Transcripts of the viroid central conserved region contain the local tertiary structural element found in full‐length viroid

The viroid central conserved region (CCR) is highly conserved among different viroids and is thought to be involved in viroid replication. A novel tertiary structure occurs in the CCR of native circular potato spindle tuber RNAs. To permit more detailed studies of this structural element, a small RNA oligonucleotide containing the CCR of the viroid genome was synthesized. The tertiary structure of these CCR transcripts was examined by UV‐crosslinking of the RNA, followed by mapping of the crosslink using limited alkaline digestion and classical RNA secondary analysis. The CCR transcript was found to undergo UV‐crosslinking between the same two bases as in full‐length viroid, indicating that the tertiary structure is the same and that the CCR transcript will be useful for the affinity purification of host components.