Detection of Chrysanthemum stunt viroid and Potato spindle tuber viroid by return‐polyacrylamide gel electrophoresis*

Abstract

Return‐polyacrylamide gel electrophoresis (R‐PAGE) is one of the methods used for the detection of viroids, in particular Chrysanthemum stunt viroid (CSVd) and Potato spindle tuber viroid (PSTVd). The method is based on temperature‐related conformational changes of the circular single‐stranded RNA molecule. This results in a characteristic electrophoretic behaviour, providing a clear separation between the viroid and nucleic acids of the plant. Since the description of R‐PAGE, several modifications of the procedure have been published. In addition, several molecular techniques have been applied for the detection of viroids. However, R‐PAGE is still particularly suitable for phytosanitary purposes because detection is not influenced by variations in the nucleotide sequence. This means that any Pospiviroid will be detected, provided the amount is above the detection threshold. In addition, relatively large amounts of leaf material can be handled in one test. This paper presents a recently developed R‐PAGE procedure, based on the use of a horizontal electrophoresis system and paper wicks as buffer reservoirs. In comparison with the existing procedures, the new procedure is easy to perform and the use of chemicals is decreased. Results of the new procedure are shown and discussed in relation to those obtained by the previous procedure.