Variations in Plasmid DNA Sequences Present in Crown Gall Tumour Lines

Abstract

The results of hybridization reactions between 3H-labeled plasmid DNA derived from 2 strains of Agrobacterium tumefaciens (Bryophyllum BB6 and Vinca rosea VBP) are shown. Each of the tumor lines appears to contain some DNA sequences complementary to bacterial plasmid DNA. The percentage of the total plasmid DNA sequences varies with the tumor line, BB6 containing about 40% and VBP about 15%. The variation in percentage does not appear to correlate with the host species of the length of time the tumor has been cultured. Only a small proportion (15% or less) of the Agrobacterium plasmid may be required for transformation. The evidence supports the hypothesis that A. tumefaciens induces tumors by transferring plasmid nucleic acid from the bacterium to the plant cells.