On the Question of Crown-Gall Tumor Initiation by DNA of Bacteriophage PS8
Journal of Virology
DNA of Agrobacterium tumefaciens bacteriophage PS8 was isolated by using several procedures. Whole phage and phage DNA were tested for tumor-inducing ability on 10 species of plants with various additions to assist such activity. The reported tumorigenicity of phage PS8 DNA could not be confirmed, and no evidence to implicate phage PS8 involvement in tumor initiation was obtained. Bacteriophage PS8, which infects several strains of Agrobacterium tumefaciens, was originally isolated from
... olated from sunflower crown-gall tissue cultivated in tissue culture for many years in the apparent absence of the tumor-inducing bacterium (10). This result, plus those of Tourneur and Morel (12) , who isolated Agrobacterium phage from several crown-gall tissues growing in sterile culture but none from cultures of normal, habituated or virus tumor tissues, is suggestive of phage involvement in crown-gall formation. Leff and Beardsley (4) reported that DNA isolated from phage PS8 could induce tumorous proliferations, albeit sporadically, on pinto bean leaves, sunflower stems, and tobacco stems. It was desirable to confirm this report of tumor-inducing ability by DNA from phage PS8 in order to study the crown-gall tumor initiation process in detail. Our experiments, however, provide no evidence for tumorigenic activity on the part of PS8 or of DNA isolated from this phage.