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Physiology and Biochemistry

Detection of Double-Stranded RNA in Ceratocystis ulmi. P. Lawrence Pusey, Graduate research associate, Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691, Present address of senior author: Appalachian Fruit Research Station, Kearneysville, WV 25430; Charles L. Wilson, Research Plant Pathologist, USDA/SEA-AR, Appalachian Fruit Research Station, Kearneysville, WV 25430. Phytopathology 72:423-428. Accepted for publication 9 July 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982. DOI: 10.1094/Phyto-72-423.

Double-stranded RNA (dsRNA) was detected in United States isolates of Ceratocystis ulmi by serology and polyacrylamide gel electrophoresis. Molecular weights of dsRNA segments ranged from about 0.4 to 2.0 × 10⁶ daltons. DsRNA segments were present in both more aggressive and less aggressive isolates; however, less aggressive isolates generally possessed more segments. The dsRNA segments that were unique to less aggressive isolates may contribute to diminished pathogenicity, although other unknown factors apparently influence pathogenicity as well. Single-conidial isolates from one less aggressive strain were of three types based on their dsRNA content and cultural characteristics. One segregant type, which contained all seven segments present in the parent strain, was less pathogenic than a second type containing only one segment or a third type having no dsRNA. Whether the dsRNA is of viral origin was not determined. Attempts to detect viruslike particles in semipurified preparations failed.