Detection of Chrysanthemum Stunt Viroid in South Africa by Polyacrylamide Gel Electrophoresis and Bioassay. Susan R. Watermeyer, Plant Virologist, Horticultural Research Institute, Private Bag X293, Pretoria, 0001, Republic of South Africa. Plant Dis. 68:485-488. Accepted for publication 21 November 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-485.

Chrysanthemum stunt viroid (CSV) was isolated from several commercial cultivars of Chrysanthemum morifolium in South Africa for the first time. Both polyacrylamide gel electrophoresis (PAGE) and bioassay were found suitable for routine detection of CSV in South African chrysanthemums. Viroid-specific RNA was isolated from infected tissues by nucleic acid extraction followed by PAGE and detected in the gels scanned at 260 nm or stained with 0.005% toluidine blue O or 0.8% ethidium bromide. A relative mobility of 0.63 of the viroid-specific RNA compared with the 5S host RNA could be used to locate viroid bands. Symptoms typical of CSV were produced by chip-budded plants of the cultivars Mistletoe, Fanfare, and Bonnie Jean maintained at 20,000 lux. Under greenhouse conditions, sap-inoculated Senecio cruentus consistently produced systemic symptoms typical of CSV infection.