Search Results (41)

The potential of Trichoderma fungi as biocontrol agents has not yet been fully explored, as there is a large repertoire of inter- and intra-species variation in their phytopathogenic antagonistic effects due to different adaptations of individual Trichoderma strains. In the present study, we investigated the biocontrol efficacy of eight native isolates of Trichoderma spp. against the soilborne phytopathogens Sclerotinia sclerotiorum and Rhizoctonia solani and a representative of the Mucoromycota, Phycomyces blakesleeanus. An in vitro dual culture test showed a complete (100%) inhibition of S. sclerotiorum and P. blakesleeanus by each tested Trichoderma strain and a high (80–100%) inhibition of R. solani. The crude chloroform extracts, whose peptide contents were confirmed by thin-layer chromatography, caused a concentration-dependent reduction in the growth of the target fungi, with inhibition comparable to the effect of the peptaibol standard alamethicin. Despite the differences between fungi from the phyla Basidiomycota, Ascomycota, and Mucoromycota, their inhibition by alamethicin followed the same dose–response dependence. The growth inhibition of P. blakesleeanus induced by Trichoderma extracts was characterized by a significantly increased activity of antioxidative defense enzymes. Both variants of biocontrol agents, the native strains of Trichoderma spp. and their extracts, are efficient in controlling fungal growth and should be considered for the development of new potent bioformulations applicable in agriculture. Full article

Soilborne diseases cause losses of 45–70% in faba bean in Ethiopia. Studies were undertaken to define soilborne pathogens and their complexes in Ethiopia. First, the severity of root rot was assessed in 150 field sites across seven Ethiopian regions. Soil samples were collected, and the DNA of 29 pests and pathogens was quantified using a commercial quantitative PCR (qPCR) soil testing service. There was a very high incidence rate of Macrophomina phaseolina, as well as Pythium clades F and I. The other detected species in order of incidence included Fusarium redolens, Rhizoctonia solani, Aphanomyces euteiches, Phytophthora megasperma, Sclerotinia sclerotiorum and S. minor, and Verticillium dahliae, as well as low levels of Thielaviopsis basicola. Five anastomosis groups (AG) of R. solani, namely AG2.1, AG2.2, AG3, AG4, and AG5, were detected, of which AG2.2 and AG4 were most prevalent. We believe this is the first report of occurrence for Ethiopia of A. euteiches, Ph. megasperma, T. basicola, and the five AGs for R. solani. There were very high incidence rates of the foliar pathogens Botrytis cinerea, B. fabae, Didymella pinodes, and Phoma pinodella and of the nematode Pratylenchus thornei, followed by P. neglectus and P. penetrans. The root rot severity and distribution varied significantly across regions, as well as with soil types, soil pH, and soil drainage. Subsequently, metabarcoding of the soil DNA was undertaken using three primer pairs targeting fungi (ITS2), Fusarium species (TEF1 α), and Oomycetes (ITS1Oo). The ITS2 and TEF1α primers emphasized F. oxysporum as the most abundant soilborne fungal pathogen and highlighted F. ananatum, F. brachygibbosum, F. brevicaudatum, F. clavum, F. flagelliforme, F. keratoplasticum, F. napiforme, F. nelsonii, F. neocosmosporiellum, F. torulosum, and F. vanettenii as first reports of occurrence for Ethiopia. The ITS1Oo primer confirmed Pythium spp. as the most prevalent of all Oomycetes. Full article

Soil-borne fungal pathogens such as Sclerotium spp., Rhizoctonia spp., and Macrophomina spp. pose significant threats to global agriculture, with soybean crops among the most severely affected due to damping-off disease. These pathogens cause substantial yield losses, making their management a critical concern. In this study, we investigated the potential of Bacillus siamensis BCL, a novel Neotropical strain, as an eco-friendly solution for managing Sclerotium, Rhizoctonia, and Macrophomina species. The strain exhibited strong antifungal activity, significantly inhibiting fungal growth in vitro, with the greatest suppression observed against Macrophomina spp., reaching up to 81%. In vivo assays further confirmed the biocontrol potential of B. siamensis. When applied at 10⁶ colony-forming units (CFU)/mL, the strain reduced disease symptoms and improved plant growth parameters—including root length, shoot biomass, and leaf number—compared to untreated, infected controls. The protective effect varied by pathogen, with the most significant recovery in root length observed against Macrophomina spp. (85%) and Sclerotium spp. (78%). In preventive treatments, fermentation extracts of the B. siamensis strain suppressed disease progression, although they did not promote seedling growth. A genomic analysis of B. siamensis BCL revealed genes encoding antimicrobial secondary metabolites, including terpenes, fengycins, and surfactins. These findings highlight B. siamensis BCL as a promising candidate for sustainable crop protection and a valuable resource for developing novel antimicrobial strategies in agriculture. Full article

From 2013 to 2021, 112 binucleate Rhizoctonia spp. (BNR) isolates were obtained from the strawberry, tomato, pepper, bean, apple, cherry, meadow grass, and soil previously cropped with strawberries from 16 locations in Serbia. Morphological and molecular analyses (ITS, LSU rDNA, RPB2, tef-1α, and atp6) confirmed infections caused by four BNR AGs: AG-G on the cherry (globally new host), bean, and tomato; AG-U on meadow grass (globally new host) and apple, AG-A on the strawberry (the most frequently isolated), and AG-F on pepper. ITS sequence analysis revealed 24 haplotypes within the worldwide population of BNR AG-A, with Serbian isolates belonging to nine. The aggressiveness of AG-A (ten isolates), AG-G (three isolates), AG-F (one isolate), and AG-U (two isolates) was tested on seedlings of 14 hosts from Poaceae, Brassicaceae, Solanaceae, Asteraceae, Fabaceae, Cucurbitaceae, Apiaceae, and Chenopodiaceae, and on detached leaf petioles of the strawberry, tomato, sunflower, and bean, as well as on two pea cultivars. Sunflower and sugar beet were the most susceptible, with AG-G being the most aggressive and AG-A the least aggressive. AG-A could not infect cabbage, while at least one isolate of each remaining AG infected all tested hosts. The consistency between seedling and petiole tests highlights the latter as a rapid method for evaluating the pathogenicity and aggressiveness of BNR isolates. Full article

In this study, seed-surface-associated bacteria from fresh fruits of Capsicum spp. were analyzed to explore potential isolates for biocontrol of phytopathogenic fungal strains. A total of 76 bacterial isolates were obtained from three different species of chili pepper (C. annuum L., C. pubescens R. & P., and C. chinense Jacq.), and two isolates were selected via mycelial growth inhibition assays based on their production of volatile organic compounds (VOCs) against six fungal strains. Genomic analysis identified these isolates as Bacillus altitudinis CH05, with a chromosome size of 3,687,823 bp and with 41.25% G+C, and Bacillus tropicus CH13, with a chromosome size of 5,283,706 bp and with 35.24% G+C. Both bacterial strains showed high mycelial growth inhibition capacities against Sclerotium rolfsii, Sclerotinia sp., Rhizoctonia solani, and Alternaria alternata but lower inhibition capacities against Colletotrichum gloesporoides and Fusarium oxysporum. VOC identification was carried out after 24 h of fermentation with 64 VOCs for B. altitudinis CH05 and 53 VOCs for B. tropicus CH13. 2,5-Dimethyl pyrazine and acetoin had the highest relative abundance values in both bacterial strains. Our findings revealed that seed-surface-associated bacteria on Capsicum spp. have the metabolic ability to produce VOCs for biocontrol of fungal strains and have the potential to be used in sustainable agriculture. Full article

This study evaluates the antibacterial and antifungal effects of ethanol extracts from Gnaphalium uliginosum L. derived from freshly harvested plant biomass, including stems, leaves, flowers, and roots. The extract was analyzed using gas chromatography-mass spectrometry (GC-MS) to determine its antimicrobial activity against phytopathogenic bacteria and fungi. Two methods were used in the experiments: agar well diffusion and double serial dilution. Extraction was carried out using the maceration method with different temperature regimes (25 °C, 45 °C, and 75 °C) and the ultrasonic method at various powers (63–352 W) for different durations (5 and 10 min). It was found that the 70% ethanol extract obtained through the ultrasonic experiment at 189 W power for 10 min and at 252 W power for 5 min had the highest antimicrobial activity compared to the maceration method. The most sensitive components of the extracts were the Gram-positive phytopathogenic bacteria Clavibacter michiganensis and the Gram-negative phytopathogenic bacteria Erwinia carotovora spp., with MIC values of 156 μg/mL. Among the fungi, the most sensitive were Rhizoctonia solani and Alternaria solani (MIC values in the range of 78–156 µg/mL). The evaluation of the antimicrobial activity of extracts using the diffusion method established the presence of a growth suppression zone in the case of C. michiganensis (15–17 mm for flowers, leaves, and total biomass), which corresponds to the average level of antimicrobial activity. These findings suggest that G. uliginosum has potential as a source of biologically active compounds for agricultural use, particularly for developing novel biopesticides. Full article

Developing innovative, eco-friendly fungicide alternatives is crucial to mitigate the substantial threat fungal pathogens pose to crop yields. In this study, we assessed the in vitro effectiveness of SiO₂, CuO, and γFe₂O₃ nanoparticles against Rhizoctonia solani. Furthermore, greenhouse experiments were conducted in artificially infested soil to evaluate the in vivo impact of nanoparticles under study. Two application methods were employed: soil drenching with 10 mL per pot at concentrations of 50, 100, and 200 mg L⁻¹, and seedling dipping in nanoparticle suspensions at each concentration combined with soil drench. The combined treatment of 200 mg L⁻¹ γFe₂O₃ or CuO nanoparticles showed the highest in vitro antifungal activity. Conversely, SiO₂ nanoparticles demonstrated the lowest in vitro activity. Notably, the application of 200 mg/L SiO₂ via the dipping and soil drenching methods decreased counts of silicate-solubilizing bacteria and Azospirillum spp. Whereas, application of 100 mg L⁻¹ γFe₂O₃ nanoparticles via soil drenching increased soil bacterial counts, and CuO nanoparticles at 50 mg L⁻¹ through dipping and soil drenching had the highest dehydrogenase value. γFe₂O₃ nanoparticles improved plant photosynthetic pigments, reduced malondialdehyde levels, and minimized membrane leakage in lettuce plants. A root anatomical study showed that 200 mg L⁻¹ CuO nanoparticles induced toxicity, whereas 200 mg L⁻¹ γFe₂O₃ or SiO₂ nanoparticles positively affected root diameter, tissue structure, and various anatomical measurements in lettuce roots. γFe₂O₃ nanoparticles hold promise as a sustainable alternative for managing crop diseases. Full article

Fungal diseases have always been a major problem for cantaloupe crops; however, synthetic fungicides are hazardous to humans and the environment. Consequently, a feasible alternative to fungicides without side effects could be by using bio agents and naturally occurring plants with antibacterial potential. This study has achieved a novel procedure for managing wilt and root rot diseases by potentially using Trichoderma sp. culture filtrates in consortium with plant extract of Calotropis procera, Rhizoctonia solani, Fusarium oxysporum, and Pythium ultimum, which were isolated from infected cantaloupe roots with identified root rot symptoms. The antagonistic activity of four Trichoderma isolates and analysis of antibiotics and filtrate enzymes of the most active Trichoderma isolate were determined as well as phytochemical analysis of C. procera plant extract using HPLC-UV. The obtained results showed that all Trichoderma isolates considerably lowered the radial growth of P. ultimum, R. solani, and F. oxysporum in varying degrees. The scanning electron micrographs illustrate the mycoparasitic nature of Trichoderma sp. on F. oxysporum. The phytochemical analysis of C. procera indicated that phenolic contents were the major compounds found in extracts, such as vanillin (46.79%), chlorogenic acid (30.24%), gallic acid (8.06%), and daidzein (3.45%) but including only a low amount of the flavonoid compounds rutin, naringenin, and hesperetin. The Pot experiment’s findings showed that cantaloupe was best protected against wilting and root rot diseases when it was treated with both Trichoderma sp. culture filtrates (10%) and C. procera extract of (15 mg/mL), both alone and in combination. This study demonstrates that the application of bio agent Trichoderma spp. filtrate with C. procera phenol extract appears useful for controlling wilting and root rot disease in cantaloupe. This innovative approach could be used as an alternative to chemical fungicide for the control of wilting and rot root diseases. Full article

This study analyzed the antifungal potential of 16 bacterial strains isolated from mangrove sediment. Bacterial selection was conducted in a solid medium. This was followed by the production and extraction of metabolites using ethyl acetate to evaluate chitinase production, antifungal activity, and toxicity toward Allium cepa and Tenebrio molitor. Bacterial strains B8, B11, and B13 produced the largest inhibition halos (>30 mm) toward Fusarium solani, Fusarium oxysporum, and Rhizoctonia solani fungi. Strains B1, B3, B6, B8, B11, B13, B14, and B16 produced chitinases. In assays using liquid media, B8 and B13 produced the largest inhibition halos. Exposing the fungal inocula to metabolic extracts of strains B6, B8, B11, B13, B14, B15, and B16 caused micromorphological alterations in the inocula, culminating in the inhibition of R. solani sporulation and spore germination. Toxicity tests using Allium cepa and Tenebrio molitor revealed that the metabolites showed low toxicity. Six of the bacterial strains were molecularly identified to species levels, and a further two to genus level. These included Serratia marcescens (B8), which exhibited activity in all tests. Mangroves provide a useful resource for the isolation of microorganisms for biocontrol. Among the isolates, Serratia marcescens and Bacillus spp. showed the greatest potential to produce metabolites for use as biocontrol agents in agriculture. Full article

Fusarium wilt, caused by the fungus Fusarium oxysporum f. sp. vanillae (Fov), is a disease that results in significant losses in commercial vanilla production. The genera Ceratobasidium (Ceratobasidiaceae) and Tulasnella (Tulasnellaceae), which are often reported as mutualistic symbionts in orchids, belong to the form genus Rhizoctonia, a paraphyletic group of fungi with potential for pathogen biocontrol. We assayed the antagonistic properties of the form genus Rhizoctonia from the roots of neotropical orchids: two Tulasnella spp. isolates (Bv3 and Er1) and one Ceratobasidium sp. (Er19). In a dual culture, we found that form genus Rhizoctonia isolates can generate a biocontrol effect against Fusarium through the mechanisms of antibiosis and competition for space and nutrients. On histological observations, orchid root endophytes also demonstrated potential for mutualistic symbiosis development by establishing themselves on the surface and within the root tissue of Vanilla planifolia accessions multiplied in vitro (NSF021 and NSF092). However, in plant assays, the form genus Rhizoctonia isolates did not reduce symptom expression or disease development due to infection by Fov in the host. These results contribute to the knowledge of the interactions between tropical orchids and their microbiota and demonstrate the need for multidisciplinary studies for the implementation of integrated management strategies for Fusarium disease in commercial systems. Full article

Bacillus spp. is one kind of the important representative biocontrol agents against plant diseases and promoting plant growth. In this study, the whole genomic sequence of bacterial strain HMB26553 was obtained. A phylogenetic tree based on the genome and ANI (average nucleotide identity), as well as dDDH (digital DNA–DNA hybridization), was constructed, and strain HMB26553 was identified as Bacillus velezensis. Fourteen biosynthetic gene clusters responsible for secondary metabolite were predicted via anti-SMASH, and six secondary metabolites were identified by UHPLC-QTOF-MS/MS (ultra-high-performance liquid chromatography coupled to quadrupole-time-of-flight tandem mass spectrometry). When the phytopathogen Rhizoctonia solani was treated with B. velezensis HMB26553, the mycelial structure changed, ROS (reactive oxygen species) accumulated, and the mitochondrial membrane potential decreased. Characteristics of strain HMB26553 were predicted and confirmed by genomic information and experiments, such as producing IAA, siderophore, extracellular enzymes and biofilm, as well as moving and promoting cotton growth. All these results suggested the mechanisms by which B. velezensis HMB26553 inhibits pathogen growth and promotes cotton growth, which likely provided the potential biocontrol agent to control cotton Rhizoctonia damping-off. Full article

The cucumber (Cucumis sativa L.) is often subjected to several fungal diseases. Rhizoctonia solani-induced cucumber damping-off and root rot are the most common diseases reported from the commercial greenhouses of the eastern area of Saudi Arabia. The objective of the current study is to explore the antagonistic activity of four Trichoderma species against R. solani in vitro and in vivo. Ten R. solani isolates (eight belonging to AG-4 and two belonging to AG-A and AG2-1) were studied. AG4 isolates were pathogenic to cucumber plants, while AG-A and AG2-1 isolates were non-pathogenic. Seven isolates of Trichoderma spp., named T. hamatum KSATR8, T. harzianum (KSATR9 and KSATR10), T. asperellum (KSATR11, KSATC, and KSAT1E), and T. longibrachiatum KSATS were isolated, and the identities of both R. solani and Trichoderma isolates were confirmed based on the phylogenetic analysis of the DNA sequence of the ITS region. The dual culture findings indicated that T. asperellum KSATC and KSAT1E exhibited the most significant inhibitory activities against R. solani, with values of 79.33 and 70.89%, respectively. Scanning electron microscope (SEM) images showed a considerable degradation in the cell wall and collapsing of R. solani hyphae by all Trichoderma species. Under greenhouse conditions, the application of T. asperellum KSATC and KSAT1E at concentrations of 2 × 10⁸ conidia/mL revealed a reduction in root rot and damping-off incidence percentages with values that did not reveal a significant (p < 0.05) difference from those of Rizolex-T fungicide. Nevertheless, the efficacy of the fungicide attained 86.67%, being higher than that of T. asperellum KSATC, which reached 80%. Trichoderma asperellum KSATC and KSAT1E were the greatest in increasing peroxidase, catalase, and chitinase enzymes activities in cucumber plants. Conversely, a significant (p < 0.05) elevation in polyphenol oxidase enzyme (0.762 and 0.97 U/g FW) and total phenol content (0.55 and 0.62 mg/g FW) was recorded in cucumber plants treated with T. harzianum KSATR9 and KSATR10, respectively. The statistical analysis results displayed no considerable variations among cucumber plants regarding total chlorophyll content as a response to treatments with Trichoderma species and fungicides. Therefore, we endorse using T. asperellum KSATC and KSAT1E as an alternative to fungicides to manage root rot and damping-off in cucumbers. Full article

The capability of endophytic Trichoderma spp. to reduce sheath blight disease in rice caused by Rhizoctonia solani was assessed under the growth conditions established by practices of the System of Rice Intensification (SRI), compared to those of standard irrigated rice cultivation. Rice seeds inoculated with a local isolate of the fungus Trichoderma asperellum SL2 were grown under respective SRI and conventional conditions with the inoculated or uninoculated plants and then infected with the pathogen R. solani. It was seen that inoculation with this strain of Trichoderma protected rice plants against R. solani infection while enhancing plant growth, photosynthetic rate, and stomatal conductance. The biocontrol effectiveness of inoculation with a particular strain of Trichoderma was significantly greater under SRI management compared to conventional cultivation. This is the first report on how a crop management system, in this case, SRI, can influence the biocontrol effectiveness of Trichoderma spp. Full article

Hypericum species and especially H. perforatum L. are well known for their therapeutic applications. The present study assessed the essential oil (EO) composition, and antifungal and aphid suppression activity of seven Bulgarian Hypericum species. The EOs were analyzed by GC–MS–FID. Two experiments were conducted. In the first experiment, H. perforatum, H. maculatum, and H. hirsutum were used. Additionally, the EO composition of H. perforatum extracted via hydrodistillation (ClevA) and via commercial steam distillation (Com) were compared. The second experiment compared the EOs of H. perforatum, H. cerastoides, H. rumeliacum, H. montbretii, and H. calycinum (flowers and leaves) extracted via hydrodistillation and collected with n-hexane. Overall, the EO constituents belonged to four classes, namely alkanes, monoterpenes, sesquiterpenes, and fatty acids. The main class for compounds in H. maculatum and H. perforatum (section Hypericum) were sesquiterpenes for both experiments except for H. perforatum (Com). Hypericum montbretii (section Drosocarpium) EO had monoterpenes (38.09%) and sesquiterpenes (37.09%) as major groups, while H. hirsutum EO (section Taeniocarpium) contained predominately alkanes (67.19%). Hypericum hirsutum EO contained cedrol (5.04%), found for the first time in Hypericum species. Fatty acids were the main compounds in H. cerastoides (section Campylopus), while monoterpenes were the most abundant class in H. rumeliacum and H. calycinum EOs. α-Pinene and germacrene D were the major EO constituents of all analyzed Hypericum species except for H. hirsutum and H. cerastoides. Hypericum perforatum EO (Com) had significant repellent and insecticidal activity against two aphid species, Rhopalosiphum padi (Bird Cherry-oat aphid) and Sitobion avenae (English grain aphid) at concentrations of 0%, 1%, 2.5%, 3.5%, 4.5%, and 5%. The tested EOs did not show significant activity against selected economically important agricultural fungal pathogens Fusarium spp., Botrytis cinerea, Colletotrichum spp., Rhizoctonia solani, and Aspergillus sp. The EO of the Hypericum species found in the Bulgarian flora could be utilized for the development of new biopesticides for aphid control. Full article

Trichoderma spp. produce multiple bioactive volatile organic compounds (VOCs). While the bioactivity of VOCs from different Trichoderma species is well documented, information on intraspecific variation is limited. The fungistatic activity of VOCs emitted by 59 Trichoderma sp. “atroviride B” isolates against the pathogen Rhizoctonia solani was investigated. Eight isolates representing the two extremes of bioactivity against R. solani were also assessed against Alternaria radicina, Fusarium oxysporum f. sp. lycopersici and Sclerotinia sclerotiorum. VOCs profiles of these eight isolates were analyzed using gas chromatography–mass spectrometry (GC-MS) to identify a correlation between specific VOCs and bioactivity, and 11 VOCs were evaluated for bioactivity against the pathogens. Bioactivity against R. solani varied among the fifty-nine isolates, with five being strongly antagonistic. All eight selected isolates inhibited the growth of all four pathogens, with bioactivity being lowest against F. oxysporum f. sp. lycopersici. In total, 32 VOCs were detected, with individual isolates producing between 19 and 28 VOCs. There was a significant direct correlation between VOC number/quantity and bioactivity against R. solani. 6-pentyl-α-pyrone was the most abundant VOC produced, but 15 other VOCs were also correlated with bioactivity. All 11 VOCs tested inhibited R. solani growth, some by >50%. Some of the VOCs also inhibited the growth of the other pathogens by >50%. This study demonstrates significant intraspecific differences in VOC profiles and fungistatic activity supporting the existence of biological diversity within Trichoderma isolates from the same species, a factor in many cases ignored during the development of biological control agents. Full article