Differentiation of Xanthomonas campestris pvs. pelargonii and hederae by Polymerase Chain Reaction

Geranium isolates of Xanthomonas campestris pv. pelargonii (Xcp) and English ivy isolates of X. campes- tris pv. hederae (Xch) were tested by polymerase chain reaction (PCR) to determine whether the two patho- vars could be discriminated using ampli®cation condi- tions developed to identify and detect Xcp in infected geraniums. Using PCR, other workers reported that the genomes of Xcp and Xch were indistinguishable. The objective of this study was to determine whether the two pathovars have sucient sequence diversity to allow them to be distinguished by molecular means. Three primer pairs were used for PCR ampli®cation. Two of the primer pairs (REP and XcpM1/XcpM2) were able to distinguish between Xch and Xcp, whereas ampli®cation with the third primer pair (ERIC) did not allow discrimination between the two pathovars. Based on PCR ampli®cation, Xcp and Xch are distinctly dif- ferent pathovars. Additionally, all three primer pairs showed discrimination between Xcp and Acidovorax, a bacterial pathogen that induces leaf spot on geranium.