Emergence of <i>Xanthomonas euvesicatoria</i> pv. <i>perforans</i> as the Causal Agent of Bacterial Spot of Tomato in Argentina

ABSTRACT A bacterial spot outbreak affecting tomato crops was recorded in January 2020 in Berazategui, Buenos Aires Province, Argentina. This disease is known to be caused by three species of Xanthomonas : X. vesicatoria , X. euvesicatoria pv. euvesicatoria , X. euvesicatoria pv. perforans , and X. hortorum pv. gardneri . To identify the causal agent of the outbreak, symptomatic leaves and fruits were collected and analysed in the laboratory. Yellow‐pigmented bacterial colonies were consistently isolated from the lesions. Four representative isolates were selected and characterised based on physiological traits, BOX‐PCR genomic fingerprinting, species‐specific PCR, and partial sequencing of the hrpB gene. Pathogenicity was assessed by immersion inoculation of the aerial parts of tomato plants in a bacterial suspension of each strain (10 6 CFU/mL). Two isolates (20.A3 and 20.A5) were identified as X. vesicatoria , while the other two (20.A2 and 20.D9) were identified as X. euvesicatoria pv. perforans . Although bacterial spot of tomato is a common disease in Argentina, to our knowledge, this is the first report of X. euvesicatoria pv. perforans infecting tomatoes in the country.