Tumorigenic Agrobacterium rhizogenes biovar 2 isolated from grapevine in Spain

Agrobacterium-like colonies were recovered from New and Kerr’s medium from a crown gall of grapevine rootstock 41B (Vitis vinifera X V. berlandieri) from a nursery located in Badajoz province. After colony purification and tomato and tobacco plant inoculations, three Agrobacterium isolates, tumorigenic in both plant species, were characterized. On the basis of biovar classification, all isolates were identified as belonging to biovar 2 of Agrobacterium (also called A. rhizogenes). Because this biovar is not common in grapevine, all isolates were also inoculated onto grapevine plants of cv. "Tempranillo", which developed typical tumors one-month after inoculations. DNA from all isolates yielded the expected amplification product when using FGPtmr530-FGPtmr701’, virB/G and VCF/VCR primer sets (Cubero et al. 1999), confirming their pathogenic nature, but not when using virA or pehA primer sets (Eastwell et al. 1995), suggesting that they did not belong to A. vitis. Moreover, 16S ribosomal DNA sequencing revealed that the three isolates presented identical sequences and confirmed their biovar classification. The complete 16S rDNA sequence of one of these isolates has been deposited in the GenBank database under the accession number EF213641. Crown gall disease in grapevine caused by Agrobacterium biovar 2 was first reported elsewhere (Panagopoulos et al. 1978; Süle, 1978), but it is still considered a rare event. This is the first report of tumorigenic Agrobacterium rhizogenes (biovar 2) isolated from grapevine in Spain.