Characterization of Agrobacterium vitis isolates obtained from galled grapevine plants in Egypt

The incidence of crown gall disease recently has been gradually increased in Egyptian vineyards and grapevine nurseries. Twelve isolates of tumorigenic bacteria were isolated from grapevines galls which are collected from different areas in Egypt. The isolates were identified as Agrobacterium vitis based on their reaction with a monoclonal antibody raised to A. vitis, their ability to induce galls and necrosis on grapevine, their reactions to standard biochemical and physiological tests and also by polymerase chain reaction amplification of specific Ti plasmid using polygalacturonase specific primers. All isolates were able to induce galls on grapevine. The isolates differed between itself in host range. All of these isolates except two were able to induce galls on kalanchoe, sunflower, datura, tobacco and chenopodium. Only five isolates produced galls on tomato. All isolates caused necrosis on grapevine explants. The genetic diversity was evaluated for these isolates by comparing DNA samples using multiplex PCR with three specific primer pairs. The isolates were segregated into three main groups, the first group that is isolated carry octopine type Ti plasmids; the second group that is isolated carry vitopine Ti plasmids and the third group that is isolated carry both octopine and vitopine type Ti plasmids. To our knowledge, this is the first report on the identification of A. vitis in Egypt.