ARIS, Fruit and Grape Research Centre, Čačak, Yugoslavia, the Institute for Molecular Genetics and Genetic Engineering and the Faculty of Biology, Belgrade, Yugoslavia

Pear stony pit associated isolate WT\ which originated from diseased pear cultivar Wu rttemberg\ was char! acterized by biological tests on woody and herbaceous indicator plants\ by serological test with polyclonal anti! sera against apple stem pitting virus "ASPV#\ as well as by the molecular methods of dsRNA analysis and reverse transcription!polymerase chain reaction "RT!PCR# with ASPV!speci_c primers[ The reactions of indicator plants Jules d|Airolles\ Beurre Hardy\ Nouveau PoiteauPyronia veitchii\ seedlings Pyrus communis\ Nicotiana occidentalis 26B and Nicotiana occidentalis obliqua infected by WT isolate indicated the relatedness of WT isolate to ASPV[ The positive serological reaction of coat protein of the WT isolate with polyclonal antibodies against ASPV in Western blot reaction was obtained[ The slowest migrating dsRNA band associated with pear stony pit co!migrated with dsRNA having the highest molecular weight in di}erent ASPV isolates from apple and pear[ The dsRNA pattern ofWTisolate was identical to dsRNAs associated with quince fruit deformation and sooty ringspot[ In RT!PCR\ the fragments were obtained of the expected 240 and 180 bp sizes using two sets of ASPV!speci_c primers from dsRNA templates in theWT isolate\ as well as in control ASPV isolates ST and CJ[ The results obtained have shown the WT isolate associ! ated with pear stony pit in cv Wu rttemberg\ to be one of the apple stem pitting isolates