Methyleugenol from Melaleuca bracteata essential oil attenuates the virulence of Dickeya fangzhongdai Onc5.

The Dickeya species cause maceration-associated diseases, which harm numerous crops and ornamental plants. In presence study, anti-quorum sensing active compound, methyleugenol (ME), was firstly isolated and identified from Melaleuca bracteata essential oil. Treatment with M. bracteata EO and ME at 10‰ and 5‰ (sub-minimal inhibitory concentration, sub-MIC) resulted in a dose-dependent reduction (p D. fangzhongdai Onc5 to EO and ME significantly reduced its virulence and infection capability in the tested hosts, including: potatoes, cabbages and carrots. The exposure of bacteria to EO and ME mainly inhibited the expression of Vfm-QS genes, including vfmH, vfmI vfmA, vfmK and vfmE. The expression of PCWDEs genes was also reduced. Collectively, the results support a mechanism by which M. bracteata EO and ME interfere with D. fangzhongdai Onc5 virulence via the Vfm-QS machinery.