From Karaj and Takestan (Iran) vineyards bacterial colonies typical of Agrobacterium were isolated from soil, plant sap and young galls on a selective medium during early spring 1996. Bacterial isolates that were gram-negative and oxidase- and catalase-positive were cultured on King's B medium in order to be distinguishable from fluorescing pseudomonads. Thirty-two Agrobacterium isolates were inoculated on test plants such as Datura, Nicotiana and Lycopersicon. Pathogenic isolates were inoculated on 10 different Iranian grape varieties for gall formation. A biovar differentiation study showed that 7 pathogenic strains and 15 non-pathogenic strains belong to A. vitis, whereas 6 non-pathogenic strains belong to biovar 1 and 4 non-pathogenic strains to biovar 2 of Agrobacterium spp. Pathogenic strains of A. vitis were characterized on the basis of phenotypic tests, protein and plasmid profiles and an antibiotic sensitivity test. Electrophoretic studies revealed that A. vitis strains were different with regard to the protein profile but shared a common high molecular weight plasmid DNA band in the agarose gel. It is concluded that the Iranian strains of A. vitis are phenotypically guile heterogeneous and distinguishable
