Huimin Ji

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.

Trichoderma, a well-known and extensively studied fungal genus, has gained significant attention for its remarkable antagonistic abilities against a wide range of plant pathogens. In this study, a total of 108 Trichoderma isolates were screened through in vitro dual antagonistic assays and culture filtrate inhibition against Fusarium graminearum. Of these, the YNQJ1002 displayed noteworthy inhibitory activities along with thermal stability. To validate the metabolic differences between YNQJ1002 and GZLX3001 (with strong and weak antagonism, respectively), UPLC-TOF-MS/MS mass spectrometry was employed to analyze and compare the metabolite profiles. We identified 12 significantly up-regulated metabolites in YNQJ1002, which include compounds like Trigoneoside, Torvoside, trans,trans-hepta-2,4,6-trienoic acid, and Chamazulene. These metabolites are known for their antimicrobial properties or signaling roles as components of cell membranes. Enriched KEGG analysis revealed a significant enrichment in sphingolipid metabolism and linoleic acid metabolism, as well as autophagy. The results demonstrated that YNQJ1002’s abundance of antimicrobial substances, resulting from specific metabolic pathways, enhanced its superior antagonistic activity against F. graminearum. Finally, YNQJ1002 was identified using the ITS, tef1-1α, and rpb2 regions, with MIST system sequence matching confirming its classification within the species. Overall, we have obtained a novel strain, T. asperellum YNQJ1002, which is rich in metabolites and shows potential antagonistic activity against F. graminearum. This study has opened promising prospects for the development of innovative Trichoderma-derived antifungal compounds, featuring a unique mechanism against pathogens.