USE OF POLYMERASE CHAIN-REACTION TO PRODUCE OLIGONUCLEOTIDE PROBES FOR MYCOPLASMALIKE ORGANISMS

Specific oligonucleotide probes for detecting apple proliferation and clover phyllody MLOs (mycoplasmalike organisms) in infected tissues we re derived from a partial sequence of their 16S ribosomal RNA genes an d were tested by dot blot hybridization against amplified DNA from bot h healthy plants and plants infected by MLOs. Probes were disease spec ific, with the exception of probes designed for the apple proliferatio n MLO, which reacted with the DNA extracted from a periwinkle infected by the plum leptonecrosis MLO. The sequenced DNAs were obtained by PC R (polymerase chain reaction) from crude nucleic acid extracts with pr imers that allowed the amplification of an 865-bp DNA fragment from in fected but not from healthy periwinkles. The amplification of a simila r fragment was obtained from all MLO-infected periwinkles examined.