A synergistic strategy for Trans-Anethole in controlling bacterial wilt: Virulence suppression and beneficial microbiome enrichment

Plant-derived terpenoids are essential secondary metabolites involved in plant disease resistance and defense and exhibit broad-spectrum antibacterial properties. Despite this, the specific bioactivities of terpenoids against Ralstonia solanacearum remains extensively unexplored. Herein, the bioactivities of 30 terpenoids against R. solanacearum were assessed, and trans-anethole (TAN) was identified as a potent antibacterial agent with a minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of 50 mg/L and 75 mg/L, respectively. Importantly, TAN was not toxic to silkworms, earthworms, tobacco seeds, plant, or E. coli. Furthermore, through biochemical and molecular analyses, we observed that TAN at concentrations above 25 mg/L significantly impeded the R. solanacearum growth, blocked ATP and exopolysaccharide (EPS) synthesis, caused DNA damage and cell rupture, and affected bacterial swimming motility and biofilm formation. TAN also notably suppressed genes involved in EPS synthesis, biofilm regulation, chemotaxis and flagellar motility in R. solanacearum. Compared with traditional thiodiazole copper (TCO) and ethylicin (ET) treatments, the application of 100 mg/L TAN effectively prevented R. solanacearum invasion, resulting in a significantly greater control efficiency at in both greenhouse and field test. Additionally, TAN enhanced the abundance of the beneficial bacteria Bacillus and Sphingomonas and inhibited Ralstonia growth. These findings highlight the antibacterial properties of TAN, which is providing a natural compound with potential for as a pesticide and bacterial wilt control agent.