Pectobacterium parmentieri causing soft rot on potato tubers in southern Europe.
Among the strains isolated from tubers exhibiting symptoms of soft rot during the growing seasons of 2009-16 in Castile and Leon (the major potato producing region in Spain), a group of 11 strains that yielded PCR amplicons of the expected size for Pectobacterium carotovorum subsp. carotovorum (∼550 bp) was found. By contrast, no PCR products were obtained using primer pairs specific for P. atrosepticum or Dickeya spp. However, 4 of these isolates (CRD 21, CRD 140, CRD 149, and CRD 274) could not be conclusively assigned to P. carotovorum subsp. carotovorum as they all failed to grow at 37°C and in 5% NaCl. Based on the results of sequence analysis of 16S ribosomal RNA gene as well as biochemical and pathogenicity tests, the 4 isolates were identified as P. parmentieri. In Europe, P. wasabiae strains infecting potato (= P. parmentieri) have only recently been reported in northwestern countries. Nevertheless, it is thought that its worldwide occurrence and geographical distribution may have been underestimated due to misidentifications caused by the phenotypic diversity of this pathogen and/or the limited tools available in the past for its identification. This paper reports for the first time that P. parmentieri is present in Spain and is a causal agent of soft rot in potato fields.