Synthesis of organic–inorganic hybrid nanocomposites modified by catalase-like catalytic sites for the controlling of kiwifruit bacterial canker

Abstract

Kiwifruit bacterial canker, caused by <i>Pseudomonas syringae</i> pv. <i>Actinidiae</i> (<i>Psa</i>), is one of the most important diseases in kiwifruit, creating huge economic losses to kiwifruit-growing countries around the world. Metal-based nanomaterials offer a promising alternative strategy to combat plant diseases induced by bacterial infection. However, it is still challenging to design highly active nanomaterials for controlling kiwifruit bacterial canker. Here, a novel multifunctional nanocomposite (ZnO@PDA-Mn) is designed that integrates the antibacterial activity of zinc oxide nanoparticles (ZnO NPs) with the plant reactive oxygen species scavenging ability of catalase (CAT) enzyme-like active sites through introducing manganese modified polydopamine (PDA) coating. The results reveal that ZnO@PDA-Mn nanocomposites can efficiently catalyze the conversion of H₂O₂ to O₂ and H₂O to achieve excellent CAT-like activity. <i>In vitro</i> experiments demonstrate that ZnO@PDA-Mn nanocomposites maintain the antibacterial activity of ZnO NPs and induce significant damage to bacterial cell membranes. Importantly, ZnO@PDA-Mn nanocomposites display outstanding curative and protective efficiencies of 47.7% and 53.8% at a dose of 200 μg mL^-1 against <i>Psa in vivo</i>, which are superior to those of zinc thiozole (20.6% and 8.8%) and ZnO (38.7% and 33.8%). The nanocomposites offer improved <i>in vivo</i> control efficacy through direct bactericidal effects and decreasing oxidative damage in plants induced by bacterial infection. Our research underscores the potential of nanocomposites containing CAT-like active sites in plant protection, offering a promising strategy for sustainable disease management in agriculture.