Résumé
Most bacteria belonging to the genus Dickeya exhibit a strong pectinolytic activity resulting in dramatic damages in hundreds of crops and ornamental plants. Dickeya, which is widely used as a model genus in phytopathology studies, is rated as one of the top ten most damaging plant pathogens based on negative economic impact [1]. Indeed, emerging species such as Dickeya solani are now classified as quarantine organisms in some countries of the European Union. Dickeya bacteria are somehow reluctant to transformation by conventional techniques such as conjugation or electroporation. However, generalized phage-mediated transduction appears as a successful technique to transform Dickeya bacteria. Bacteriophages (commonly referred to as phages) are bacteria-targeting viruses. They are considered as the most abundant biological entity on Earth (approx. 1031) and they are found in all ecological niches harboring bacteria. Forty years ago, the temperate bacteriophage PhiEC2 has been discovered and shown to be able to infect Dickeya bacteria [2]. We recently used this phage to successfully achieve the transfer of large DNA fragments from one Dickeya strain to another, and therefore decided to fully characterize it beyond the scarce initial description from 1984. We sequenced the genome of the phage PhiEC2 as well as of the D. dadantii 3937 lysogenic strain harboring the corresponding prophage. We combined genome sequence analyses and electron microscopy imaging to unravel many features of the Dickeya-specific PhiEC2 bacteriophage, including morphological data and information about the insertion of the prophage within the genome of the lysogen.