Trichoderma harzianum

About: Trichoderma harzianum is a research topic. Over the lifetime, 4731 publications have been published within this topic receiving 96796 citations.

Biological control of seedling blight of wheat caused by Fusarium graminearum with beneficial rhizosphere microorganisms

Abstract: Fusarium graminearum is associated with the cereal damping-off complex which reduces germination, seedling stand and yield. Fifty-two bacterial strains and six Trichoderma spp. isolated from the wheat rhizosphere were evaluated for biocontrol of seedling blight of wheat caused by F. graminearum. Their potential as biocontrol agents was tested in vitro and in the greenhouse. Isolates varied in their ability to inhibit the mycelial growth of F. graminearum in agar plate bioassays by 0–79%. This parameter was not related with biocontrol efficacy of in vivo assays. In greenhouse trials, all isolates were initially evaluated for reducing disease on wheat cultivars Klein Centauro (moderately resistant to F. graminearum) and Pro INTA Oasis (susceptible) planted in sterilized soil artificially infested with the pathogen. Among the 25 bacteria and six fungal isolates that exhibited a pronounced suppressive effect, the most efficient 10 for both cultivars were further assayed on eight cultivars (Buck Candil, Buck Catriel, Buck Chambergo, Buck Poncho, Buck Topacio, Klein Cacique, Klein Centauro and Pro INTA Oasis) potted in cultivated–inoculated soil. Three weeks after sowing, plant stand, percentage of diseased emerging seedlings, plant height and dry weight were evaluated. Among the antagonists only Stenotrophomonas maltophilia was significantly better than the control for the average of the eight cultivars for plant stand, height and dry weight. Stenotrophomonas maltophilia also caused a non-significant decrease in the percentage of diseased plants. Three strains of Bacillus cereus and one isolate of Trichoderma harzianum gave also a good control in some cultivars. The ability of these isolates to affect the infection of wheat seedlings by F. graminearum may be of potential value in field trials.

Application of Trichoderma and Gliocladium in alginate pellets for control of Rhizoctonia damping-off

Abstract: Alginate pellets were prepared from wet fermentor biomass of 11 isolates of Trichoderma spp. and Gliocladium virens, with wheat bran as a food base carrier. Pellets with eight of the isolates reduced survival (34-78%) of Rhizoctonia solani in infested beet seed in soil. Pellets containing a T. harzianum isolate (Th-58) and a T. hamatum isolate (TRI-4) were the most effective. All isolates significantly reduced growth of the pathogen from infested beet seed into natural soil. Populations of isolates proliferated in soil to 106−1011 colony-forming units/g (cfu) from propagules within the pellets. Pellets with TRI-4 reduced pathogen survival and growth (>70%) in six different soils and were effective against six R. solani isolates in a natural loamy sand. Survival of R. solani in infested beet seed was not reduced when TRI-4 pellets were added to soil 1-6 weeks before the pathogen; however, saprophytic growth was prevented. Small amounts of biomass (3.0–7.5 g wet weight) in pellets were as effective as a large amount (300 g) in suppressing the pathogen. The storage of pellets for more than 6 weeks at 5 or 25C reduced their effectiveness against R. solani. Pellets prepared with four and three of the 11 isolates prevented damping-off of cotton and sugar beet in the greenhouse, respectively.

Expression regulation of the endochitinase chit36 from Trichoderma asperellum (T. harzianum T-203)

Abstract: 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. asperellum is regulated both by glucose and nitrogen levels. Stress conditions, colloidal chitin and N-acetyl-glucosamine are effective inducers of this gene. The promoter of chit36Y was cloned and was used to direct expression of a gfp reporter gene in Trichoderma transformants. Confrontation experiments with the plant pathogen Rhizoctonia solani revealed that direct contact between the fungi is not necessary for gfp expression. The R. solani-inducing factor appears to be a soluble molecule capable of diffusing through a dialysis membrane (<12 kDa). CHIT36 recombinant protein from the yeast Pichia pastoris was active against different phytopathogens, confirming the importance of this endochitinase in the mycoparasitic activity of Trichoderma antagonistic strains.

Mycoparasitism studies of Trichoderma species against three phytopathogenic fungi: evaluation of antagonism and hydrolytic enzyme production

Abstract: Trichoderma spp. are used for biocontrol of several plant pathogens. However, their efficient interaction with the host needs to be accompanied by production of secondary metabolites and cell wall-degrading enzymes. Three parameters were evaluated after interaction between four Trichoderma species and plant-pathogenic fungi: Fusarium solani, Rhizoctonia solani and Sclerotinia sclerotiorum. Trichoderma harzianum and T. asperellum were the most effective antagonists against the pathogens. Most of the Trichoderma species produced toxic volatile metabolites, having significant effects on growth and development of the plant pathogens. When these species were grown in liquid cultures with cell walls from these plant pathogens, they produced and secreted β-1,3-glucanase, NAGAse, chitinase, acid phosphatase, acid proteases and alginate lyase.

Efficacy of Biological and Chemical Treatments for Control of Fusarium Root and Stem Rot on Greenhouse Cucumber

Abstract: Potential disease control methods were evaluated against root and stem rot of cucumber (Cucumis sativus) caused by Fusarium oxysporum f. sp. radicis-cucumerinum. Crab/shrimp shell chitin; three composted media; the biological control agents Pseudomonas chlororaphis strain 63-28, Trichoderma harzianum (RootShield Drench), Streptomyces griseoviridis (Mycostop), Gliocladium catenulatum (Prestop WP, Prestop Mix), and Trichoderma (Gliocladium) virens (SoilGard); and the fungicides thiram or benomyl were added at seeding time followed by inoculation with the pathogen. The addition of chitin (4%, vol/vol) to a peat-based medium significantly (P ≤ 0.05) enhanced seedling growth, increased soil pH, and reduced F. oxysporum f. sp. radicis-cucumerinum populations, but the severity of disease was increased. The addition of composted media (greenhouse compost, windrow composted dairy solids, and vermi-composted dairy solids) to the seeding cavity in a rock wool block medium, followed 48 h later by inoculation with F. oxysporum f. sp. radicis-cucumerinum, reduced seedling mortality when measured after 37 days. Greenhouse compost was significantly (P ≤ 0.05) more suppressive than the other two composts, and the suppression was partially eliminated by sterilization of the compost. The biological control agent G. catenulatum (formulated as Prestop WP and Prestop Mix) significantly reduced seedling mortality when it was applied at seeding 24 h prior to inoculation with the pathogen in the rock wool block medium. None of the other biological control agents reduced disease incidence when compared with control plants under these experimental conditions. Pseudomonas chlororaphis and the fungicide thiram both significantly reduced plant mortality at 17 and 24°C when pathogen-infested seed was treated, or when bacteria-treated and fungicide-treated seed were planted into pathogen-infested peat medium at 24°C. Under semicommercial propagation conditions, treatments consisting of Prestop WP, RootShield Drench, My-costop, and windrow composted dairy solids reduced the severity of disease caused by F. oxysporum f. sp. radicis-cucumerinum in two out of three trials. The efficacy of the biological control agents was affected by seasonal differences in growing conditions, which affected the incidence and severity of the disease. The results from this study indicate that several different approaches can be used at seeding to control Fusarium root and stem rot on greenhouse cucumber.