A SURVEY OF THE INCIDENCE OF POTATO SPINDLE TUBER VIROID IN PRINCE EDWARD ISLAND USING TWO TESTING METHODS

Abstract
Return-polyacrylamide gel electrophoresis (R-PAGE) and nucleic acid hybridization (dot-blot) were used for the detection of potato spindle tuber viroid (PSTV) from potato leaves. Both methods detected potato plants experimentally infected in the first season or those produced from infected tubers (secondarily infected). PSTV concentration was lower in the first-season infected plants than those in the second. Both methods detected PSTV in a single leaf disc from field-grown infected plants combined with 399 – 499 discs from field-grown healthy plants. The sensitivity of detection by R-PAGE was lower for certain cultivars and increased with the age of plants. About 85 000 leaf samples collected from 123 tablestock fields, 170 seed fields, and 63 cultivars from the Fox Island Elite Seed Farm in Prince Edward Island were found to be free from PSTV infection. Reasons for PSTV absence in the potato crop are discussed.Key words: Diagnosis, dot-blot, return polyacrylamide gel electrophoresis, nucleic acid hybridization, Solanum tuberosum, potato