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Techniques

Electrophoretic Separation of a Severe From Mild Strains of Potato Spindle Tuber Viroid. R. P. Singh, Research scientist, Agriculture Canada Research Station, P.O. Box 20280, Fredericton, New Brunswick, Canada E3B 4Z7; A. Boucher, Virology technician, Agriculture Canada Research Station, P.O. Box 20280, Fredericton, New Brunswick, Canada E3B 4Z7. Phytopathology 77:1588-1591. Accepted for publication 1 July 1987. Copyright 1987 Department of Agriculture. Government of Canada.. DOI: 10.1094/Phyto-77-1588.

When nucleic acid extracts from leaves infected with various strains of potato spindle tuber viroid (PSTV) were electrophoresed by Return-polyacrylamide gel electrophoresis (R-PAGE), viroid RNA migrated more slowly than other nucleic acids in the extract. Electrophoretic mobility of viroid bands from samples containing a severe strain (S-PSTV) was 3–4 mm slower in the return direction than those containing mild strains (M-PSTV). Mixed preparations of severe and various mild strains separated into well-defined bands, which verified the differential migration of S-PSTV from M-PSTV strains. The origin of extracts from different organs of the potato (sprout, tuber, stolon, and leaf) or different plant species (tomato, potato, and Scopolia sinensis) did not affect the migration pattern of viroid strains. This method, if verified with more severe isolates, may enable separation and identification of mild and severe strains of PSTV within a few hours, as compared with several weeks required for the standard biological cross-protection test.