The Vfm Quorum Sensing (QS) system is preponderant for the virulence of different species of phytopathogenic bacteria of the genus Dickeya. The vfm gene cluster includes 26 genes involved in the biosynthesis, sensing or transduction of the Vfm signal. The transduction of the Vfm signal was shown to result into the activation of the promoter of the gene vfmE encoding a transcriptional regulator of the AraC family which itself activates the promoter of genes encoding the plant cell wall degrading enzymes (PCWDEs). The transcriptional regulator VfmE was shown to also activate promoters of the vfm gene cluster, allowing an exponential auto-induction of the Vfm QS system. Additionally, the activity of the transcriptional regulator VfmE was shown to also be controlled by Vfm-independent regulatory pathways involving the secondary messenger c-di-GMP and/or transcriptional regulators encoded outside of the vfm gene cluster. Here, we used a reporter gene fused to the promoter of the gene vfmE and compared the activity of the vfmE promoter among strains of Dickeya.