The International Trade of Ware Vegetables and Orna-Mental Plants-An Underestimated Risk of Accelerated Spreading of Phytopathogenic Bacteria in the Era of Globalisation and Ongoing Climatic Changes.

Bacteria of the genus Pectobacterium are globally occurring pathogens that infect a broad spectrum of plants. The plant cell wall degrading enzymes allow them to cause diseases like soft rot and blackleg. Worldwide trade and exchange of plant material together with the accompanying microorganisms contributed to the rapid spread and consequently the acquisition of new traits by bacteria. The 161 pectinolytic strains were isolated from symptomless vegetables and ornamental plants acquired from Polish and foreign local food markets. All strains except four Dickeya isolates were identified as belonging to the Pectobacterium genus by PCR with species-specific primers and recA gene sequencing. The newly isolated bacteria were assigned to eight species, P. versatile (50 strains), P. carotovorum (33), P. brasiliense (27), P. atrosepticum (19), P. parmentieri (12), P. polaris (11), P. parvum (3) and P. odoriferum (2). ERIC PCR and phenotypic characteristics revealed high heterogeneity among P. carotovorum, P. brasiliense and P. versatile isolates. Moreover, a subset of the newly isolated strains was characterised by high tolerance to changing environmental conditions such as salinity, pH and water availability. These bacteria can effectively macerate the tissues of various plants, including potato, chicory and orchid. Our results indicate that Pectobacterium strains isolated from internationally traded, symptomless vegetables and ornamental plants have high potential for adaptation to adverse environmental conditions and to infect various host plants. These features may contribute to the success of the genus Pectobacterium in spreading between different climatic zones and facilitate the colonisation of different ecological niches.