Fabrication of Isopropanolamine-Decorated Coumarin Derivatives as Novel Quorum Sensing Inhibitors to Suppress Plant Bacterial Disease.

Emerging pesticide-resistant phytopathogenic bacteria have become a stumbling block in the development and use of pesticides. Quorum sensing (QS) blockers, which interfere with bacterial virulence gene expression, are a compelling way to manage plant bacterial disease without resistance. Herein, a series of isopropanolamine-decorated coumarin derivatives were designed and synthesized, and their potency in interfering with QS was investigated. Notably, compound A 5 exhibited a better bioactivity with median effective concentration (EC 50 ) values of 6.75 mg L -1 against Xanthomonas oryzae pv. oryzae ( Xoo ) than bismerthiazol (EC 50 = 21.9 mg L -1 ). Further biochemical studies revealed that compound A 5 disturbed biofilm formation and suppressed bacterial virulence factors and so forth. Moreover, compound A 5 decreased the expression of QS-related genes. Interestingly, compound A 5 had the acceptable control effect (53.2%) toward Xoo in vivo . Overall, this study identifies a novel lead compound for the development of bactericide candidates to control plant bacterial diseases by interfering with QS.