Design, synthesis, and multitarget anti-Xanthomonas oryzae pv. oryzae mechanism of indole-3-substituted aryl urea derivatives.

BACKGROUND: Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae (Xoo), severely threatens rice production and global food security. Current commercial bactericides such as thiadiazole copper (TC) and bismerthiazol (BT) are losing efficacy due to widespread Xoo resistance, while research on structural modification and activity optimization of indole derivatives for Xoo control remains scarce, highlighting an urgent need for novel, safe, and effective anti-Xoo agents and filling this research gap. RESULTS: Twenty-nine indole derivatives (A1-A29) were synthesized from 3-carboxyindole (structures confirmed by 1H NMR, 13C NMR, HRMS). A29 showed superior anti-Xoo activity (EC50 = 1.24 μg/mL), low phytotoxicity, high selectivity, and better greenhouse efficacy (51% curative, 50% preventive) than BT and TC. Mechanistically, A29 exerts its effects through multiple pathways that include EPS and biofilm modulation, ROS-mediated apoptosis induction, and regulation of key genes, as validated by RT-qPCR. CONCLUSION: A29, safe, potent multi-mechanistic lead, exerts multimodal anti-Xoo effects by disrupting key processes, virulence, promising as novel agrochemical for BLB. © 2026 Society of Chemical Industry.