VIEW ARTICLE

Resistance

Clones of Solanum berthaultii Resistant to Potato Spindle Tuber Viroid. R. P. Singh, Research scientist, Agriculture Canada Research Station, P.O. Box 20280, Fredericton, New Brunswick, Canada, E3B 4Z7; Phytopathology 75:1432-1434. Accepted for publication 3 July 1985. Copyright 1985 Department of Agriculture, Government of Canada. DOI: 10.1094/Phyto-75-1432.

Seventeen plant introductions (PI) of Solanum berthaultii were tested. Two clones (1726 and 1729) of S. berthaultii (PI 473340) were resistant to the mild and severe strains of potato spindle tuber viroid (PSTV). Both clones were resistant to PSTV by sap inoculation but were susceptible by graft inoculation. Even after graft inoculation, plants remained symptomless and PSTV was not detected by polyacrylamide gel electrophoresis. However, bioassay on Scopolia sinensis and dot-blot tests detected PSTV in such plants. Both clones were susceptible to potato viruses A, S, X, and Y by sap inoculation and to leafroll virus upon grafting. The importance of the PSTV resistance in these clones is discussed in connection with multiple insect resistance found in clones of S. berthaultii.