Antibacterial Activities of Prenylated Flavonoids from Sophora flavences against Xanthomonas oryzae pv oryzae

The increasing resistance of phytopathogenic bacteria to chemical pesticides has underscored the urgent need for novel bactericidal agents. Sophora flavescens produces a wide range of secondary metabolites with a wide range of biological activities. Here, eight prenylated flavonoids were evaluated for the activity against phytopathogenic bacteria. Among the compounds tested, sophoraflavanone G (SFG) demonstrated broad-spectrum activity, showing a MIC₅₀ of 1.56 μg/mL against Xanthomonas oryzae pv oryzae (Xoo). Subsequently, the mechanism of SFG on Xoo was initially explored. SFG inhibited biofilm formation and metabolic activity by reducing the production of xanthomonadins and exopolysaccharides as well as decreasing extracellular enzyme activity and surface hydrophobicity. It also affected chemotaxis by down-regulating the genes involved in the chemotaxis of Xoo, which decreased the motility of the flagellum. Furthermore, SFG induced the production of ROS, reduced ATP generation, disrupted mitochondrial membrane potential, and ultimately triggered apoptosis. Therefore, SFG is expected to be a lead compound in the development of bactericidal agents for plants.