They have demonstrated

a high diversity of polymorphism between these subspecies. To survive, colonize and cause disease, plant-pathogenic bacteria modulate expression of their genes often using two-component signal transduction systems (TCS). These systems typically consist of two conserved components, a sensor histidine kinase and a response regulator [12]. P. carotovorum subsp. carotovorum employs different two-component systems for controlling production of virulence determinants [13–16]. PmrA-PmrB is one example of TCS for plant pathogenic bacteria, which affects production of extracellular enzymes, virulence and bacterial survival in potato tubers as well as in Arabidopsis leaves and generally in planta[17]. Belnacasan concentration The main target genes of this TCS encode products with sequence similarity to DNA binding response regulators and autophosphorylatable histidine Tanespimycin manufacturer kinases. The pmrA locus is required for resistance to the cationic peptide antibiotic polymyxin B and to other plant-derived antimicrobial peptides in

Pectobacterium. It controls the production of proteins that mediate the modification of the lipopolysaccharide (LPS) core and lipid A [17–19]. The changes in LPS structure leads to reduction of the negative charges at cell surface and hence altered interactions with iron and cationic peptides [20]. This gene was found in almost all Enterobacteriaceae[20]. In P. carotovorum subsp. carotovorum, pmrA gene encodes a protein of 222 amino acid (aa) that reveals 59.7% of identity to pmrA of Salmonella and BasR of E. coli. Its inactivation in P. carotovorum

subsp. carotovorum does not reduce the maceration ability of the bacterium on potato tuber but nevertheless remains essential for survival under adverse environmental conditions [16, 20, 21]. Phylogenies built with single genes have been used already to examine the relationships of the plant-pathogenic enterobacteria [22–25]. In this study, pmrA sequence analysis was used to identify the Pectobacterium carotovorum subsp. carotovorum isothipendyl and to estimate their genetic diversity. In addition, in at least one other system, this analysis was better correlated with Enterobacterial Repetitive Intergenic Consensus PCR (ERIC-PCR) assays and phylogenies built from 16S rDNA genes [10]. Results and discussion Twenty-nine isolates from soft-rotted potato tubers (Table 1) were used in this study. They have been identified by biochemical and phenotypic tests ([2] and Additional file 1 Table S1). A part of the strains were already confirmed as P. carotovorum subsp. carotovorum using ERIC-PCR [2, 10]. However, all strains yielded a 434 bp DNA fragment in PCR with the Y1 and Y2 specific primers for pectate lyase (pel) genes of Pectobacterium spp. [26, 27] and a 666pb with specifics primers for pmrA of Pectobacterium carotovorum subsp. carotovorum (F0145 and E2477 [16]) (Figure 1). Our purpose in this study was to develop a tool with a high specificity to detect typical Pectobacterium carotovorum subsp.