PCR AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM OF A PEL GENE AS A TOOL TO IDENTIFY ERWINIA-CAROTOVORA IN RELATION TO POTATO DISEASES

Using a sequenced pectate lyase-encoding gene (pel gene), we developed a PCR test for Erwinia carotovora. A set of primers allowed the ampli fication of a 434-bp fragment in E. carotovora strains. Among the 89 E . carotovora strains tested, only the Erwinia carotovora subsp. betava sculorum strains were not detected. A restriction fragment length poly morphism (RFLP) study was undertaken on the amplified fragment with se ven endonucleases. The Sau3AI digestion pattern specifically identifie d the Erwinia carotovora subsp. atroseptica strains, and the whole set of data identified the Erwinia carotovora subsp. wasabiae strains. Ho wever, Erwinia carotovora subsp. carotovora and Erwinia carotovora sub sp. odorifera could not be separated. Phenetic and phylogenic analyses of RFLP results showed E. carotovora subsp. atroseptica as a homogene ous group while E. carotovora subsp. carotovora and E. carotovora subs p. odorifera strains exhibited a genetic diversity that may result fro m a nonmonophyletic origin. The use of RFLP on amplified fragments in epidemiology and for diagnosis is discussed.