Revisiting the Identification of Xanthomonas arboricola Strains Isolated from Cherry in Montenegro Through Genome Analysis and Pathogenicity Testing

Abstract

Xanthomonas arboricola pv. pruni (Xap) is a well-known phytopathogenic bacterium responsible for bacterial spot in Prunus species. Although cherry has historically been listed as a potential host for this pathogen, the occurrence of Xap bacterial spot in cherry is rare. In the present study, two bacterial strains isolated from cherry in Montenegro and initially identified as Xap were subjected to genomic and pathogenicity analyses. The results showed substantial genetic divergence, along with distinct phenotypic profiles, between these strains and reference Xap strains known to be pathogenic in Prunus. These findings are consistent with recent studies reporting the existence of nonpathogenic, less virulent, or atypical strains of X. arboricola that had previously been misidentified as Xap due to limitations of previous diagnostic methods. The results, together with the historically low number of verified Xap infections in cherry and evidence that some strains may have been misidentified or confused with nonpathogenic or misclassified strains, contribute to the hypothesis that cherry may not be a highly relevant natural host for Xap and should therefore be reevaluated. This could have implications for monitoring strategies, risk assessment, and regulatory measures concerning Xanthomonas management in cherry cultivation