Changes in Peptaibol Production of Trichoderma Species during In Vitro Antagonistic Interactions with Fungal Plant Pathogens

Trichoderma species are widely used as biofungicides for the control of fungal plant pathogens. Several studies have been performed to identify the main genes and compounds involved in Trichoderma–plant–microbial pathogen cross-talks. However, there is not much information about the exact mechanism of this profitable interaction. Peptaibols secreted mainly by Trichoderma species are linear, 5–20 amino acid residue long, non-ribosomally synthesized peptides rich in α-amino isobutyric acid, which seem to be effective in Trichoderma–plant pathogenic fungus interactions. In the present study, reversed phase (RP) high-performance liquid chromatography (HPLC) coupled with electrospray ionization (ESI) mass spectrometry (MS) was used to detect peptaibol profiles of Trichoderma strains during interactions with fungal plant pathogens. MS investigations of the crude extracts deriving from in vitro confrontations of Trichoderma asperellum and T. longibrachiatum with different plant pathogenic fungi (Fusarium moniliforme, F. culmorum, F. graminearum, F. oxysporum species complex, Alternaria solani and Rhizoctonia solani) were performed to get a better insight into the role of these non-ribosomal antimicrobial peptides. The results revealed an increase in the total amount of peptaibols produced during the interactions, as well as some differences in the peptaibol profiles between the confrontational and control tests. Detection of the expression level of the peptaibol synthetase tex1 by qRT-PCR showed a significant increase in T. asperellum/R. solani interaction in comparison to the control. In conclusion, the interaction with plant pathogens highly influenced the peptaibol production of the examined Trichoderma strains.