Role of motility and chemotaxis in the pathogenesis of Dickeya dadantii 3937 (ex Erwinia chrysanthemi 3937)

Abstract

Dickeya dadantii 3937 (ex Erwinia chrysanthemi), a member of the Enterobacteriaceae, causes soft rot in many economically important crops. A successful pathogen has to reach the interior of the plant in order to cause disease. To study the role of motility and chemotaxis in the pathogenicity of D. dadantii 3937, genes involved in the chemotactic signal transduction system (cheW, cheB, cheY and cheZ) and in the structure of the flagellar motor (motA) were mutagenized. All the mutant strains grew like the wild-type in culture media, and the production and secretion of pectolytic enzymes was not affected. As expected, the swimming ability of the mutant strains was reduced with respect to the wild-type: motA (94 %), cheY (80 %), cheW (74 %), cheB (54 %) and cheZ (48 %). The virulence of the mutant strains was analysed in chicory, Saintpaulia and potato. The mutant strains were also tested for their capability to enter into Arabidopsis leaves. All the mutants showed a significant decrease of virulence in certain hosts; however, the degree of virulence reduction varied depending on the virulence assay. The ability to penetrate Arabidopsis leaves was impaired in all the mutants, whereas the capacity to colonize potato tubers after artificial inoculation was affected in only two mutant strains. In general, the virulence of the mutants could be ranked as motA,cheY,cheB5cheW,cheZ, which correlated with the degree to which swimming was affected. These results clearly indicate that motility plays an important role in the pathogenicity of this bacterium.

Commensal Effect of Pectate Lyases Secreted from Dickeya dadantii on Proliferation of Escherichia coli O157:H7 EDL933 on Lettuce Leaves

“…We hypothesized that the virulence determinants of D. dadantii 3937 may play a role in facilitating the growth of the animal pathogen O157:H7 on plant leaves. Bacterial motility, T3SS, and CWDEs are major virulence determinants in D. dadantii 3937 (3,13,54). In order to determine whether these virulence factors of D. dadantii 3937 may affect EDL933 proliferation on postharvest lettuce, leaves were coinoculated with EDL933 and either wild-type D. dadantii or its mutant derivatives Ech166 (⌬fliA), Ech169 (⌬hrpA), A1919 (⌬outC), or Ech159 (⌬rpoS) ( Table 1), and the population dynamics of these strains were initially surveyed.…”

“…In the pathogenicity of D. dadantii 3937, T3SS, motility, and CWDEs are considered major virulence factors (3,13,54), which are partially regulated by the general stress response factor RpoS (2,27,32). In addition, among T2SS-dependent CWDEs, Pels are known to play a central role in tissue maceration to cause soft-rot symptoms on host plants (13).…”

“…In this bacterium, several virulence determinants mutually cooperate to cause plant disease. Initially, D. dadantii senses the plant hormone jasmonate, which is synthesized in wounded plant tissues, and moves toward the wound openings by chemotaxis and motility mechanisms (3,4). Entry of the bacteria into the plant host induces expression of the type III secretion system (T3SS), which transfers several type III (T3) effectors directly into host cells to suppress host defenses and facilitate proliferation (1,54).…”

SlyA regulates motA and motB, virulence and stress-related genes under conditions induced by the PhoP-PhoQ system in Dickeya dadantii 3937

“…Flagellar rotation is an important pathogenicity factor in phytopathogenic bacteria such as P. carotovorum EC1 [29], D. dadantii 3937 [39], and Pseudomonas syringae pv. tabaci 6605 [40].…”

Genetic Modulation of c-di-GMP Turnover Affects Multiple Virulence Traits and Bacterial Virulence in Rice Pathogen Dickeya zeae

“…The bacterium was inoculated in the middle of the plate using a toothpick. Plates were incubated at 28°C for 24 hours, and the diameter of the bacterial radial growth was measured[32]. …”