A specific PCR (polymerase chain reaction) primer pair have been developed using RAPD (random amplified polymorphic DNA) to detect Pseudomonas cichorii. Totally sixty random primers were used to find specific DNA fragments of P. cichorii, and a specific DNA fragment of 1,100 bp amplified by the primer OPX17 was cloned into the pCR(superscript @)Ⅱ-TOPO vector and further sequenced to design a specific primer pair SfL1/SfR2. The primer pair could amplify a distinct band of 379 bp that was specific to P. cichorii, and no DNA fragment amplified by the same primer pair from the other tested 21 bacterial species in 6 genera. Sensitivity of PCR for detection of P. cichorii with primer pair SfL1/SfR2 was between 5~10 pg for purified DNA and 5.5~9 cfu for cultured cells. Non-target bacteria did not affect the efficiency of specific amplification of P. cichorii in PCR assay with primer pair SfL1/SfR2. PCR technique using primer pair SfL1/SfR2 identifies the culture of P. cichorii within 3-4 hours and detected the bacterium in artificially inoculated sunflower leaf tissue. Based on the data provided, we conclude that the primer pair SfL1/SfR2 might be a useful tool for rapid identification and diagnosis of P. cichorii.
