Tumor formation on plants by mixtures of attenuated Agrobacterium tumefaciens T-DNA mutants.

The inoculation of plants with mixtures consisting of an A. tumefaciens mutant with a mutation in the auxin-locus of the T-DNA and a mutant with a mutation in the cytokinin-locus of the T-DNA invariably led to full tumor induction, in spite of the low oncogenicity of each of the mutants when inoculated separately. A similar complementation was observed when mixtures of certain auxin-locus mutants were used for infection. In these experiments the auxin-locus mutants fell into two classes. One class appeared to have mutations in the T-DNA region for transcript 1, while the other class had a mutation in the region for transcript 2. The intra-locus complementation observed suggests that the T-DNA genes in the auxin-locus together determine the production of a trans-acting product.