PCR method to identify Xanthomonas axonopodis pv. citri (X. campestris pv. citri)
A PCR method was developed to identify Xanthomonas axonopodis pv. citri (X. campestris pv. citri - EPPO A1 quarantine pest). This method is based on the amplification by nested-PCR of a region within plasmid DNA which is highly conserved in X. axonopodis pv. citri. A colorimetric procedure (DIANA: detection of immobilized amplified nucleic acids) is applied to detect amplification products in a microtiter plate. With this method, amplification was obtained with all strains of X. axonopodis pv. citri and four out of six strains of X. axonopodis pv. aurantifolii, but not with other Xanthomonads (except X. axonopodis pv. vignicola and one strain isolated from Feronia elephantiacum). No amplification products were obtained with X. axonopodis pv. citrumelo. Extracts from citrus tissues initially inhibited PCR reaction, as well as copper oxychloride (used as a chemical treatment), but the use of immunocapture reduces these negative effects and improves the sensitivity of the test by 100 fold. The authors concluded that considering the sensitivity, specificity and speed of this test, it could be widely used both for quarantine and certification purposes.
Hartung, J.S.; Pruvost, O.P.; Villemot, I.; Alvarez, A. (1996) Rapid and sensitive colorimetric detection of Xanthomonas axonopodis pv. citri by immunocapture and a nested-polymerase chain reaction assay.
Phytopathology, 86(1), 95-101.