The viability of lytic bacteriophage ΦD5 in potato-associated environments and its effect on Dickeya solani in potato (Solanum tuberosum L.) plants.

Dickeya solani is one of the most important pectinolytic phytopathogens responsible for high losses in potato, especially in seed potato production in Europe. Lytic bacteriophages can affect the structure of the host population and may influence spread, survival and virulence of the pathogen and in consequence, infection of the plant. In this study, we aimed to acquire information on the viability of the broad host lytic bacteriophage ΦD5 on potato, as well as to apprehend the specific effect of this bacteriophage on its host D. solani type-strain in different settings, as a preliminary step to target co-adaptation of phages and host bacteria in plant environment. Viability of the ΦD5 phage in tuber extract, on tuber surface, in potting compost, in rainwater and on the leaf surface, as well as the effect of copper sulfate, were examined under laboratory conditions. Also, the interaction of ΦD5 with the target host D. solani in vitro and in compost-grown potato plants was evaluated. ΦD5 remained infectious in potato tuber extract and rain water for up to 72 h but was inactivated in solutions containing 50 mM of copper. The phage population was stable for up to 28 days on potato tuber surface and in potting compost. In both, tissue culture and compost-grown potato plants, ΦD5 reduced infection by D. solani by more than 50%. The implications of these findings are discussed.

Application of zinc chloride precipitation method for rapid isolation and concentration of infectious Pectobacterium spp. and Dickeya spp. lytic bacteriophages from surface water and plant and soil extracts.

This is the first report describing precipitation of bacteriophage particles with zinc chloride as a method of choice to isolate infectious lytic bacteriophages against Pectobacterium spp. and Dickeya spp. from environmental samples. The isolated bacteriophages are ready to use to study various (ecological) aspects of bacteria-bacteriophage interactions. The method comprises the well-known precipitation of phages from aqueous extracts of the test material by addition of ZnCl2, resuscitation of bacteriophage particles in Ringer's buffer to remove the ZnCl2 excess and a soft agar overlay assay with the host bacterium to isolate infectious individual phage plaques. The method requires neither an enrichment step nor other steps (e. g., PEG precipitation, ultrafiltration, or ultracentrifugation) commonly used in other procedures and results in isolation of active viable bacteriophage particles.

The complete genome, structural proteome, comparative genomics and phylogenetic analysis of a broad host lytic bacteriophage ϕD3 infecting pectinolytic Dickeya spp.

Plant necrotrophic Dickeya spp. are among the top ten most devastating bacterial plant pathogens able to infect a number of different plant species worldwide including economically important crops. Little is known of the lytic bacteriophages infecting Dickeya spp. A broad host lytic bacteriophage ϕD3 belonging to the family Myoviridae and order Caudovirales has been isolated in our previous study. This report provides detailed information of its annotated genome, structural proteome and phylogenetic relationships with known lytic bacteriophages infecting species of the Enterobacteriaceae family.

Genomic, proteomic and morphological characterization of two novel broad host lytic bacteriophages ΦPD10.3 and ΦPD23.1 infecting pectinolytic Pectobacterium spp. and Dickeya spp.

Pectinolytic Pectobacterium spp. and Dickeya spp. are necrotrophic bacterial pathogens of many important crops, including potato, worldwide. This study reports on the isolation and characterization of broad host lytic bacteriophages able to infect the dominant Pectobacterium spp. and Dickeya spp. affecting potato in Europe viz. Pectobacterium carotovorum subsp. carotovorum (Pcc), P. wasabiae (Pwa) and Dickeya solani (Dso) with the objective to assess their potential as biological disease control agents. Two lytic bacteriophages infecting stains of Pcc, Pwa and Dso were isolated from potato samples collected from two potato fields in central Poland. The ΦPD10.3 and ΦPD23.1 phages have morphology similar to other members of the Myoviridae family and the Caudovirales order, with a head diameter of 85 and 86 nm and length of tails of 117 and 121 nm, respectively. They were characterized for optimal multiplicity of infection, the rate of adsorption to the Pcc, Pwa and Dso cells, the latent period and the burst size. The phages were genotypically characterized with RAPD-PCR and RFLP techniques. The structural proteomes of both phages were obtained by fractionation of phage proteins by SDS-PAGE. Phage protein identification was performed by liquid chromatography-mass spectrometry (LC-MS) analysis. Pulsed-field gel electrophoresis (PFGE), genome sequencing and comparative genome analysis were used to gain knowledge of the length, organization and function of the ΦPD10.3 and ΦPD23.1 genomes. The potential use of ΦPD10.3 and ΦPD23.1 phages for the biocontrol of Pectobacterium spp. and Dickeya spp. infections in potato is discussed.

Complete genome sequence of a broad-host-range lytic Dickeya spp. bacteriophage ϕD5.

Little is known about lytic bacteriophages infecting plant-pathogenic Dickeya spp. These bacteria cause economically significant losses in arable crops and ornamental plant production worldwide. At present, there is no effective control of diseases caused by Dickeya spp. A novel bacteriophage, ϕD5, belonging to the family Myoviridae, order Caudovirales, that could be used to control these bacteria was isolated previously. This report provides information on its characterization. The ϕD5 genome consists of 155,346-bp-length double-stranded DNA with a GC content of 49.7 % and is predicted to have 196 open reading frames (ORFs) with an average length of 711 nucleotides each. The ORFs were classified into functional groups, including phage structure, packaging, DNA metabolism, regulation, and additional functions. The phage lifestyle predicted from PHACTS indicated that ϕD5 may be a lytic phage and therefore can efficiently kill plant-pathogenic Dickeya spp.