Visible-Light-Absorbing Photosensitizer Nanostructures for Treatment of Pathogenic Bacteria and Induction of Systemic Acquired Resistance

Induction of systemic acquired resistance (SAR) in plants to control bacterial diseases has become an effective solution to the problems of agrochemical resistance and ecological environment damage caused by long-term and large-scale use of traditional bactericides. However, current SAR-inducing compounds are often unable to rapidly eliminate pathogenic bacteria in infected plant tissues to prevent further spread of the disease, severely restraining the potential for extensive application in agriculture. Herein, we address the limitations by developing a series of visible-light-absorbing aggregation-induced emission photosensitizers suitable for agricultural use. The photosensitizer (MTSQ2) is modulated by molecular engineering to have optimal optical properties, reactive oxygen species (ROS) generation efficiency, and bacterial targeting affinity, thereby exhibiting an effective antibacterial photodynamic activity against the phytopathogenic bacteria Pseudomonas syringae pv tomato DC3000 in the model plant Arabidopsis thaliana under white light illumination. Moreover, the ROS produced in situ by MTSQ2 can further regulate the ROS-AzA-G3P signaling pathway, thus allowing to induce SAR throughout the plant to prevent secondary infections. The current study can provide a feasible strategy for developing desirable photosensitizers to achieve sustainable management of plant diseases.