Biocontrol Potential of Native <i>Trichoderma</i> Strains Toward Soil-Borne Phytopathogenic and Saprotrophic Fungi

The potential of <i>Trichoderma</i> fungi as biocontrol agents has not yet been fully explored, as there is a large repertoire of inter- and intra-species variation in their phytopathogenic antagonistic effects due to different adaptations of individual <i>Trichoderma</i> strains. In the present study, we investigated the biocontrol efficacy of eight native isolates of <i>Trichoderma</i> spp. against the soilborne phytopathogens <i>Sclerotinia sclerotiorum</i> and <i>Rhizoctonia solani</i> and a representative of the Mucoromycota, <i>Phycomyces blakesleeanus</i>. An <i>in vitro</i> dual culture test showed a complete (100%) inhibition of <i>S. sclerotiorum</i> and <i>P. blakesleeanus</i> by each tested <i>Trichoderma</i> strain and a high (80–100%) inhibition of <i>R. solani</i>. The crude chloroform extracts, whose peptide contents were confirmed by thin-layer chromatography, caused a concentration-dependent reduction in the growth of the target fungi, with inhibition comparable to the effect of the peptaibol standard alamethicin. Despite the differences between fungi from the phyla Basidiomycota, Ascomycota, and Mucoromycota, their inhibition by alamethicin followed the same dose–response dependence. The growth inhibition of <i>P. blakesleeanus</i> induced by <i>Trichoderma</i> extracts was characterized by a significantly increased activity of antioxidative defense enzymes. Both variants of biocontrol agents, the native strains of <i>Trichoderma</i> spp. and their extracts, are efficient in controlling fungal growth and should be considered for the development of new potent bioformulations applicable in agriculture.