Phenotypical characterization of Iranian isolates of Agrobacterium vitis, the causal agent of crown gall disease of grapevine

From Karaj and Takestan (Iran) vineyards bacterial colonies typical of Agro bacterium were isolated from soil, plant sap and young galls on a selective medium during early spring 1996. Bacterial isolates that were gram-negativ e and oxidase- and catalase-positive were cultured on King's B medium in or der to be distinguishable from fluorescing pseudomonads. Thirty-two Agrobac terium isolates were inoculated on test plants such as Datura, Nicotiana an d 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 s trains to biovar 2 of Agrobacterium spp. Pathogenic strains of A. vitis wer e characterized on the basis of phenotypic tests, protein and plasmid profi les and an antibiotic sensitivity test. Electrophoretic studies revealed th at A, vitis strains were different with regard to the protein profile but s hared a common high molecular weight plasmid DNA band in the agarose gel. I t is concluded that the Iranian strains of A. vitis are phenotypically guil e heterogeneous and distinguishable.