Novel Curcumin Derivatives as Potent FtsZ-Targeting Bactericides against Rice Bacterial Leaf Blight

Rice bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae (Xoo), poses a serious threat to global rice production. Given the critical role of filamentous temperature-sensitive protein Z (FtsZ) in bacterial cell division, thirty-five curcumin derivatives were designed targeting XooFtsZ for combating BLB. Among them, compound B01 exhibited outstanding anti-Xoo activity, with an EC50 value of 3.74 μg/mL, significantly outperforming curcumin (41.92 μg/mL) and the commercial bactericides bismerthiazol (10.85 μg/mL) and thiodiazole copper (10.48 μg/mL). In greenhouse trials, B01 achieved 73.2% disease control efficacy against BLB at 200 μg/mL, with no obvious phytotoxicity observed on rice plants. Morphological evidence revealed that B01 induced cell elongation, suggesting division inhibition. Molecular interaction assays identified B01's specific binding to XooFtsZ at the residues LEU71, GLY74, GLY110, and THR111. Furthermore, B01 simultaneously inhibited GTPase activity and disrupted FtsZ polymerization. This work established B01 as a promising XooFtsZ-targeted lead for novel bactericides.