Mechanism Determining the Host Specificity of Tobacco Mosaic Virus

I. Formation of Polysomes Containing Infecting Viral Genome in Various Plants

Abstract

In order to know the mechanism controling the host specificity of tobacco mosaic virus (TMV), three species of plants showing various degrees of resistance to TMV or TMV-RNA infection were selected and the fate of infecting viral genome was studied. Extract was obtained from leaves 0.5-6hr after inoculation of ³²P-TMV or ³²P-TMV-RNA and analyzed by sucrose density gradient centrifugation. It was found that polysomes containing infecting 32P-RNA were formed in plants resistant to TMV to the same extent as in susceptible tobacco plants, suggesting that the host specificity of TMV is determined at a stage of viral multiplication later than the step of translation of infecting viral genome.