ABSTRACT
An RNA bound to the reverse transcriptase of Agrobacterium tumefaciens has been isolated and shown to be oncogenic for stem tissues of Datura stramonium grown under axenic conditions. The tumorous nature of the cellular change induced by the infectious rna was demonstrated by serial grafts of tumors on Datura stems and by cultivation of tumorous tissue in vitro on a medium without supplemental auxins and cytokinins. Active cellular proliferation within tissues of Datura stems was a prerequisite for expression of the oncogenic potential of the RNA. Further, infectious RNA was isolated from avirulent and attenuated strains of Agrobacterium tumefaciens including attenuated derivatives of strain AC58 which have been "heat-cured" of the plasmid associated with virulence. It is proposed that the infectious RNA is an essential but not the sole component of the tumor-inducing mechanism of the crown-gall bacterium.
Subject(s)
Datura stramonium , Plant Tumors , Plants, Medicinal , Plants, Toxic , RNA, Bacterial , Rhizobium , Cell-Free System , Mutation , RNA, Bacterial/metabolism , RNA-Directed DNA Polymerase/metabolism , Rhizobium/metabolism , Rhizobium/pathogenicity , Ribosomes/metabolism , VirulenceABSTRACT
The determination of the tumorous nature of an overgrowth provides one of the most essential information for all research concerning animal and plant cancerisation. The experimental procedure which will be described here answers to this imperative: it allows to prove the tumorous characteristics of proliferations obtained by inoculation of Agrobacterium tumefaciens RNA fractions to Datura stems.
Subject(s)
Plant Tumors , RNA, Bacterial/pharmacology , Cell Transformation, Neoplastic , Datura stramonium/drug effects , Indoleacetic Acids , Neoplasms, Experimental , Plants, Medicinal , Plants, Toxic , RhizobiumABSTRACT
Two RNA fractions have been isolated and purified from both oncogenic and nononcogenic strains of Agrobacterium tumefaciens. Both RNAs are capable of inducing the formation of transplantable tumors when introduced at wound sites in stems of Datura stramonium plants. One of these RNA fractions was found to be bound to an RNA-directed DNA polymerase, while the other was associated with the bacterial DNA. Physical evidence suggests that both are single stranded and small in size; linear sucrose gradients show that their size corresponds to a value of 5-6 S. A concentration of 4-5 mug of the RNAs dissolved in 0.01 ml of water is effective in initiating the formation of transplantable tumors in Datura plants.
