DOUBLE-STRANDED RIBONUCLEIC-ACID IN BARSOY BARLEY

A large double-stranded RNA (dsRNA) resistant to digestion by three restriction endonucleases, by deoxyribonuclease I and by ribonuclease A at a salt concentration of 0.3 M but not at 0.03 M, was isolated by CF11 cellulose chromatography and agarose electrophoresis from Hordeum vulgare L. cv. Barsoy. The molecule was detected in Barsoy from six seed sources but not in nine other barley cultivars. Subsequent analysis identified a similar dsRNA in the parental lines of Barsoy and in a cultivar derived from Barsoy. Results of nuclease S1 and electron microscopy studies suggest that the dsRNA is fully base paired. Transmission of the dsRNA to progeny occurred via pollen and egg. It was not transmitted by several species of aphids and was not mechanically transmissible. No obvious symptoms were observed associated with the dsRNA in plants and no ultrastructural cytopathology was observed in leaf cells from dsRNA containing plants. No virus-like particles have been observed in tissues fixed for electron microscopy. A range of virus purification protocols failed to isolate virus-like particles from Barsoy tissue when analyzed by electron microscopy and density gradient centrifugation. The size of the dsRNA was estimated to be 8.7 x 10(6) M(r) (13.2 kb pairs) by electron microscopy.