Novel Antifungal Scaffold Targeting Tubulin Overcomes Sclerotinia Sclerotiorum Resistance

The increasing prevalence of pesticide resistance in pathogenic bacteria, particularly among broad-host-range fungal pathogens such as S. sclerotiorum, poses a significant threat to global crop production and food security. Addressing this challenge requires the development of targeted compounds with novel mechanisms of action. Herein, a novel chromone-acylhydrazone hybrid scaffold is designed and synthesized to specifically target fungal tubulin. Bioassay results identified compound G24 as a highly potent inhibitor of S. sclerotiorum (EC₅₀ = 0.21 µg mL^-1), exhibiting superior efficacy compared to conventional fungicides. Mechanistic investigations, including molecular docking, molecular dynamics, and immunofluorescence staining, revealed that G24 effectively disrupts tubulin polymerization by forming hydrogen bonds with key tubulin residues. Notably, G24 exhibits selective antifungal activity while maintaining mammalian safety, addressing critical toxicity concerns. To enhance field performance, polyurethane microcapsules loaded with G24 (G24-Loaded PU-MCs) are developed with an encapsulation efficiency of 89.41%, facilitating slow-release kinetics, improved foliar adhesion, and prolonged pathogen suppression. This integrated approach, combining targeted compound design with microencapsulation, offers a promising and sustainable strategy for combating pesticide resistance and promoting global food security.