A class of photosensitizer highly effective to control bacterial infection in plants even on rainy days with dim light

Bacterial infections of plants are widespread and highly virulent, causing serious economic losses in agricultural production worldwide. These infections become particularly prevalent during rainy weather, characterized by high humidity and low light intensity (about 2–10% of a sunny day). Here we identified a class of photosensitizers that were effective in inhibiting plant bacterial infections under rainy weather with dim light. One of these compounds, compound 1, demonstrated exceptional efficacy by eliminating more than 4 logs (99.99%) of either Xanthomonas perforans or Xanthomonas citri subsp. citri (Xcc) strain at a concentration of 6.25 μM under rainy weather conditions with a light exposure of 28.51 J/cm2. For Clavibacter michiganensis (Cm), compound 1 demonstrated a comparable bactericidal effect at a lower concentration of 3.13 μM. Furthermore, compound 1 was effective in controlling plant leaf infections during rainy weather. Moreover, compound 1 exhibited a potent inhibitory effect on the biofilms pertinent to tomato spot disease and citrus canker under natural illumination on rainy days. Additionally, compound 1 displayed remarkable resilience to rain-wash on plant leaves, retaining 41.20% of its initial concentration following exposure to three simulated rain events. These findings provide a new strategy for plant pathogen disease management highlight its feasibility even during rainy weather.