A summary of

The isolation of YS, a spontaneous variant of the CAM strain of tobacco rattle virus, is described. Unlike CAM, YS produced yellow symptoms in several species of host plant. In experiments with mixtures of virus particles from the two strains, this character was shown to be controlled by RNA-2. However, the coat proteins of YS and CAM were indistinguishable by serology, by electro-phoresis in polyacrylamide g ls or by tryptic peptide mapping. It is concluded that the mutation responsible for the yellow symptoms i not in the coat protein gene, but elsewhere in RNA-2