Ilan Chet

Hebrew University of Jerusalem | HUJI · Department of Microbiology and Molecular Genetics

Trichoderma virens populations that were earlier classified into two strains (P and Q) based on secondary metabolites profiling are also phenotypically and genetically distinct, with the latter being ineffective in controlling the devastating, broad host range plant pathogen Sclerotium rolfsii . The two strains also provoke distinct as well as over...

List of genes and fold changes that are significantly differentially expressed in Arabidopsis roots 24 hours after application of Trichoderma as monitored by microarray analysis. (XLS)

MapMan screenshot showing the effects of Trichoderma root inoculation on the root transcriptome. The MapMan software was queried with the list of differentially regulated genes 24 hours after the application of Trichoderma. Blue shades indicate induction; Red shades indicate repression of gene expression. (PNG)

Complete overview of statistically significant enriched biological processes. (XLS)

qPCR verification of microarray data. (XLS)

Targeted LC-IT/ESIMS based quantification of indole glucosinolates in Arabidopsis roots 24 hours after colonization by T. asperelloides. Abbreviation: 4MI3MG, 4-methoxy-indol-3-ylmethylglucosinolate; 1MI3MG, 1-methoxy-3-indolyl-methyl glucosinolate; I3M, Indolyl-methyl glucosinolate. Each of the glucosinolate shows a significant difference (P<0.001...

A summary of the genes up-regulated in the microarray experiments with known role in plant hormone biosynthesis process, responses to hormone stimulation, salt tolerance and osmoprotection processes. (XLS)

Sequences of all primers used in qPCR analyses. (XLS)

Trichoderma spp. are versatile opportunistic plant symbionts which can colonize the apoplast of plant roots. Microarrays analysis of Arabidopsis thaliana roots inoculated with Trichoderma asperelloides T203, coupled with qPCR analysis of 137 stress responsive genes and transcription factors, revealed wide gene transcript reprogramming, proceeded by...

Application of crab shell chitin or pentamer chitin oligosaccharide to Arabidopsis seedlings increased tolerance to salinity in wild-type but not in knockout mutants of the LysM Receptor-Like Kinase1 (CERK1/LysM RLK1) gene, known to play a critical role in signaling defense responses induced by exogenous chitin. Arabidopsis plants overexpressing th...

Trichoderma (teleomorph Hypocrea) is a fungal genus found in many ecosystems. Trichoderma spp. can reduce the severity of plant diseases by inhibiting plant pathogens in the soil through their highly potent antagonistic and mycoparasitic activity. Moreover, as revealed by research in recent decades, some Trichoderma strains can interact directly wi...

In the present study we have assessed, by transcriptional and metabolic profiling, the systemic defence response of Arabidopsis thaliana plants to the leaf pathogen Pseudomonas syringae pv. tomato DC3000 (Pst) induced by the beneficial fungus Trichoderma asperelloides T203. Expression analysis (qPCR) of a set of 137 Arabidopsis genes related to Pst...

Trichoderma species are free-living fungi that are common in soil and root ecosystems. Some strains establish root colonization and enhance growth and development, crop productivity, resistance to abiotic stresses and uptake and use of nutrients. Trichoderma species can antagonize and control a wide range of economically important plant pathogenic...

Trichoderma harzianum excreted β-1, 3-glucanase and chitinase into the medium when grown on laminarin and chitin, respectively, or on cell walls of the pathogen Sclerotium rolfsii, as sole carbon source. Trichoderma harzianum also showed high activity of both enzymes when grown on homogenized S. rolfsii sclerotia. Glucanase activity increased by 67...

Sclerotium rolfsii, grown in a shaken submerged culture, developed a potential for the formation of sclerotia. This potential was inhibited by the presence of glucose in the culture medium. The cultures were capable of producing sclerotia, after transfer to stationary incubation, when glucose was exhausted and the biomass reached its maximal level....

Sublethal heating of sclerotia of Sclerotium rolfsii at 50 °C for 30 min increased leakage of 14C-labelled water-soluble organic compounds from the sclerotia, and increased their colonization by bacteria and streptomycetes 574- and 1420-fold, respectively. Disease incidence in bean plants inoculated with heat-treated sclerotia was 43% less than dis...

Protoplasts from two auxotrophic mutants of Trichoderma harzianum Rifai (ATCC 32173), obtained from young thalli following cell wall digestion by NovoZym 234, were fused in 33% PEG suspended in 10 mM Tris-HCl and 10 mM CaCl2, pH 7.5. The frequency of fusion between lysine- and arginine-requiring auxotrophs resulting in prototrophic strains was abou...

The effects of carbohydrates, amino acids, sulphur-containing compounds, temperature, pH, and light on growth and sclerotium production in Aspergillus ochraceus were studied. The maximal number of sclerotia was formed on medium containing sucrose at a concentration of 2 × 10−1 M, while on the lactose, galactose, and arabinose media no sclerotia wer...

Studies on the germination of Trichoderma viride spores indicate that they lose their resistance to heat at an early stage of germination. Whereas dormant conidia were resistant to 46 °C, the same treatment given 4 h after the onset of germination was lethal to the germinating spores. A milder thermal treatment (45 °C for 10 min) given during the f...

Sclerotia of Sclerotium rolfsii germinated without the addition of an exogenous nutrient source. The germinating sclerotia excreted sugars and amino acids to the surrounding medium. Continuous washing of sclerotia prevented germination. In germinating sclerotia, the rate of uptake and incorporation into macromolecules of [3H]uridine and[3H]leucine...

Five sediments of extracellular, soluble polysaccharides were extracted from washings of Sclerotium rolfsii Sacc. grown in submerged culture. Only the first sediment contained the β-(1—3)-glucan. laminarin, which was degradable by an endo β-(1—3)-glucanase extracted from S. rolfsii. The four remaining sediments were glycoproteins differing in their...

Sclerotial initials of Sclerotium rolfsii reached the maturation phase when transferred onto a new growth medium only if taken from original medium with their surrounding mycelium; but when transferred onto a medium supplemented with 10−4 M iodoacetic acid or 10−2−10−3 M disodium ethylene-diaminetetraacetic acid (Na2EDTA), initials continued their...

Punctured sclerotia of Sclerotium rolfsii Sacc. germinated more rapidly than unpunctured ones, especially on water agar. Discs of agar with mycelium and sclerotia in different stages of development were transferred to medium supplemented with 14C-iodoacetic acid. The radioisotope was not incorporated into mature sclerotia. It was concluded that the...

In the frame of the TrichoNema (EU, Marie Curie) project, several Trichoderma species and isolates have been tested against plant-parasitic nematodes. The main targets are the root-knot nematodes Meloidogyne incognita and M. javanica, which are polyphagous sedentary-endoparasitic species, damaging worldwide. Biocontrol pot experiments are conducted...

1-aminocyclopropane-1-carboxylate (ACC) deaminase activity was evaluated in the biocontrol and plant growth-promoting fungus Trichoderma asperellum T203. Fungal cultures grown with ACC as the sole nitrogen source showed high enzymatic activity. The enzyme encoding gene (Tas-acdS) was isolated, and an average 3.5-fold induction of the gene by 3 mM A...

A new family of synthetic, membrane-active, ultrashort lipopeptides composed of only four amino acids linked to fatty acids was tested for the ability to induce systemic resistance and defense responses in plants. We found that two peptides wherein the third residue is a d-enantiomer (italic), C16-KKKK and C16-KLLK, can induce medium alkalinization...

p align="justify"> Se evaluó la eficacia biológica de ocho aislamientos de Trichoderma spp. provenientes de suelos de Colombia para el control de los agentes causales de volcamiento, Sclerotium rolfsii y Rhizoctonia solani , bajo condiciones in vitro y de invernadero. Los análisis in vitro mostraron la capacidad antagónica de todos los aislamientos...

Swollenin, a protein first characterized in the saprophytic fungus Trichoderma reesei, contains an N-terminal carbohydrate-binding module family 1 domain (CBD) with cellulose-binding function and a C-terminal expansin-like domain. This protein was identified by liquid chromatography-mass spectrometry among many other cellulolytic proteins secreted...

The main purpose of this work was to study the host-parasite relationship between attacking fungi and the infected climacteric fruit. The study dealt mainly with physiological changes such as respiration and ethylene evolution pattern occurring in fruit inoculated with different fungi after picking. These physiological changes in infected fruit wer...

The enzymatic activity and the biocontrol ability of two new isolates of Trichoderma spp. (T-68 and Gh-2) were compared in laboratory and glasshouse experiments with a previously studied T. harzianum strain (T-35). In dual culture tests with Fusarium oxysporum f. sp. melonis and F. oxysporum f. sp. vasinfectum, isolates T-68 and Gh-2 overgrew the c...

Crops e. g., pecan, persimmon and passionflower, which show resistance to the fungus Dematophora necatrix, the causal agent of white root rot disease, contain phenolic compounds which inhibit its growth. Roots of resistant crops contain higher concentrations of phenolic compounds than those of suceptible crops, e. g., apple, almond and peach. The f...

The uhrastructural changes during parasitism of the biocontrol agents Trichoderma harzianum and T. hamatum, were observed under a transmission electron microscope. Electron micrographs show that during the interaction of Trichoderma spp. with either Sclerotium rolfsii or Rhizoctonia solani the hyphae of the parasites contact their host, and then en...

A new isolate of Trichoderma harzianum (T-35) was isolated from the rhizosphere of cotton plants from a field infested with Fusarium. Under glasshouse conditions, the antagonist was applied to soil growing in a bran/peat mixture (1:1, v/v) or as a conidial suspension or used as a seed coating. When T. harzianum was tested against Fusarium oxysporum...

Monoclonal and polyclonal antibodies that bind to eggs and/or second-stage juveniles of the nematode Meloidogyne javanica were tested for their effects on the parasitic interactions between this nematode and the fungus Trichoderma. Parasitism of Trichoderma asperellum-203 and Trichoderma atroviride on nematode egg masses, eggs and juveniles was enh...

SUMMARY Peptaibols, the products of non-ribosomal peptide synthetases (NRPS), are linear peptide antibiotics produced by Trichoderma and other fungal genera. Trichoderma virens strain Gv29-8, a well-known biocontrol agent and inducer of plant defence responses, produces three lengths of peptaibols, 11, 14 and 18 residues long, with several isoforms...

Plant diseases constitute an emerging threat to global food security. Many of the currently available antimicrobial agents for agriculture are highly toxic and nonbiodegradable and cause extended environmental pollution. Moreover, an increasing number of phytopathogens develop resistance to them. Recently, we have reported on a new family of ultras...

Trichoderma (T. asperellum-203, 44 and GH11; T. atroviride-IMI 206040 and T. harzianum-248) parasitism on Meloidogyne javanica life stages was examined in vitro. Conidium attachment and parasitism differed beween the fungi. Egg masses, their derived eggs and second-stage juveniles (J2) were parasitized by Trichoderma asperellum-203, 44, and T. atro...

Application of cells of two isolates of fluorescent pseudomonads from soil to wheat seedlings prior to inoculation with Mycosphaerella graminicola (anamorph, Septoria tritici) or Puccinia recondita f.sp. tritici markedly reduced symptom expression. These Pseudomonas isolates, LEC 1 and LEC 2. also reduced in vitro growth of Geotrichum candidum. Rhi...

A fluorescent Pseudomonas sp. (strain LEC 1) isolated from soil suppressed Septoria tritici by 88% and Puccinia recondita by 98% when applied to wheat seedlings 3 h prior to inoculation with the pathogens. Fractionation and analysis of two inhibitory compounds from cultures of strain LEC 1 on thin-layer chromatography plates yielded the phenazine a...

Under laboratory conditions, isolate TH–203 of Trichoderma harzianum was found to be tolerant of up to 20 000 ppm methyl bromide (MB) (v/v), whereas the plant pathogen Rhizoctonia solani was susceptible to a dose of less than 9000 ppm (v/v). Exposure to sub–lethal concentrations of MB had no effect on the in vitro antagonistic ability of T. harzian...

A preparation of Trichoderma harzianum was sprayed on cucumber plants in greenhouses in order to control fruit and stem grey mould. Up to 90% control was achieved by the biocontrol agent (0·5–1·0 g/l) which in most experiments under commercial conditions was as effective as the dicarboximide fungicides iprodione or vinclozolin (0·5 g/l each) alone...

The fungal biocontrol agent Trichoderma asperellum has been recently shown to induce systemic resistance in plants through a mechanism that employs jasmonic acid and ethylene signal transduction pathways. Mitogen-activated protein kinase (MAPK) proteins have been implicated in the signal transduction of a wide variety of plant stress responses. Her...

SUMMARY A hydrophobin-like clone (TasHyd1) was isolated during a PCR differential mRNA display analysis conducted on Trichoderma asperellum mycelia interacting with plant roots. The open reading frame encodes a 145-amino-acid protein showing similarity to Pbhyd1, a Class I hydrophobin from the dimorphic fungus Paracoccidioides brasiliensis. TasHyd1...

The broad host range of arbuscular mycorrhizal (AM) fungi differs from the specificity encountered in biotrophic pathogens. We summarize here the basic plant strategies of defence plant responses to colonization with pathogenic micro-organisms and evaluate their possible involvement in AM performance. Detailed evidence is presented that, during ear...

Two biological control agents of Serratia plymuthica, strains IC1270 and IC14 applied separately and in combination were evaluated for suppressing Penicillium digitatum (green mould) or Penicillium italicum (blue mould) on orange. These bacteria were effective and controlled both pathogens at 1×108cells/mL. Disease suppression was increased when bo...

Comprehensive studies in our laboratory revealed the nematicidal potential of waste products from crustacean shells, or other proteinaceous compounds, for controlling species of several plant-parasitic nematodes. The bacteria Telluria chitinolytica sp. nov, and Bacillus cereus, which were isolated, grown and identified in our laboratory, appeared t...

To study the regulation of expression of the Serratia plymuthica gene chiA encoding a 58-kDa endochitinase, its 586-bp-long upstream regulatory region was cloned, sequenced and fused to a promoterless lac operon in phage lambdaRS45 to obtain a single-copy transcriptional fusion (P F1chiA )-lac in lysogens of Escherichia coli wild-type strains or th...

The role of a mitogen-activated protein kinase (MAPK) TmkA in inducing systemic resistance in cucumber against the bacterial pathogen Pseudomonas syringae pv. lacrymans was investigated by using tmkA loss-of-function mutants of Trichoderma virens. In an assay where Trichoderma spores were germinated in proximity to cucumber roots, the mutants were...

Improved viability and antagonistic activity of biocontrol agents during soil inoculation is of crucial importance to their effective application. The chitinolytic bacterium Serratia marcescens was used as a model organism to study the efficacy of freeze-dried alginate beads (in comparison to their non-dried counterparts) as possible carriers for i...

The effectiveness of di-nitrogen tetroxide (DNTO) as a substitute for methyl bromide in controlling soil-borne nematodes, fungi and bacteria was evaluated. Application of DNTO to soil packed into columns resulted in a reduction of the bacterial population by three orders of magnitude within 1 h, and a complete elimination after 2 h. The same treatm...

ABSTRACT Trichoderma spp. are effective biocontrol agents for a number of soilborne plant pathogens, and some are also known for their ability to enhance plant growth. It was recently suggested that Trichoderma also affects induced systemic resistance (ISR) mechanism in plants. Analysis of signal molecules involved in defense mechanisms and applica...

Immobilization refers to the prevention of free cell movement by natural or artificial means. It has always been assumed that immediately after an immobilization procedure is performed, cells are distributed homogeneously in the beads that entrap them. However, in this study, Escherichia coli and Trichoderma asperellum distribution in alginate-gel...

Trichoderma asperellum and cucumber seedlings were used as a model to study the modulation of Trichoderma gene expression during plant root colonization. Seedlings were grown in an aseptic hydroponics medium and inoculated with Trichoderma spore suspension. Proteins differentially secreted into the medium were isolated. Three major proteins of fung...

The biocontrol activity of various fluorescent pseudomonads towards plant-pathogenic fungi is dependent upon the GacA/GacS-type two-component system of global regulators and the RpoS transcription sigma factor. In particular, these components are required for the production of antifungal antibiotics and exoenzymes. To investigate the effects of the...

Trichoderma asperellum is a mycoparasitic fungus which is used as a biocontrol agent against plant pathogens. Its hydrolytic enzymes take part in its parasitic interaction, degrading the pathogen cell wall and thereby helping to control disease. One of those enzymes, beta- N-acetyl- d-glucosaminidase (GlcNAcase), degrades chitin, which is a major c...

Freeze-dried hydrocolloid beads can be used as carriers for many food, non-food and biotechnological operations. Information on their shape and surface properties, how different features are produced on their outer surface as a result of technological procedures, and the influence of fillers and other ingredients on external and internal shape and...

Trichoderma spp. are free-living fungi that are common in soil and root ecosystems. Recent discoveries show that they are opportunistic, avirulent plant symbionts, as well as being parasites of other fungi. At least some strains establish robust and long-lasting colonizations of root surfaces and penetrate into the epidermis and a few cells below t...

Most studies on the reduction of disease incidence in soil treated with Trichoderma asperellum have focused on microbial interactions rather than on plant responses. This study presents conclusive evidence for the induction of a systemic response against angular leaf spot of cucumber (Pseudomonas syringae pv. lachrymans) following application of T....

Soil microorganisms in general and biocontrol agents in particular are very sensitive to UV light. The packaging of biocontrol microorganisms into cellular solids has been developed as a means of reducing loss caused by exposure to environmental UV radiation. The bacterial and fungal biocontrol agents Pantoea agglomerans and Trichoderma harzianum w...

Plant-associated strain IC14 of the Gram-negative bacterium Serratia plymuthica isolated from soil around melon roots was shown to suppress a wide range of phytopathogenic fungi in vitro. Foliar application of strain IC14 protected cucumber against Botrytis cinerea gray mold and Sclerotinia sclerotiorum white mold diseases of leaves under greenhous...

Improved viability of Gram-negative bacteria during freeze-dehydration, storage, and soil inoculation is of crucial importance to their efficient application. The chitinolytic Pantoae (Enterobacter) agglomerans strain IC1270, a potential biocontrol agent of soil-borne plant-pathogenic fungi, was used as a model organism to study the efficacy of fre...

The use of specific mycolytic soil microorganisms to control plant pathogens is an ecological approach to overcome the problems caused by standard chemical methods of plant protection. The ability to produce lytic enzymes is a widely distributed property of rhizosphere-competent fungi and bacteria. Due to the higher activity of Trichoderma spp. lyt...

The presence of the endochitinase CHIT36 from Trichoderma harzianum TM was assessed in several antagonistic Trichoderma strains belonging to different molecular taxonomic groups. CHIT37 from T. harzianum CECT 2413 was sequenced and found to display 89% homology with CHIT36 at the amino acid level. Northern analysis showed that chit36Y from T. asper...

The soil fungus Trichoderma atroviride, a mycoparasite, responds to a number of external stimuli. In the presence of a fungal host, T. atroviride produces hydrolytic enzymes and coils around the host hyphae. In response to light or nutrient depletion, asexual sporulation is induced. In a biomimetic assay, different lectins induce coiling around nyl...

Summary • Phytohormones are known to play a pivotal role in various developmental processes in plants and in arbuscular–mycorrhizal (AM) fungal–host symbiosis. This study focuses on characterizing the changes in the concentrations of auxins, cytokinins and gibberellins in tobacco (Nicotiana tabacum) during the early stages of colonization by Glomus...

Transgenic canola plants containing high, constitutive levels of bean endochitinase have been shown to be more resistant to infection by the soil-borne pathogen, Rhizoctonia solani, than are wild-type plants that lack the chimeric chitinase gene. To determine whether the resistance of the 35S-chitinase plants to Rhizoctonia infection results from a...

Biocontrol of Soilborne Diseases

The potential of the biocontrol agent Trichoderma harzianum strain T-203 to induce a growth response in cucumber plants was studied in soil and under axenic hydroponic growth conditions. When soil was amended with T. harzianum propagules, a 30% increase in seedling emergence was observed up to 8 days after sowing. On day 28, these plants exhibited...

ABSTRACT The fungal biocontrol agent, Trichoderma harzianum, was evaluated for its potential to control the root-knot nematode Meloidogyne javanica. In greenhouse experiments, root galling was reduced and top fresh weight increased in nematode-infected tomatoes following soil pretreatment with Trichoderma peat-bran preparations. The use of a protei...

A novel 36-kDa endochitinase named chit36 has been isolated and characterized from Trichoderma harzianum Rifai TM. Partial amino acid sequences from the purified protein were used to clone the fungal cDNA, based on polymerase chain reaction with degenerate primers. The complete open reading frame encodes a 344-amino acid protein which shows 84% sim...

Defense responses of alfalfa roots to the pathogenic fungus Rhizoctonia solani were reduced significantly in roots simultaneously infected with the vesicular arbuscular mycorrhizal (AM) fungus Glomus intraradices. R. solani induced five- to tenfold increases in the steady-state levels of chalcone isomerase and isoflavone reductase mRNAs a doubling...

A rapid and convenient method for the detection of chitinases accumulating in filamentous fungal cultures was developed. The assay is performed on cultures growing in microtiter plates, with a fluorogenic substrate: 4-methylumbelliferyl-N-acetyl-d-glucosaminide (4-MeUNAG). The fluorescence of the product, 4-methylumbelliferone, was detected. This m...

The biochemical nature of the interaction between the antagonistic fungus Trichoderma harzianum strain T-203 and cucumber roots was studied during the early stages of root colonization by the fungus. Pathogenesis related (PR) proteins of the plant and enzyme activity of the fungus following the penetration and colonization of the roots by T. harzia...

New nematode control measures are required due to the likely removal of effective nematicides from the market because of increasing concerns of possible effects on human health and the environment. Biological control, organic and inorganic soil amendments, naturally occurring nematicides, induced resistance, interruption of host recognition and tra...

Nematode control methods without using nematicides have been studied. Biological control by nematode antagonists, use of soil amendments to build up antagonistic microorganisms and release toxic compounds to nematodes, detection of naturally occurring nematicides in plants, interruption of nematode's host-recognition process and study of nematode c...

The β-1,3-glucanase system of the mycoparasitic T. harzianum, isolate T-Y, was found to be composed of at least five different enzymes. Their migration distance in acrylamide gels corresponded to peptides with molecular masses of 30–200 kDa, and they were named accordingly. The largest enzyme —Gβ-1,3–200, was the most abundant when T-Y was grown wi...

The development of leaf disease symptoms and the accumulation of pathogenesis-related (PR) proteins were monitored in leaves of tobacco (Nicotiana tabacum cv. Xanthinc) plants colonized by the arbuscular mycorrhizal fungus Glomus intraradices. Leaves of mycorrhizal plants infected with the leaf pathogens Botrytis cinerea or tobacco mosaic virus sho...

The mycoparasite Trichoderma harzianum, a biocontrol agent, forms coils and other mycoparasitic structures upon contact with host fungi. A biomimetic system consisting of nylon fibres was used to test the involvement of signal transduction pathways in the induction of coils. Two activators of G protein-mediated signal transduction induced coiling o...

Zielsetzung Im Rahmen der Arbeiten sollten durch die Kombination von chemischen, enzymologischen und verfahrenstechnischen Untersuchungen Erkenntnisse ber die ersten Schritte gewonnen werden, die beim Holzabbau durch Pilze ablaufen und welche Auswirkungen diese auf die Verarbeitung des Holzes ausben. Dabei wurde von der These ausgegangen, da eine V...