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The first complete genome sequence characterization for a myoviridal bacteriophage, [Phi]Ea21-4, infecting Erwinia amylovora, Erwinia pyrifoliae, and Pantoea agglomerans strains is described. The findings identified five [Phi]Ea21-4 genes coding for virion structural proteins, including the major capsid protein.

Molecular analysis of 50 bacteriophage isolates of Erwinia amylovora from fire blight infected soil indicate that the isolates fall into six distinct groups. Electron microscopic analysis show distinct morphologies with Group 1 and 2 phages displaying tail and contractility and Groups 3 to 6 exhibiting short tails and thin appendages.

Lytic bacteriophages are in development as biological control agents for the prevention of fire blight disease caused by E rwinia amylovora. Temperate phages should be excluded as biologicals since lysogeny produces the dual risks of host resistance to phage attack and the transduction of virulence determinants between bacteria. The extent of lysogeny was estimated in wild populations of E . amylovora and P antoea agglomerans with real-time polymerase chain reaction primers developed to detect E . amylovora phages belonging to the M yoviridae and P odoviridae families. P antoea agglomerans, an orchard epiphyte, is easily infected by E rwinia spp. phages, and it serves as a carrier in the development of the phage-mediated biological control agent. Screening of 161 E . amylovora isolates from 16 distinct geographical areas in North America, Europe, North Africa and New Zealand and 82 P . agglomerans isolates from southern Ontario, Canada showed that none possessed prophage. Unstable phage resistant clones or lysogens were produced under laboratory conditions. Additionally, a stable lysogen was recovered from infection of bacterial isolate Ea110R with P odoviridae phage ΦEa35-20. These laboratory observations suggested that while lysogeny is possible in E . amylovora, it is rare or absent in natural populations, and there is a minimal risk associated with lysogenic conversion and transduction by E rwinia spp. phages. [ABSTRACT FROM AUTHOR]

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The article provides information concerning the bacteriophages and the control of Erwinia carotovora subsp. carotova in Canada. Fourteen bacteriophages of Erwinia carotovora subsp. carotova were isolated from samples of fertilizer solutions taken from a greenhouse producing calla lily. Molecular characterization of the phages with restriction endonuclease digestions shows that two distinct types had been isolated.

The article provides information about plum pox virus including the physical and molecular features of the viral pathogen, symptoms of the disease and geographical distribution in Canada. Symptoms in peach and apricot include mild yellowing bordering secondary and tertiary veins and diffuse or blurred chlorotic rings, lines or spots on both leaves and fruit. Three viral proteases are attractive targets for inhibiting the virus replication cycle.

Erwinia amylovora is a globally devastating pathogen of apple, pear, and other Rosaceous plants. The use of lytic bacteriophages for disease management continues to garner attention as a possible supplement or alternative to antibiotics. A quantitative productive host range was established for 10 Erwinia phages using 106 wild type global isolates of E. amylovora, and the closely related Erwinia pyrifoliae, to investigate the potential regional efficacy of these phages within a biopesticide. Each host was individually infected with each of the 10 Erwinia phages and phage production after 8 h incubation was measured using quantitative real time PCR (qPCR) in conjunction with a standardized plasmid. PCR amplicons for all phages used in the study were incorporated into a single plasmid, allowing standardized quantification of the phage genome copy number after the infection process. Nine of the tested phages exhibited a broad host range, replicating their genomes by at least one log in over 88% of tested hosts. Also, every Amygdaloideae infecting E. amylovora host was able to increase at least one phage by three logs. Bacterial hosts isolated in western North America were less susceptible to most phages, as the mean genomic titre produced dropped by nearly two logs, and this phenomenon was strongly correlated to the amount of exopolysaccharide produced by the host. This method of host range analysis is faster and requires less effort than traditional plaque assay techniques, and the resulting quantitative data highlight subtle differences in phage host preference not observable with typical plaque-based host range assays. These quantitative host range data will be useful to determine which phages should be incorporated into a phage-mediated biocontrol formulation to be tested for regional and universal control of E. amylovora. [ABSTRACT FROM AUTHOR]