Detection of tumor-inducing plasmid DNA sequence in Agrobacterium tumefaciens by DNA-DNA hybridization.

Absence of plasmid DNA sequences in non-tumorigenic (crown gall tumor) strains of Agrobacterium tumefaciens was confirmed by DNA-DNA hybridization between purified tumor-inducing (Ti) plasmid DNAs isolated from the progenitor tumorigenic strains and 3H-labeled whole cell DNAs from tumorigenic strains and their non-tumorigenic derivatives. The genes controlling tumorigenicity in plant and utilizability of nopaline as their sole nitrogen source were confirmed to locate on Ti-plasmids.