Sustainable Strategy of Natural trans-Anethole in Controlling Bacterial Wilt: Virulence Suppression and Beneficial Microbiome Enrichment

Plant-derived terpenoids are essential secondary metabolites exhibiting broad-spectrum antibacterial properties. However, the bioactivities of terpenoids against Ralstonia solanacearum remain 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 concentration and minimum bactericidal concentration of 50 and 75 mg/L, respectively. TAN was low-toxic to silkworms, earthworms, seeds, and E. coli. Furthermore, TAN (>25 mg/L) significantly impeded the R. solanacearum growth, blocked ATP and exopolysaccharide (EPS) synthesis, caused DNA damage and cell rupture, and affected swimming motility and biofilm formation, and suppressed expressions of related genes. Compared with thiodiazole copper, and ethylicin, 100 mg/L TAN had a significantly greater control efficiency in both greenhouse and field tests. Importantly, TAN enhanced the abundance of the beneficial bacteria Bacillus and Sphingomonas. These findings highlight TAN as a potential bacterial wilt control agent.