Widespread Occurrence of Viroid-like RNAs in Grapevines

Abstract

A survey of sample grapevines of both commercial importance and historical interest has been made for the presence of viroid-like RNAs. Tissues were collected from mature vines at the University of California, Davis, which had been indexed for virus diseases. Three viroid-like RNAs, designated grapevine viroid 1,2, and 3 (GV₁, GV₂, GV₃), ranging in size between 300 and 370 nucleotides, and displaying both circular and linear forms were detected by polyacrylamide gel electrophoresis. All of the 24 vines tested contained at least one of the viroid-like RNAs. The largest, GV₁, and the smallest, GV₃, were the most widely distributed. GV₂ was identified in only four of the vines. Seedlings of one tested variety, Emperor, were found to be free of all viroid-like RNAs even though the plants from which the seeds were gathered contained GV₁ and GV₃. No definitive correlation could be made between the viroid-like RNAs and any of the well-known grape diseases.