Pectinolytic bacteria have been recently isolated from diseased potato plants exhibiting blackleg and slow wilt symptoms found in a number of European countries and Israel. These Gram-reaction-negative, motile, rods were identified as belonging to the genus Dickeya , previously the Pectobacterium chrysanthemi complex ( Erwinia chrysanthemi ), on the basis of production of a PCR product with thepelADEprimers, 16S rRNA gene sequence analysis, fatty acid methyl esterase analysis, the production of phosphatases and the ability to produce indole and acids from α-methylglucoside. 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 recognized taxa within the genus Dickeya . The novel isolates formed a distinct genetic clade in multilocus sequence analysis (MLSA) using concatenated sequences of the intergenic spacer (IGS), as well asdnaX,recA,dnaN,fusA,gapA,purA,rplB,rpoSandgyrA.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 Dickeya dadantii , these isolates represent a novel species within the genus Dickeya , for which the nameDickeya solanisp. nov. (type strain IPO 2222^T = LMG25993^T = NCPPB4479^T) is proposed.

The soft rot Enterobacteriaceae (SRE) Pectobacterium and Dickeya species (formerly classified as pectinolytic Erwinia spp.) cause important diseases on potato and other arable and horticultural crops. They may affect the growing potato plant causing blackleg and are responsible for tuber soft rot in storage thereby reducing yield and quality. Efficient and cost‐effective detection and identification methods are essential to investigate the ecology and pathogenesis of the SRE as well as in seed certification programmes. The aim of this review was to collect all existing information on methods available for SRE detection. The review reports on the sampling and preparation of plant material for testing and on over thirty methods to detect, identify and differentiate the soft rot and blackleg causing bacteria to species and subspecies level. These include methods based on biochemical characters, serology, molecular techniques which rely on DNA sequence amplification as well as several less‐investigated ones.

Bacteria from the genera Dickeya (formerly Erwinia chrysanthemi) and Pectobacterium (formerly E. carotovora) are the agents of blackleg and soft rot on many important crops. In 2005, Dickeya solani was isolated for the first time in Poland from a symptomatic potato plant. To establish the presence and diversity of Dickeya spp. in Poland, we surveyed potato fields and water sources, including surface waters near potato fields and water from potato-processing facilities and sewage plants. Only D. dianthicola and D. solani were isolated from symptomatic potato, and only D. zeae and D. chrysanthemi were isolated from water sources. The Dickeya spp. isolated from potato formed a relatively homogenous group, while those from water sources were more diverse. To our knowledge, this is the first comprehensive characterization of Dickeya spp. isolated during several years from regions with a temperate climate in Central Europe.

A multiplex polymerase chain reaction (PCR) assay for simultaneous, fast and reliable detection of the main soft rot and blackleg potato pathogens in Europe has been developed. It utilises three pairs of primers and enables detection of three groups of pectinolytic bacteria frequently found in potato, namely: Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. carotovorum together with Pectobacterium wasabiae and Dickeya spp. in a multiplex PCR assay. In studies with axenic cultures of bacteria, the multiplex assay was specific as it gave positive results only with strains of the target species and negative results with 18 non‐target species of bacteria that can possibly coexist with pectinolytic bacteria in a potato ecosystem. The developed assay could detect as little as 0.01 ng µL^–1 of Dickeya sp. genomic DNA, and down to 0.1 ng µL^–1 of P. atrosepticum and P. carotovorum subsp. carotovorum genomic DNA in vitro. In the presence of competitor genomic DNA, isolated from Pseudomonas fluorescens cells, the sensitivity of the multiplex PCR decreased tenfold for P. atrosepticum and Dickeya sp., while no change was observed for P. carotovorum subsp. carotovorum and P. wasabiae. In spiked potato haulm and tuber samples, the threshold level for target bacteria was 10¹ cfu mL^–1 plant extract (10² cfu g^–1 plant tissue), 10² cfu mL^–1 plant extract (10³ cfu g^–1 plant tissue), 10³ cfu mL^–1 plant extract (10⁴ cfu g^–1 plant tissue), for Dickeya spp., P. atrosepticum and P. carotovorum subsp. carotovorum/P. wasabiae, respectively. Most of all, this assay allowed reliable detection and identification of soft rot and blackleg pathogens in naturally infected symptomatic and asymptomatic potato stem and progeny tuber samples collected from potato fields all over Poland.