Formation of multimers of cucumber mosaic virus satellite RNA.

Double-stranded RNA multimers of cucumber mosaic virus (CMV) satellite RNA were detected in CMV-infected plants. RT-PCR showed that plus-sense and minus-sense monomers and plus-sense multimers of satellite RNA were present. Multimeric minus-sense RNA was not present except in the form of multimeric dsRNA. Sequence analysis of 52 cloned junction regions in head-to-tail repeats of unit-length satellite RNA indicated that about 35% of the junction sequences were precise fusions of monomer units, 56% lacked sequence of the 5' component, and 10% lacked sequence of both 3' and 5' components. No junction contained additional nucleotides. Deletions at the junction regions may have accumulated during CMV multiplication in inoculated plants. These data suggest that replicase is not released from the template during synthesis of multimeric molecules of satellite RNA.