Abstract:

A polymerase chain reaction (PCR) method with high sensitivity and specificity has been developed with a pair of oligonucleotide primers designed and synthesized according to the DNA sequence specific to paulownia witches' broom mycoplasmalike organism (PWB-MLO). Under optimum conditions, i. e. 22. 5mM of Mg^2＋, 3.0 units of Taq DNA polymerase in a 100μl PCR reaction mixture and annealing at 55℃, a unique 377-bp DNA fragment was amplified aftter 30 cycles from all field-grown, MLO-infected paulownia tissues with or without PWB symptom. No amplified DNA was detected under the same conditions in the samples from healthy paulowina, healthy and MLO-infected jujube and rhododendron plants. With the established PCR system, the PWB-MLO DNA from approximately 2pg of crude DNA from diseased paulownia petiole tissues could be detected. This method is suitable for practical diagnosis and customs quarantine.

Key words: microbial diversity, resource conservation