Showing papers on "Trichoderma harzianum published in 2022"

Biological Control and Plant Growth Promotion Properties of Volatile Organic Compound-Producing Antagonistic Trichoderma spp.

Abstract: Trichoderma is environmentally vital due to their plant growth-promoting effects (such as enhancement of nutrients supply, suppression of plant pathogens, and promotion of plant defense). Biogenic volatile organic compounds (VOCs) are diverse chemical substances emitted by Trichoderma spp. The potential role of VOCs in biological control and plant growth promotion has recently been recognized. Here, the Trichoderma-VOCs' performance for plant growth promotion and suppression of plant pathogens are evaluated. We further investigated VOC emission profiles of T. harzianum using GC–MS. The Trichoderma-VOCs exhibited significant (p < 0.05) antifungal properties against all tested pathogenic fungi. T. atroviride-VOCs showed a decisive inhibition of Alternaria panax, Botrytis cinerea, Cylindrocarpon destructans, and Sclerotinia nivalis. The germinating seeds demonstrated growth enhancement in the presence of Trichoderma-VOCs emitted by different strains. Low levels of cyclopentasiloxane, decamethyl, cyclotetrasiloxane, and octamethyl were found in T. harzianum KNU1 strain whereas cyclopentasiloxane, decamethyl, cyclotetrasiloxane, and octamethyl showed higher emission levels as Si-containing compounds. The results reveal the potentiality of VOCs as a biocontrol resource against deleterious rhizosphere microorganisms and underline the importance of Trichoderma-VOCs emissions in regulating plant growth and development.

Biocontrol Activity of Trichoderma Species Isolated from Grapevines in British Columbia against Botryosphaeria Dieback Fungal Pathogens

Abstract: Botryosphaeria dieback (BD) is a grapevine trunk disease (GTD) causing significant yield losses and limiting the lifespan of vineyards worldwide. Fungi responsible for BD infect grapevines primarily through pruning wounds, and thus pruning wound protection, using either synthetic chemicals or biological control agents (BCAs), is the main available management strategy. However, no products to control GTDs are currently registered in Canada. With a focus on more sustainable grapevine production, there is an increasing demand for alternatives to chemical products to manage GTDs. Accordingly, the objective of this study was to identify Trichoderma species from grapevines in British Columbia (BC) and evaluate their potential biocontrol activity against BD fungi Diplodia seriata and Neofusicoccum parvum. Phylogenetic analyses identified seven species, including T. asperelloides, T. atroviride, T. harzianum, T. koningii, T. tomentosum, and two novel species, T. canadense and T. viticola. In vitro dual culture antagonistic assays showed several isolates to inhibit fungal pathogen mycelial growth by up to 75%. In planta detached cane assays under controlled greenhouse conditions identified T. asperelloides, T. atroviride and T. canadense isolates from BC as providing 70% to 100% pruning wound protection against BD fungi for up to 21 days after treatment. In addition, these isolates were shown to provide similar or better control when compared against commercial chemical and biocontrol products. This study demonstrates the potential that locally sourced Trichoderma species can have for pruning wound protection against BD fungi, and further supports the evaluation of these isolates under natural field conditions.

Iron and zinc micronutrients and soil inoculation of Trichoderma harzianum enhance wheat grain quality and yield

Abstract: Malnutrition is mainly caused by iron and zinc micronutrient deficiencies affecting about half of the world's population across the globe. Biofortification of staple crops is the right approach to overcome malnutrition and enhance nutrient contents in the daily food of humans. This study aimed to evaluate the role of foliar application of iron and zinc in Trichoderma harzianum treated soil on various growth characteristics, quality, and yield of wheat varieties. Plants were examined in the absence/presence of T. harzianum, and iron and zinc micronutrients in both optimal and high-stress conditions. Although the symbiotic association of T. harzianum and common wheat is utilized as an effective approach for wheat improvement because of the dynamic growth promoting the ability of the fungus, this association was found tremendously effective in the presence of foliar feeding of micronutrients for the enhancement of various growth parameters and quality of wheat. The utilization of this approach positively increased various growth parameters including spike length, grain mass, biomass, harvest index, and photosynthetic pigments. The beneficial role of T. harzianum in combination with zinc and iron in stimulating plant growth and its positive impact on the intensities of high molecular weight glutenin subunits (HMW-GS) alleles make it an interesting approach for application in eco-friendly agricultural systems. Further, this study suggests a possible alternative way that does not merely enhances the wheat yield but also its quality through proper biofortification of iron and zinc to fulfill the daily needs of micronutrients in staple food.

Influence of biochar and microorganism co-application on stabilization of cadmium (Cd) and improved maize growth in Cd-contaminated soil

Abstract: Cadmium (Cd) is one the leading environmental contaminants. The Cd toxicity and its potential stabilization strategies have been investigated in the recent years. However, the combined effects of biochar and microorganisms on the adsorption of Cd and maize plant physiology, still remained unclear. Therefore, this experiment was conducted to evaluate the combined effects of biochar (BC) pyrolyzed from (maize-straw, cow-manure, and poultry-manure, and microorganisms [Trichoderma harzianum (fungus) and Bacillus subtilis (bacteria)], on plant nutrient uptake under various Cd-stress levels (0, 10, and 30 ppm). The highest level of Cd stress (30 ppm) caused the highest reduction in maize plant biomass, intercellular CO2, transpiration rate, water use efficiency, stomatal conductance, and photosynthesis rate as compared to control Cd0 (0 ppm). The sole application of BC and microorganisms significantly improved plant growth, intercellular CO2, transpiration rate, water use efficiency, stomatal conductance, and photosynthesis rate and caused a significant reduction in root and shoot Cd. However, the co-application of BC and microorganisms was more effective than the sole applications. In this regard, the highest improvement in plant growth and carbon assimilation, and highest reduction in root and shoot Cd was recorded from co-application of cow-manure and combined inoculation of Trichoderma harzianum (fungus) + Bacillus subtilis (bacteria) under Cd stress. However, due to the aging factor and biochar leaching alkalinity, the effectiveness of biochar in removing Cd may diminish over time, necessitating long-term experiments to improve understanding of biochar and microbial efficiency for specific bioremediation aims. Graphical Abstract

Optimized Synthesis of Small and Stable Silver Nanoparticles Using Intracellular and Extracellular Components of Fungi: An Alternative for Bacterial Inhibition

Abstract: Silver nanoparticles (AgNPs) represent an excellent option to solve microbial resistance problems to traditionally used antibiotics. In this work, we report optimized protocols for the production of AgNPs using extracts and supernatants of Trichoderma harzianum and Ganoderma sessile. AgNPs were characterized using UV-Vis spectroscopy and transmission electron microscopy, and the hydrodynamic diameter and Z potential were also determined. The obtained AgNPs were slightly larger using the fungal extract, and in all cases, a quasi-spherical shape was obtained. The mean sizes of AgNPs were 9.6 and 19.1 nm for T. harzianum and 5.4 and 8.9 nm for G. sessile using supernatant and extract, respectively. The AgNPs were evaluated to determine their in vitro antibacterial effect against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The minimum inhibitory concentration (MIC) was determined, and in all cases the AgNPs showed an antimicrobial effect, with a MIC varying from 1.26–5.0 µg/mL, depending on the bacterial strain and type of nanoparticle used. Cytotoxicity analyses of AgNPs were carried out using macrophages and fibroblast cell lines. It was determined that the cell viability of fibroblasts exposed for 24 h to different concentrations of AgNPs was more than 50%, even at concentrations of up to 20 µg/mL of silver. However, macrophages were more susceptible to exposure at higher concentrations of AgNPs as their viability decreased at concentrations of 10 µg/mL. The results presented here demonstrate that small AgNPs are obtained using either supernatants or extracts of both fungal strains. A remarkable result is that very low concentrations of AgNPs were necessary for bacterial inhibition. Furthermore, AgNPs were stable for more than a year, preserving their antibacterial properties. Therefore, the reported optimized protocol using fungal supernatants or extracts may be used as a fast method for synthesizing small AgNPs with high potential to use in the clinic.

Trichogenic Silver-Based Nanoparticles for Suppression of Fungi Involved in Damping-Off of Cotton Seedlings

Abstract: Mycogenic silver nanoparticles (AgNPs) produced by some biocontrol agents have shown the ability to inhibit the growth of numerous plant pathogenic fungi, which may be a unique method of disease management. This study describes the extracellular production of AgNPs by Trichoderma harzianum. The size, shape, charge, and composition of the AgNPs were subsequently studied by UV-visible spectroscopy, DLS, zeta potential, TEM, SEM, and EDX, among other methods. The AgNPs had sizes ranging from 6 to 15 nm. The antifungal activities of bio-synthesized AgNPs and two commercial fungicides (Moncut and Maxim XL) were tested against three soil-borne diseases (Fusarium fujikuroi, Rhizoctonia solani, and Macrophomina phaseolina). Cotton seedling illnesses were significantly reduced under greenhouse settings after significant in vitro antifungal activity was documented for the control of plant pathogenic fungi. The use of biocontrol agents such as T. harzianum, for example, may be a safe strategy for synthesizing AgNPs and using them to combat fungus in Egyptian cotton.

Screening and biocontrol evaluation of indigenous native Trichoderma spp. against early blight disease and their field assessment to alleviate natural infection

Abstract: Abstract Background Early blight disease of tomato caused by pathogenic fungi Alternaria solani is the most significant and common disease throughout the world as well as in Kingdom of Saudi Arabia. The aim of this study was to isolate and identify native Trichoderma species from the Jeddah region in Saudi Arabia; evaluate their antagonistic potential against A. solani ; and study their influence early blight disease severity in greenhouse and in open field. Results The present study focused to explore the biocontrolling potential of native Trichoderma spp. against A. solani strain to compare with a conventional fungicide . Out of 21, 3 Trichoderma isolates showed an antifungal activity and significantly inhibited the mycelial growth of pathogen that were identified as Trichoderma atroviride, T. harzianum and T. longibrachiatum by their ITS region sequence analysis. Strong in vitro mycelial growth suppression (70.66%) was also recorded at 400 ppm Mancozeb (90%WP ® ) fungicide. Further, these Trichoderma bioagents and fungicide were further evaluated in greenhouse (artificially inoculated) and in field on naturally infected tomato plants. In greenhouse, (13.74%) disease severity after T. harzianum treatment was recorded, followed by T. longibrachiatum (25.83%) and T. atroviride (21.67%). The disease severity after fungicide (50 mg/L; 10 ml per plant) application was (7.91%). Further, positive impact on the plant biomarkers was demonstrated by all selected Trichoderma isolates in greenhouse. Under natural infection in season I, the disease severity (%) after T. longibrachiatum , T. atroviride and T. harzianum treatments was 11.5, 13.26 and 16.81%, respectively, followed by control (32.12%), whereas 7.18% disease severity was recorded after fungicide application. Conclusions The results revealed that native Trichoderma of this region had potential to mitigate the early blight disease intensity in field.

Novel Trichoderma Isolates Alleviate Water Deficit Stress in Susceptible Tomato Genotypes

Abstract: Symbiotic fungi in the genus Trichoderma can induce abiotic stress tolerance in crops. The beneficial effects of Trichoderma on water deficit stress are poorly understood and may be isolate-specific. Our objective was to evaluate a collection of Nepalese Trichoderma isolates and their efficacy to improve tomato (Solanum lycopersicum) growth under water deficit. Variable growth in low moisture environments was observed among Trichoderma isolates from Nepal, Ohio, and commercial sources using in vitro assays. The overall performance of the population decreased when cultured under conditions of decreasing matric water potential (0.0, –2.8, –4.8, and –8.5 Ψ). Twelve isolates were selected for evaluation for their potential to elicit drought tolerance in greenhouse-grown ‘Roma Organic’ tomatoes. Plants treated with T. asperelloides-NT33 had higher shoot weight than the non-inoculated control (T0) under water deficit stress conditions. Further, the stress-reducing efficacy of isolates T. asperelloides-NT33, T. asperellum-NT16, T. asperelloides-NT3, and commercial T. harzianum-T22 were tested on tomato genotypes with differing tolerance to drought [‘Roma Organic,’ ‘Jaune Flamme,’ and ‘Punta Banda’]. The water deficit susceptible genotypes ‘Roma Organic’ and ‘Jaune Flamme’ inoculated with isolate NT33 had significantly higher shoot weight (37 and 30% respectively; p < 0.05) compared to the non-inoculated control under water deficit stress conditions. In drought tolerant ‘Punta Banda,’ shoot weight was also significantly greater in NT33 inoculated plants under water deficit stress conditions, but with lower magnitude difference (8%; p < 0.05). Our results demonstrate differences in the ability of Trichoderma isolates to confer tolerance to water deficit in tomato with NT33 potentially relieving stress. Tomato genotypes also play a role in the outcome of interactions with the Trichoderma isolates we tested.

Influence of plant growth-promoting endophytes Colletotrichum siamense and Diaporthe masirevici on tomato plants (Lycopersicon esculentum Mill.)

Abstract: ABSTRACT The protective and growth-promoting activities of Colletrotrichum and Diaporthe endophytes on tomato plants (Lycopersicon esculentum Mill.) are underexplored. We screened 40 endophytic fungi associated with Mexican shrimp plant (Justicia brandegeana) using an in vitro dual culture assay for Fusarium oxysporum, one of the most important phytopathogens of tomato plants. The three best antagonists, Colletotrichum siamense (JB224.g1), C. siamense (JB252.g1), and Diaporthe masirevicii (JB270), were identified based on multilocus sequence analysis. They were assessed in vitro for their inhibition of F. oxysporum and phosphate solubilisation capacity, and for the production of indole acetic acid. Greenhouse experiments verified the growth-promoting effects of these endophytes and the suppression of F. oxysporum symptoms in tomato plants. Under greenhouse conditions, the JB252.g1 and JB270 isolates showed positive results for seedling emergence speed. The radicular system depth of plants inoculated with JB270 was greater than that in uninoculated plants (27.21 vs 21.95 cm). The soil plant analysis development chlorophyll metre (SPAD) index showed statistically significant results, especially for the endophyte JB224.g1 (36.99) compared to the control plants (30.90) and plants infected solely with F. oxysporum (33.64).

Root Morphology, Allometric Relations and Rhizosheath of Ancient and Modern Tetraploid Wheats (Triticum durum Desf.) in Response to Inoculation with Trichoderma harzianum T-22

Abstract: Early root traits and allometrics of wheat are important for competition and use of resources. They are under-utilized in research and un-explored in many ancient wheats. This is especially true for the rhizosheath emerging from root-soil interactions. We investigated root morphology, root/shoot relations and the amount of rhizosheath of four tetrapoid wheat seedlings (30 days after emergence): the italian landrace Saragolle Lucana and modern varieties Creso, Simeto and Ciclope, and tested the hypothesis that inoculation with Trichoderma harzianum T-22 (T-22) enhances rhizosheath formation and affects wheat varieties differently. Overall growth of non-inoculated plants showed different patterns in wheat varieties, with Saragolle and Ciclope at the two extremes: Saragolle invests in shoot rather than root mass, and in the occupation of space with highest (p < 0.05) shoot height to the uppermost internode (5.02 cm) and length-to-mass shoot (97.8 cm g-1) and root (more than 140 m g-1) ratios. This may be interpreted as maximizing competition for light but also as a compensation for low shoot efficiency due to the lowest (p < 0.05) recorded values of optically-measured chlorophyll content index (22.8). Ciclope invests in biomass with highest shoot (0.06 g) and root (0.04 g) mass and a thicker root system (average diameter 0.34 mm vs. 0.29 in Saragolle) as well as a highest root/shoot ratio (0.95 g g-1 vs. 0.54 in Saragolle). Rhizosheath mass ranged between 22.14 times that of shoot mass in Ciclope and 43.40 in Saragolle (different for p < 0.05). Inoculation with Trichoderma increased the amount of rhizosheath from 9.4% in Ciclope to 36.1% in Simeto and modified root architecture in this variety more than in others. Ours are the first data on roots and seedling shoot traits of Saragolle Lucana and of Trichoderma inoculation effects on rhizosheath. This opens to new unreported interpretations of effects of Trichoderma inoculation on improving plant growth.

It Works! Organic-Waste-Assisted Trichoderma spp. Solid-State Fermentation on Agricultural Digestate

Abstract: This study aimed at valorizing digestate through Trichoderma spp. solid-state fermentation (SSF) to produce a potentially ameliorated fertilizer combined with fungal biomass as a value-added bioproduct. Plant-growth-promoting Trichoderma atroviride Ta13, T. reesei RUT-C30, T. asperellum R, and T. harzianum T-22 were tested on different SSF substrates: whole digestate (WD), digestate dried up with wood sawdust (SSF1), and digestate enriched with food waste and dried up with wood sawdust (SSF2). The fungal biomass was quantified by using a qPCR assay. The growth of the four Trichoderma spp. was only observed on the SSF2 substrate. The highest quantity of mycelium was produced by T. reesei RUT-30 (689.80 ± 80.53 mg/g substrate), followed by T. atroviride Ta13, and T. asperellum R (584.24 ± 13.36 and 444.79 ± 91.02 mg/g substrate). The germination of Lepidium sativum seeds was evaluated in order to assess the phytoxicity of the Trichoderma-enriched substrate. The treatments with 7.5% SSF2-R, 3.75% SSF2-T-22, and 1.8% SSF2-Ta13 equally enhanced the root elongation in comparison to the non-fermented SSF-2. This study demonstrated that digestate, mixed with agro-food waste, was able to support the cultivation of Trichoderma spp., paving the way to the valorization of fermented digestate as a proper biofertilizer.

The Newly Identified Trichoderma harzianum Partitivirus (ThPV2) Does Not Diminish Spore Production and Biocontrol Activity of Its Host

Abstract: A new partititvirus isolated from a Trichoderma harzianum strain (T673), collected in China, was characterized and annotated as Trichoderma harzianum partitivirus 2 (ThPV2). The genome of ThPV2 consists of a 1693 bp dsRNA1 encoding a putative RNA-dependent RNA polymerase (RdRp) and a 1458 bp dsRNA2 encoding a hypothetical protein. In comparative studies employing the ThPV2-infected strain (T673) and a strain cured by ribavirin treatment (virus-free strain T673-F), we investigated biological effects of ThPV2 infection. While the growth rate of the virus-infected fungus differed little from that of the cured variant, higher mycelial density, conidiospore, and chlamydospore production were observed in the virus-infected strain T673. Furthermore, both the ThPV2-infected and the cured strain showed growth- and development-promoting activities in cucumber plants. In vitro confrontation tests showed that strains T673 and T673-F inhibited several important fungal pathogens and an oomycete pathogen in a comparable manner. Interestingly, in experiments with cucumber seeds inoculated with Fusarium oxysporum f. sp. cucumerinum, the ThPV2-infected strain T673 showed moderately but statistically significantly improved biocontrol activity when compared with strain T673-F. Our data broaden the spectrum of known mycoviruses and provide relevant information for the development of mycoviruses for agronomic applications.

Bio-Priming with Compatible Rhizospheric Microbes Enhances Growth and Micronutrient Uptake of Red Cabbage

Abstract: : Red cabbage is known as the millennium’s functional food, which has a lot of importance in our diet because of the health-promoting ingredients present in it. The current study investigated the synergistic relationship of rhizospheric-competent microbial agents ( Trichoderma harzianum , Pseudomonas fluorescens , and Bacillus subtilis ) in modulating the performance of red cabbage under the field conditions of Middle Gangetic Plains, India. Growth parameters were studied at three developmental stages, viz., pre-cupping, early head formation, and maturity. Our results suggested that the dual application of T . harzianum + P . fluorescens along with the 75% recommended dose of fertilizers (RDF) increased the number of leaves (24.6), leaf area (537.2 cm 2 ), root length (19.8 cm), and micronutrient uptake (Fe, Mn, and Cu) by head of the crop, whereas the co-inoculation of P . fluorescens and B . subtilis along with 75% RDF enhanced plant spread (39.0 cm), earliness (95.2 days), and Zn uptake. Maximum plant height (28.7 cm) and chlorophyll (SPAD, 77.3) were recorded in 100% RDF (120:60:60 kg ha − 1 ) and the combination of T . harzianum + B . subtilis along with 75% RDF, respec-tively. Interestingly, consortium ( T . harzianum + P . fluorescens ) bio-primed plants recorded about 14% higher root length in comparison to plants receiving sole fertilizers. The regression analysis revealed a significant relationship of Fe and Mn uptake with chlorophyll (SPAD) and between Zn uptake and the earliness of the crop. The present study indicated that seedling bio-priming with the dual consortium of efficient bio-agents is a viable strategy to lessen our dependence on for improving red cabbage production.

Screening and biocontrol evaluation of indigenous native Trichoderma spp. against early blight disease and their field assessment to alleviate natural infection

Abstract: Abstract Background Early blight disease of tomato caused by pathogenic fungi Alternaria solani is the most significant and common disease throughout the world as well as in Kingdom of Saudi Arabia. The aim of this study was to isolate and identify native Trichoderma species from the Jeddah region in Saudi Arabia; evaluate their antagonistic potential against A. solani ; and study their influence early blight disease severity in greenhouse and in open field. Results The present study focused to explore the biocontrolling potential of native Trichoderma spp. against A. solani strain to compare with a conventional fungicide . Out of 21, 3 Trichoderma isolates showed an antifungal activity and significantly inhibited the mycelial growth of pathogen that were identified as Trichoderma atroviride, T. harzianum and T. longibrachiatum by their ITS region sequence analysis. Strong in vitro mycelial growth suppression (70.66%) was also recorded at 400 ppm Mancozeb (90%WP ® ) fungicide. Further, these Trichoderma bioagents and fungicide were further evaluated in greenhouse (artificially inoculated) and in field on naturally infected tomato plants. In greenhouse, (13.74%) disease severity after T. harzianum treatment was recorded, followed by T. longibrachiatum (25.83%) and T. atroviride (21.67%). The disease severity after fungicide (50 mg/L; 10 ml per plant) application was (7.91%). Further, positive impact on the plant biomarkers was demonstrated by all selected Trichoderma isolates in greenhouse. Under natural infection in season I, the disease severity (%) after T. longibrachiatum , T. atroviride and T. harzianum treatments was 11.5, 13.26 and 16.81%, respectively, followed by control (32.12%), whereas 7.18% disease severity was recorded after fungicide application. Conclusions The results revealed that native Trichoderma of this region had potential to mitigate the early blight disease intensity in field.

Mycosynthesized Fe2O3 nanoparticles diminish brown rot of apple whilst maintaining composition and pertinent organoleptic properties

Abstract: Iron oxide nanoparticles (Fe2O3 NPs) were mycosynthesized using Trichoderma harzianum and applied to control brown rot of apple. The influence of Fe2O3 NPs on the quality of fruit was also studied.

Isolation and Molecular Characterization of The Pathogens Trichoderma harzianum and Pseudomonas tolaasii on the Edible Mushroom Agaricus bisporus and Evaluation of Some Desert Plant Extracts for Control Them

Abstract: Seven isolates of Pseudomonas bacteria were isolated from the casing soil and 11 fungal isolates from mushroom farm residues in the mushroom production farm - College of Agriculture , Tikrit University. According to the pathogenicity test, the highest infection rate was recorded by the bacterial isolate 1077, It was diagnosed to the species level as Pseudomonas tolaasii according to the nucleotide sequence of the 16S rRNA gene. It was registered globally in the NCBI website within the accession number MW085029.1, this record is the first for this bacteria in Iraq, while the fungal isolate 1076 showed the highest pathogenicity and this isolate was diagnosed phenotypically to the level of the genus Trichoderma and diagnosed to the level of species T. harzianum according to the nucleotide sequences of the 5.8S rRNA gene and registered globally in the NCBI website within the accession number MW147763.1. In studying the effect of treatments of alcoholic extracts of Atriplex tatarica and Haloxylon salicornicum and their powder in the presence of the pathogenic fungus T. harzianum (Th) and the pathogenic bacteria P. tolaasii (P.t) on the morphological characteristics, infection rate, productivity and quality of mushroom Agaricus bisporus, the results showed that the pathogens had no effect on the most of the morphological characteristics, while the treatment (A. tatarica and H.salicornicum extracts 4 mg/ml + P. tolaasii + T. harzianum) was the best treatment that increased the productivity of the A. bisporus, reduced the severity and rate of infection, and improved of some qualitative characteristics.

Effective and Promising Strategy in Management of Tomato Root-Knot Nematodes by Trichoderma harzianum and Arbuscular Mycorrhizae

Abstract: The ecosystem is considerably affected due to the extensive use of chemical pesticides and fertilizers. As an alternative strategy, this study aimed to assess the biocontrol potential of the bioagents arbuscular mycorrhizal fungi and plant growth-promoting Trichoderma harzianum MZ025966 against tomato root-knot nematodes (Meloidogyne javanica). T. harzianum showed a great potentiality to produce indole acetic acid (IAA) (12.11 ± 2.12 μg/mL) and exhibited a noticeable activity of ammonification. Furthermore, T. harzianum revealed protease and lipase enzymatic activity of 28.36 ± 2.82 U/mL and 12.30 ± 0.31 U/mL, respectively, which may illustrate the control mechanism of nematode eggs and juveniles. As in mycorrhizal and/or T. harzianum inoculated tomato plants, the penetration rates of nematodes, as well as the number of juveniles, females, egg mass, and galls were significantly reduced. The lowest number of juveniles was observed in the case of either single mycorrhizal inoculation (45%) or in combination with T. harzianum (55%). The enzymatic activity of glutathione peroxidase and catalase was enhanced in tomato plants inoculated with the bioagents to overcome the negative impact of nematode parasitism. Our results proved that the application of biocontrol agents not only reduced the nematode population and penetration rate but also improved the plant growth, increased the nutritional elemental content and stimulated the plant’s systematic resistance.

Green synthesis of copper nanoparticles extracted from guar seedling under Cu heavy-metal stress by Trichoderma harzianum and their bio-efficacy evaluation against Staphylococcus aureus and Escherichia coli

Abstract: Copper nanoparticles were successfully synthesized with the help of agriculturally beneficial fungus Trichoderma harzianum through a simple green and eco-friendly route. The objectives of this study were to: (1) evaluate the application of T. harzianum and assess the effect of guar plant cultivation on heavy metal contaminated lands of copper in municipal and industrial wastewaters, and (2) develop a method to increase the antibacterial effects on the risk of two bacteria (Staphylococcus aureus and Escherichia coli). Two factors were investigated: (1) two copper (Cu) levels, Natural Hoagland Arnold solution as a control, and application of 100 μL Cu in Hoagland Arnold solution, and (2) two bio-fertilizer levels, no application, and fungus application. TEM and SEM photographs showed that synthesized Cu-NPs had spherical shapes. The formations of Cu-NPs were corroborated by FTIR and XRD analysis. Furthermore, the MIC and MBC of Cu-NPs towards bacterial growth were evaluated. The Cu-NPs and T. harzianum fungi presented antibacterial activity against Gram positive and Gram negative bacteria. The results suggested that green synthesis of nanoparticles using guar extracts can increase their antibacterial effect. The effect of Cu and fungi on biochemical properties of guar was also investigated. The results showed that the highest antioxidant enzymatic activity and proline amino acid were obtained at 100 μL Cu and T. harzianum application. Moreover, the results suggested that the use of T. harzianum can be useful in increasing the resistance to heavy metal stress in plants by increasing the activity of some antioxidant enzymes and secondary metabolites.

Induction of resilience strategies against biochemical deteriorations prompted by severe cadmium stress in sunflower plant when Trichoderma and bacterial inoculation were used as biofertilizers

Abstract: Background Cadmium (Cd) is a highly toxic heavy metal. Its emission is suspected to be further increased due to the dramatic application of ash to agricultural soils and newly reclaimed ones. Thereby, Cd stress encountered by plants will exacerbate. Acute and chronic exposure to Cd can upset plant growth and development and ultimately causes plant death. Microorganisms as agriculturally important biofertilizers have constantly been arising as eco-friendly practices owing to their ability to built-in durability and adaptability mechanisms of plants. However, applying microbes as a biofertilizer agent necessitates the elucidation of the different mechanisms of microbe protection and stabilization of plants against toxic elements in the soil. A greenhouse experiment was performed using Trichoderma harzianum and plant growth-promoting (PGP) bacteria (Azotobacter chroococcum and Bacillus subtilis) individually and integrally to differentiate their potentiality in underpinning various resilience mechanisms versus various Cd levels (0, 50, 100, and 150 mg/kg of soil). Microorganisms were analyzed for Cd tolerance and biosorption capacity, indoleacetic acid production, and phosphate and potassium solubilization in vitro. Plant growth parameters, water relations, physiological and biochemical analysis, stress markers and membrane damage traits, and nutritional composition were estimated. Results Unequivocal inversion from a state of downregulation to upregulation was distinct under microbial inoculations. Inoculating soil with T. harzianum and PGPB markedly enhanced the plant parameters under Cd stress (150 mg/kg) compared with control plants by 4.9% and 13.9%, 5.6% and 11.1%, 55.6% and 5.7%, and 9.1% and 4.6% for plant fresh weight, dry weight, net assimilation rate, and transpiration rate, respectively; by 2.3% and 34.9%, 26.3% and 69.0%, 26.3% and 232.4%, 135.3% and 446.2%, 500% and 95.6%, and 60% and 300% for some metabolites such as starch, amino acids, phenolics, flavonoids, anthocyanin, and proline, respectively; by 134.0% and 604.6% for antioxidants including reduced glutathione; and by 64.8% and 91.2%, 21.9% and 72.7%, and 76.7% and 166.7% for enzymes activity including ascorbate peroxidase, glutathione peroxidase, and phenylalanine ammonia-lyase, respectively. Whereas a hampering effect mediated by PGP bacterial inoculation was registered on levels of superoxide anion, hydroxyl radical, electrolyte leakage, and polyphenol oxidase activity, with a decrease of 0.53%, 14.12%, 2.70%, and 5.70%, respectively, under a highest Cd level (150 mg/kg) compared with control plants. The available soil and plant Cd concentrations were decreased by 11.5% and 47.5%, and 3.8% and 45.0% with T. harzianum and PGP bacterial inoculation, respectively, compared with non-inoculated Cd-stressed plants. Whereas, non-significant alternation in antioxidant capacity of sunflower mediated by T. harzianum action even with elevated soil Cd concentrations indicates stable oxidative status. The uptake of nutrients, viz., K, Ca, Mg, Fe, nitrate, and phosphorus, was interestingly increased (34.0, 4.4, 3.3, 9.2, 30.0, and 1.0 mg/g dry weight, respectively) owing to the synergic inoculation in the presence of 150 mg of Cd/kg. Conclusions However, strategies of microbe-induced resilience are largely exclusive and divergent. Biofertilizing potential of T. harzianum showed that, owing to its Cd biosorption capability, a resilience strategy was induced via reducing Cd bioavailability to be in the range that turned its effect from toxicity to essentiality posing well-known low-dose stimulation phenomena (hormetic effect), whereas using Azotobacter chroococcum and Bacillus subtilis, owing to their PGP traits, manifested a resilience strategy by neutralizing the potential side effects of Cd toxicity. The synergistic use of fungi and bacteria proved the highest efficiency in imparting sunflower adaptability under Cd stress.

Efecto del Manejo Agroecológico sobre el Crecimiento de Plántulas de Theobroma cacao L. en Fase de Vivero

Abstract: El cacao Theobroma cacao L. ha sido un rubro muy importante en la producción agrícola del país durante muchos años, contribuyendo con su desarrollo económico y social. El manejo agronómico actual a las plántulas de cacao en vivero, implica el uso de agroquímicos, que pudiesen ocasionar un perjuicio ambiental. En esta investigación se evaluó el efecto del manejo agroecológico sobre el crecimiento de plántulas de cacao en fase de vivero en el municipio Sucre del estado Zulia, Venezuela. El diseño experimental fue totalmente al azar con 5 tratamientos y 10 repeticiones: T1, fórmula completa 12-12-17; T2, lixiviado de raquis de plátano + Trichoderma harzianum + Beauveria bassiana; T3, vermicompost líquido + Trichoderma harzianum + Beauveria bassiana; T4, lixiviado de raquis de plátano + Trichoderma harzianum + trampa y T5, vermicompost líquido + Trichoderma harzianum + trampa. Los datos de crecimiento de las plántulas se analizaron siguiendo la metodología de medidas repetidas, observándose que en fase de vivero, las mismas se pueden manejar sin el uso de agroquímicos. El modelo de estimación para el tamaño de plántulas de cacao a través del tiempo, permitiría obtener información en un momento determinado de su proceso de crecimiento.

Coculture of Trichoderma harzianum and Bacillus velezensis Based on Metabolic Cross-Feeding Modulates Lipopeptide Production

Abstract: Cocultures have been widely explored for their use in deciphering microbial interaction and its impact on the metabolisms of the interacting microorganisms. In this work, we investigate, in different liquid coculture conditions, the compatibility of two microorganisms with the potential for the biocontrol of plant diseases: the fungus Trichoderma harzianum IHEM5437 and the bacterium Bacillus velezensis GA1 (a strong antifungal lipopeptide producing strain). While the Bacillus overgrew the Trichoderma in a rich medium due to its antifungal lipopeptide production, a drastically different trend was observed in a medium in which a nitrogen nutritional dependency was imposed. Indeed, in this minimum medium containing nitrate as the sole nitrogen source, cooperation between the bacterium and the fungus was established. This is reflected by the growth of both species as well as the inhibition of the expression of Bacillus genes encoding lipopeptide synthetases. Interestingly, the growth of the bacterium in the minimum medium was enabled by the amendment of the culture by the fungal supernatant, which, in this case, ensures a high production yield of lipopeptides. These results highlight, for the first time, that Trichoderma harzianum and Bacillus velezensis are able, in specific environmental conditions, to adapt their metabolisms in order to grow together.