Effect of dsRNA associated with isolates of Cryphonectria parasitica from the central Appalachians and their relatedness to other dsRNAs from North America and Europe

A 12-kb segment of double-stranded (ds) RNA was associated with 25% of the isolates of Cryphonectria parasitica recovered from actively growing cankers in the central Appalachians. The relative virulence of these dsRNA-containing isolates ranged from a level comparable to that of the dsRNA-containing hypovirulent control isolate GH-2 to a level significantly greater than that of the dsRNA-free virulent control isolate Ep-155. When dsRNA-containing isolates and their dsRNA-free progeny were inoculated into Golden Delicious apples, excised dormant chestnut stems, or American chestnut sprouts, none of the lesions produced by the dsRNA-free progeny was significantly larger than those produced by the dsRNA-containing isolate from which they were derived [...]