Design, Synthesis, and Antifungal Activity of Benzoxazole Amides: Focusing on Target Research against Verticillium Dahliae

A series of benzoxazole amide derivatives were synthesized, and their antifungal activities against phytopathogens were tested by mycelial growth inhibition method. Compound L9 exhibited potent activity against Verticillium dahliae with an EC50 of 0.18 μM. In vivo experiments revealed its curative efficacy on eggplant verticillium wilt was 80.00%. Phenotypic results indicated that L9 damaged the integrity of fungal cell wall and membrane. Transcriptome and RT-qPCR screening identified β-N-acetylhexosaminidase as the core gene. Molecular docking predicted stable binding of L9 to this protein, which was further verified by time-series enzyme activity assays showing obvious inhibition of enzyme activity. This study constructs a complete phenotype-pathway-target evidence chain, offering lead compounds for novel antifungal agrochemicals.