In vivo and in vitro translation of the RNAs of four tobamoviruses.

The RNAs from four tobamoviruses [tobacco mosaic virus(TMV) vulgare, TMV dahlemense, TMV U2, and the cowpea strain of TMV (CcTMV)] were translated in a cell-free ribosome system from reticulocytes. Among the translation products found were two polypeptides with molecular weights of 170,000 and 120,000 which were produced by all the viral RNAs tested. These two polypeptides comigrated with the corresponding virus-specific proteins synthesized in tobacco protoplasts infected with any of the four tobamoviruses. A 30,000 molecular weight protein was encoded by all four RNAs. However, this protein was synthesized in different amounts and differed slightly in size for each virus. When TMV vulgare or dahlemense RNAs were used as templates, this protein was one of the major translation products, whereas trace amounts were produced in the presence of U2 or CcTMV RNA. Only the CcTMV RNA directed the in vitro synthesis of a protein which had about the same electrophoretic mobility as coat protein.