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Temperature Effects on the Relationships Between Xanthomonas pruni and its Virulent Phages. E. L. Civerolo, Research Plant Pathologist, Fruit Laboratory, Agricultural Research Service, Beltsville, Maryland 20705; Phytopathology 64:1248-1255. Accepted for publication 30 April 1974. DOI: 10.1094/Phyto-64-1248.

The effects of temp on phage-Xanthomonas pruni interactions are described. The plating efficiencies of eight virulent X. pruni phage variants, isolated from morphologically distinct plaques, are about the same on four X. pruni isolates from 10 to 27 C. Growth of an apricot isolate of X. pruni is inhibited in the presence of phage isolate Xp3-A/ApB at 35 C and may be due to a type of abortive infection. Irreversible adsorption of phage Xp3-A/ApB to cells of the apricot isolate of X. pruni grown at 35 C is markedly reduced, presumably due to the inaccessibility or absence of phage-specific receptor sites. In addition, replication of phage Xp3-A/ApB and cell lysis at 35 C are inhibited in cells of this X. pruni isolate previously infected at 27 C. The same numbers of lesions develop at inoculation sites on seedling leaves of peach cultivar Sunhigh following inoculation with cells of the apricot isolate of X. pruni grown at 27 or 35 C. Thus, structural alterations, presumably of the cell wall, which occur on cells grown at 35 C, and that result in the reduced capacity of cells to irreversibly adsorb virulent pruniphages are apparently not related to virulence of this X. pruni isolate.