Regulators Involved in Dickeya solani Virulence, Genetic Conservation and Functional Variability

International audienceBacteria from the genus Dickeya (formerly Erwinia chrysanthemi) are plant pathogens causing severe diseases in many economically important crops. A majority of the strains responsible for potato disease in Europe belong to a newly identified Dickeya solani species. Although some ecological and epidemiological studies have been carried out, little is known about the regulation of D. solani virulence. The characterization of four D. solani strains indicates significant differences in their virulence on potato, although they are genetically similar based on genomic fingerprinting profiles. A phenotypic examination included an analysis of virulence on potato; growth rate in culture; motility; Fe3+ chelation; and pectate lyase, cellulase, protease, biosurfactant, and blue pigment production. Mutants of four D. solani strains were constructed by inactivating the genes coding either for one of the main negative regulators of D. dadantii virulence (kdgR, pecS, and pecT) or for the synthesis and perception of signaling molecules (expI and expR). Analysis of these mutants indicated that PecS, PecT, and KdgR play a similar role in both species, repressing, to different degrees, the synthesis of virulence factors. The thermoregulator PecT seems to be a major regulator of D. solani virulence. This work also reveals the role of quorum sensing mediated by ExpI and ExpR in D. solani virulence on potato

Draft Genome Sequence of a Highly Virulent Strain of the Plant Pathogen Dickeya solani, IFB0099

Dickeya solani is an important bacterial pathogen of potato cultivars in Europe. Here, we present the draft genome of D. solani strain IFB0099 isolated from potato in Poland that shows a high level of pectinolytic activity and a high virulence. This genome sequence is 5,094,121 bp and contains 4,365 protein-coding sequences

Soft rot Pectobacteriaceae: A Brief Overview

Bacterial soft rot diseases devastate a wide range of crops, vegetables and ornamental plants worldwide. Amongst the most damaging agents of these diseases are members of the Pectobacterium and Dickeya genera belonging to the family Pectobacteriaceae in the order Enterobacterales. As an introduction to the topics of this book, this chapter presents a brief overview on taxonomy history, presence in multiple environments, disease characteristics, population dynamics, management and economic impact of these bacteria

Isolation, detection and characterization of Pectobacterium and Dickeya species

This chapter outlines isolation, detection and characterization methods for soft rot Pectobacteriaceae (SRP) and finishes with recommendations for diagnostics of SRP and perspectives for improved detection using metagenomic and pan-genomic approaches. For dilution plating and isolation of SRP, crystal violet pectate is still the medium of preference, although it is poorly selective. To improve the diagnostic sensitivity of detection methods, enrichment methods are used in which selective growth of the pathogen is enhanced by incubation in a pectate broth under low oxygen conditions. For molecular characterization, various finger printing techniques are described, but today analysis based on phylogenetic markers are preferred, in particular multi-locus sequence typing of housekeeping genes and comparative genetics using whole-genome sequences. For phenotypic characterization, methods are used based on serological, biochemical and physiological features. Currently the most precise phenotyping method is protein mass fingerprinting using a MALDI-TOF Mass Spectrometry. For detection of the pathogen, DNA-based amplification methods are generally used, including conventional PCR, real time (TaqMan) PCR assays and LAMP assays. They can detect the pathogen at a low density and allow recognition of the pathogens at different taxonomic levels. An inventory has been included of recently developed primer and probe combinations

Diseases Caused by Pectobacterium and Dickeya Species Around the World

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