Genomic overview of the phytopathogen Pectobacterium wasabiae strain RNS 08.42.1A suggests horizontal acquisition of quorum-sensing genes

The blackleg and soft-rot diseases caused by pectinolytic enterobacteria such as Pectobacterium and Dickeya are major causes of losses affecting potato crop in the field and upon storage. In this work, we report the isolation, characterization and genome analysis of the Pectobacterium wasabiae (formely identified as Pectobacterium carotovorum subsp. carotovorum) strain RNS 08.42.1A, that has been isolated from a Solanum tuberosum host plant in France. Comparative genomics with 3 other P. wasabiae strains isolated from potato plants in different areas in North America and Europe, highlighted both a strong similarity at the whole genome level (ANI > 99 %) and a conserved synteny of the virulence genes. In addition, our analyses evidenced a robust separation between these four P. wasabiae strains and the type strain P. wasabiae CFBP 3304T, isolated from horseradish in Japan. In P. wasabiae RNS 08.42.1A, the expI and expR nucleotidic sequences are more related to those of some Pectobacterium atrosepticum and P. carotovorum strains (90 % of identity) than to those of the other potato P. wasabiae strains (70 to 74 % of identity). This could suggest a recruitment of these genes in the P. wasabiae strain RNS 08.42.1A by an horizontal transfer between pathogens infecting the same potato host plant.