Project description:Pectobacterium atrosepticum (Pba) is a gram-negative bacterium which causes blackleg and tuber soft rot on potato. To investigate the molecular processes and responses involved in Pba-host (potato) and Pba-non-host (radish) interactions, under laboratory conditions, we used total RNA-sequencing to measure the gene expression patterns from all three species. Samples from infected and non-infected plant roots were collected after fourteen days of inoculation with Pba SCRI_1039 and subjected to total RNA-sequencing on an Illumina sequencing platform.
Project description:The Lon protein is a protease implicated in virulence of many pathogenic bacteria, including some plant pathogens. However, little is known about the role of Lon in bacteria from genus Dickeya. This group of bacteria include important potato pathogens, with the most aggressive species, D. solani. To determine the importance of Lon for pathogenicity and response to stress conditions of bacteria, we constructed a D. solani Δlon strain. The mutant bacteria showed increased sensitivity to certain stress conditions, in particular osmotic and high-temperature stresses. Furthermore, qPCR analysis showed an increased expression of the lon gene in D. solani under these conditions. The deletion of the lon gene resulted in decreased motility, lower activity of secreted pectinolytic enzymes and finally delayed onset of blackleg symptoms in the potato plants. In the Δlon cells, the altered levels of several proteins, including virulence factors and proteins associated with virulence, were detected by means of MS-SWATCH analysis. These included components of the type III secretion system and proteins involved in bacterial motility. Our results indicate that Lon protease is important for D. solani to withstand stressful conditions and effectively invade the potato plant.
Project description:Application of microarray comparative genomic hybridisation analysis to enterobacterial plant pathogens. Comparison of two-colour reference type design and single colour design.
Project description:Here, we report two annotated draft genome sequences of Dickeya dianthicola isolates from potatoes collected in Delaware and West Virginia. The genomes of strains DE440 and WV516 show 99% similarity to each other and 96% and 95% similarity to the European strains IPO 980 and RNS04.9, respectively.
Project description:Dickeya spp. are bacterial pathogens causing soft-rot and blackleg diseases on a wide range of ornamental plants and crops. In this paper, we announce the PacBio complete genome sequences of the plant pathogens Dickeya solani RNS 08.23.3.1.A (PRI3337) and Dickeya dianthicola RNS04.9.
Project description:BACKGROUND:Several small diffusible molecules are involved in bacterial quorum sensing and virulence. The production of autoinducers-1 and -2, quinolone, indole and ?-amino butyrate signaling molecules was investigated in a set of soft-rot bacteria belonging to six Dickeya or Pectobacterium species including recent or emerging potato isolates. METHODOLOGY/PRINCIPAL FINDINGS:Using bacterial biosensors, immunoassay, and chromatographic analysis, we showed that soft-rot bacteria have the common ability to produce transiently during their exponential phase of growth the N-3-oxo-hexanoyl- or the N-3-oxo-octanoyl-l-homoserine lactones and a molecule of the autoinducer-2 family. Dickeya spp. produced in addition the indole-3-acetic acid in tryptophan-rich conditions. All these signaling molecules have been identified for the first time in the novel Dickeya solani species. In contrast, quinolone and ?-amino butyrate signals were not identified and the corresponding synthases are not present in the available genomes of soft-rot bacteria. To determine if the variations of signal production according to growth phase could result from expression modifications of the corresponding synthase gene, the respective mRNA levels were estimated by reverse transcriptase-PCR. While the N-acyl-homoserine lactone production is systematically correlated to the synthase expression, that of the autoinducer-2 follows the expression of an enzyme upstream in the activated methyl cycle and providing its precursor, rather than the expression of its own synthase. CONCLUSIONS/SIGNIFICANCE:Despite sharing the S-adenosylmethionine precursor, no strong link was detected between the production kinetics or metabolic pathways of autoinducers-1 and -2. In contrast, the signaling pathway of autoinducer-2 seems to be switched off by the indole-3-acetic acid pathway under tryptophan control. It therefore appears that the two genera of soft-rot bacteria have similarities but also differences in the mechanisms of communication via the diffusible molecules. Our results designate autoinducer-1 lactones as the main targets for a global biocontrol of soft-rot bacteria communications, including those of emerging isolates.
Project description:Soft Rot Pectobacteriaceae (SRP; Pectobacterium spp. and Dickeya spp., formerly known as pectinolytic Erwinia spp.) are necrotrophic bacterial pathogens infecting a large number of plant species worldwide, including agriculturally-important crops. Despite the SRP importance in agriculture, little is known about the bacteriophages infecting them, and even less about the prophages present in their genomes. Prophages are recognized as factors underlying bacterial virulence, genomic diversification and ecological fitness that contribute to the novel phenotypic properties of bacterial hosts. Likewise, they are recognized as a driving force of bacterial evolution. In this study, 57 complete genomes of Pectobacterium spp. and Dickeya spp. deposited in NCBI GenBank, were analyzed for the presence of prophage-like elements. Viral sequences were discovered in 95% of bacterial genomes analyzed with the use of PHASTER, PhiSpy, and manual curation of the candidate sequences using NCBI BLAST. In total 37 seemingly intact and 48 putatively defective prophages were found. The 37 seemingly intact prophages (27 sequences in Dickeya spp. genomes and 10 sequences in Pectobacterium spp. genomes) were annotated using RAST. Analysis of the prophage genes encoding viral structural proteins allowed classification of these prophages into different families of the order Caudovirales (tailed bacteriophages) with the SRP prophages of the Myoviridae family (81% of found prophages) being the most abundant. The phylogenetic relationships between prophages were analyzed using amino acid sequences of terminase large subunit (gene terL), integrase (gene int), holin (gene hol), and lysin (gene lys). None of these markers however proved fully useful for clear phylogenetic separation of prophages of SRP into distinct clades. Comparative analyses of prophage proteomes revealed six clusters: five present in Dickeya spp. and one within Pectobacterium spp. When screened for the presence of bacterial genes in the genomes of intact prophages, only one prophage did not contain any ORFs of bacterial origin, the other prophages contained up to 23 genes acquired from bacterial hosts. The bacterial genes present in prophages could possibly affect fitness and virulence of their hosts. The implication of prophage presence in the genomes of Pectobacterium spp. and Dickeya spp. is discussed.