Polyethylenimine-Coated MXene Quantum Dots Integrate Anti-Oomycete Activity with Host Immunity Activation for Plant Oomycete Control

Pathogenic oomycetes can infect hundreds of crops, leading to significant economic losses globally. This study synthesized polyethylenimine-coated MXene quantum dots (PEI-MQDs) and investigated their antioomycete potential using the vegetable oomycete pathogen Phytophthora capsici as a model system. PEI-MQDs demonstrated potent antioomycete activity against P. capsici by damaging cellular structures and subverting asexual reproduction (zoosporangium/zoospore formation). Transcriptomic profiling demonstrated that treatment with PEI-MQDs induced extensive transcriptional changes in P. capsici genes, primarily affecting antioxidant activities, structural constituents, and metabolic pathways. Greenhouse pepper experiments showed that PEI-MQDs exerted both protective and curative effects against P. capsici infection, as effectively as the commercial oomycide metalaxyl. Additionally, PEI-MQDs can promote hot pepper immunity and growth through different pathways, as revealed by transcriptomic analysis. These findings make PEI-MQDs a novel nano-oomycide in agricultural applications, offering a sustainable platform for crop protection and expanding the functional scope of quantum dots in plant health.