Bioprospecting for Trichoderma spp. on the mycelial growth of Colletotrichum cliviae and C. truncatum

Abstract

The use of antagonists in the control of plant pathogens has been extensively studied in recent decades, especially fungi from genus Trichoderma spp., due to their ability to act as biocontrolling agents and inducers of plant resistance against diseases. Thus, we aimed to select Trichoderma spp. with potential to control growth of pathogenic fungi. We used 56 Trichoderma strains from the isolate bank of the microbiology laboratory of Federal University of Tocantins. The strains were isolated from soil samples collected in southern Tocantins state, Brazil. The studied pathogens of foliar diseases were Colletotrichum cliviae and Colletotrichum truncatum, both of which were isolated from soybean plants showing disease symptoms. To evaluate the antagonistic potential of  Trichoderma spp., we used the dual culture assay and expressed the results as percentage of colonization and grade scale. Grade evaluation revealed that 46 Trichoderma strains were effective antagonists of the two pathogens. Regarding the percentage of pathogen growth inhibition, effective antagonists were represented by 22 strains showing more than 75% inhibition of  Colletotrichum cliviae and three strains showing more than 90% inhibition of Colletotrichum truncatum.