Synergistic effect of peptide KF3 and citronellal against F. graminearum ACCC 37687 and their application in maize...

Maize faces a major threat from Fusarium graminearum, which leads to significant yield reduction and contamination by deoxynivalenol (DON), an immunosuppressive mycotoxin. This study examined the antifungal activity of peptide KF3 combined with citronellal against this pathogen. The KF3/citronellal combination displayed a strong synergistic effect against its spores (fractional inhibitory concentration index (FICI) =0.25), potently inhibiting hyphal extension and reducing liquid culture mycelial biomass by 79.97%, with stable efficacy under pH, high-temperature and ionic stress. Mechanistically, the combination accelerated fungal killing (Δ log₁₀ > 8 within 12 h), suppressed biofilm formation and induced severe cell membrane disruption; KF3-mediated membrane damage promoted citronellal penetration to exacerbate cellular dysfunction. ROS accumulation and inhibited respiratory chain dehydrogenase activity impaired energy metabolism, and global suppression of ribosome biogenesis and protein synthesis (3114 differentially expressed genes enriched in ribosome and energy metabolism pathways) ultimately caused fungal death. Notably, citronellal mitigated KF3-induced fungal resistance, cutting KF3's MIC increase from 64-fold to 8-fold after 30 serial passages, due to the combination's low effective dose and multi-target mechanism. In vivo assays verified that the combination effectively controlled F. graminearum contamination and reduced DON levels in maize, exhibiting great application potential in the food and feed industries for post-harvest grain preservation. Though its production cost exceeds that of synthetic fungicides, advancing biotechnology is expected to narrow this gap.