Evaluation of different PCR primers for identification of tumorigenic bacteria associated with grapevine crown gall.

Grapevine crown gall caused by Allorhizobium vitis, or less frequently by Agrobacterium tumefaciens complex and Rhizobium rhizogenes, may seriously impact production in nurseries and vineyards worldwide. Although rapid and efficient detection and identification of tumorigenic bacteria is facilitated by PCR-based methods, high genetic diversity of these pathogens may hinder use of these methods in the disease diagnosis. Therefore, reliability of 11 primer pairs targeting fragments located on Ti plasmid or chromosomal DNA was tested on extensive collection of All. vitis, A. tumefaciens complex and R. rhizogenes strains isolated from grapevine throughout the world. Only primers VCF3/ VCR3 targeting virC gene located on Ti plasmid clearly and accurately identified all tested tumorigenic strains associated with grapevine crown gall. Moreover, this primer pair coupled with primers specific for chromosomal pehA gene (PGF/PGR) in duplex PCR, may be recommended as the method of choice for routine preliminary identification of tumorigenic strains and differentiation of All. vitis.