Abstract
Electron microscopy of ultrathin sections indicated that nucleoprotein particles of raspberry ringspot (RRV) and tobacco rattle (strain CAM; TRV-CAM) viruses occurred in mixed aggregates in cells of doubly infected Nicotiana benthamiana leaves, and in protoplasts doubly infected by inoculation. RRV particles were attached to the sides and ends of TRV-CAM particles that were mostly bound to mitochondria. RRV particles attached to TRV-CAM particles linking mitochondria in clusters are considered to be the structures represented by the aggregates of RRV particle antigen found previously by fluorescent antibody staining in doubly infected protoplasts but not in those infected with RRV alone.