Tumor formation was studied in inbred radish lines that produce tumors on plant roots during flowering. In all radish lines under consideration, the sequences homologous to oncogenes tmr/tml of Agrobacterium tumefaciens were revealed by Southern hybridization. No sequences homologous to the tms locus of A. tumefaciens and the oncogenes of A. rhizogenes were determined. It was found that auxin sensitivity and the tumor-producing capacity were coinherited. We suggest that tumor phenotype arise as a result of a combination between agrobacterial "cytokinin" oncogenes and certain alleles of "auxin" radish genes.