ABSTRACT
Recently, the multiplication of cauliflower mosaic virus (CaMV) in rapidly dividing pieces of callus and in protoplast-derived callus clones from infected tissue, has been examined. In vitro-infected turnip protoplasts are widely tolerant of nutritive culture conditions for CaMV synthesis, although in the presence of complex media, the extent of synthesis became more reproducible. This probably represents an influence upon host physiology rather than demonstrating a specific requirement for efficient CaMV replication. If naked viral DNA were responsible for systemic spread then it would have to be in a form different from encapsidated infectious DNA, since this is barely detectable in a free form in infected tissue or protoplasts. This chapter considers CaMV to be typical of the caulimovirus group, but it cannot be discounted that differences in inclusion body structure and synthesis and the distribution of virus particles may be virus and/or host specific.
