Double-stranded RNA in isolates ofDiscula destructiva from the Eastern United States

Phenol-chloroform extraction and CF-11 chromatography were used to examine 83 isolates ofDiscula sp. for the presence of dsRNA. Agarose-gel electrophoresis revealed three major size classes: large (ca. 8–12 kbp), medium (ca. 3–4 kpb), and small (ca. 1.5–2.5 kbp). Additional segments were present in two isolates. Double-stranded RNA was demonstrated in 80/80 isolates ofDiscula destructiva, but not in three isolates of an unidentifiedDiscula sp. commonly referred to asDiscula, Type 2. Twenty-two isolates contained one or more large segments. Isolates with large segments were more common in collection sites on the eastern slope of the Appalachian Mountains. The most common banding profile consisted of two medium and two small bands.