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Showing papers on "Trichoderma harzianum published in 2016"


Journal ArticleDOI
22 Feb 2016-Planta
TL;DR: It is suggested that a dose of 30 g/L was the most effective in improving drought tolerance in rice, and its potential exploitation will contribute to the advancement of rice genotypes to sustain crop productivity under drought stress.
Abstract: This study demonstrates a dose-dependent response of Trichoderma harzianum Th-56 in improving drought tolerance in rice by modulating proline, SOD, lipid peroxidation product and DHN / AQU transcript level, and the growth attributes. In the present study, the effect of colonization of different doses of T. harzianum Th-56 strain in rice genotypes were evaluated under drought stress. The rice genotypes treated with increasing dose of T. harzianum strain Th-56 showed better drought tolerance as compared with untreated control plant. There was significant change in malondialdehyde, proline, higher superoxide dismutase level, plant height, total dry matter, relative chlorophyll content, leaf rolling, leaf tip burn, and the number of scorched/senesced leaves in T. harzianum Th-56 treated rice genotypes under drought stress. This was corroborated with altered expression of aquaporin and dehydrin genes in T. harzianum Th-56 treated rice genotypes. The present findings suggest that a dose of 30 g/L was the most effective in improving drought tolerance in rice, and its potential exploitation will contribute to the advancement of rice genotypes to sustain crop productivity under drought stress. Interaction studies of T. harzianum with three aromatic rice genotypes suggested that PSD-17 was highly benefitted from T. harzianum colonization under drought stress.

130 citations


Journal ArticleDOI
TL;DR: The results indicated suitability of Trichoderma harzianum BHU51 as a bio-priming agent in improving NUE and wheat crop productivity and root length and N uptake were the most important property to improve the NUE.
Abstract: This study was aimed to investigate an impact of bio-priming by Trichoderma harzianum BHU51, varied N doses (100%, 75%, 50% and 25% RDN) along with varied soils types (alluvial, red and black) on wheat ( Triticum aestivum L.) under greenhouse conditions. Results revealed that significantly enhanced plant height, chlorophyll content, root length, effective tillers growth and yield parameters of wheat with different soil type under greenhouse conditions by the application of various treatments. Significantly higher effective tillers, chlorophyll content and root length were recorded with recommended dose of fertilizers (RDF) of NPK @ 120-60-60 kg ha −1 followed by seed bio-priming with T. harzianum +3/4th N and RDF of PK. The seed bio-priming also enhanced the plant growth and nitrogen use efficiency (NUE). Agronomic use efficiency (AUE) and physiological use efficiency (PUE) were significantly higher with alluvial soil as compared to black and red soils. The principal component analysis revealed that root length and N uptake were the most important property to improve the NUE. The results indicated suitability of Trichoderma harzianum BHU51 as a bio-priming agent in improving NUE and wheat crop productivity.

112 citations


Journal ArticleDOI
TL;DR: T-aloe displayed biocontrol potential against S. sclerotiorum and soybean plants, the first report of unraveling biocOntrol potential of Trichoderma Spp.

104 citations


Journal ArticleDOI
TL;DR: In this paper, a laccase enzyme was used to decolorization pigment secreted from deteriorated pigmented fungi on paper and parchment during 30 days by using a pieces of parchment inoculated by spore suspension, the results indicated that a high removal effect of fungal pigment on paper (71.21%) was recorded comparing to parchment samples (32.39%).

100 citations


Journal ArticleDOI
TL;DR: The data reported here indicate that the T22-based strategy may be the most effective measure against CMV, and treating with T22 before or simultaneously to CMV infection led to a systemic resistance by jasmonic acid/ethylene and salicylic acid signaling pathways.
Abstract: Understanding the induction of plant defenses against viruses using biocontrol agents is essential for developing new strategies against these pathogens, given the ineffectiveness of chemical treatments. The ability of Trichoderma harzianum, strain T-22 (T22) to control Cucumber mosaic virus (CMV) in Solanum lycopersicum var. cerasiforme plants and the changes in the physiology of tomato treated/infected with T22/CMV were examined. Plant growth-promoting effects, photosynthetic performance, reactive oxygen species (ROS) scavenging enzymes, and phytohormones were investigated. T22 improved tomato growth in terms of plant height and improved photosynthesis, total chlorophyll content and plant gas exchange. In contrast, CMV induced a negative effect on dry matter accumulation and inhibited the photosynthetic capacity. The analysis of plant hormones demonstrated that treating with T22 before or simultaneously to CMV infection, led to a systemic resistance by jasmonic acid/ethylene and salicylic acid signaling pathways. Conversely, systemic resistance was abscissic acid-dependent when T22 treatment was administered after the CMV infection. In conclusion, the data reported here indicate that the T22-based strategy may be the most effective measure against CMV.

79 citations



Journal ArticleDOI
TL;DR: Differential gene expression analyses revealed that jasmonate and salicylate may act in an antagonistic manner in affecting the hormone biosynthesis, signaling, and downstream defense responses in G. boninense-treated oil palm roots.
Abstract: Basal stem rot (BSR) is a fungal disease in oil palm (Elaeis guineensis Jacq.) which is caused by hemibiotrophic white rot fungi belonging to the Ganoderma genus. Molecular responses of oil palm to these pathogens are not well known although this information is crucial to strategize effective measures to eradicate BSR. In order to elucidate the molecular interactions between oil palm and G. boninense and its biocontrol fungus Trichoderma harzianum, we compared the root transcriptomes of untreated oil palm seedlings with those inoculated with G. boninense and T. harzianum, respectively. Differential gene expression analyses revealed that jasmonate (JA) and salicylate (SA) may act in an antagonistic manner in affecting the hormone biosynthesis, signaling, and downstream defense responses in G. boninense-treated oil palm roots. In addition, G. boninense may compete with the host to control disease symptom through the transcriptional regulation of ethylene (ET) biosynthesis, reactive oxygen species (ROS) production and scavenging. The strengthening of host cell walls and production of pathogenesis-related proteins as well as antifungal secondary metabolites in host plants, are among the important defense mechanisms deployed by oil palm against G. boninense. Meanwhile, endophytic T. harzianum was shown to improve the of nutrition status and nutrient transportation in host plants. The findings of this analysis have enhanced our understanding on the molecular interactions of G. boninense and oil palm, and also the biocontrol mechanisms involving T. harzianum, thus contributing to future formulations of better strategies for prevention and treatment of BSR.

75 citations


Journal ArticleDOI
TL;DR: The results indicated that the absence of Epl-1 protein affects the expression of all mycoparasitism genes analyzed in direct confrontation assays against phytopathogen Sclerotinia sclerotiorum as well as T. harzianum itself; the host myCoparasitic coiling process and expression modulation of plant defense genes showing different pattern compared with wild type strain.
Abstract: Trichoderma harzianum species are well known as biocontrol agents against important fungal phytopathogens. Mycoparasitism is one of the strategies used by this fungus in the biocontrol process. In this work, we analyzed the effect of Epl-1 protein, previously described as plant resistance elicitor, in expression modulation of T. harzianum genes involved in mycoparasitism process against phytopathogenic fungi; self cell wall protection and recognition; host hyphae coiling and triggering expression of defense-related genes in beans plants. The results indicated that the absence of Epl-1 protein affects the expression of all mycoparasitism genes analyzed in direct confrontation assays against phytopathogen Sclerotinia sclerotiorum as well as T. harzianum itself; the host mycoparasitic coiling process and expression modulation of plant defense genes showing different pattern compared with wild type strain. These data indicated the involvement T. harzianum Epl-1 in self and host interaction and also recognition of T. harzianum as a symbiotic fungus by the bean plants.

74 citations


Journal ArticleDOI
TL;DR: It is demonstrated that functional Thph1 and Thph2 may be required in T. harzianum to activate ISR in maize and the genes related to the jasmonate/ethylene signaling pathway were up-regulated in the wild-type maize strain.
Abstract: Trichoderma harzianum is well known to exhibit induced systemic resistance (ISR) to Curvularia leaf spot. We previously reported that a C6 zinc finger protein (Thc6) is responsible for a major contribution to the ISR to the leaf disease, but the types of effectors and the signals mediated by Thc6 from Trichoderma are unclear. In this work, we demonstrated that two hydrolases, Thph1 and Thph2, from T. harzianum were regulated by Thc6. Furthermore, an electrophoretic mobility shift assay (EMSA) study revealed that Thc6 regulated mRNA expression by binding to GGCTAA and GGCTAAA in the promoters of the Thph1 and Thph2 genes, respectively. Moreover, the Thph1 and Thph2 proteins triggered the transient production of reactive oxygen species (ROS) and elevated the free cytosolic calcium levels in maize leaf. Furthermore, the genes related to the jasmonate/ethylene signaling pathway were up-regulated in the wild-type maize strain. However, the ΔThph1- or ΔThph2-deletion mutants could not activate the immune defense-related genes in maize to protect against leaf disease. Therefore, we conclude that functional Thph1 and Thph2 may be required in T. harzianum to activate ISR in maize.

71 citations


Journal ArticleDOI
TL;DR: Efficacy of both fungi increased as their inoculum densities increased, especially at the highest used density (1010 spore/g soil) which resulted in the best control.

70 citations


Journal ArticleDOI
TL;DR: A synergistic biological approach integrating application of Gm and BOF for TBW protection seems promising, and application of BOF and Gm alone or in combination changed the diversity of the rhizospheric microbial community.

Journal ArticleDOI
TL;DR: The results suggested that a part of the inhibitory effect of T. harzianum isolates on soybean charcoal rot might be related to the indirect influence on M. phaseolina in vivo.
Abstract: Throughout the world, charcoal rot, caused by Macrophomina phaseolina, is one of the most destructive and widespread dis- eases of crop plants such as soybean. In this study, the biological control capability of 11 Trichoderma spp. isolates against M. phaseolina was investigated using screening tests. Among all the tested Trichoderma spp. isolates, inhibition varied from 20.22 to 58.67% in dual culture tests. Dual culture, volatile and non-volatile tests revealed that two isolates of Trichoderma harzianum (including the isolates T7 and T14) best inhibited the growth of M. phaseolina in vitro. Therefore, these isolates were selected for biocontrol of M. phaseolina in vivo. The results of greenhouse experiments revealed that disease severity in the seed treatment with T. harzianum isolates was significantly lower than that of the soil treatment. In most of the cases, though, soil treatment with T. harzianum resulted in higher plant growth parameters, such as root and shoot weight. The effects of T. harzianum isolates on the activity of peroxidase enzyme and phenolic contents of the soybean root in the presence and absence of M. phaseolina were determined in greenhouse conditions. Our results suggested that a part of the inhibitory effect of T. harzianum isolates on soybean charcoal rot might be related to the indirect influence on M. phaseolina. Plant defense responses were activated as an elicitor in addition to the direct effect on the pathogen growth.

Journal ArticleDOI
TL;DR: Results suggest that T. harzianum – mediated protection against R. solani may be associated with alleviation of oxidative burst in host cells, and the protection provided by the two biocontrol agents was associated with increasing activities of ascorbate peroxidase (APX), guaiacol peroxIDase (GPX), superoxide dismutase (SOD) and catalase (CAT) at the early stage after pathogen challenges.

Journal ArticleDOI
TL;DR: There was a positive correlation between the antagonistic capacity of Trichoderma isolates towards fungal pathogens and their lytic enzyme production, and ERG-1 gene showed heterogeneity among some antagonistic isolates and indicated the possibility of occurrence of squalene epoxidase driven triterpene biosynthesis as an alternative biocontrol mechanism in Trichodma species.
Abstract: The use of Trichoderma isolates with efficient antagonistic activity represents a potentially effective and alternative disease management strategy to replace health hazardous chemical control. In this context, twenty isolates were obtained from tomato rhizosphere and evaluated by their antagonistic activity against four fungal pathogens (Fusarium oxysporum f. sp. lycopersici, Alternaria alternata, Colletotrichum gloeosporoides and Rhizoctonia solani). The production of extracellular cell wall degrading enzymes of tested isolates was also measured. All the isolates significantly reduced the mycelial growth of tested pathogens but the amount of growth reduction varied significantly as well. There was a positive correlation between the antagonistic capacity of Trichoderma isolates towards fungal pathogens and their lytic enzyme production. The Trichoderma isolates were initially sorted according to morphology and based on the translation elongation factor 1-α gene sequence similarity, the isolates were designated as Trichoderma harzianum, T. koningii, T. asperellum, T. virens and T. viride. PCA analysis explained 31.53, 61.95, 62.22 and 60.25% genetic variation among Trichoderma isolates based on RAPD, REP-, ERIC- and BOX element analysis, respectively. ERG-1 gene, encoding a squalene epoxidase has been used for the first time for diversity analysis of antagonistic Trichoderma from tomato rhizosphere. Phylogenetic analysis of ERG-1 gene sequences revealed close relatedness of ERG-1sequences with earlier reported sequences of Hypocrea lixii, T. arundinaceum and T. reesei. However, ERG-1 gene also showed heterogeneity among some antagonistic isolates and indicated the possibility of occurrence of squalene epoxidase driven triterpene biosynthesis as an alternative biocontrol mechanism in Trichoderma species.

Journal ArticleDOI
TL;DR: The major metabolites detected in liquid culture treated by T. harzianum were: 14-hydroxy-descladinosyl- and descladinoyl-clarithromycin, which are pharmacologically inactive products not dangerous for the environment.

Journal ArticleDOI
TL;DR: The most advantageous strategy to increase potato tuber weight was by inoculating the cover crop, and root colonization by arbuscular mycorrhizal fungi and abundance of Trichoderma harzianum in soil were evaluated.

Journal ArticleDOI
TL;DR: T12 isolate was mostly effective in field experiments, observable in the attained minimum plant disease indices both in the soil incorporation and seed inoculation treatments, in comparison to isolates T2 and T10.
Abstract: Macrophomina phaseolina (Tassi) Goid remains the prevailing causal agent of charcoal rot disease that significantly suppresses the yield of a variety of oilseed crops. Its wide host range and ability to survive under arid conditions, coupled with the ineffective use of fungicides against it, have spurred scientific endeavours for alternative avenues to control this phytopathogen. Hence, the present study aimed to provide empirical evidence of the efficacy of three fungal isolates (T2, T10 and T12) of Trichoderma harzianum as biological control agents against charcoal rot in soybean (Glycine max L.). The results of the in vitro studies revealed that all three fungal isolates significantly inhibited the growth of M. phaseolina phytopathogen, with T12 showing considerably higher inhibition effect than T2 and T10 isolates. T12 inhibited the growth of M. phaseolina in the dual culture (72.31%) and volatile production (63.36%) assays, and the hyperparasitism test indicated cell lysis following the inter...

Journal ArticleDOI
TL;DR: The production of cellulase enzymes using glycerol for high cell density growth of Trichoderma harzianum followed by induction with a cellulosic material proved to be a promising approach for improving cellulolytic enzymes production, and could potentially contribute to adding value to biomass within the biofuels sector.
Abstract: The use of glycerol obtained as an intermediate of the biodiesel manufacturing process as carbon source for microbial growth is a potential alternative strategy for the production of enzymes and other high-value bioproducts. This work evaluates the production of cellulase enzymes using glycerol for high cell density growth of Trichoderma harzianum followed by induction with a cellulosic material. Firstly, the influence of the carbon source used in the pre-culture step was investigated in terms of total protein secretion and fungal morphology. Enzymatic productivity was then determined for cultivation strategies using different types and concentrations of carbon source, as well as different feeding procedures (batch and fed-batch). The best strategy for cellulase production was then further studied on a larger scale using a stirred tank bioreactor. The proposed strategy for cellulase production, using glycerol to achieve high cell density growth followed by induction with pretreated sugarcane bagasse, achieved enzymatic activities up to 2.27 ± 0.37 FPU/mL, 106.40 ± 8.87 IU/mL, and 9.04 ± 0.39 IU/mL of cellulase, xylanase, and β-glucosidase, respectively. These values were 2 times higher when compared to the control experiments using glucose instead of glycerol. This novel strategy proved to be a promising approach for improving cellulolytic enzymes production, and could potentially contribute to adding value to biomass within the biofuels sector.

Journal ArticleDOI
TL;DR: It is suggested that CECT 2413 is not able to persist in a metabolically-active form when applied as a spore suspension, which may have strong implications in the way this BCA should be introduced and/or formulated to be effective against Verticillium wilt of olive.
Abstract: Trichoderma harzianum Rifai is a well-known biological control agent (BCA) effective against a wide range of phytopathogens. Since colonization and persistence in the target niche is crucial for biocontrol effectiveness we aimed to: (i) shed light on the olive roots colonization process by T. harzianum CECT 2413, (ii) unravel the fate of its biomass upon application, and (iii) study the in planta interaction with the soil-borne pathogen Verticillium dahliae Kleb. Fluorescently-tagged derivatives of CECT 2413 and V. dahliae and confocal laser scanning microscopy were used. In vitro assays showed for the first time mycoparasitism of V. dahliae by T. harzianum, evidenced by events such as hyphal coiling. In planta assays revealed that CECT 2413 profusely colonized the rhizoplane of olive roots. Interestingly, biomass of the BCA was visualized mainly as chlamydospores. This observation was independent on the presence or absence of the pathogen. Evidence of inner colonization of olive roots by CECT 2413 was not obtained. These results suggest that CECT 2413 is not able to persist in a metabolically-active form when applied as a spore suspension. This may have strong implications in the way this BCA should be introduced and/or formulated to be effective against Verticillium wilt of olive.

Journal ArticleDOI
TL;DR: Assessment of resistance in inoculated glasshouse trials and innate activity levels of three pathogenesis-related proteins in apoplastic fluids of five non-inoculated spring wheat cultivars showed the lowest disease severity on cv.

Journal ArticleDOI
TL;DR: From the results, a strategy based on the use of T. polysporum LCB50 and an organic matter source is proposed for the integrated management for melon wilt.

Journal ArticleDOI
TL;DR: Use of Aspergillus niger as bio-inoculant could be a sustainable approach to improve soil P availability, promote plant growth and alleviate adverse effect of salt stress.

Journal ArticleDOI
TL;DR: The preliminary screening of 119 Trichoderma strains for cellulolytic and xylanolytic activity showed the real potential of all Trichodma species originating from wood with decay symptoms to produce cellulases andxylanases—the key enzymes in plant cell wall degradation.
Abstract: The aim of this study was to explore the species diversity of Trichoderma obtained from samples of wood collected in the forests of the Gorce Mountains (location A), Karkonosze Mountains (location B) and Tatra Mountains (location C) in Central Europe and to examine the cellulolytic and xylanolytic activity of these species as an expression of their probable role in wood decay processes. The present study has led to the identification of the following species and species complex: Trichoderma atroviride P. Karst., Trichoderma citrinoviride Bissett, Trichoderma cremeum P. Chaverri & Samuels, Trichoderma gamsii Samuels & Druzhin., Trichoderma harzianum complex, Trichoderma koningii Oudem., Trichoderma koningiopsis Samuels, C. Suarez & H.C. Evans, Trichoderma longibrachiatum Rifai, Trichoderma longipile Bissett, Trichoderma sp. (Hypocrea parapilulifera B.S. Lu, Druzhin. & Samuels), Trichoderma viride Schumach. and Trichoderma viridescens complex. Among them, T. viride was observed as the most abundant species (53 % of all isolates) in all the investigated locations. The Shannon's biodiversity index (H), evenness (E), and the Simpson's biodiversity index (D) calculations for each location showed that the highest species diversity and evenness were recorded for location A-Gorce Mountains (H' = 1.71, E = 0.82, D = 0.79). The preliminary screening of 119 Trichoderma strains for cellulolytic and xylanolytic activity showed the real potential of all Trichoderma species originating from wood with decay symptoms to produce cellulases and xylanases-the key enzymes in plant cell wall degradation.

Journal ArticleDOI
TL;DR: This study shows the complex connection between increased hormone accumulation and transport, altered sugar partitioning and enhanced photosynthetic efficiency induced by T. harzianum 6776, and how growth promotion is the result of the combination of these drastic changes in Micro-Tom plants.
Abstract: Trichoderma harzianum 6776 is a novel and beneficial tomato fungal isolate. To investigate the mechanisms underlying the T. harzianum 6776-tomato interaction, several physiological and biochemical responses were explored on dwarf tomato plants, cv. Micro-Tom. Growth of treated and untreated plants was evaluated by measuring the height and biomass production of plants. The leaf pigment content and sugar partitioning in plant organs were evaluated by biochemical analysis. The photosynthetic parameters were measured by a miniaturized PAM fluorometer and a portable gas-exchange system. The hormonal analysis in root and xylem sap was performed by gas cromatography- mass spectrometry (GC-MS). T. harzianum 6776 positively affected plant growth, increasing the leaf pigment content and improving the photosynthetic activity at both stomatal and non-stomatal levels. Differences in pigment composition and photosynthetic performance were reflected in the carbohydrate content and their partitioning. In the absence of a pathogen, root and xylem vessel stress and growth-related hormone balance were affected by the interaction with T. harzianum 6776, with an increase in jasmonic and indoleacetic acids and a decrease in salicylic acid content. This study shows the complex connection between increased hormone accumulation and transport, altered sugar partitioning and enhanced photosynthetic efficiency induced by T. harzianum 6776, and how growth promotion is the result of the combination of these drastic changes in Micro-Tom plants.

Journal ArticleDOI
TL;DR: Trichoderma harzianum showed a complex and diverse arsenal of proteins that are secreted in response to the presence of FSCW, with novel proteins not previously described in mycoparasitic‐related studies.
Abstract: Trichoderma harzianum is a fungus well known for its potential as a biocontrol agent against many fungal phytopathogens. The aim of this study was to characterize the proteins secreted by T. harzianum ALL42 when its spores were inoculated and incubated for 48 h in culture media supplemented with glucose (GLU) or with cell walls from Fusarium solani (FSCW), a phytopathogen that causes severe losses in common bean and soy crops in Brazil, as well as other crop diseases around the world. Trichoderma harzianum was able to grow in Trichoderma Liquid Enzyme Production medium (TLE) and Minimal medium (MM) supplemented with FSCW and in TLE+GLU, but was unable to grow in MM+GLU medium. Protein quantification showed that TLE+FSCW and MM+FSCW had 45- and 30- fold, respectively, higher protein concentration on supernatant when compared to TLE+GLU, and this difference was observable on 2D gel electrophoresis (2DE). A total of 94 out of 105 proteins excised from 2DE maps were identified. The only protein observed in all three conditions was epl1. In the media supplemented with FSCW, different hydrolases such as chitinases, β-1,3-glucanases, glucoamylases, α-1,3-glucanases and proteases were identified, along with other proteins with no known functions in mycoparasitism, such as npp1 and cys. Trichoderma harzianum showed a complex and diverse arsenal of proteins that are secreted in response to the presence of FSCW, with novel proteins not previously described in mycoparasitic-related studies.

Journal ArticleDOI
TL;DR: The methodology described in this manuscript will be useful for the bio-prospection of key enzymes, including cellulases and other accessory enzymes, for the development and/or improvement of enzymatic cocktails designed to produce ethanol from plant biomass.
Abstract: The conversion of biomass-derived sugars via enzymatic hydrolysis for biofuel production is a challenge. Therefore, the search for microorganisms and key enzymes that increase the efficiency of the saccharification of cellulosic substrates remains an important and high-priority area of study. Trichoderma harzianum is an important fungus known for producing high levels of cellulolytic enzymes that can be used for cellulosic ethanol production. In this context, β-glucosidases, which act synergistically with cellobiohydrolases and endo-β-1,4-glucanases in the saccharification process, are potential biocatalysts for the conversion of plant biomass to free glucose residues. In the present study, we used RNA-Seq and genomic data to identify the major β-glucosidase expressed by T. harzianum under biomass degradation conditions. We mapped and quantified the expression of all of the β-glucosidases from glycoside hydrolase families 1 and 3, and we identified the enzyme with the highest expression under these conditions. The target gene was cloned and heterologously expressed in Escherichia coli, and the recombinant protein (rThBgl) was purified with high yields. rThBgl was characterized using a comprehensive set of biochemical, spectroscopic, and hydrodynamic techniques. Finally, we determined the crystallographic structure of the recombinant protein at a resolution of 2.6 A. Using a rational approach, we investigated the biochemical characteristics and determined the three-dimensional protein structure of a β-glucosidase that is highly expressed by T. harzianum under biomass degradation conditions. The methodology described in this manuscript will be useful for the bio-prospection of key enzymes, including cellulases and other accessory enzymes, for the development and/or improvement of enzymatic cocktails designed to produce ethanol from plant biomass.

Journal ArticleDOI
TL;DR: In Trichoderma-tomato interaction assays, amdS transformants were able to promote plant growth to a greater extent than the wild-type T34, although compared with this strain the transformants showed similar capability to colonize tomato roots.
Abstract: Trichoderma is a fungal genus that includes species that are currently being used as biological control agents and/or as biofertilizers. In addition to the direct application of Trichoderma spp. as biocontrol agents in plant protection, recent studies have focused on the beneficial responses exerted on plants, stimulating the growth, activating the defenses, and/or improving nutrient uptake. The amdS gene, encoding an acetamidase of Aspergillus, has been used as a selectable marker for the transformation of filamentous fungi, including Trichoderma spp., but the physiological effects of the introduction of this gene into the genome of these microorganisms still remains unexplored. No evidence of amdS orthologous genes has been detected within the Trichoderma spp. genomes and the amdS heterologous expression in Trichoderma harzianum T34 did not affect the growth of this fungus in media lacking acetamide. However, it did confer the ability for the fungus to use this amide as a nitrogen source. Although a similar antagonistic behavior was observed for T34 and amdS transformants in dual cultures against Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum, a significantly higher antifungal activity was detected in amdS transformants against F. oxysporum, compared to that of T34, in membrane assays on media lacking acetamide. In Trichoderma-tomato interaction assays, amdS transformants were able to promote plant growth to a greater extent than the wild-type T34, although compared with this strain the transformants showed similar capability to colonize tomato roots. Gene expression patterns from aerial parts of 3-week-old tomato plants treated with T34 and the amdS transformants have also been investigated using GeneChip Tomato Genome Arrays. The downregulation of defense genes and the upregulation of carbon and nitrogen metabolism genes observed in the microarrays were accompanied by (i) enhanced growth, (ii) increased carbon and nitrogen levels, and (iii) a higher sensitivity to B. cinerea infections in plants treated with amdS transformants as detected in greenhouse assays. These observations suggest that the increased plant development promoted by the amdS transformants was at expense of defenses.

Journal ArticleDOI
TL;DR: The findings confirm the traditional use of Breonadia salicina and demonstrate the potential value of developing biopesticides from plants.
Abstract: Background: Medicinal plants are used by many ethnic groups as a source of medicine for the treatment of various ailments in both humans and domestic animals. These plants produce secondary metabolites that have antimicrobial properties, thus screening of medicinal plants provide another alternative for producing chemical fungicides that are relatively non-toxic and cost-effective. Materials and methods: Leaf extracts of selected South African plant species (Bucida buceras, Breonadia salicina, Harpephyllum caffrum, Olinia ventosa, Vangueria infausta and Xylotheca kraussiana) were investigated for activity against selected phytopathogenic fungi (Aspergillus niger, Aspergillus parasiticus, Colletotricum gloeosporioides, Penicillium janthinellum, P. expansum, Trichoderma harzianum and Fusarium oxysporum). These plant fungal pathogens causes major economic losses in fruit industry such as blue rot on nectaries and postharvest disease in citrus. Plant species were selected from 600 evaluated inter alia, against two animal fungal pathogens (Candida albicans and Cryptococcus neoformans). Antioxidant activity of the selected plant extracts were investigated using a qualitative assay (2, 2-diphenyl-1-picrylhydrazyl (DPPH)). Bioautography assay was used to determine the number of antifungal compounds in plant extracts. Results: All plant extracts were active against the selected plant phytopathogenic fungi. Moreover, Bucida buceras had the best antifungal activity against four of the fungi, with minimum inhibitory concentration (MIC) values as low as 0.02 mg/ml and 0.08 mg/ml against P. expansum, P. janthinellum, T. harzianum and F. oxysporum. The plant extracts of five plant species did not possess strong antioxidant activity. However, methanol extract of X. kraussiana was the most active radical scavenger in the DPPH assay amongst the six medicinal plants screened. No antifungal compounds were observed in some of the plant extracts with good antifungal activity as shown in the microdilution assay, indicating possible synergism between the separated metabolites. Conclusion: The results showed that acetone was the best extractant. Furthermore, our findings also confirm the traditional use of Breonadia salicina and demonstrate the potential value of developing biopesticides from plants.

Journal ArticleDOI
TL;DR: The results revealed that Trichoderma harzianum, isolate N-8, was found to inhibit effectively the radial mycelial growth of the pathogen and was chosen to be the most promising bio-control agent for F. oxysporum f.
Abstract: Trichoderma spp. have long been used as biological control agents against plant fungal diseases, but the mechanisms by which the fungi confer protection are not well understood. Our goal in this study was to isolate species of Trichoderma, that exhibit high levels of biocontrol efficacy from natural environments and to investigate the mechanisms by which these strains confer plant protection. In this study, efficacy of the native isolates of Trichoderma species to promote the growth and yield parameters of tomato and to manage Fusarium wilt disease under in vitro and in vivo conditions were investigated. The dominant pathogen, which causes Fusarium wilt of tomato, was isolated and identified as Fusarium oxysporum f. sp. lycopersici (FOL). Twenty eight native Trichoderma antagonists were isolated from healthy tomato rhizosphere soil in different geographical regions of Mazandaran province, Iran. Under in vitro conditions, the results revealed that Trichoderma harzianum, isolate N-8, was found to inhibit effectively the radial mycelial growth of the pathogen (by 68.22%). Under greenhouse conditions, the application of T. harzianum (N-8) exhibited the least disease incidence (by 14.75%). Also, tomato plants treated with T. harzianum (N-8) isolate showed a significant stimulatory effect on plant height (by 70.13 cm) and the dry weight (by 265.42 g) of tomato plants, in comparison to untreated control (54.6 cm and 195.5 g). Therefore, the antagonist T. harzianum (N-8) is chosen to be the most promising bio-control agent for F. oxysporum f. sp. lycopersici. On the base of present study, the biocontrol agents of plant diseases might be exploited for sustainable disease management programs to save environmental risk.

Journal ArticleDOI
TL;DR: Despite lacking detectable glycoside activity, the addition of swollenin of T. harzianum increased by two‐fold the hydrolysis efficiency of a commercial cellulase cocktail, and the findings are of interest in enriching enzyme cocktail with this important accessory protein which takes part in the cellulose amorphogenesis.
Abstract: This study demonstrates the production of an active enzyme cocktail produced by growing Trichoderma harzianum on sugarcane bagasse. The component enzymes were identified by LCMS-MS. Glycosyl hydrolases were the most abundant class of proteins, representing 67% of total secreted protein. Other carbohydrate active enzymes involved in cell wall deconstruction included lytic polysaccharide mono-oxygenases (AA9), carbohydrate-binding modules, carbohydrate esterases and swollenin, all present at levels of 1%. In total, proteases and lipases represented 5 and 1% of the total secretome, respectively, with the rest of the secretome being made up of proteins of unknown or putative function. This enzyme cocktail was efficient in catalysing the hydrolysis of sugarcane bagasse cellulolignin to fermentable sugars for potential use in ethanol production. Apart from mapping the secretome of T. harzianum, which is a very important tool to understand the catalytic performance of enzyme cocktails, the gene coding for T. harzianum swollenin was expressed in Aspergillus niger. This novel aspect in this work, allowed increasing the swollenin concentration by 95 fold. This is the first report about the heterologous expression of swollenin from T. harzianum, and the findings are of interest in enriching enzyme cocktail with this important accessory protein which takes part in the cellulose amorphogenesis. Despite lacking detectable glycoside activity, the addition of swollenin of T. harzianum increased by two-fold the hydrolysis efficiency of a commercial cellulase cocktail. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:327-336, 2016.