Characteristics of Greek Isolates of Agrobacterium tumefaciens (E. F. Smith & Townsend) Conn

The characteristics of 51 Greek isolates (40 virulent and 11 avirulent) of Agrobacterium tumefaciens obtained from almond, peach, pear and grapevine were studied. Both biotypes of Keane, Kerr & New (1970) were recognized and the characterization of these extended with further tests. The position of 7 heterogeneous isolates which do not conform to the above biotypes is discussed. Biotype 2, widespread in Greece, was found in most hosts examined and seems to be of common occurrence. Grapevine isolates belonging to biotype 1 and to a third group were found to be host specialized. Evidence for the stability of tests used for the characterization of the organism is presented.