Strain E26 of agrobacterium vitis, a biological control agent of grapevine crown gall, does not contain virA and virG pathogenic determinants

Risk assessment of biological control agents (BCAs) for the control of plant diseases in the field and/or laboratories has now become a necessary procedure before developing and producing novel BCAs. Agrobacterium vitis strain E26 is a promising potential biocontrol agent of grapevine crown gall disease. However, much less is understood about its safety or environmental risks. In this study, polymerase chain reaction (PCR) and Southern blot analyses were used to determine whether five essential virulence genes (virA, virG, iaaH, iaaM and ipt) were present in strain E26. Primers and probes were designed based on the conserved regions of each gene. The overall results obtained indicated that A. vitis strain E26 does not contain the virA and virG determinants, suggesting that this strain would be unlikely to elicit crown gall symptoms in either host or non-host plants. It seems that the iaaH, iaaM, or ipt gene were not present in strain E26 either. An applicable new approach combining PCR and Southern blot analyses to examine the pathogenicity of potential BCAs, particularly BCAs from the genus of Agrobacterium spp. was described.