Mesoporous Catechin Nanoparticles Enhance Plant Antiviral Immunity Through Multiscale Defense Signaling

ABSTRACT Plant viruses remain an under‐addressed challenge to global crop productivity, and sustainable antiviral strategies capable of both directly intercepting viral particles and coordinating host defense pathways are urgently needed. Here, we report mesoporous catechin nanoparticles (MCN) fabricated through cooperative assembly and covalent crosslinking of catechin. The resulting nanostructures exhibit uniform size and interactions with to the Tobacco mosaic virus (TMV) coat protein, enabling multivalent virus‐material interactions and virion destabilization. In Nicotiana benthamiana , MCN conferred robust antiviral protection, reducing TMV expression by 64% at 14 days post‐infilration, while alleviating systemic chlorosis and necrosis. Notably, MCN preferentially accumulated at stomatal apertures and penetrated substomatal cavities, supporting a stomata‐associated antiviral interception route together with broader in planta distribution following foliar application. Integrated transcriptomic‐metabolomic profiling further revealed that MCN coordinate the jasmonic acid‐salicylic acid‐reactive oxygen species‐flavonoid (JA‐SA‐ROS‐flavonoid) defense axis, promoting coordinated redox regulation, antioxidant remodeling, and immune priming across tissues. This study demonstrates that assembly‐directed mesostructuring transforms a natural polyphenol into multifunctional antiviral nanoparticles that integrate direct virion neutralization with coordinated host defense activation, offering a sustainable framework for next‐generation plant antiviral design.