Disarmed A. tumefaciencs strain KYRT1, derived from a highly tumorigenic strain identified as A. tumefaciens strain Chry5. Disarming is accomplished by inactivation of plasmid pTiChry5 T-DNA sequences by, for example, deletion of sequences comprising the T-DNA right border. Methods of making transgenic plants using the novel A. tumefaciens strains are also provided
