Harnessing CNC-Carrier Nanomaterials for Enhanced Zn2+-Mediated Inhibition of Oomycete Asexual Reproduction

Abstract

Oomycetes are devastating plant pathogens causing major crop losses, with spores as key infection sources. Inhibiting asexual reproduction, especially sporangium formation and spore release, is crucial for disease prevention. Zn²⁺ has shown potential in inhibiting oomycete reproduction, but excessive concentrations can cause cytotoxicity and environmental risks. To address this, we used polydopamine (PDA) to complex Zn²⁺ and form a PDA@Zn²⁺ coating on cellulose nanocrystals (CNCs) through hydrogen bonding. This ionic nanopesticide (CNC@PDA@Zn²⁺) enhances effectiveness against oomycetes while reducing dosage and improving biosafety. Bioexperimental results indicate that CNC@PDA@Zn²⁺ significantly inhibits sporangium formation and spore release from Phytophthora capsici (P. capsici) by suppressing the expression of key sporulation genes (PcATP4, cdc, and G-protein), disrupting spore cell membranes, and altering organelle structures. In vivo, it reduces P. capsici infection on pepper leaves, even in the presence of mycelium. This study highlights CNC@PDA@Zn²⁺ as a promising biobased nanomaterial for sustainable crop protection.