All fungal species exhibited optimal growth in the temperature range 25–30 °C, although D. eres and N. roseae showed a good adaptability in the range 5–10 °C. Since some of the identified pathogens were isolated from the same trees, cross-pairing assays were conducted, revealing that these fungi can coexist within the same ecological niche while maintaining their viability. Given the need for sustainable management options against these co-occurring pathogens, biological control strategies were evaluated. In vitro experiments demonstrated that both Bacillus and Trichoderma biological control agents (BCAs) inhibit the investigated pomegranate pathogens, highlighting their potential inclusion in integrated management strategies targeting these newly identified fungal pathogens. Full article

Hymenoscyphus fraxineus is the causal agent of ash dieback, a devastating disease of European ash (Fraxinus excelsior). Although the pathogen is believed to have originated in East Asia and has been confirmed in Japan, European ash trees cultivated in the Sapporo Experimental Forest of Hokkaido University remain asymptomatic despite the presence of H. fraxineus. In this study, we investigated the early infection behavior of H. fraxineus and associated host defense responses by comparing asymptomatic F. excelsior with the susceptible control species F. angustifolia. Leaflets were inoculated with ascospores, and fungal development as well as host responses were examined microscopically during early infection stages. In addition, we analyzed the accumulation of selected coumarins, which have been proposed as candidate compounds associated with ash dieback tolerance, and assessed their effects on ascospore germination. We found that fungal growth was consistently restricted on F. excelsior at 7 days post inoculation, particularly at the stage of invasion into adjacent epidermal cells. Fraxetin was detected in F. excelsior leaflets but not in F. angustifolia, and fraxetin treatment significantly reduced ascospore germination in vitro. While typical markers of induced resistance were not clearly detected at the examined time points, these results indicate that constitutive chemical traits, including fraxetin accumulation, may contribute to early-stage suppression of H. fraxineus growth in F. excelsior. Together, our findings provide insight into early host–pathogen interactions associated with ash dieback tolerance and highlight the potential role of constitutive defenses during initial infection. Full article

Urban forests are highly valued for the multiple benefits they provide to city dwellers. The strategic provision of ecosystem services by these forests is threatened by climate change, warming conditions being responsible for heat waves and chronic droughts that inflict stress and mortality on trees. A three-year study (2011–2013) conducted at Parco Nord Milano (PNM) (Milano, Italy) assessed the impact of thinning interventions on the dynamics of fungal pathogens in declining forest plots. Symptomatic trees of the genera Alnus, Acer, Fraxinus, Platanus, Quercus and Ulmus, exhibited in thinned subplot pronounced decline/dieback, exhibiting symptoms like microphyllia, leaf yellowing, leaf shedding, sunken cankers, shoot wilting and branch dieback. Comparative analyses between the thinned and unthinned subplots revealed a significantly higher incidence of pathogens in the thinned one. Five species of Botryosphaeriaceae, namely Botryosphaeria dothidea, Diplodia corticola, Diplodia seriata, Dothiorella omnivora and Neofusicoccum parvum, were consistently isolated from tissues of declining hosts. There is evidence that thinning altered plot-level microclimate conditions and microbial equilibrium, favoring the proliferation of latent, pathogenic Botryosphaeriaceae. In fact, during the study period, the presence of N. parvum increased tenfold and that of B. dothidea fivefold in thinned subplot. Conversely, in unthinned subplot, the same pathogenic taxa maintained stable proportions. These results demonstrate that thinning altered ecological balances increasing tree susceptibility to harmful, cosmopolitan botryosphaeriaceous fungi. Our findings challenge assumptions about thinning as a universally beneficial practice, emphasizing the need for silvicultural strategies that take into account host and pathogen ecology and the microclimatic resilience of forest stands. This study emphasizes the importance of adaptive management in urban forestry to mitigate the unintended ecological consequences of climate change. Full article

Hibernation profoundly alters host–pathogen dynamics by suppressing metabolism and immune function, posing unique challenges for infection control. In this study, we examined how genomic variation modulates infection and physiological traits in temperate bats during hibernation. We combined infection screening, haematology, blood biochemistry, and whole-genome sequencing across five vespertilionid species, identifying over 170,000 single nucleotide variants (SNVs) and assessing their associations with 23 health-related variables. Using the phylogenetically informed treeWAS framework, we detected 515 significant SNVs linked to traits including fungal, protozoan and bacterial infections, acid–base balance, and blood cell indices. These SNVs mapped to 137 unique genes, which were enriched for functional domains related to cytoskeletal dynamics, membrane trafficking, and intracellular signalling (e.g., SH3, C2, BAR, semaphorin). Notably, canonical immune effector genes were underrepresented, and several trait-associated SNVs appeared in blocks across multiple scaffolds, pointing to regulatory loci as key modulators of hibernator health. Our findings support the hypothesis that bats rely on infection tolerance rather than resistance during hibernation, with genomic variation in regulatory and signalling pathways shaping their physiological responses to infection under energy-limited conditions. Full article