Regulation of Peptaibol Profile by Velvet LAE1/VEL1 in Trichoderma Species During In Vitro Confrontations with...

Peptaibols, predominantly secreted by Trichoderma species, are a class of linear peptides composed of five to twenty amino acid residues, synthesized non-ribosomally and enriched with α-amino isobutyric acid. These unique peptides appear to be highly effective in mediating the interactions between Trichoderma and plant pathogenic fungi. In this study, Ultra-Performance Liquid Chromatography-Quadrupole Time-Of-Flight Mass Spectrometry/Mass Spectrometry (UPLC-QTOF-MS/MS) technology was used to detect peptaibols profiles of Trichoderma strains during their interactions with the pathogen Fusarium graminearum. MS investigations of crude extracts derived from in vitro confrontations of Trichoderma atroviride T23 and its genetically modified counterparts, dual-culture assays of Mlae1, Mvel1, OElae1, and OEvel1 with F. graminearum were performed to shed light on the regulatory role of the velvet complex composed of LAE1&VEL1 in the synthesis of peptaibols during the microbial interaction. These results revealed intriguing variations in the total peptaibols produced during the interactions, as well as some differences in the specific peptaibol profiles between the confrontation and control tests. The overexpression strains, OElae1 and OEvel1, distinguished themselves by their proficiency in inducing long-residue peptaibols synthesis, attaining an impressive biocontrol index of up to 76%. The crude extracts containing peptaibols of OElae1 and OEvel1 demonstrated a capability to enhance cell membrane permeability and decrease DON toxin production in F. graminearum, and the crude extracts of OElae1 strains exhibited more effectiveness in reducing DON toxin production. In conclusion, the interaction with F. graminearum significantly impacted the peptaibol production in the examined Trichoderma strain, emphasizing the intricate interplay and reciprocal influence of genetic factors and environmental stimuli.