Further studies on double‐stranded RNA species from raspberry plants infected with aphid‐borne viruses

Abstract

SUMMARYAnalysis by electrophoresis in polyacrylamide gels, followed by silver staining, of dsRNA extracted from many samples of raspberry leaves infected with raspberry leaf mottle virus (RLMV) and/or raspberry leaf spot virus (RLSV) failed to detect reliably any significant quantities of dsRNA species in excess of 1·0 × 106mol. wt. This contrasts with results reported from Canada where three dsRNA species of estimated mol. wt 2·6 × 1061·6 × 106and 1·1 × 106were consistently associated with infection with RLSV but none were associated with RLMV. However, in Scotland, four dsRNA species of estimated mol. wt 2·4 × 1061·6 × 1060·7 × 106and 0·3 × 106were detected in raspberry infected with apple mosaic ilarvirus. These results suggest that the dsRNA species reported from Canada are not those of RLSV but are probably those of a second virus, possibly an ilarvirus, which occurs together with RLSV and/or induces similar symptoms. A few samples from plants infected with RLMV and RLSV contained very small amounts of two dsRNA species of estimated mol. wt 4·7 × 106and 4·5 × 106. It is not known whether these species are those of RLMV and RLSV.