Fusarium Wilt Of Tomato Research Articles

Antifungal activity of citral against Fusarium wilt in tomatoes and induction of the upregulation of glucanase, chitinase, and thaumatin-like protein plant defense genes

Fusarium wilt of tomatoes, caused by the soil-borne fungus Fusarium oxysporum f. sp lycopersici (FOL), is one of the devastating diseases of tomatoes, causing substantial economic losses worldwide. It is primarily controlled with chemical fungicides. The present study assessed the antifungal activity of citral against FOL under greenhouse conditions and investigated its effects on three plant defense genes: glucanase, chitinase, and thaumatin-like protein (TLP) using Real-time- quantitative PCR (RT-qPCR). Greenhouse experiments demonstrated that citral oil at 1024 and 512 µg/mL significantly reduced wilt severity from 61.7 % to 28.3 and 33.3 %, respectively. RT-qPCR results revealed that citral upregulates the expression of the three defense genes to varying extents, highlighting their role in resistance induction in tomatoes against FOL. Chitinase showed the highest differential expression with a 9.54-fold increase at 12 hours post-treatment (hpt), followed by TLP with a 6.96-fold increase at 12hpt, and glucanase with a 3.68-fold increase at 24hpt. These findings suggest citral is a promising biocontrol agent against fusarium wilt in tomatoes. However, field trials are recommended to validate these results under open field conditions.

Green synthesis of silver nanoparticles for antifungal activity against tomato fusarium wilt caused by Fusariumoxysporum

Fusarium wilt caused by Fusarium oxysporum f. sp. radicis-lycopersici is one of the most important diseases in tomatoes, resulting in severe yield loss and mycotoxin infection in food and feed. The management of Fusarium wilt is based heavily on chemical fungicides, but these chemicals have many environmental concerns. Silver nanoparticles (AgNPs) are gaining importance as emerging resistance-free alternatives of chemical fungicides. In this study, AgNPs were synthesized using the aqueous leaf extract of Viola odorata as a green approach. The antifungal activity of these biosynthesised AgNPs was evaluated in vitro against F. oxysporum using the agar well diffusion method. AgNPs were also evaluated against tomato Fusarium wilt diseases using the foliar spray method in the greenhouse. The characterization of AgNPs revealed that AgNPs were of spherical shape, crystalline in nature, and had an average size of 18 nm. In the antifungal assay, 60 mg/l AgNPs strongly inhibited the growth of F. oxysporum with a growth zone of 18 ± 0.89 mm compared to fungicide (23 ± 1.20 mm) and AgNO3 (52 ± 2.33 mm). Similarly, 60 mg/l of AgNPs when sprayed on tomato plants in the greenhouse showed a survival rate of about 80% with no observable phytotoxic effect. This study provides a first baseline to control Fusarium wilt in tomato using biosynthesised AgNPs without affecting the health of crops.

Novel Fungicide from Waste Oil Palm Fruit Bunch for Sustainable Management of Tomato Wilt Disease Caused by Fusarium oxysporum - experimental and in silico studies

Tomato wilt, a widespread and persistent disease caused by the fungus Fusarium oxysporum, can be effectively controlled through biological approaches, promoting ecosystem sustainability and enhancing agricultural productivity and quality. This study explored the use of empty oil palm fruit bunch (EOPFB) waste as a natural fungicide to control tomato Fusarium wilt disease through in vitro, pilot scale, and molecular docking experiments. EOPFB aqueous extract showed the highest mycelium growth inhibition of 68.3 %, with the commercial fungicide Mancozeb exhibiting a moderate 42.30 % inhibition, and sterile distilled water having a negligible effect of 0.24 %. The inhibition rate varied with concentration, peaking at 72.63 % at 0.15 g/mL and dropping to 54.80 % at 0.01 g/mL. In terms of wilt disease incidence and severity, EOPFB performed best, recording the lowest incidence of 47.20 % and severity of 15.58 %. Mancozeb followed closely, with an incidence of 46.30 % and severity of 26.23 %. Sterile distilled water, on the other hand, showed the highest incidence of 76.28 % and severity of 56.17 %. Molecular docking simulations corroborated the experimental results, validating the potency of EOPFB as an inhibitor of trypsin from F. oxysporum, and identifying 2-amino-5,6-dimethyl-3 H-pyrimidine-4-one as the primary active compound responsible for the fungicidal activity. This phytochemical, abundant in the crude ethanolic extract of EOPFB, was found to have a higher binding affinity (6.1 kcal/mol) than Mancozeb (4.8 kcal/mol), at the trypsin target. These findings demonstrate the potential of EOPFB, an agricultural waste product, as a sustainable and eco-friendly solution for managing tomato Fusarium wilt disease, contributing to increased tomato production. It also highlights the potential of 2-amino-5,6-dimethyl-3 H-pyrimidine-4-one as a lead compound for the development of novel, natural fungicides, and underscores the value of EOPFB as a rich source of bioactive compounds with agricultural and biotechnological applications.

In vitro Evaluation of Efficacy of Fungicides Against Fusarium oxysporum f. sp. Lycopersici (Sacc.) Synder and Hansen Causing Wilt Disease of Tomato

Fusarium wilt of tomato caused by Fusarium oxysporum f.sp. lycopersici is one of the most devastating and economically important fungal diseases of tomatoes. The study was conducted to assess the effectiveness of commercially available fungicides against Fusarium oxysporum f. sp lycopersici, a Nepali isolate by poisoned food technique. The experiment was carried out in a Completely Randomized Design (CRD) with five replications, in the Plant Protection Laboratory of the Ministry of Industry, Agriculture and Cooperatives, Jhumka, Sunsari. Six different fungicides: Mancozeb, Copper oxychloride, Carbendazim, Azoxystrobin, Kasugamycin + Copper oxychloride, Azoxystrobin + Difenoconazole at four different concentrations (100 ppm, 150 ppm, 200 ppm and 250 ppm) were tested for their ability to inhibit mycelial growth of the fungus, in vitro. The mycelial growth of the fungus was measured at 2, 4, 6, 8 and 10 days after inoculation (DAI). Among these fungicides Carbendazim, at all concentrations, showed the highest mycelial growth inhibition (100%) followed by Azoxystrobin in combination with Difenoconazole (82.79%) and Azoxystrobin alone (61.04%) at 250 ppm on 10 DAI. The results suggest that Carbendazim was the most effective at the lowest concentration (100 ppm) at in vitro inhibition of the fungus. Therefore, it can be a candidate to be explored for in vivo management of fusarium wilt of tomato caused by Fusarium oxysporum f.sp. lycopersici.

Antifungal metabolites produced by Pseudomonas hunanensis SPT26 effective in biocontrol of fusarium wilt of Lycopersicum esculentum under saline conditions.

In past few years, salinity has become one of the important abiotic stresses in the agricultural fields due to anthropogenic activities. Salinity is leading towards yield losses due to soil infertility and increasing vulnerability of crops to diseases. Fluorescent pseudomonads are a diverse group of soil microorganisms known for promoting plant growth by involving various traits including protecting crops from infection by the phytopathogens. In this investigation, salt tolerant plant growth promoting bacterium Pseudomonas hunanensis SPT26 was selected as an antagonist against Fusarium oxysporum, causal organism of fusarium wilt in tomato. P. hunanensis SPT26 was found capable to produce various antifungal metabolites. Characterization of purified metabolites using Fourier transform infrared spectroscopy (FT-IR) and liquid chromatography-electron spray ionization-mass spectrometry(LC-ESI/MS) showed the production of various antifungal compounds viz., pyrolnitrin, pyochelin and hyroxyphenazine by P. hunanensis SPT26. In the preliminary examination, biocontrol activity of purified antifungal metabolites was checked by dual culture method and results showed 68%, 52% and 65% growth inhibition by pyrolnitrin, 1- hydroxyphenazine and the bacterium (P. hunanensis SPT26) respectively. Images from scanning electron microscopy (SEM) revealed the damage to the mycelia of fungal phytopathogen due to production of antifungal compounds secreted by P. hunanensis SPT26. Application of bioinoculant of P. hunanensis SPT26 and purified metabolites significantly decreased the disease incidence in tomato and increased the plant growth parameters (root and shoot length, antioxidant activity, number of fruits per plant, etc.) under saline conditions. The study reports a novel bioinoculant formulation with the ability to promote plant growth parameters in tomato in presence of phytopathogens even under saline conditions.

Suppressive Effect of Black Soldier Fly Larvae Frass on Fusarium Wilt Disease in Tomato Plants.

This study investigated the effect of black soldier fly larvae (BSFL) frass derived from BSFL reared on a diet composed of fruit/vegetable/bakery/brewery residues (FVBB diet) and on the Gainesville diet (GV diet) on the development of tomato (Solanum lycopersicum) Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL). Tomato plants were grown in a substrate inoculated with FOL that was amended (10%, v:v) or not (control) with either a commercial compost, pasteurized (70 °C for 1 h) frass from BSFL reared on a FVBB diet, non-pasteurized frass from BSFL reared on a FVBB diet, pasteurized frass from BSFL reared on the GV diet, or non-pasteurized frass from BSFL reared on the GV diet. The results show that frass from BSFL reared on the GV diet, irrespective of pasteurization, inhibited FOL root colonization and reduced the severity of tomato Fusarium wilt to a far greater extent than frass from BSFL reared on a FVBB diet and commercial compost made of peat, seaweed, and shrimps. This study suggests that BSFL frass, depending on the larval rearing diet, has the potential to serve as a pasteurized or non-pasteurized soil amendment with prophylactic properties against FOL in tomato plants, opening new avenues of research for the valorization of BSFL frass.

Biostimulant and antagonistic potential of endophytic fungi against fusarium wilt pathogen of tomato Fusarium oxysporum f. sp. lycopersici

Endophytic fungal-based biopesticides are sustainable and ecologically-friendly biocontrol agents of several pests and diseases. However, their potential in managing tomato fusarium wilt disease (FWD) remains unexploited. This study therefore evaluated effectiveness of nine fungal isolates against tomato fusarium wilt pathogen, Fusarium oxysporum f. sp. lycopersici (FOL) in vitro using dual culture and co-culture assays. The efficacy of three potent endophytes that inhibited the pathogen in vitro was assessed against FWD incidence, severity, and ability to enhance growth and yield of tomatoes in planta. The ability of endophytically-colonized tomato (Solanum lycopersicum L.) plants to systemically defend themselves upon exposure to FOL were also assessed through defence genes expression using qPCR. In vitro assays showed that endophytes inhibited and suppressed FOL mycelial growth better than entomopathogenic fungi (EPF). Endophytes Trichoderma asperellum M2RT4, Hypocrea lixii F3ST1, Trichoderma harzianum KF2R41, and Trichoderma atroviride ICIPE 710 had the highest (68.84–99.61%) suppression and FOL radial growth inhibition rates compared to EPF which exhibited lowest (27.05–40.63%) inhibition rates. Endophytes T. asperellum M2RT4, H. lixii F3ST1 and T. harzianum KF2R41 colonized all tomato plant parts. During the in planta experiment, endophytically-colonized and FOL-infected tomato plants showed significant reduction of FWD incidence and severity compared to non-inoculated plants. In addition, these endophytes contributed to improved growth promotion parameters and yield. Moreover, there was significantly higher expression of tomato defence genes in T. asperellum M2RT4 colonized than in un-inoculated tomato plants. These findings demonstrated that H. lixii F3ST1 and T. asperellum M2RT4 are effective biocontrol agents against FWD and could sustainably mitigate tomato yield losses associated with fusarium wilt.

Biological Management of Fusarium Wilt of Tomato caused by Fusarium oxysporum f. sp. lycopersici

Biological Management of Fusarium Wilt of Tomato caused by Fusarium oxysporum f. sp. lycopersici

Identification of antimicrobial compounds from the plant growth promoting bacteria (PGPR) tested against Fusarium wilt of tomato caused by Fusarium oxysporum f.sp. Lycopersici

Infections and pests affecting plants pose significant threats to global food security. Over the top utilize of chemical pesticides is frequently utilized to diminish the impacts of plant illnesses caused by bacterial and parasitic pathogens. The greatest concern as we work towards more feasible horticulture is expanding agrarian efficiency for a developing populace. Microbial biocontrol operators (MBCAs) have illustrated their viability as a green procedure to oversee plant illnesses, invigorate edit development and execution, and increment yields. Other than their growth-promoting part, plant growth-promoting bacteria/fungi (PGPR/PGPF) can stifle plant illnesses by creating inhibitory chemicals and actuating a plant resistant reaction against plant pathogens. As biofertilizers and biopesticides, PGPR and PGPF are considered financially practical and appealing strategies for economical horticulture; This leads to a “win–win” circumstance. A few strains of PGPR and PGPF have been distinguished as compelling BCAs beneath controlled natural conditions. In common, any MBCA must overcome certain challenges some time recently it can be enrolled or broadly utilized for disease/pest control. Viable MBCA gives a down to earth arrangement to progress nursery edit execution with decreased fertilizer inputs and chemical pesticide utilization. This current audit points to fill the current crevice in information on plant growth-promoting microorganisms (PGPM), drawing consideration to the logical premise for arrangement, improvement proposals and extra investigate related to commercial utilize of PGPM.

Biocontrol mechanism of Bacillus siamensis sp. QN2MO-1 against tomato fusarium wilt disease during fruit postharvest and planting

Tomato fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (Fol) is a highly destructive disease, resulting in severe economic losses of global tomato production annually. An eco-friendly alternative to chemical fungicide using biological control agents (BCAs) is urgently needed. Here, Bacillus siamensis QN2MO-1 was isolated from Noli fruit and had a strong antagonistic activity against Fol in vitro and in vivo. Strain QN2MO-1 also exhibited a broad-spectrum antifungal activity against the selected 14 phytopathogenic fungi. The crude protein produced by strain QN2MO-1 could inhibit the spore germination of Fol and destroy the spore structure. It was closely related with the generation of chitinase and β-1,3-glucanase secreted by strain QN2MO-1. In a pot experiment, the application of B. siamensis QN2MO-1 effectively alleviated the yellowing and wilting symptoms of tomato plants. The disease index and incidence rate were decreased by 72.72% and 80.96%, respectively. The rhizospheric soil in tomato plants owed a high abundance of microbial community. Moreover, strain QN2MO-1 also enhanced the plant growth and improved the fruit quality of tomato. Therefore, B. siamensis QN2MO-1 will be explored as a potential biocontrol agent and biofertilizer.

Host RNAi-mediated silencing of Fusarium oxysporum f. sp. lycopersici specific-fasciclin-like protein genes provides improved resistance to Fusarium wilt in Solanum lycopersicum.

Tomato transgenics expressing dsRNA against FoFLPs act as biofungicides and result in enhanced disease resistance upon Fol infection, by downregulating the endogenous gene expression levels of FoFLPs within Fol. Fusarium oxysporum f. sp. lycopersici (Fol) hijacks plant immunity by colonizing within the host and further instigating secondary infection causing vascular wilt disease in tomato that leads to significant yield loss. Here, RNA interference (RNAi) technology was used to determine its potential in enduring resistance against Fusarium wilt in tomato. To gain resistance against Fol infection, host-induced gene silencing (HIGS) of Fol-specific genes encoding for fasciclin-like proteins (FoFLPs) was done by generating tomato transgenics harbouring FoFLP1, FoFLP4 and FoFLP5 RNAi constructs confirmed by southern hybridizations. These tomato transgenics were screened for stable siRNA production in T0 and T1 lines using northern hybridizations. This confirmed stable dsRNAhp expression in tomato transgenics and suggested durable trait heritability in the subsequent progenies. FoFLP-specific siRNAs producing T1 tomato progenies were further selected to ascertain its disease resistance ability using seedling infection assays. We observed a significant reduction in FoFLP1, FoFLP4 and FoFLP5 transcript levels in Fol, upon infecting their respective RNAi tomato transgenic lines. Moreover, tomato transgenic lines, expressing intended siRNA molecules in the T1 generation, exhibit delayed disease onset with improved resistance. Furthermore, reduced fungal colonization was observed in the roots of Fol-infected T1 tomato progenies, without altering the plant photosynthetic efficiency of transgenic plants. These results substantiate the cross-kingdom dsRNA or siRNA delivery from transgenic tomato to Fol, leading to enhanced resistance against Fusarium wilt disease. The results also demonstrated that HIGS is a successful approach in rendering resistance to Fol infection in tomato plants.

Complete genome sequence of Bacillus velezensis B31, a potential biocontrol agent with ability of tolerance to fusaric acid and antagonism against Fusarium oxysporum.

Bacillus velezensis B31 is tolerant to fusaric acid, exhibits antagonism against Fusarium oxysporum, and has an excellent control effect on tomato fusarium wilt. Here, we present the complete genome sequence of B31, which contains 4,056,755 bp DNA with a G + C ratio of 46.39%. The genome has 3,838 protein-coding genes.

A biodegradable oxidized starch/carboxymethyl chitosan film coated with pesticide-loaded ZIF-8 for tomato fusarium wilt control

Film mulching is one of the most important methods to control soil-borne diseases. However, the traditional mulch may cause microplastic pollution and soil ecological damage. Herein, a biodegradable film was developed using oxidized starch and carboxymethyl chitosan and incorporated ZIF-8 carrying fludioxonil to sustainably control soil-borne disease. The microstructure, mechanical properties, optical properties, and water barrier properties of the composite films (Flu@ZIF-8-OS/CMCS) were investigated. The results show that Flu@ZIF-8-OS/CMCS had a smooth and uniform surface and excellent light transmittance. The excellent mechanical properties of the films were verified by tensile strength, elongation at break and Young's modulus. Higher contact angle and lower water vapor permeability indicate water retention capacity of the soil was improved through using Flu@ZIF-8-OS/CMCS. Furthermore, the release properties, biological activity, degradability and safety to soil organisms of Flu@ZIF-8-OS/CMCS was determined. The addition of ZIF-8 significantly improved the film's ability to retard the release of Flu, while the Flu@ZIF-8-OS/CMCS has good soil degradability. In vitro antifungal assays and pot experiments demonstrated excellent inhibitory activity against Fusarium oxysporum f. sp. Lycopersici. Flu@ZIF-8-OS/CMCS caused only 13.33 % mortality of earthworms within 7 d. This research provides a new approach to reducing microplastic pollution and effectively managing soil-borne diseases.

Physiological and Biochemical Mechanisms of Wood Vinegar-Induced Stress Response against Tomato Fusarium Wilt Disease.

Wood vinegar, a by-product of charcoal biomass pyrolysis, has been used as a biofungicide in plant disease management because of its antimicrobial properties. However, the physiological and biochemical mechanisms through which wood vinegar alleviates biotic stress are poorly understood. In this study, pot experiments were conducted to investigate the resistance and regulation mechanism of wood vinegar prepared from different raw materials (ZM) and from a single raw material (SM) in controlling tomato (Solanum lycopersicum "Bonny Best") Fusarium wilt at different concentrations (0.3%, 0.6%, 0.9%, 1.2%, and 1.5%). The results showed that ZM and SM had significant control effects on tomato fusarium wilt under different concentrations in the same growth cycle. Under biotic stress, the two kinds of wood vinegar significantly increased the plant height, stem diameter, leaf area and yield of tomato under the concentration of 0.3%, 0.6%, 0.9% and 1.2%, and significantly reduced the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in tomato leaves. The effect of 0.9% treatment was the most significant, ZM and SM significantly increased tomato yield by 122% and 74%, respectively, compared with CK under 0.9% treatment. However, the plant height, stem diameter and leaf area of tomato were significantly reduced under 1.5% treatment, but the content of soluble sugar, soluble protein and vitamin C in tomato fruit was the best. Compared with CK, ZM significantly increased by 14%, 193% and 67%, respectively, and SM significantly increased by 28%, 300% and 159%, respectively. Except for 0.3% treatment, both significantly increased the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in tomato leaves. The response intensity of two kinds of wood vinegar-physiological and biochemical-to tomato disease resistance, growth and development, showed ZM > SM. The disease index of tomato showed highly significant negative correlation with plant height, stem thickness, leaf area and antioxidant physiology CAT, and highly significant positive correlation with MDA and H2O2 content. In conclusion, ZM was more effective than SM in enhancing tomato disease resistance by promoting tomato growth and development, decreasing leaf MDA and H2O2 content, and inducing antioxidant enzyme activity in leaves at moderate concentrations.

In Silico and In Vitro Assessment of Virulent Proteins of Fusarium wilt in Tomato and Identification, Designing of New Trichoderma Compounds

In Silico and In Vitro Assessment of Virulent Proteins of Fusarium wilt in Tomato and Identification, Designing of New Trichoderma Compounds

Controlling Tomato Fusarium Wilt Disease through Bacillus thuringiensis-Mediated Defense Primining.

Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. lycopersici (Fol) (Sacc.) W.C. Snyder and H.N. Hans is one of the most prevalent and devastating diseases of tomato plants (Solanum lycoprsicum L.) that leads to a severe reduction in crop yield almost worldwide. Evaluation of biocontrol potential of Bacillus thuringiensis (Bt) isolate IBRC-M11096, against Fol in tomato through primin. qRT-PCR technique was applied to analyze the effect of the strain on the hormonal defensive pathways; transcriptional responses of jasmonic acid (COI1, Pin2) and salicylic acid (NRP1 and PR1) pathway genes in Bt-treated plants following inoculation of Fol as compared to the plants only challenged with Fol. Also, the potential of the bacterial strain as a biocontrol agent was studied by evaluating growth indices and area under disease progress curve (AUDPC). The transcription of both defensive hormonal pathway genes (COI1, Pin2, NPR1, PR1) increased due to bacterial priming. The bacterial priming reduced the AUDPC compared to the inoculation with only Fol. The strain reduced the disease symptoms, and compared to the plants only challenged with the fungus, the bacterial strain significantly raised shoot dry and fresh weights and root dry weight. Priming with the Bt strain led to improved shoot and root growth indices, reduced AUDPC, and fortified responses of both JA and SA hormonal pathways. However, further full-span studies are required to judge the efficacy of the bacterial strain in the biological control of tomato fusarium wilt under field conditions.

Crude Saponins from Chenopodium quinoa Willd. Reduce Fusarium Wilt Infection in Tomato Seedlings

Quinoa saponins are pentacyclic triterpene compounds composed of one triterpenoid glycoside and two different sugar chains. Previous studies have showed that natural quinoa saponins showed little or no antifungal activity, and there are few reports about their antifungal effects in recent decades. Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) is the most serious for tomatoes in the field and under greenhouse conditions. The main objective of this study was to investigate the effectiveness of different concentrations and application modes of crude saponins from quinoa bran against the causal pathogen of tomato wilt under a greenhouse experiment. The results showed that the anti-FOL activity of quinoa saponins was weak in vitro, but significantly enhanced in vivo. Tomato seeds and seedlings treated with solution of quinoa saponins at 0.5 and 1.0 g/L significantly reduced the disease incidence (%) of tomato Fusarium wilt. The treatment types of saponin solution have influence on the preventive effects (%) of tomato seedlings against Fusarium wilt, among them, root soaking > foliar spray > seed soaking. The treatment of seed soaking with quinoa saponins inhibited germination of tomato seeds to some extent. However, the germination rate of tomato seeds after saponin soaking was comparable to the chemical pesticide (thiram carboxin); therefore, it could be used to control tomato wilt disease. This is due to the fact that the antifungal activity of quinoa saponins in vivo was much higher than that in vitro when the saponin concentration was between 0.5–1.0 g/L, indicating that the antifungal activity of quinoa saponins may be achieved mainly by inducing resistance. This investigation supports the potential use of quinoa saponins as a supplier of antifungal compounds, and could be the foundation for a future study examining the use of quinoa bran as a new resource against FOL.

Bio-management of Fusarium wilt of tomato (Fusarium oxysporum f.sp. lycopersici) with multifacial Trichoderma species

Fusarium oxysporum f.sp. lycopersici (FOL), the incitant of the Fusarium wilt of tomato, is a highly damaging and prevalent disease in the majority of tomato growing areas. Keeping into consideration of high disease occurrence and incidence of FOL in tomato crop, the present investigation was undertaken to develop an effective bio-management approach to combat this disease. Initially, the studies were conducted to evaluate six multi-facial biocontrol isolates of Trichoderma species viz., Trichoderma harzianum AMUTH-1, T. harzianum AMUTH-2, T. harzianum AMUTH-3, T. asperellum (= T. viride) AMUTV-1, T. asperellum AMUTV-3 and T. virens (= Gliocladium virens) AMUTS-1 against FOL in vitro. Among these antagonists, T. harzianum AMUTH-1 and T. asperellum AMUTV-3 exhibited the maximum inhibitory effect while T. virens AMUTS-1 was recorded as the least effective Trichoderma isolate against FOL in vitro. Interestingly, T. harzianum AMUTH-1 and T. asperellum AMUTV-3 were found to produce indole acetic acid, siderophore and possess high enzymatic activities (cellulase, chitinase, ligninase and protease) in vitro. Further, pot trials were conducted and the chemical fungicide, carbendazim was used to compare the effectiveness of Trichoderma isolates. Pot trials also verified the efficacy of T. harzianum AMUTH-1 with 9–28% enhancement in the plant-growth parameters and 15–21% biomass production, and 88% decrease in the soil population of FOL. The effect of T. harzianum AMUTH-1 was also at par with fungicides, carbendazim.

RETRACTED: Biocontrol of Fusarium wilt in tomato by Trichoderma spp

Tomato is the most economically important vegetable crop in Florida where produces the most fresh-market tomatoes in the United States. Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici (FOL), is an important disease in tomato production in Florida, particularly due to lacking effective chemicals for soil treatment. Biological control is an alternative approach in the management of plant diseases, including those caused by soilborne pathogens. In this study, we evaluated two Trichoderma strains (T. atroviride T11 and T. asperellum T25) on their effects against FOL in vitro and in planta. T. asperellum T25 and its cultural filtrate showed inhibitory effects against mycelial growth of FOL in vitro and significantly reduced disease severity of Fusarium wilt in tomato in the greenhouse when T25 was mixed into soil at seeding. Although the mechanisms for biocontrol are still under investigation, results from this study indicate that T25 has great potential in the management of Fusarium wilt in tomato production.

Suppression mechanism of soilborne diseases by biochar: Immobilization and deactivation of pathogenic enzymes and toxic metabolites

Greenhouse vegetable production aggravates soilborne diseases. Biochar has been recently considered as soil amendment to effectively prevent soilborne diseases. This study evaluates the immobilization and deactivation of pathogen-produced cell wall degrading enzymes (CWDEs) and toxic metabolites (TMs) by biochar to understand the mechanism involved in tomato Fusarium wilt, with activated carbon as the control. The results reveal that cellulase takes shorter time to reach the adsorption equilibrium than pectinase does. The adsorption isotherm of pectinase follows the Langmuir model, and the adsorption isotherm of cellulase follows the Freundlich model. The adsorption capacity of pectinase is greater than that of cellulase on biochar (on activated carbon). The adsorbed enzymes are completely immobilized and observably deactivated. The activity of immobilized pectinase decreases as 43.01 % of the original activity on biochar and 44.91 % on activated carbon. But the activity of immobilized cellulase decreases only as 1.88 % on biochar and 3.89 % on activated carbon. The tomato seedling bioassay analysis demonstrates that the adsorption of CWDEs and TMs is conducive to the reduction of disease severity. However, these established models (or laboratory simulation) cannot explain the enzyme adsorption process of biochar in the real soil, which requires the further exploration in the future.