Identification of Agrobacterium vitis as a causal agent of grapevine crown gall in Serbia

In 2010, a serious outbreak of crown gall disease was observed on grapevines (Vitis vinifera L. cv. Cabernet Sauvignon) in several commercial vineyards located in the Vojvodina province, Serbia. Bacteria were isolated from the young tumor tissue on nonselective YMA medium and five representative strains were selected for further identification. Tumorigenic (Ti) plasmid was detected in all strains by PCR using primers designed to amplify the virC pathogenicity gene, producing a 414-bp PCR product. The strains were identified as Agrobacterium vitis using differential physiological and biochemical tests, and a multiplex PCR assay targeting 23S rRNA gene sequences. In the pathogenicity assay, all strains induced characteristic symptoms on inoculated tomato and grapevine plants. They were less virulent on tomato plants in comparison to the reference strains of A. tumefaciens and A. vitis.