Trichoderma Strains – Antagonists of Plant Pathogenic Micromycetes

Abstract

Species of the genus Trichoderma are known as the producers of many biologically active substances, in particular, enzymes that have found their practical application in many industries. In addition, the active Trichoderma strains are used as biological control agents of plant pathogenic micromycetes. Trichoderma strains are able to exhibit antagonistic properties against plant pathogens very effectively due to their peculiarities: high growth rate; synthesis of chitinolytic enzymes and secondary metabolites with antifungal activity. Thus, highly active Trichoderma strains has been successfully used to control plant pathogenic isolates of Fusarium, Alternaria, Botrytis, Sclerotinia, Verticillium, Pythium and other genera. The aim of the study was to evaluate the antagonistic activity of 100 Trichoderma strains against eight test-cultures of plant pathogenic micromycetes of different species and to select the most active strains for further studies of their physiological properties. Methods. Cultures of the studied fungi were grown on potato-dextrose agar. The antagonistic activity of fungi of the genus Trichoderma against fungal plant pathogens was carried out using the conventional method of dual culture. The percentages of growth inhibition of plant pathogens were calculated, and on the basis of these values the antagonistic activity of strains were concluded. Microsoft Excel and Origin 8.0 (OriginLab) packages were used for statistical data processing. Results. According to the results of a study of the antagonistic activity of Trichoderma strains against plant pathogenic micromycetes in general, it was shown that the strains have a high level of antifungal activity. Thus, the most numerous group (38%) of the total studied Trichoderma strains were “highly active” ones that inhibited the growth of plant pathogens from 70 to 80%. The second largest group (27%) was “moderately active” strains with 60–70% inhibition of plant pathogenic test cultures. The smallest (6%) but the most active group consisted of the “most active” strains with an average value of the inhibition more than 80%. Thus, almost three quarters (71%) of the studied Trichoderma strains showed a high level of antagonistic activity against plant pathogens with the inhibition more than 60%. In addition, only 17% of Trichoderma strains were “inactive” and 12% of them showed insufficient activity with growth inhibition of plant pathogens less than 50%. Notably, 35% of Trichoderma strains were active against all eight test cultures of plant pathogenic micromycetes. Conclusions. The studied Trichoderma strains have significant antagonistic potential both for individual strains of plant pathogenic micromycetes and for all studied plant pathogens. The involvement of a wide range of test cultures of plant pathogens, as well as significant amount (100) of Trichoderma strains allowed a more objective and systematic assessment of the antagonistic potential of fungi of this genus. Thus, our study of action of the wide range of Trichoderma strains against test cultures of different species showed that the fungi of the genus Trichoderma were effective antagonists of plant pathogenic fungi. The 38% of Trichoderma strains showed a high level of antifungal action and inhibited the growth of plant pathogens by 70% and more. Only 12% of strains showed less than 50% activity. In addition, 35% of Trichoderma strains were active against all eight tested plant pathogen test cultures. The significant amount of studied Trichoderma strains was highly active, and they can be used as a basis for further research to obtain effective biological control agents of plant pathogenic micromycetes.