Dickeya solani sp. nov., a pectinolytic plant pathogenic bacterium isolated from potato (Solanum tuberosum)

Pectinolytic bacteria were recently isolated from diseased potato plants exhibiting blackleg and slow wilt symptoms found in a number of European countries and Israel. These Gram-negative, motile, rods were identified as belonging to the genus Dickeya, previously the Pectobacterium chrysanthemi complex (Erwinia chrysanthemi), on the basis of a positive PCR reaction with pelADE primers, 16S rDNA sequence analyis, fatty acid methyl esterase analysis, the production of phosphatases and the ability to produce indole and acids from a-methyl glucoside. Differential physiological assays used previously to differentiate between strains of E. chrysanthemi, showed that these isolates belonged to biovar 3. Eight of the isolates, seven from potato and one from hyacinth, were analysed together with 21 reference strains representing all currently recognised taxa within the genus Dickeya. The new isolates formed a distinct genetic clade in multilocus sequence analysis (MLSA) using concatenated sequences of the intergenic spacer (IGS), as well as genes dnaX, recA, dnaN, fusA, gapA, purA, rplB, rpoS and gyrA. Characterization by whole-cell MALDI-TOF mass spectrometry, pulsed field gel electrophoresis after digestion of whole genome DNA with rare cutting restriction enzymes, average nucleotide identity analysis and DNA-DNA hybridization studies, showed that although related to D. dadantii, these isolates represent a novel species within the genus Dickeya, for which the name Dickeya solani sp. nov. (type strain IPO 2222T =LMG25993T =NCPPB4479T) is proposed