Showing papers on "Trichoderma harzianum published in 2007"
TL;DR: In this article, the authors evaluated 10 isolates belonging to three species of Trichoderma (Trichodermas viride, trichoderm harzianum, and trichodorma virens) against four isolates of Fusarium oxysporum f. sp. ciceris (Padwick) Matuo and K. Sato.
333 citations
TL;DR: The potential of using this strain to control the disease and the plant growth promoter effect was confirmed in three experiments carried out in fields artificially and naturally infested with the pathogen.
223 citations
TL;DR: The interaction between fifteen isolates of Trichoderma harzianum and the soil-borne plant pathogen, Rhizoctonia solani, was studied and it was revealed that growth inhibition of the pathogen occurred soon after contact with the antagonist.
Abstract: The genus Trichoderma is a potential biocontrol agent against several phytopathogenic fungi. One parameter for its successful use is an efficient coiling process followed by a substantial production of hydrolytic enzymes. The interaction between fifteen isolates of Trichoderma harzianum and the soil-borne plant pathogen, Rhizoctonia solani, was studied by light microscopy and transmission electron microscopy (TEM). Macroscopic observations of fungal growth in dual cultures revealed that growth inhibition of the pathogen occurred soon after contact with the antagonist. All T. harzianum isolates tested exhibited coiling around the hyphae of R. solani. The strains ALL23, ALL40, ALL41, ALL43 and ALL49 did not differ in coiling frequency and gave equal coiling performances. No correlation between coiling frequency and the production of cell wall-degrading chitinases, N-acetyl-beta-D-glucosaminidase and beta-1,3-glucanases, was found.
164 citations
TL;DR: The molecular mechanism underlying fungal ability to colonize the tomato-root system, the T. harzianum transcriptome was analyzed during the early stages of the plant-fungus interaction and the expression of fungal genes related to redox reactions, lipid metabolism, detoxification, and sugar or amino-acid transport increased.
Abstract: The capacity of the fungus Trichoderma harzianum CECT 2413 to colonize roots and stimulate plant growth was analyzed. Tobacco seedlings (Nicotiana benthamiana) transferred to Petri dishes inoculated with T. harzianum conidia showed increased plant fresh weight (140%) and foliar area (300%), as well as the proliferation of secondary roots (300%) and true leaves (140%). The interaction between strain CECT 2413 and the tomato-root system was also studied during the early stages of root colonization by the fungus. When T. harzianum conidia were inoculated into the liquid medium of hydroponically grown tomato plants (Lycopersicum esculentum), profuse adhesion of hyphae to the plant roots as well as colonization of the root epidermis and cortex were observed. Confocal microscopy of a T. harzianum transformant that expressed the green fluorescent protein (GFP) revealed intercellular hyphal growth and the formation of plant-induced papilla-like hyphal tips. Analysis of the T. harzianum-tomato interaction in soil indicated that the contact between T. harzianum and the roots persisted over a long period of time. This interaction was characterized by the presence of yeast-like cells, a novel and previously undescribed developmental change. To study the molecular mechanism underlying fungal ability to colonize the tomato-root system, the T. harzianum transcriptome was analyzed during the early stages of the plant-fungus interaction. The expression of fungal genes related to redox reactions, lipid metabolism, detoxification, and sugar or amino-acid transport increased when T. harzianum colonized tomato roots. These observations are similar to those regarding the interactions of mycorrhiza and pathogenic fungi with plants.
146 citations
TL;DR: Fungal strain was found comparatively better candidate for uranium biosorption than algae and mass balance studies revealed that uranium recovery was 99.9%, for T. harzianum, and 97.3% for RD256 and RD257, respectively, by 0.1M Hydrochloric acid.
141 citations
TL;DR: A combination of two compatible micro-organisms, Trichoderma harzianum and Streptomyces rochei, both antagonistic to the pathogen Phytophthora capsici, was used to control root rot in pepper, reducing the population of the pathogenic in soil by 75% and developing a compound with antioomycete property secreted by the bacteria.
Abstract: A combination of two compatible micro-organisms, Trichoderma harzianum and Streptomyces rochei, both antagonistic to the pathogen Phytophthora capsici, was used to control root rot in pepper. The population of the pathogen in soil was reduced by 75% as a result. Vegetative growth of the mycelium of P. capsici was inhibited in vitro on the second day after P. capsici and T. harzianum were placed on the opposite sides of the same Petri plate. Trichoderma harzianum was capable of not only arresting the spread of the pathogen from a distance, but also after invading the whole surface of the pathogen colony, sporulating over it. Scanning electron microscopy showed the hyphae of P. capsici surrounded by those of T. harzianum, their subsequent disintegration, and the eventual suppression of the pathogen's growth. Streptomyces rochei produced a zone of inhibition, from which was obtained a compound with antioomycete property secreted by the bacteria. When purified by high-pressure liquid chromatography, this compound was identified as 1-propanone, 1-(4-chlorophenyl), which seems to be one of the principal compounds involved in the antagonism. A formulation was prepared that maintained the compound's capacity to inhibit growth of the pathogen for up to 2 years when stored at room temperature in the laboratory on a mixture of plantation soil and vermiculite. The two antagonists, added as a compound formulation, were effective at pH from 3.5 to 5.6 at 23-30°C. The optimal dose of the antagonists in the compound formulation was 3.5 x 10 8 spores/ml of T. harzianum and 1.0 x 10 9 FCU/ml of S. rochei. This is the first report of a compound biocontrol formulation of these two antagonists with a potential to control root rot caused by P. capsici.
136 citations
TL;DR: This is the first report of tree growth stimulation by application of Trichoderma to roots, and is especially important as willow is a major source of wood fuel in the quest for renewable energy.
Abstract: We investigated if the plant growth promoting fungus Trichoderma harzianum Rifai 1295-22 (also known as “T22”) could be used to enhance the establishment and growth of crack willow (Salix fragilis) in a soil containing no organic or metal pollutants and in a metal-contaminated soil by comparing this fungus with noninoculated controls and an ectomycorrhizal formulation commercially used to enhance the establishment of tree saplings. Crack willow saplings were grown in a temperature-controlled growth room over a period of 5 weeks’ in a garden center topsoil and over 12 weeks in a soil which had been used for disposal of building materials and sewage sludge containing elevated levels of heavy metals including cadmium (30 mg kg−1), lead (350 mg kg−1), manganese (210 mg kg−1), nickel (210 mg kg−1), and zinc (1,100 mg kg−1). After 5 weeks’ growth in clean soil, saplings grown with T. harzianum T22 produced shoots and roots that were 40% longer than those of the controls and shoots that were 20% longer than those of saplings grown with ectomycorrhiza (ECM). T. harzianum T22 saplings produced more than double the dry biomass of controls and more than 50% extra biomass than the ECM-treated saplings. After 12 weeks’ growth, saplings grown with T. harzianum T22 in the metal-contaminated soil produced 39% more dry weight biomass and were 16% taller than the noninoculated controls. This is the first report of tree growth stimulation by application of Trichoderma to roots, and is especially important as willow is a major source of wood fuel in the quest for renewable energy. These results also suggest willow trees inoculated with T. harzianum T22 could be used to increase the rate of revegetation and phytostabilization of metal-contaminated sites, a property of the fungus never previously demonstrated.
136 citations
TL;DR: It is argued that cohabitation of these strains triggered antibiotic production via interspecific interactions and that the growth reduction of fungi was a side-effect caused by the sensitivity of the fungi to bacterial secondary metabolites.
123 citations
TL;DR: Examination of signalling pathways underlying Trichoderma biocontrol revealed that mycoparasitism-associated coiling and chitinase production as well as secondary metabolism are affected by the internal cAMP level; in addition, a cross talk between regulation of light responses and the cAMP signalling pathway was found in Trichodma atroviride.
Abstract: Fungi of the genus Trichoderma are used as biocontrol agents against several plant pathogenic fungi like Rhizoctonia spp., Pythium spp., Botrytis cinerea and Fusarium spp. which cause both soil-borne and leaf- or flower-borne diseases of agricultural plants. Plant disease control by Trichoderma is based on complex interactions between Trichoderma, the plant pathogen and the plant. Until now, two main components of biocontrol have been identified: direct activity of Trichoderma against the plant pathogen by mycoparasitism and induced systemic resistance in plants. As the mycoparasitic interaction is host-specific and not merely a contact response, it is likely that signals from the host fungus are recognised by Trichoderma and provoke transcription of mycoparasitism-related genes. In the last few years examination of signalling pathways underlying Trichoderma biocontrol started and it was shown that heterotrimeric G-proteins and mitogen-activated protein (MAP) kinases affected biocontrol-relevant processes such as the production of hydrolytic enzymes and antifungal metabolites and the formation of infection structures. MAPK signalling was also found to be involved in induction of plant systemic resistance in Trichoderma virens and in the hyperosmotic stress response in Trichoderma harzianum. Analyses of the function of components of the cAMP pathway during Trichoderma biocontrol revealed that mycoparasitism-associated coiling and chitinase production as well as secondary metabolism are affected by the internal cAMP level; in addition, a cross talk between regulation of light responses and the cAMP signalling pathway was found in Trichoderma atroviride.
116 citations
01 Jan 2007
92 citations
TL;DR: Results obtained by Northern blot analyses demonstrated that the genes within a family are differentially regulated in response to different culture conditions, suggesting that they have diverse functional roles.
Abstract: Proteolytic enzymes (EC 3.4) secreted by Trichoderma strains are receiving increasing attention because of their potential implication in the Trichoderma biocontrol abilities. We have used an expressed sequence tag (EST) approach to identify genes encoding extracellular peptidases in T. harzianum CECT 2413 grown under several biocontrol-related conditions. Based on BlastX results and Gene Ontology annotation, a total of 61 (among 3478) unique sequences (unisequences) were predicted to encode enzymes with peptidase activity, three corresponding to secreted peptidases already known from this Trichoderma strain (PAPA, PRA1 and P6281). Further manual screening based on the functional identity and cellular location of the best matches revealed ten unisequences encoding novel extracellular peptidases. We report the characterization of the corresponding genes as well as a potential orthologous gene of the intracellular peptidase PAPB from T. asperellum. In each case, full-length coding sequences were obtained, and deduced proteins were compared at phylogenetic level with peptidases from other organisms. T. harzianum CECT 2413 novel peptidases included six serine endopeptidases (EC 3.4.21) belonging to the families S1, S8 and S53, three aspartic endopeptidases (EC 3.4.23) of the family A1, one metallo-endopeptidase (EC 3.4.24) of the family M35, and one aminopeptidase (EC 3.4.11) of the family M28. Results obtained by Northern blot analyses demonstrated that the genes within a family are differentially regulated in response to different culture conditions, suggesting that they have diverse functional roles.
TL;DR: Under field conditions, spraying of a spore suspension of T. harzianum at 108 spore ml−1 significantly reduced the disease severity (DS) and disease incidence (DI) on the plant leaves, and also significantly increased the grain yield, total grain carbohydrate, and protein, and led to a significant increase in the total photosynthetic pigments in rice leaves.
Abstract: Rice brown spot, caused by Bipolaris oryzae, can be a serious disease causing a considerable yield loss. Trichoderma harzianum is an effective biocontrol agent for a number of plant fungal diseases. Thus, this research was carried out to investigate the mechanisms of action by which T. harzianum antagonizes Bipolaris oryzae in vitro, and the efficacy of spray application of a spore suspension of T. harzianum for control of rice brown spot disease under field conditions. In vitro, the antagonistic behavior of T. harzianum resulted in the overgrowth of B. oryzae by T. harzianum, while the antifungal metabolites of T. harzianum completely prevented the linear growth of B. oryzae. Light and scanning electron microscope (SEM) observations showed no evidence that mycoparasitism contributed to the aggressive nature of the tested isolate of T. harzianum against B. oryzae. Under field conditions, spraying of a spore suspension of T. harzianum at 10(8)spore ml(-1) significantly reduced the disease severity (DS) and disease incidence (DI) on the plant leaves, and also significantly increased the grain yield, total grain carbohydrate, and protein, and led to a significant increase in the total photosynthetic pigments (chlorophyll a and b and carotenoids) in rice leaves.
TL;DR: The results indicate that the transformation with the antifungal endochitinase gene may represent a strategy for disease control in citrus crops.
Abstract: Antifungal genes from micro-organisms were inserted into the genome of a number of plant species, representing a promising strategy for conferring genetic disease resistance against a broad range of plant pathogenic fungi. In the present study, the chit42 gene from Trichoderma harzianum (codifying the antifungal protein endochitinase) was introduced into the ‘Femminello siracusano’ lemon by Agrobacterium tumefaciens, in order to regenerate transgenic plants resistant to fungal disease. Three polymerase chain reaction (PCR)-positive clones were obtained. Southern blot confirmed the integration of the transgene in the lemon genome and revealed that one or two copies had been inserted. Reverse transcriptase-PCR, Northern blot and Western analysis were performed and the results confirmed the expression of the inserted gene. The transgenic clones were tested in vitro and in vivo for disease resistance. Conidia germination and fungal growth of Phoma tracheiphila were strongly inhibited in vitro by the transgenic foliar proteins, while no effects were observed with the controls. Disease resistance assays were performed in vivo with Botrytis cinerea, the causal agent of grey mould in fruit. Transgenic lemon plants, inoculated with lemon petals infected by a single-conidial isolate of B. cinerea, showed significantly less lesion development than the controls. On the whole, the results indicate that the transformation with the antifungal endochitinase gene may represent a strategy for disease control in citrus crops.
TL;DR: Two strains of Trichoderma harzianum used for biological control of fungal plant pathogens were investigated for the production of serine protease, chitinase and antibiotic activity in relation to entomopathogenicity, suggesting that the virulence factors involved in biocontrol are the same as those for insect pathogenicity.
TL;DR: To evaluate the biocontrol efficacy of culture filtrate containing chitinase from Trichoderma harzianum against Heliothis.
Abstract: Aims: To evaluate the biocontrol efficacy of culture filtrate containing chitinase from Trichoderma harzianum against Heliothis.
Methods and Results: T. harzianum was cultured by submerged fermentation using colloidal chitin as sole carbon source. The ability of the culture filtrate to hydrolyse colloidal chitin indicated the presence of chitinase as one of its components. Biocontrol assay on Heliothis showed that the culture filtrate is a potent antifeedant as it reduced the feeding rate and body weight of the larvae. It reduced the successful pupation and increased larval and pupal mortality in a dosage-dependent manner when applied topically. The highest mortalities (70%) were recorded for groups treated with 2000 U ml−1 chitinase activity. The percentage of adult emergence was zero for the highest chitinase concentration (2000 U ml−1) tried.
Conclusions: The studies showed that the culture filtrate containing chitinase from T. harzianum is capable of negatively affecting the growth and metamorphosis of Heliothis larvae.
Significance and Impact of the Study: In view of the need for safer and environmentally friendly pest management tools, the present study could help in the development of enzyme-based biopesticides against Heliothis.
TL;DR: The application of these formulations on chickpea and groundnut plants significantly reduced the percent mortality due to chickPEa wilt complex and groundnuts collar rot disease, respectively.
TL;DR: The results indicate that the treatment with the invert emulsion formulation of T. harzianum protected fruit from infection by the primary postharvest pathogens of the fruit tested for up to 2 months and reduced the diameters of decay lesion up to 86% and is a promising treatment to prolong the postHarvest shelf-life of fresh fruit.
TL;DR: P pH regulation is mediated by the transcriptional factor Pac1 (homologous to PacC regulator in other fungi), encoded by pac1 whose expression increases with pH, which modulates T. harzianum antifungal activity since wild type and mutants inhibit several phytopathogenic fungal strains at various degrees in different assays.
TL;DR: Results point to a significant role for Qid74 both in cell wall protection and adhesion to hydrophobic surfaces.
TL;DR: Soil solarization and Trichoderma were tested in three consecutive annual production cycles in Huelva (southwestern Spain) an environment representative of the coastal strawberry production area, to evaluate the effectiveness in enhancing strawberry yield and the relationship between Trichodyma soil population, root colonization by Trichodma, yield and root weight.
Journal Article•
TL;DR: In the present study, integrated management of stem rot disease of groundnut using a combined application of Rhizobium and Trichoderma harzianum was performed and results indicated that the application of these native micro-organisms successfully decreases the stem rot incidence and also increases the growth of the groundnut plants.
Abstract: Soil-borne plant pathogenic fungi cause heavy crop losses all over the world. With variable climate from region to region, most crops grown in India are susceptible to diseases caused by soil-borne fungal pathogens. Among tropical and subtropical land crops, groundnut (Arachis hypogaea L.) is an important oil seed crop, providing vegetable oil as human food and oil cake meal as animal poultry feed. A large number of diseases attack groundnut plants in India; of these, stem rot (collar rot) caused by Sclerotium rolfsii is the most common disease. Certain well-studied chemical pesticide management strategies are available for reducing damage by S. rolfsii, but increasing awareness about the health hazards and environmental problems due to the use of chemical pesticides resulted in the development of Integrated Pest Management. In the present study, integrated management of stem rot disease of groundnut using a combined application of Rhizobium and Trichoderma harzianum (ITCC - 4572) was performed. The results indicated that the application of these native micro-organisms successfully decreases the stem rot incidence and also increases the growth of the groundnut plants. The plant growth promoting activity and disease control ability of these microbial agents are discussed.
TL;DR: The cloning and characterization of the Trichoderma harzianum hmgR gene encoding a hydroxymethylglutaryl CoA reductase (HMGR), a key enzyme in the biosynthesis of terpene compounds, are described and a reduction in their antifungal activity against the plant-pathogen fungi Rhizoctonia solani and Fusarium oxysporum is shown.
Journal Article•
TL;DR: The cellulase production by Trichoderma harzianum MTCC 8230 was studied using rice straw as substrate that supported better cellul enzyme production than carboxymethyl cellulose (CMC).
Abstract: The cellulase production by Trichoderma harzianum MTCC 8230 was studied using rice straw as substrate that supported better cellulase production than carboxymethyl cellulose (CMC). The optimum conditions for cellulase production were (NH4)2SO4, 0.5 g L as nitrogen source, pH (5.0), temperature (28°C) and incoulum size (10 spores ml). Tween 80 (0.1%) improved the overall cellulase production as under these optimized conditions, C1, Cx and CB activities of 0.127, 0.15 and 1.65 U ml -1 respectively were produced. The enzyme was concentrated 2.65 folds with a yield of 73.8% using ammonium suplhate precipitation followed by dialysis.
TL;DR: Trichoderma harzianum reduced the severity of symptoms, expressed as ‘rhizoctonia stem lesion index’ (RSI), during the first 7 days post-inoculation when the inoculum of R. solani was placed at certain distances (30‐60 mm) from the host.
Abstract: Stem canker and black scurf are diseases of potato caused by the fungus Rhizoctonia solani . Spatiotemporal experimentation and empirical modelling were applied for the first time to investigate the effect of antagonistic Trichoderma harzianum on the dynamics of soilborne R. solani on individual potato plants. Trichoderma harzianum reduced the severity of symptoms, expressed as ‘rhizoctonia stem lesion index’ (RSI), during the first 7 days post-inoculation when the inoculum of R. solani was placed at certain distances (30‐60 mm) from the host. For example, with inoculum at 40 mm from the host, RSI was 6 and 40 with and without T. harzianum , respectively. At later observation times, the antagonistic effect was overcome. Trichoderma harzianum reduced the severity of black scurf on progeny tubers. Furthermore, the mean number of progeny tubers per potato plant was reduced by the biocontrol treatment (means of 6·5 ± 1·1 and 9·9 ± 2·7 tubers per plant with and without T. harzianum , respectively), as was the proportion of small (0·1‐20·0 g) tubers (48% and 66% with and without T. harzianum , respectively). Additionally, there were fewer malformed and green-coloured tubers in pots treated with T. harzianum than in those without T. harzianum .
TL;DR: Lack of N-acetyl-β-d-mannosamine utilization as a specific trait of strains with the chitinase-overproducing haplotype is identified and used to develop a plate screening assay for rapid microbiological identification of the strains.
Abstract: Selection of suitable strains for biotechnological purposes is frequently a random process supported by high-throughput methods. Using chitinase production by Hypocrea lixii/Trichoderma harzianum as a model, we tested whether fungal strains with superior enzyme formation may be diagnosed by DNA bar codes. We analyzed sequences of two phylogenetic marker loci, internal transcribed spacer 1 (ITS1) and ITS2 of the rRNA-encoding gene cluster and the large intron of the elongation factor 1-alpha gene, tef1, from 50 isolates of H. lixii/T. harzianum, which were also tested to determine their ability to produce chitinases in solid-state fermentation (SSF). Statistically supported superior chitinase production was obtained for strains carrying one of the observed ITS1 and ITS2 and tef1 alleles corresponding to an allele of T. harzianum type strain CBS 226.95. A tef1-based DNA bar code tool, TrichoCHIT, for rapid identification of these strains was developed. The geographic origin of the strains was irrelevant for chitinase production. The improved chitinase production by strains containing this haplotype was not due to better growth on N-acetyl-β-d-glucosamine or glucosamine. Isoenzyme electrophoresis showed that neither the isoenzyme profile of N-acetyl-β-glucosaminidases or the endochitinases nor the intensity of staining of individual chitinase bands correlated with total chitinase in the culture filtrate. The superior chitinase producers did not exhibit similarly increased cellulase formation. Biolog Phenotype MicroArray analysis identified lack of N-acetyl-β-d-mannosamine utilization as a specific trait of strains with the chitinase-overproducing haplotype. This observation was used to develop a plate screening assay for rapid microbiological identification of the strains. The data illustrate that desired industrial properties may be an attribute of certain populations within a species, and screening procedures should thus include a balanced mixture of all genotypes of a given species.
TL;DR: The study implies that it is possible to develop a dye removal system by using T. harzianum biomass, which occurs as sludge in waste stream of fermentation industries, and shows that the pseudo-second-order kinetic model provided the best correlation of the equilibrium data.
TL;DR: In contrast to other hydrolytic enzymes produced by the same T. harzianum isolate, the b-1,3-glucanase showed no effect on the cell wall of the phytopathogenic fungus Crinipellis perniciosa.
Abstract: A b-1,3-glucanase was produced by Trichoderma harzianum in cultures containing chitin as the sole substrate. Two proteins showing b-1,3-glucanase activity were purified to apparent homogeneity by hydrophobic chromatography. The molecular masses of these proteins were 29 and 36 kDa. The 36 kDa protein was further characterized. It was active on a broad pH range, and maximal activity was detected at pH 5.0. The optimum temperature of the 36 kDa b-1,3-glucanase was 50oC, but the purified enzyme was very sensitive to temperature. It lost about 60% or more of the activity after incubation for 30 min at 45, 50 and 60oC. The apparent KM and Vmax for hydrolysis of laminarin at pH 5.0 and 37oC, were 0.099 mg of reducing sugar/mL and 0.3 mg of reducing sugar/min.mL, respectively. The enzyme was insensitive to organic compound and metal ions, except for the ferric ion which inhibited about 100% of the original activity at the concentration of 1 mM. In contrast to other hydrolytic enzymes (a chitinase and a protease) produced by the same T. harzianum isolate (1051), the b-1,3-glucanase showed no effect on the cell wall of the phytopathogenic fungus Crinipellis perniciosa.
TL;DR: It might be claimed that the pesticide photodegradation may result in significant changes in soil microbiota, as well as formation of biologically harmful degradates.
Abstract: Our study aimed at acquiring information about the biological effect of pesticides and their degradates produced by UV-treatment on microbiological activity. Five photosensitive pesticides (carbendazim, acetochlor, simazine, chlorpyrifos, EPTC) and six representative soil microbes (Bacillus subtilis, Pseudomonas fluorescens, Mycobacterium phlei, Fusarium oxysporum, Penicillium expansum, Trichoderma harzianum) were applied throughout our model experiments. The antimicrobial effects of the pesticides and their degradates were assessed with filter paper disk method. The antimicrobial effect of the degradation products exhibited marked differences in terms of pesticide types, irradiation time, and the test organisms. Acetochlor and its photolytic degradation products were found to be more toxic to bacteria than fungi. All the three bacteria proved to be sensitive to the basic compound and its degradation products as well. The end product of carbendazim was weakly antibacterial against P. fluorescens and B. subtilis but strongly antifungal against T. harzianum. Chlorpyrifos and its end product inhibited neither test organisms, but the degradates hindered the growth of four of them. The basic compound of EPTC and the degradates of simazine exhibited significant toxicity to the test bacteria. It might be claimed that the pesticide photodegradation may result in significant changes in soil microbiota, as well as formation of biologically harmful degradates.
TL;DR: Investigation of the interactions between eight Trichoderma spp.
Abstract: The interactions between eight Trichoderma spp. isolates and Fusarium moniliforme were investigated. The results obtained from dual culture and the tests on volatile activity showed that the two isolates of T. harzianum T23 and T16 exhibited considerable antagonistic potential. Quantitative analysis of 6-pentyl-alpha-pyrone (6PAP), purified from culture filtrate of T. harzianum isolate T23, revealed that the optimal harvesting time for 6PAP production was 12 days post inoculation (dpi) (72.3 mg l–1). In in vitro studies, 6PAP demonstrated potent inhibitory properties upon mycelial growth and sporulation of F. moniliforme in both volatile and non-volatile tests as well as on conidia germination and length of germ tubes. Mycelial growth was inhibited by 93.5% using 250 µg ml–1 of 6PAP. Conidia production of the target fungus was inhibited by 250 µg ml–1 of 6PAP in non-volatile and volatile assays by 98.0% and 78.6%, respectively. Germ tube growth was also inhibited by more than 94% using 300 µg ml–1 of 6PAP. The results obtained demonstrated that the metabolite 6PAP exhibited rather fungistatic than fungicidal effects.
TL;DR: Only when it was applied at rooting did Trichoderma produce positive effects on the morpho-phisiological characteristics of grapevine and increased its tolerance to stress–related diseases, such as forms of esca found in the nursery.
Abstract: Summary. In order to prevent or reduce infection in grapevine nurseries, greenhouse and nursery trials were carried out to evaluate the effects of Trichoderma harzianum (Rootshield ® ) on the morpho-physiological characteristics of grapevine and on Phaeomoniella chlamydospora artificially inoculated on potted cuttings. The long-distance activity of Trichoderma against Botrytis cinerea was also examined. The study was performed in a commercial nursery where plants were grown organically. Results greatly depended on the vine-growth stage at which Trichoderma was applied. Treatment at rooting was the most effective, whilst callusing-box application or treatments at both rooting and callusing gave inconsistent but generally negative results. Treatment at rooting further improved the quantitative and qualitative characteristics of the root system, and increased the percentage of certifiable vines produced. Moreover, Trichoderma application also reduced the necrotic area caused by B. cinerea inoculated on the leaves collected from Trichoderma-treated plants and the extent of necrosis of P. chlamydospora-inoculated cuttings. This reduction in necrosis was significantly higher 15 months after inoculation. On the other hand, Trichoderma increased vine mortality at the end of the growing season compared with untreated plants. On the whole, only when it was applied at rooting did Trichoderma produce positive effects on the morpho-phisiological characteristics of grapevine and increased its tolerance to stress–related diseases, such as forms of esca found in the nursery.