Showing papers on "Trichoderma harzianum published in 1994"
TL;DR: When the enzymes and the peptaibols were tested together, an antifungal synergistic interaction was observed and the 50% effective dose values obtained were in the range of those determined in the culture supernatants.
Abstract: Chitinase, beta-1,3-glucanase, and protease activities were formed when Trichoderma harzianum mycelia, grown on glucose as the sole carbon source, were transferred to fresh medium containing cell walls of Botrytis cinerea. Chitobiohydrolase, endochitinase, and beta-1,3-glucanase activities were immunologically detected in culture supernatants by Western blotting (immunoblotting), and the first two were quantified by enzyme-linked immunosorbent assay. Under the same conditions, exogenously added [U-14C]valine was incorporated in acetone-soluble compounds with an apparent M(r) of < 2,000. These compounds comigrated with the peptaibols trichorzianines A1 and B1 in thin-layer chromatography and released [U-14C]valine after incubation in 6N HCl. Incorporation of radioactive valine into this material was stimulated by the exogenous supply of alpha-aminoisobutyric acid, a rare amino acid which is a major constituent of peptaibols. The obtained culture supernatants inhibited spore germination as well as hyphal elongation of B. cinerea. Culture supernatants from mycelia placed in fresh medium without cell walls of B. cinerea did not show hydrolase activities, incorporation of [U-14C]valine into peptaibol-like compounds, and inhibition of fungal growth. Purified trichorzianines A1 and B1 as well as purified chitobiohydrolase, endochitinase, or beta-1,3-glucanase inhibited spore germination and hyphal elongation, but at concentrations higher than those observed in the culture supernatants. However, when the enzymes and the peptaibols were tested together, an antifungal synergistic interaction was observed and the 50% effective dose values obtained were in the range of those determined in the culture supernatants. Therefore, the parallel formation and synergism of hydrolytic enzymes and antibiotics may have an important role in the antagonistic action of T. harzianum against fungal phytopathogens.
450 citations
TL;DR: Four cell wall-degrading enzymes were tested as mixtures containing two, three, or all four proteins in all possible combinations and their antifungal activity was compared with that obtained for an endochitinase and a chitin 1,4-β-chitobiosidase.
Abstract: A glucan 1,3-β-glucosidase (EC 3.2.1.58) and an N-acetyl-β-glucosaminidase (EC 3.2.1.30) were purified to homogeneity from the culture filtrate of Tricloderma harzianum strain PI. The molecular masses and the pIs were 78 kDa and 6.2, respectively, for the glucan 1,3-β-glucosidase and 72 kDa and 4.6, respectively, for the N-acetyl-β-glucosaminidase. The glucan 1,3-β-glucosidase and the N-acetyl-β-glucosaminidase were tested against Botrytis cinerea, and their antifungal activity was compared with that obtained for an endochitinase and a chitin 1,4-β-chitobiosidase also purified from T. harzianun strain P1. The four cell wall-degrading enzymes were also tested as mixtures containing two, three, or all four proteins in all possible combinations [...]
273 citations
TL;DR: Results revealed the Trichoderma-treated plants to be more resistant to damping-off disease and to be much more developed and vigorous and had higher chlorophyll contents.
Abstract: Trichoderma harzianum was applied to cucumber and pepper seedlings as a peat-bran preparation incorporated into the propagative mixture in a commercial production nursery. On marketing day (after 18 and 30 days for cucumber and pepper, respectively), significant increases of 23.8% and 17.2% in seedling height, 96.1% and 50% in leaf area, and 24.7% and 28.6% in plant dry weight were observed in cucumber and pepper seedlings, respectively, as compared to their non-treated counterparts.Trichoderma-treated seedlings were much more developed and vigorous and had higher chlorophyll contents. No significant differences were found in N, P or K content between treatments. Cucumber seedlings were then transplanted to a commercial greenhouse and analyzed over two successive growth cycles following soil fumigation with methyl bromide (500 kg/ha). Results revealed theTrichoderma-treated plants to be more resistant to damping-off disease. During the first cycle, immediately after soil fumigation, no damping-off was observed with either treatment, except in border beds where 4% of the non-treated plants died, as compared to no damping-off in theTrichoderma-treated plants. During the second growing cycle however, significant reductions in damping-off of 67% and 52% were obtained in middle and border beds, respectively, as compared to the non-treated controls.
234 citations
TL;DR: A gene (ech-42) coding for one of the endochitinases produced by the biocontrol agent Trichoderma harzianum IMI206040 was cloned and characterized as mentioned in this paper.
Abstract: A gene (ech-42; previously named ThEn-42) coding for one of the endochitinases produced by the biocontrol agent Trichoderma harzianum IMI206040 was cloned and characterized. Expression of the cDNA clone in Escherichia coli resulted in bacteria with chitinase activity. This chitinase has been shown to have lytic activity on Botrytis cinerea cell walls in vitro. The ech-42 gene was assigned to a double chromosomal band (chromosome V or VI) upon electrophoretic separation and Southern analysis of the chromosomes. Primer extension analysis indicated that transcription of the gene begins preferentially 109 bp upstream of the translation initiation codon. Expression of ech-42 was strongly enhanced during direct interaction of the mycoparasite with a phytopathogenic fungus when confronted in vitro and by growing it in minimal medium containing chitin as sole carbon source. Similarly, light-induced sporulation resulted in high levels of transcript, suggesting developmental regulation of the gene. The implications of these findings are discussed.
227 citations
TL;DR: Among enzymes tested, the highest levels of synergism with synthetic fungicides were detected for the endochitinase from T. harzianum strain P1, which was the most effective chitinolytic enzyme against phytopathogenic fungi of those tested.
Abstract: Different classes of cell wall degrading enzymes produced by the biocontrol fungi Trichoderma harzianum and Gliocladium virens inhibited spore germination of Botrytis cinerea in a bioassay in vitro. The addition of any chitinolytic or glucanolytic enzyme to the reaction mixture synergistically enhanced the antifungal properties of five different fungitoxic compounds against B. cinerea. The chemicals tested were gliotoxin, flusilazole, miconazole, captan and benomyl. Dose response curves were determined for each combination of toxin and enzyme, and in all cases the ED50 values of the mixtures were substantially lower than ED50 values of the two compounds used alone. For instance, the addition of endochitinase from T. harzianum at a concentration of 10λg ml-1 reduced the ED50 values of toxins up to 86-fold. The level of synergism appeared to be higher when enzymes were combined with toxins having primary sites of action associated with membrane structure, compared with pesticides having multiple or cytoplasmic sites of action. Among enzymes tested, the highest levels of synergism with synthetic fungicides were detected for the endochitinase from T. harzianum strain P1, which, when used alone, was the most effective chitinolytic enzyme against phytopathogenic fungi of those tested. The use of hydrolytic enzymes to synergistically enhance the antifungal ability of fungitoxic compounds may reduce the impact of some chemical pesticides on plants and animals.
215 citations
TL;DR: A cDNA of Trichoderma harzianum (chit42), coding for an endochitinase of 42 kDa, has been cloned using synthetic oligonucleotides corresponding to aminoacid sequences of the purified chit inase, revealing post-translational processing of a putative signal peptide and a second peptide of 12 amino acids.
Abstract: A cDNA of Trichoderma harzianum (chit42), coding for an endochitinase of 42 kDa, has been cloned using synthetic oligonucleotides corresponding to aminoacid sequences of the purified chitinase. The cDNA codes for a protein of 423 amino acids. Analysis of the N-terminal amino-acid sequence of the chitinase, and comparison with that deduced from the nucleotide sequence, revealed post-translational processing of a putative signal peptide of 22 amino acids and a second peptide of 12 amino acids. The chit42 sequence presents overall similarities with filamentous fungal and bacterial chitinases and to a lesser extent with yeast and plant chitinases. The deduced aminoacid sequence has putative catalytic, phosphorylation and glycosylation domains. Expression of chit42 mRNA is strongly induced by chitin and chitin-containing cell walls and is subjected to catabolite repression. Southern analysis shows that it is present as a single-copy gene in T. harzianum. chit42 is also detected in several tested mycoparasitic and non-mycoparasitic fungal strains.
147 citations
TL;DR: The genetic diversity in Trichoderma harzianum isolates from mushroom compost was assessed using various molecular techniques and group 2 isolates could be clearly distinguished from the isolates belonging to the other two groups.
Abstract: The genetic diversity in Trichoderma harzianum isolates from mushroom compost was assessed using various molecular techniques. Restriction fragment length polymorphism (RFLP) analysis of ribosomal DNA (rDNA) and mitochondrial DNA (mtDNA) divided the 81 isolates into three major groups, 1, 2 and 3. There was no variation within a group in rDNA, while a low degree of polymorphism was detected in mtDNA. Random amplified polymorphic DNA (RAPD) analysis of 30 randomly chosen isolates, with six primers, in general confirmed the RFLP groups. Nucleotide sequence determination of rDNA internal transcribed spacer (ITS) 1 revealed three distinct ITS types, 1, 2 and 3, possessed by isolates from the respective groups 1, 2 and 3. Based on these molecular data, group 2 isolates, which are aggressive colonizers of mushroom compost, could be clearly distinguished from the isolates belonging to the other two groups.
130 citations
TL;DR: Six Trichoderma spp.
Abstract: In a series of repeated trials, six Trichoderma spp strains, applied as a dried powder from a liquid fermentation in molasses/yeast medium, proved to be consistent at promoting the growth of lettuce (Latuca sativa L) seedlings grown in a peat-sand potting compost in the glasshouse Strains WT, 92, 20, and 75 at 075% or 1% w:w concentrations increased shoot dry weight by up to 26%, although WT did inhibit germination For example, after 4 days only 13% of seeds sown in WT 1% w:w treated compost had germinated, whereas in other treatments germination was consistently greater than 32% WT increased shoot fresh and dry weights by 143 g and 06 g per pot, respectively, without affecting the root dry weights, to give concomitant increases in shoot: root ratios of fresh and dry weight The potential use of these Trichoderma spp strains for plant growth promotion is discussed
127 citations
TL;DR: Saprophytic yeasts were screened for their ability to reduce the sporulation of Botrytis cinerea and the severity of gray mold and one isolate of Rhodotorula glutinis and two isolatcs of Cryptococcus albidus effectively controlled disease on bean and tomato plants.
Abstract: Saprophytic yeasts were screened for their ability to reduce the sporulation of Botrytis cinerea and the severity of gray mold. One isolate of Rhodotorula glutinis and two isolatcs of Cryptococcus albidus effectively controlled disease on bean and tomato plants. Their ability to reduce the germination of conidia and the severity of rot symptoms on detached leaves and to control the disease on whole plants at calculated concentrations of 750-7,500 cells per square centimeter under growth-room conditions was consistently as effective as the known biological control agent Trichoderma harzianum T39 (unformulated). Glucose and KH 2 PO 4 (0.02 M each) were added to conidial suspensions of B. cinerea to enhance infection
126 citations
TL;DR: It is suggested that alternate sprays of the biocontrol preparation with a fungicide should be employed in vineyards in order to reduce the use of chemicals.
113 citations
TL;DR: A strong relationship was found between the production of the pyrone by T. harzianum and the antagonistic ability of this fungus in vitro and the germination of Fusarium spores.
TL;DR: Harzianum A showed no cytotoxicity against baby hamster kidney cells, no activity against Gram-negative and Gram-positive bacteria, but modest antifungal activity at 100 micrograms/ml.
Abstract: A new trichothecene, harzianum A [1], was isolated from the soil-borne fungus Trichoderma harzianum. The structure of 1 was determined by extensive spectral analyses including the nmr techniques of PS-COSY, HMQC, HMBC, and NOESY. Harzianum A [1] contains a (Z,E,E)-2,4,6-octatriendioic acid esterified on the 4 beta hydroxyl group of trichodermol and is structurally related to the trichoverroids. Harzianum A [1] showed no cytotoxicity against baby hamster kidney cells, no activity against Gram-negative and Gram-positive bacteria, but modest antifungal activity at 100 micrograms/ml.
TL;DR: Using a biomimetic system based on binding of the lectin to the surface of inert nylon fibres revealed that the presence of the purified agglutinin on thesurface of the fibres specifically induced mycoparasitic behaviour in Trichoderma harzianum.
Abstract: A novel lectin was isolated and purified from the culture filtrate of the soilborne plant pathogenic fungus Sclerotium rolfsii by anion-exchange chromatography using a DEAE-Sepharose column. The lectin came through column with the flow-through, whereas all the non-agglutinating proteins present in the crude preparation remained bound to the column until elution in a NaCI gradient. SDS-PAGE analysis of the agglutinating fraction revealed single band corresponding to a protein with a molecular mass of approximately 45 kDa. Agglutination of Escherichia coli cells by the purified lectin was not inhibited by any of the mono- or disaccharides tested, wheres the glycoproteins mucin and asialomucin did inhibit agglutination. Protease as well as 1,3-β-glucanase, were found to be totally destructive to agglutination activity, indicating that both protein and 1,3-β-glucan are necessary for agglutination. Using a biomimetic system based on binding of the lectin to the surface of inert nylon fibres revealed that the presence of purified agglutinin on the surface of the fibres specifically induced mycoparasitic behaviour in Trichoderma harzianum. Trichoderma formed tightly adhering coils, which were significantly more frequent with the purified agglutinin-treated fibres than with untreated ones or with those treated with non-agglutinating extracellular proteins from S. rolfsii. Other mycoparasite-related structures, such as appressorium-like bodies and hyph loops, were only observed in the interaction between T. harzianum and the purified agglutinin-treated fibres.
TL;DR: Four fungi capable of reducing the incidence of onion white rot relative to the untreated control in two soil-box trials are demonstrated.
Abstract: Four fungi (Chaetomium globosum, Trichoderma viride, T. harzianum, Trichoderma sp.) capable of reducing the incidence of onion white rot relative to the untreated control in two soil-box trials. When applied as a soil additive (sand: bran: fungal homogenate, 1:1:2) at the rate of 0-1% wheat bran/g dry soil, all fun gal isolates provided levels of disease control equivalent to the fungicide (procymidone 0-5 g a.i./100 g seed) treatment. The best results were achieved with the Chaetomium globosum and Trichoderma (C62) isolates which gave 78% and 73% control of white rot, respectively, in trial 1 and 67% and 73% control, respectively, in trial 2. Reduced control was observed when the test fungi were applied as seed coatings or incorporated into alginate pellets [...]
TL;DR: Sixty isolates of saprophytic microorganisms were screened for their ability to reduce the severity of grey mould infection and sporulation and most of these selected fungi and bacteria were capable of reducing lesion expansion.
Abstract: Sixty isolates of saprophytic microorganisms were screened for their ability to reduce the severity of grey mould (Botrytis cinerea) infection and sporulation. Isolates of the bacteriaXanthomonas maltophilia, Bacillus pumilus, Lactobacillus sp., andPseudomonas sp. and the fungusGliocladium catenulatum reduced germination of conidia of the pathogen and controlled disease on bean and tomato plants. Their activity under growth room conditions was good, consistent, and similar to the activity of the known biocontrol agent,Trichoderma harzianum T39 (non-formulated). Although the tested isolates may for nutrients with the germinating conidia ofB. cinerea, resistance induced in the host by live or dead cells were also found to be involved. Inhibitory compounds were not detected on treated leaves. Sporulation ofB. cinerea after its establishment on leaves was also reduced by the above mentioned isolates and byPenicillium sp.,Arthrinium montagnei, Ar. phaeospermum, Sesquicillium candelabrum, Chaetomium globosum, Alternaria alternata, Ulocladium atrum, andT. viride. These sporulation-inhibiting fungi did not reduce the infection of leaves byB. cinerea. Most of these selected fungi and bacteria were capable of reducing lesion expansion.
TL;DR: The specific mechanisms promoting increased biocontrol capacity of insect + fungus combinations, though not clearly defined here, must lie within a complex of factors including preference of R. solani as a food source for P. minuta, aversion of the insect to the two sporulating Hyphomycetes used for biOControl, and direct parasitism of P. Solani by the fungal agents.
Abstract: A rhizosphere-inhabiting collembolan, Proisotoma minuta (Insecta: Isotomidae), and three known biocontrol fungi were studied in sterilized and non-sterilized soil for suppression of Rhizoctonia solani on cotton in a greenhouse environment. R. solani in dried oat culture was incorporated into soil at four inoculum densities ranging from 10 to 150mg kg−1. Trichoderma harzianum on wheat bran and Gliocladium virens as dried oatmeal culture were incorporated at 200 and 50 mg kg−1 soil, respectively, and Laetisaria arvalis dried, micromilled mycelium was applied as a seed dressing. Each fungus was applied either alone or with a population of P. minuta at 1000 kg− soil. Most effective biological control occurred in sterilized soil when the fungal biocontrol agents were integrated with the insect population; all combinations provided more effective disease suppression than the fungal agents used alone. In non-sterilized soil, having a natural competitive microflora, only P. minuta used alone and the L. arvalis + P. minuta treatment provided consistently significant disease reduction compared to R. solaniinfested soil without added agents. Moderate disease control in non-sterilized soil was obtained with T. harzianum or G. virens when combined with the insect population. Plant-growth dry weight measurements did not consistently reflect the disease control benefit. The specific mechanisms promoting increased biocontrol capacity of insect + fungus combinations, though not clearly defined here, must lie within a complex of factors including preference of R. solani as a food source for P. minuta, aversion of the insect to the two sporulating Hyphomycetes used for biocontrol, and direct parasitism of R. solani by the fungal agents.
Patent•
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TL;DR: In this paper, a novel L-amino acid oxidase having a broad substrate specificity and being obtainable from the species Trichoderma harzianum was presented, which can be incorporated into detergent compositions designed to inhibit the transfer of dye from a dyed fabric to another fabric during washing.
Abstract: The present invention relates to a novel L-amino acid oxidase having a broad substrate specificity and being obtainable from the species Trichoderma harzianum. The enzyme of the invention may advantageously be incorporated into detergent compositions designed to inhibit the transfer of dye from a dyed fabric to another fabric during washing.
TL;DR: Analysis of different patent strains and gamma-ray induced mutants of Trichoderma harzianum by DNA fingerprinting and PCR fingerprinting revealed the same sequence for all mutant strains and the original wild-type strain.
Abstract: We have analyzed different patent strains and gamma-ray induced mutants of Trichoderma harzianum by DNA fingerprinting and PCR fingerprinting (RAPD). Applying wild-type phage M13 DNA, with the oligonucleotides (CT)8 and (GTG)5 as probes for hybridization, as well as the oligonucleotides GGCATCGGCC, (GTG)5, (CAC)5 and the M13 sequence GAGGGTGGCGGTTCT as primers in PCR, we were able to obtain different and discriminative fingerprint patterns for all strains and mutants investigated. Irradiation of fungi led to mutations which resulted in new fingerprint patterns. Consequently, irradiation-induced mutants can be clearly distinguished from the original wild-type isolates by genomic fingerprinting which is of importance for the patent protection of fungal strains. Sequencing of the ITS-1 and ITS-2 regions of the rDNA gene complex revealed the same sequence for all mutant strains and the original wild-type strain.
TL;DR: New peptaibols, trichokindins I-VII, have been isolated from the fungus Trichoderma harzianum and were found to induce Ca(2+)-dependent catecholamine secretion from bovine adrenal medullary chromaffin cells.
Abstract: New peptaibols, trichokindins I-VII, have been isolated from the fungus Trichoderma harzianum. Their structures were characterized by spectrometric methods. Trichokindins, which are 18-residue peptides containing one to three isovaline residues, were found to induce Ca(2+)-dependent catecholamine secretion from bovine adrenal medullary chromaffin cells.
TL;DR: Trichoderma harzianum caused a great reduction in the infection level of damping-off and root-rot diseases, and resulted in increased root weight both in pot aand field experiments during two successive growing seasons.
Patent•
05 Jul 1994TL;DR: A DNA construct comprising a DNA sequence encoding an enzyme with endoglucanase activity, which DNA sequence comprises the DNA sequence shown in SEQ ID No. 1 or an analogous sequence thereof being at least 70 % homologous to the DNA sequences shown in Seq ID No 1 as mentioned in this paper.
Abstract: A DNA construct comprising a DNA sequence encoding an enzyme with endoglucanase activity, which DNA sequence comprises the DNA sequence shown in SEQ ID No. 1 or an analogous sequence thereof being at least 70 % homologous to the DNA sequence shown in SEQ ID No. 1. The DNA sequence may be isolated from a strain of Trichoderma harzianum. The endoglucanase expressed from the DNA construct may be used for the degradation or modification of plant materials.
TL;DR: A cDNA clone encoding a putative cell wall protein (Qid3) was isolated from a library prepared from chitin-induced mRNA in cultures of the mycoparasitic fungus Trichoderma harzianum, showing a potential signal peptide, several hydrophobic domains and certain motifs that are structurally similar to proline-rich and glycine-rich plant cell wall proteins.
Abstract: A cDNA clone encoding a putative cell wall protein (Qid3) was isolated from a library prepared from chitin-induced mRNA in cultures of the mycoparasitic fungus Trichoderma harzianum. The predicted 14 kDa protein shows a potential signal peptide, several hydrophobic domains and certain motifs that are structurally similar to proline-rich and glycine-rich plant cell wall proteins. Expression of the qid3 gene is derepressed in the absence of glucose. When introduced in yeast, qid3 expression causes cell division arrest into cytokinesis and cell separation, probably due to its cell wall localization.
TL;DR: Modifications to the nitrogen and iron concentrations of the minimal medium provided indications that the level of these two elements could prove important in the biological control of the dry rot fungus in wood.
TL;DR: Production of the antibiotic, homothallin II, by a UV-induced mutant strain of Trichoderma harzianum is reported, the wild-type parent of which was not an isonitrile antibiotic-producer.
TL;DR: The results provide additional information on the role of lytic enzymes in processes of biocontrol and strongly suggest the use of Lytic enzymes and their genes for biological control of plant diseases.
Abstract: Fungal cell wall degrading enzymes produced by the biocontrol fungiTrichoderma harzianum andGliocladium virens are strong inhibitors of spore germination and hyphal elongation of a number of phytopathogenic fungi. The purified enzymes include chitinolytic enzymes with different modes of action or different substrate specificity and glucanolytic enzymes with exo-activity. A variety of synergistic interactions were found when different enzymes were combined or associated with biotic or abiotic antifungal agents. The levels of inhibition obtained by using enzyme combinations were, in some cases, comparable with commercial fungicides. Moreover, the antifungal interaction between enzymes and common fungicides allowed the reduction of the chemical doses up to 200-fold. Chitinolytic and glucanolytic enzymes fromT. harzianum were able to improve substantially the antifungal ability of a biocontrol strain ofEnterobacter cloacae. DNA fragments containing genes encoding for different chitinolytic enzymes were isolated from a cDNA library ofT. harzianum and cloned for mechanistic studies and biocontrol purposes. Our results provide additional information on the role of lytic enzymes in processes of biocontrol and strongly suggest the use of lytic enzymes and their genes for biological control of plant diseases.
TL;DR: All fungicide resistant-biotypes retained the ability to antagonize the pathogen Sclerotium cepivorum in dual culture and, in two instances, exhibited greater antagonism as evidenced by the production of larger inhibition zones.
Abstract: The sensitivity of four fungal antagonists (Chaetomium globosum, Trichoderma harzianum, T. viride, Trichoderma sp.) to six fungicides was evaluated. The fungi were insensitive to captan, mancozeb and thiram but were sensitive to benomyl (EC50 < 0 3/μg/ml) and the two dicarboximides iprodione and procymidone (EC50 < 3 3/μg/ml). Conidia and mycelia of the four fungi were exposed to a series of ultraviolet irradiations in order to select biotypes resistant to benomyl and iprodione. Resistance to benomyl was not induced but a number of biotypes of each fungus were isolated from irradiated cultures that showed resistance to iprodione (EC50 values of up to 56·4, 177·8, 171·5 and 216·4/μg/ml for Chaetomium globosum, Trichoderma harzianum, T. viride and Trichoderma sp., respectively). With three exceptions, all selected biotypes retained their fungicide-resistance after being extensively cultured on fungicide-free medium. In general, growth of the fungicide resistant biotypes on MEA plates and in MYE liquid medium was equal to that of the corresponding wild-type strains. One resistant biotype of Trichoderma sp. (C62UV3) grew significantly (P < 0·05) better both on solid and in liquid medium. This resistant biotype was also observed to have greatly enhanced conidial production on agar plates. All fungicide resistant-biotypes retained the ability to antagonize the pathogen Sclerotium cepivorum in dual culture and, in two instances (A53UV1, A53UV5), exhibited greater antagonism as evidenced by the production of larger inhibition zones. Similarly, with two exceptions, the resistant biotypes retained the ability to control onion white rot disease caused by S. cepivorum in the glasshouse. In particular, two fungicide-resistant biotypes (Trichoderma sp. C62UV3 and Chaetomium globosum A53UV1) reduced white rot of onion more effectively than did their respective wild-type parents.
TL;DR: Jin et al. as mentioned in this paper proposed three components are necessary for effective implementation of biological control: 1) a superior bioprotectant, 2) a process to produce large quantities of effective propagules, and 3) a delivery system that permits full expression of the biological control properties of the strain.
Abstract: B iological control or biocontrol has the potential to replace or augment conventional plant disease management practices based on the use of synthetic pesticides, Biocontrol provides a nonpolluting means for control of plant pathogens through the use of indigenous or genetically modified organisms. Biological control practices are consistent with the goals of sustainable agriculture and integrated pest management to minimize the use of synthetic pesticides. Biological control agents or bioprotectants may be used alone or in combination with specific chemical pesticides that are compatible with the bioprotectant. Thus, biocontrol has the potential for commercial use; however, a comprehensive system must be in place to ensure adequate plant protection under a wide range of field conditions. Three components are necessary for effective implementation of biological control: 1) a superior bioprotectant, 2) a process to produce large quantities of effective propagules, and 3) a delivery system that permits full expression of the biological control properties of the strain (Jin et
TL;DR: In this paper, four transformants were analysed for survival ability on the phylloplane of tomato plants grown under glasshouse conditions in comparison with their prototype and a yellow, hygromycin B-sensitive mutant.
Abstract: A propiconazole-resistant Trichoderma harzianum strain with high phylloplane survival capability was transformed with the E. coli hygromycin B phosphotransferase gene (hph), coding for hygromycin B resistance. Four transformants were analysed for survival ability on the phylloplane of tomato plants grown under glasshouse conditions in comparison with their prototype and a yellow, hygromycin B-sensitive mutant. Over 2 weeks, the four transformants showed higher survival rates in comparison with the wild-type strain. The yellow mutant TF3/973 did not significantly differ in survival from the transformants. Both hygromycin B resistance and mitotic stability of transformants were evaluated during growth in vitro and after reisolation from tomato phylloplane. Hybridization patterns with the complete plasmid indicated that all four transformants were mitotically stable after several rounds of vegetative growth without selective pressure and during 2 weeks on tomato plants. None of the transformants had lost the ability to grow in the presence of both propiconazole and hygromycin B after growth under the same conditions. The results are discussed in relation to risk assessment of the release of transgenic fungi.
TL;DR: Most isolates significantly inhibited the growth of Armillaria but the highest inhibition was noted with one of the isolates of T. koningii, T. longibrachiatum and T. harzianum.
Abstract: The interaction of 11 Trichoderma isolates against Armillaria root rot fungus of tea was investigated. Most isolates significantly inhibited the growth of Armillaria. The highest inhibition was noted with one of the isolates of T. koningii, T. longibrachiatum and T. harzianum. The isolates with highest inhibitory properties tended to produce a pigment into the nutrient broth. The implications of these results in view of the future management strategies of Armillaria root rot of tea in Kenya are discussed.