Xanthomonas Species Causing Bacterial Spot of Tomato in the Russian Federation

Bacterial spot of tomato, caused by Xanthomonas euvesicatoria (Group A), X. vesicatoria (Group B), X. perforans (group C) and X. gardneri (Group D) (Jones et al., 2004), formerly known as X. campestris pv. vesicatoria, has become very important in the Russian Federation. Leaf spots and wilt symptoms were observed in 2006 in tomato fields located in southern European part of Russia. Field symptoms were first observed in early July of 2006 and had spread to over 30% of the plants in some fields by late August. Yellow-pigmented Xanthomonas-like bacteria were isolated from plants using yeast extract-CaCO3 agar. Forty-three original strains were cloned and characterized based on morphologic and biochemical properties, by genetic analysis including rep-PCR, AP-PCR and gene sequencing. Reference strains included XV153 (group A), NCPPB 422(T) (Group B), XV 938 (Group C), XV GA2, XV444 (Group D), and 15 strains stored since 1947. Phenotypic and genetic properties of newly isolated and archived Russian strains were similar. Twenty-three strains that were not amylolytic or pectolytic and failed to utilize cis-aconitic acid were identified as X. gardneri and 18 strains that were strongly amylolytic and pectolytic were identified as X. vesicatoria; neither X. euvesicatoria nor X. perforans were found.