Fabrication of a dual-stimuli-responsive mesoporous organosilica nanoplatform for co-delivery of fungicide and plant immune inducer toward synergistic disease management.

The multifunctional nanoplatform, featuring stimuli-responsive controlled release and co-delivery of fungicides with distinct modes of action, exhibits considerable promise for plant disease control. In this study, a novel CYM@MON-SA nanoplatform was developed by grafting the plant immune inducer (salicylic acid, SA) onto disulfide-bridged mesoporous organosilica nanoparticles (MON-NH₂), followed by loading the fungicide cymoxanil (CYM) into the mesopores. Physicochemical characterization confirmed its successful step-by-step preparation and demonstrated its biodegradability as well as the controlled release of SA and CYM, triggered by dual stimuli-responsiveness to glutathione (GSH) and amidase (AM). Photodegradation experiments revealed that CYM@MON-SA exhibited a significantly extended half-life (3.22-fold) under UV irradiation compared to technical CYM. Importantly, CYM@MON-SA achieved an 86.22% control efficacy against cucumber downy mildew (CDM), significantly surpassing the direct mixture of SA and CYM, which attributed to the enhanced photostability of CYM and prolonged effectiveness of SA. Furthermore, CYM@MON-SA also activated the plant immune response through the upregulation of four disease-resistance-related genes (CsNPR1, CsPR1, CsERF004, and CsWRKY50), reduction of catalase (CAT) activity, and decrease in malondialdehyde (MDA) levels. Additionally, this nanoplatform also showed a favorable biosafety in plants. Overall, this stimuli-responsive nanoplatform provides a sustainable and synergistic strategy for plant disease management, demonstrating significant potential.