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Use of Polymerase Chain Reaction to Produce Oligonucleotide Probes for Mycoplasmalike Organisms. Giuseppe Firrao, Dipartimento di Biologia Applicata alla Difesa delle Piante, Università di Udine, Udine, I-33100, Italy; Emanuela Gobbi, and Romano Locci. Dipartimento di Biologia Applicata alla Difesa delle Piante, Università di Udine, Udine, I-33100, Italy. Phytopathology 83:602-607. Accepted for publication 29 January 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-602.

Specific oligonucleotide probes for detecting apple proliferation and clover phyllody MLOs (mycoplasmalike organisms) in infected tissues were derived from a partial sequence of their 16S ribosomal RNA genes and were tested by dot blot hybridization against amplified DNA from both healthy plants and plants infected by MLOs. Probes were disease specific, with the exception of probes designed for the apple proliferation MLO, which reacted with the DNA extracted from a periwinkle infected by the plum leptonecrosis MLO. The sequenced DNAs were obtained by PCR (polymerase chain reaction) from crude nucleic acid extracts with primers that allowed the amplification of an 865-bp DNA fragment from infected but not from healthy periwinkles. The amplification of a similar fragment was obtained from all MLO-infected periwinkles examined.