ABSTRACT
Protoplast systems have been established for many virus species, and studies are progressing to elucidate how viruses function in protoplasts and how protoplasts respond to viral infection. Inoculation is usually carried out by exposing protoplasts to a virus or viral RNA inoculum in a buffered mannitol solution in the presence of poly-L-ornithine. One interesting question is whether the host range of a virus species is wider at the level of protoplasts than at the level of intact plants. Protoplast systems have been established for investigating a number of viruses with multipartite genomes, i.e., viruses composed of more than one species of nucleoprotein into which one virus genome is partitioned. In plant pathological studies, the isolated protoplasts from leaf tissues are excellent materials for studying virus infection, since they probably maintain some of the properties of the tissues from which they were isolated.
