RESTRICTION FRAGMENT LENGTH POLYMORPHISMBASED IDENTIFICATION OF ‘DICKEYA SOLANI’ A NEW GENETIC CLADE OF DICKEYA spp
M. Waleron, R. Czajkowski, K. Waleron, E. Lojkowska
Bacteria belonging to Pectobacterium and Dickeya spp. (previously known as pectinolytic Erwinia spp.) cause soft rot diseases in a great variety of crops worldwide, particularly in potato, tomato, maize, and ornamental plants and other hosts. Infections by these pathogens may lead to severe economic losses to the crops, partially due to the lack of effective detection/identification tools and incomplete knowledge of their behavior in the environment. Since 2005, an increase in blackleg and soft rot diseases of potato has been observed in Europe due to the appearance of the new genetic clade of Dickeya spp. provisionally named ‘Dickeya solani’. This pathogen is more aggressive in most cases than bacteria of the Pectobacterium species and cause plant tissue maceration under a wide range of conditions. The present study provides a simple and reliable three-step PCR-based method for rapid differentiation of ‘D. solani’ isolates from other Dickeya spp. and Pectobacterium spp. Bacterial isolates are classified as Dickeya spp. on the basis of the PCR reaction with Dickeya spp. specific primers. Isolates identified positively as Dickeya spp. are tested by PCR for the presence of recA with the primers universal for bacteria of the former genus Erwinia. The PCR product is then digested with XbaI restriction endonuclease. The differentiation of ‘D. solani’ is based on the presence of a unique XbaI restriction site in the ‘D. solani’ recA gene that is absent in the recA sequences of other Dickeya species.