Virulence and biofilm inhibition of 3‐methoxycinnamic acid against Agrobacterium tumefaciens
AimsIn the current study the anti‐virulence and anti‐biofilm activities of the cinnamic acid derivative, 3‐methoxycinnamic acid, was investigated against Agrobacterium tumefaciens.Methods and ResultsBased on the disc diffusion test and β‐galactosidase activity assay, 3‐methoxycinnamic acid was shown to interfere with the quorum sensing (QS) system of A. tumefaciens. Crystal violet staining assay, phenol‐sulfuric acid method, Bradford protein assay and confocal laser scanning microscopy (CLSM) revealed that the biofilm formation of A. tumefaciens was inhibited after the treatment of 3‐methoxycinnamic acid. Employing high‐performance liquid chromatography (HPLC) analysis of culture supernatant revealed that the production of 3‐oxo‐octanoylhomoserine lactone (3‐oxo‐C8‐HSL) decreased concentration‐dependently after treatment with 3‐methoxycinnamic acid. Swimming and chemotaxis assays also indicated that 3‐methoxycinnamic acid had a good effect on reducing the motility and chemotaxis of A. tumefaciens. In addition, the RT‐qPCR, molecular docking and simulations further demonstrated that 3‐methoxycinnamic acid could competitively inhibit the binding of 3‐oxo‐C8‐HSL to TraR and down‐regulate virulence‐related genes.Conclusions3‐Methoxycinnamic acid is proved to have good anti‐virulence and anti‐biofilm activities against A. tumefaciens.Significance and Impact of the StudyThis is the first study that investigates the anti‐virulence and anti‐biofilm activities of 3‐methoxycinnamic acid against A. tumefaciens. With its potential QS‐related virulence and biofilm inhibitory activities, 3‐methoxycinnamic acid is expected to be developed as a potent pesticide or adjuvant for the prevention and treatment of crown gall caused by A. tumefaciens.
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