Search Results (129)

Antagonistic endophytes are one of the most effective methods for crop disease biocontrol. This study reports on a convenient method termed ‘Targeted Identification of Disease-resistant Endophytes’ (TIDRE), which combines the isolation of culturable endophytic isolates from plant tissues with the screening of phytopathogen-antagonistic microbes. In addition to the direct discovery of endophytes with resistance to specific phytopathogens, the TIDRE method also facilitates the screening of endophyte-based disease-resistant crop lines. Using the TIDRE protocol, we successfully isolated endophytic bacterial strains with antagonistic activity against the pathogenic fungus Fusarium oxysporum from a traditional Chinese medicinal herb Panax notoginseng. These candidate bacteria included three Bacillus subtilis strains, a Stenotrophomonas maltophilia strain, a Pantoea brenneri strain, and a Bacillus sp. strain. Furthermore, we identified grapevine cutting clones with strong resistance to three fungal pathogens: Botrytis cinerea, F. solani, and F. graminearum, by using the TIDRE protocol. The endophytic bacterial strains (Bacillus) isolated from the highly resistant grapevine clones confer significant antagonistic effects against the fungal pathogens. Compared to existing methods, TIDRE offers superior speed and efficiency, and great potential for advancing the development and utilization of beneficial endophytic resources in sustainable agriculture. Full article

To explore superior biocontrol resources for Rhododendron brown spot disease, five antagonistic fungal strains exhibiting significant inhibitory activity against the pathogen responsible for RBS were isolated from healthy Rhododendron hybridum Ker Gawl leaves. Among them, strain DJW5-2-1 demonstrated the highest inhibition rate, reaching 63.88% against the pathogenic fungus. Based on morphological characteristics and multigene phylogenetic analysis (ITS, β-tubulin, and tef1-α), DJW5-2-1 was identified as Diaporthe phoenicicola (Traverso & Spessa) Udayanga, Crous & K.D. Hyde. Dual culture assays further confirmed its broad-spectrum antifungal activity, with inhibition rates ranging from 39.15% to 72.54% against various phytopathogenic fungi. Biochemical analyses revealed that DJW5-2-1 secretes multiple extracellular enzymes and exhibits plant growth-promoting traits. In both in vitro and potted plant efficacy assays, the biocontrol efficacy of strain DJW5-2-1 against RBS was 49.67% and 50.61%, respectively, indicating that strain DJW5-2-1 exhibits a certain level of control efficacy against RBS. Through pot experiments, we found that strain DJW5-2-1 could promote the growth of rhododendron seedlings and significantly increase growth indicators. Among these indicators, the growth-promoting rates of plant height and stem diameter were 15.27% and 41.27%, respectively. Moreover, DJW5-2-1 contributed to improved host resistance by elevating the activities of key defense-related enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and polyphenol oxidase (PPO). Taken together, these findings suggest that strain DJW5-2-1 represents a promising microbial agent for the integrated control of RBS and the development of fungal-based biofertilizers. Further investigation is warranted to assess its performance under field conditions and elucidate its underlying mechanisms of action. Full article

Fusaric acid (FSA) is a mycotoxin produced by pathogenic Fusarium species that inhibits the growth of various beneficial microbes. In this study, we investigated the molecular mechanisms by which Trichoderma harzianum NJAU4742 (Th), a beneficial fungus, responds to FSA-induced stress. Here, by combining a transcriptome analysis, a gene knockout, and physiological data measurements, our study investigated the molecular mechanisms underlying the response of Trichoderma harzianum NJAU4742 (Th) to FSA stress. The results showed that FSA can induce severe oxidative stress in Th, and an aldehyde dehydrogenase (Thaldh3) in Th plays a critical role in alleviating FSA stress. Deleting Thaldh3 significantly decreased the γ-aminobutyrate (GABA) content, causing more severe oxidative damage in Th. Furthermore, we also provide evidence demonstrating that Thaldh3 alleviates FSA stress by enhancing the activities of key enzymes involved in the tricarboxylic acid cycle and ATP content. A pot experiment showed that an enhanced tolerance to FSA increased the Th biomass, strengthening its antagonistic capacity against pathogens and reducing the disease index in tomatoes. In conclusion, these observations provide new insight into the role of beneficial microbes in promoting plant health. Full article

The major objective was to investigate the protective capabilities of endophytic bacterial strains isolated from a number of medicinal plant species towards Aspergillus spp. secured from the internal tissues of fungi-infected peanuts. Among 32 fungal isolates surveyed for mycotoxin production in various culture media (PDA, RBCA, YES, CA), 10 isolates qualitatively producing AFB₁, besides 10 OTA-producers, were assayed by HPLC for quantitative toxin production. Aspergillus spp. isolate Be 13 produced an extraordinary quantity of 1859.18 μg mL⁻¹ AFB₁, against the lowest toxin level of 280.40 μg mL⁻¹ produced by the fungus isolate IS 4. The estimated amounts of OTA were considerably lower and fell in the range 0.88–6.00 μg mL⁻¹; isolate Sa 1 was superior, while isolate Be 7 seemed inferior. Based on ITS gene sequencing, the highly toxigenic Aspergillus spp. isolates Be 13 and Sa 1 matched the description of A. novoparasiticus and A. ochraceus, respectively, ochraceus, respectively, which are present in GenBank with identity exceeding 99%. According to 16S rRNA gene sequencing, these antagonists labeled Ar6, Ma27 and So34 showed the typical characteristics of Pseudomonas aeruginosa, Bacillus subtilis and Bacillus velezensis, respectively, with similarity percentages of 99–100. The plant growth-promoting activity measurements of the identified endophytes indicated the production of 16.96–80.00 μg/100 mL culture medium of IAA. Phosphate-solubilizing capacity varied among endophytes from 2.50 to 21.38 μg/100 mL. The polysaccharide production pool of bacterial strains ranged between 2.74 and 6.57 mg mL⁻¹. P. aeruginosa Ar6 and B. velezensis successfully produced HCN, but B. subtilis failed. The in vitro mycotoxin biodegradation potential of tested bacterial endophytes indicated the superiority of B. velezensis in degrading both mycotoxins (AFB₁-OTA) with average percentage of 88.7; B. subtilis ranked thereafter (85.6%). The 30-day old peanut (cv. Giza 6) seedlings grown in gnotobiotic system severely injured due to infection with AFB₁/OTA-producing fungi, an effect expressed in significant reductions in shoot and root growth traits. Simultaneous treatment with the endophytic antagonists greatly diminished the harmful impact of the pathogens; B. velezensis was the pioneer, not P. aeruginosa Ar6. In conclusion, these findings proved that several endophytic bacterial species have the potential as alternative tools to chemical fungicides for protecting agricultural commodities against mycotoxin-producing fungi. Full article

Inonotus hispidus growing on Morus alba is traditionally regarded as the authentic source of the medicinal fungus. However, this species is also found on other host trees, such as Ulmus macrocarpa and Acer truncatum; yet, whether these strains share comparable genomic and functional traits with Morus-derived strains remains unknown. Here, we performed whole-genome sequencing of a strain isolated from U. macrocarpa (UMI) using Illumina and PacBio platforms and conducted comparative genomic analysis with strains from M. alba (MAI) and A. truncatum (AMI). Antagonistic interactions were also evaluated via dual-culture confrontation assays. The UMI genome was 36.44 Mb in size, comprising 9097 predicted genes, of which 6991 and 1672 were annotated in the KEGG and COG databases, respectively. SNP analysis revealed 623,498 and 335,343 variants in AMI and MAI, with AMI showing greater genomic variation. Core–pan genome analysis identified 2651 core genes and 1046, 1424, and 1217 strain-specific genes in UMI, AMI, and MAI, respectively. Phenotypic assays demonstrated distinct mycelial growth dynamics and antagonistic behaviors, which likely reflect host-related environmental adaptation. Overall, I. hispidus strains from non-Morus hosts exhibit unique genomic and phenotypic features, providing a valuable basis for resource evaluation, artificial domestication, and the medicinal development of wild Sanghuang strains beyond traditional sources. Full article

Monilinia spp., which causes brown rot, is one of the most damaging pathogens in stone fruits. Researchers are exploring epiphytic and endophytic microorganisms with the potential to suppress pathogens, control pathogenic microorganisms, and/or promote plant growth. In this study, microorganisms with antagonistic activity against three Monilinia species were isolated from plum orchard soil and plum fruits. Antagonism tests in vitro showed strong antagonistic properties of six strains of bacteria and two yeast-like fungi against M. fructigena, M. fructicola, and M. laxa, with growth inhibition from 45.5 to 84.6%. The antagonists were identified and characterized at the genetic level using whole genome sequencing (WGS). Genes involved in antibiotic resistance, virulence, secondary metabolite synthesis, and plant growth promotion were identified and characterized through genome mapping, gene prediction, and annotation. None of the microorganisms studied were predicted to be pathogenic to humans. The results of this study indicate that the bacteria Bacillus pumilus, B. velezensis, two strains of Lysinibacillus agricola, Pseudomonas chlororaphis isolated from stone fruit orchard soil, and the yeast-like fungus Aureobasidium pullulans, isolated from plums, are promising candidates for the biological control of Monilinia spp. Full article

This study aimed to investigate the biocontrol activity of rhizosphere isolates against late blight disease of tomatoes caused by the fungus Phytophthora infestans. A total of 30 rhizospheric bacterial isolates were evaluated for their antagonistic activity against P. infestans in vitro and in vivo. The results demonstrated that among the 30 isolates tested, six (RS65, RP6, RS47, RS46, RP2, and RS61) exhibited a highly significant inhibitory effect (p < 0.001) on the mycelial growth of P. infestans in vitro, with the inhibition rate exceeding 67%. Among the isolates, RS65 exhibited the highest inhibition rate at 78.48%. For antagonistic mechanisms, the results demonstrated that the six isolates exhibited significant enzymatic activity, including proteolytic, lipolytic, and chitinolytic activity, as well as the production of HCN, cellulase, and pectinase. Isolate RS65, which showed the highest inhibition rate, was further evaluated under greenhouse conditions. This investigation revealed significant differences in the severity of late blight between the control and the RS65 treatment. The control showed a severity level of 31.26%, whereas the RS65 treatment achieved the lowest severity of 16.54%. Molecular identification results indicated that the RS65 isolate (accession numbers PV208381) is a Bacillus genus with 99% proximity to Bacillus velezensis. This finding suggests that the Bacillus RS65 treatment could provide effective protection against P. infestans infection in tomato plants. These findings highlight the potential of Bacillus RS65 as a biocontrol agent in integrated disease management for tomato late blight. Full article

Nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) play crucial roles in the development and pathogenicity of the entomopathogenic fungus Beauveria bassiana. However, they are among the few biosynthetic gene clusters with unknown functions in B. bassiana. To investigate the role of the hybrid PKS–NRPS synthetase gene BBA_09856 in B. bassiana, we constructed a mutant strain, ∆BBA09856-WT, by deleting the BBA_09856 gene through Agrobacterium-mediated transformation. We then analyzed the biological characteristics of the mutant strain and the virulence of the mutant strain toward Ostrinia furnacalis larvae, as well as its antagonistic effects against the phytopathogen Botrytis cinerea. We found that the average growth rate of the three mutant strains, ∆BBA09856-WT, was significantly higher compared to the wild-type (WT) strain on the 15th day of culture on potato dextrose agar (PDA) plates (7.01 cm vs. 6.30 cm, p < 0.01). Additionally, the average spore production(3.16 × 10⁷/cm² vs. 9.95 × 10⁶/cm², p < 0.001) and germination rate (82.50% vs. 54.72%, 12 h, p < 0.001) were significantly different between the three mutant strains, ∆BBA09856-WT, and the WT strain. The average survival rates of O. furnacalis infected with the WT strain and the three mutant strains, ∆BBA09856-WT, after 8 days were 61.66%, and 30.00%, respectively, indicating that the pathogenicity of the tested mutant strains was significantly greater than that of the WT strain. The results of the dual culture test indicated that the inhibitory rates of the WT and ∆BBA09856-WT strains against B. cinerea were 40.25% and 47.65%, respectively (p < 0.001). Similarly, in the dual culture test, the WT strain reduced the growth of B. cinerea by 9.90%, while the ∆BBA09856-WT exhibited a significantly greater inhibition rate of 28.29% (p < 0.05). The diameters of disease spots, measured 6 d after inoculation with B. cinerea in the tomato treatment groups, revealed significant differences in endophytic colonization between the WT and ∆BBA09856-WT strains in the WT+Bc and ∆BBA09856-WT+Bc treatment groups (15.26 mm vs. 12.16 mm, p < 0.01). Notably, ∆BBA09856-WT exhibited enhanced virulence toward O. furnacalis larvae and increased antagonistic activity against B. cinerea. Our results indicate that the gene BBA_09856 may have a negative correlation with the development and virulence of B. bassiana toward the insect pest O. furnacalis larvae, as well as its antagonism against B. cinerea. These findings suggest that molecular techniques, such as gene editing, could be employed to develop superior strains of B. bassiana for the biological control of plant diseases and insect pests. Full article

The substrate for button mushroom (Agaricus bisporus) cultivation includes a highly complex microbiome. The aim of the study was to evaluate ecological interactions (synergistic, antagonistic, or additive) between a commercial population of the entomopathogenic nematode Steinernema feltiae (EPN) and beneficial microorganisms, bacterium Bacillus amyloliquefaciens B-241 (BA) or actinobacterium Streptomyces flavovirens A06 (SF). Their relationships were evaluated in efficacy against the pathogenic fungus Trichoderma aggressivum and the fungus gnat Lycoriella ingenua. Moreover, their impact on mushroom yield was estimated. The synergy factor was calculated as the ratio of observed to expected values regarding their efficacy against T. aggressivum/L. ingenua and influence on mushroom production. Additive relationships in efficacy against T. aggressivum were observed between EPN and BA or SF. As for the impact on yield, synergistic interactions were indicated between each beneficial microorganism and EPN. Considering suppression of L. ingenua, a mild antagonistic reaction between EPN and each beneficial microorganism was observed in plots without T. aggressivum and additive in plots inoculated with the pathogenic fungus, although high efficacy was achieved in all combinations (>80%). Tested native strains of both beneficial microorganisms could be combined with the commercial EPN strain for successful biological pest and disease control in mushroom production. Full article

Olive trees are a cornerstone of Mediterranean agriculture but face significant threats from diseases such as Verticillium wilt and olive anthracnose. These diseases, caused by Verticillium dahliae and Colletotrichum spp., respectively, result in significant economic losses and degrade olive oil quality. While traditional chemical treatments present environmental risk, sustainable alternatives such as biological control agents (BCAs) are gaining attention. Epicoccum nigrum, an antagonistic fungus, has shown potential as a BCA due to its production of antimicrobial secondary metabolites. This study aimed to observe whether E. nigrum has an antagonistic ability against V. dahliae and C. acutatum, and to elucidate the metabolic interactions between these fungi using NMR-based metabolomics. E. nigrum showed inhibitory effects on the growth of C. acutatum and V. dahlia of 44.97% and 38.73% respectively. Metabolomic profiling revealed distinct biochemical responses in E. nigrum, V. dahliae, and C. acutatum under mono- and dual-culture. Multivariate statistical analysis highlighted the metabolic shifts in mycelia and identified the primary metabolites, such as glutamine, 4-aminobutyrate, and phenylalanine that are involved in adaption for survival in stress conditions such as the presence of a competitor. The results could be important for a better understanding of the primary fungal metabolism, which is still poorly characterized. Further investigation is needed, but these results suggest that E. nigrum could serve as a BCA, offering a more sustainable approach to managing olive diseases. Full article

Using Bacillus species as bioagents for environmentally sustainable and economically viable plant disease management is a viable strategy. Thus, it is important to promote their use in agriculture. In this study, two Bacillus species were isolated from the rhizosphere of tomato plants, while three fungal species were isolated from samples of tomato plants that were infected with damping-off disease. The Bacillus strains were tested in vitro for their antagonistic activity against fungal species using a dual culture technique. In a greenhouse experiment, the effectiveness of applying antagonistic bacteria with soilborne fungal disease on induced damping-off of tomato (cv. Super Strain B) plants, their physiological attributes, antioxidant enzymes, mineral content, and yield under greenhouse conditions during the 2022 and 2023 seasons were determined. The fungal isolates were identified as Fusarium oxysporum KT224063, Pythium debaryanum OP823136, and Rhizoctonia solani OP823124, while the Bacillus isolates were identified as B. subtilis OP823140 and B. amyloliquefaciens OP823147 on the basis of the rRNA gene sequences. The dual culture test revealed that B. subtilis outperformed B. amyloliquefaciens in resistance to R. solani and F. oxysporum, which were recorded as 28.33 and 33.00 mm, respectivley. In contrast, B. amyloliquefaciens caused the highest antagonistic effect against tested P. debaryanum fungus. Additionally, in a greenhouse experiment, tomato plants treated with each of these antagonistic Bacillus strains significantly suppressed fungal disease, displayed improved plant growth parameters, had an increased content of photosynthetic pigments, antioxidants enzymes, and total phenols, and an increased macronutrient content and yield during the two growing seasons. In conclusion, effective applications of B. subtilis and B. amyloliquefaciens had the potential to mitigate damping-off disease, which is caused by F. oxysporum, P. debaryanum, and R. solani in tomato plants, while simultaneously promoting growth dynamics. Full article

This study characterized an endophytic fungus, DJE2023, isolated from healthy banana sucker of the cultivar (cv.) Dajiao. Its potential as a biocontrol agent against banana Fusarium wilt was assessed, aiming to provide a novel candidate strain for the biological control of the devastating disease. The fungus was isolated using standard plant tissue separation techniques and fungal culture methods, followed by identification through morphological comparisons, multi-gene phylogenetic analyses, and molecular detection targeting Fusarium oxysporum f. sp. cubense (Foc) race 1 and race 4. Furthermore, assessments of its characteristics and antagonistic effects were conducted through pathogenicity tests, biological trait investigations, and dual-culture experiments. The results confirmed isolate DJE2023 to be a member of the Fusarium oxysporum species complex but distinct from Foc race 1 or race 4, exhibiting no pathogenicity to banana plantlets of cv. Fenza No.1 or tomato seedlings cv. money maker. Only minute and brown necrotic spots were observed at the rhizomes of banana plantlets of ‘Dajiao’ and ‘Baxijiao’ upon inoculation, contrasting markedly with the extensive necrosis induced by Foc tropical race 4 strain XJZ2 at those of banana cv Baxijiao. Notably, co-inoculation with DJE2023 and XJZ2 revealed a significantly reduced disease severity compared to inoculation with XJZ2 alone. An in vitro plate confrontation assay showed no significant antagonistic effects against Foc, indicating a suppressive effect rather than direct antagonism of DJE2023. Research on the biological characteristics of DJE2023 indicated lactose as the optimal carbon source for its growth, while maltose favored sporulation. The optimal growth temperature for this strain is 28 °C, and its spores can germinate effectively within the range of 25–45 °C and pH 4–10, demonstrating a strong alkali tolerance. Collectively, our findings suggest that DJE2023 exhibits weak or non-pathogenic properties and lacks direct antagonism against Foc, yet imparts a degree of resistance against banana Fusarium wilt. The detailed information provides valuable insight into the potential role of DJE2023 in integrated banana disease control, presenting a promising candidate for biocontrol against banana Fusarium wilt. Full article

Wheat (Triticum aestivum L.) is one of the most agriculturally and economically important crops in the world. Wheat fungal diseases are becoming more severe and frequent due to global climate change, threatening wheat yields and security. While fungal diseases such as fusarium head blight, stripe rust, and powdery mildew have been extensively studied, the newly emerged fungal pathogens in wheat are still under-researched. In May 2023, black mold symptoms were observed on wheat spikes in Xinxiang City, Henan Province, China. However, the causal agent of this disease was not known. We employed a combination of morphological examination and molecular techniques to identify the pathogen. The internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (tef1), and actin (act) genes of the fungus were partially sequenced (accession no. OR186209, PQ271633 and PQ271632) and showed 99.59–100% identity with the previously reported Cladosporium cladosporioides, which affects wheat, pokeweed, and black-eyed pea. The pathogenicity of this fungus was confirmed by fulfilling Koch’s postulates. Through a rigorous screening process, we found Simplicillium aogashimaense, Trichothecium roseum, and Bacillus velezensis as effective biocontrol agents, with B. velezensis demonstrating the most potent antagonistic activity against the Cladosporium mold. This discovery showed the potential of B. velezensis as a biocontrol agent for wheat disease management. The findings underscore the importance of the present study in advancing the control of this disease. Full article

Fungal trunk disease (FTD) poses a significant threat to hazelnut (Corylus avellana L.) production worldwide. In Chile, the fungus Diplodia mutila, from the Botryosphaeriaceae family, has been frequently identified causing this disease in the Maule and Ñuble Regions. However, control measures for D. mutila remain limited. This research aimed to evaluate the effectiveness of chemical and biological fungicides against D. mutila under in vitro, controlled pot experiment, and field conditions. An in vitro screening of 30 fungicides was conducted. The effectiveness was assessed by measuring the length of vascular lesions in hazelnut branches inoculated with D. mutila mycelium disks under controlled and field conditions. Field trials were conducted in a hazelnut orchard in Ñiquén, Ñuble Region, Chile. The results showed that three biological and five chemical fungicides were selected in vitro with >31% inhibition after 14 days. In pot experiments, all fungicides reduced necrotic lesions on branches by 32% to 61%. In field experiments, the most effective systemic fungicides were fluopyram/tebuconazole, fluxapyroxad/pyraclostrobin, and tebuconazole, while the effectiveness of antagonists Pseudomonas protegens ChC7 and Bacillus subtilis QST713 varied with seasonal temperatures. Effective conventional and biological fungicides against D. mutila could be integrated into disease management programs to protect hazelnut wounds from infections. Full article

In this study, antagonistic endophytic fungi were isolated from postharvest chestnut fruits; endophytic antagonistic fungi and their combination of inhibitory effects on the fungal pathogen Neofusicoccum parvum were evaluated. A total of 612 endophytic fungi were isolated from 300 healthy chestnut kernels, and 6 strains out of them including NS-3, NS-11, NS-38, NS-43, NS-56, and NS-58 were confirmed as antagonistic endophytic fungi against Neofusicoccum parvum; these were separately identified as Penicillium chermesinum, Penicillium italicum, Penicillium decaturense, Penicillium oxalicum, Talarmyces siamensis, and Penicillium guanacastense. Some mixed antagonistic endophytic fungi, such as NS-3-38, NS-11-38, NS-43-56, and NS-56-58-38, exhibited a much stronger antifungal activity against N. parvum than that applied individually. Among them, the mixture of NS-3-38 showed the highest antifungal activity, and the inhibition rate was up to 86.67%. The fermentation broth of NS-3, NS-38, and their combinations exhibited an obvious antifungal activity against N. parvum, and the ethyl acetate phase extract of NS-3-38 had the strongest antifungal activity, for which the inhibitory rate was up to 90.19%. The NS-3-38 fermentation broth combined with a chitosan coating significantly reduced N. parvum incidence in chestnuts from 100% to 19%. Furthermore, the fruit decay and weight loss of chestnuts during storage were significantly decreased by the NS-3-38 fermentation broth mixture along with a chitosan coating. Therefore, a mixture of P. chermesinum and P. decaturense could be used as a potential complex biocontrol agent to control postharvest fruit decay in chestnuts. Full article