PReclassification of Pseudomonas syringae pv avellanae as Pseudomonas avellanae (spec nov), the bacterium causing canker of hazelnut (Corylus avellana L)

Fourteen Pseudomonas strains causing canker of hazelnut in Greece and Italy were compared by analysis of plasmid DNA, whole cell fatty acids, whole cell proteins, and restriction fragment patterns of 16S rRNA. Moreover, fatty acid and protein profiles, 16S rRNA sequences and percentages of DNA similarity were compared with those of other Pseudomonas bacteria, including P. aeruginosa, P. cichorii, P. corrugata, P. viridiflava, P. syringae pv. syringae, P. s. pv. porri, P. s. pv. phaseolicola, P. s. pv. maculicola, P. s. subsp. savastanoi and P. fluorescens. The bacterium causing canker of hazelnut originally was named P. syringae pv. avellanae on the basis of biochemical tests. Strains of the hazelnut organism were very homogeneous, which was confirmed by our work. Only in the number of plasmids, especially in Italian strains, some variation was observed. Fatty acid and protein profiles, as well as 16S rRNA sequence analysis and percentage of DNA-DNA hybridization with other Pseudomonas strains indicated that the bacterium causing canker of hazelnut is very much apart from all pathovars of P. syringae rested, including pv. syringae. The strains were only very distantly related to P. syringae and other Pseudomonas species tested. All other Pseudomonas species tested were closer to P. syringae than the bacterium causing canker of hazelnut. We therefore propose to reclassify P. syringae pv. avellanae into P. avellanae.