- Volume 60, Issue 2, 1982

The in vitro translation of tomato black ring virus genomic and satellite RNAs which had been treated with protease to remove the genome-linked protein was compared with that of untreated RNA. There were no differences in the amount or size distributions of the translation products and no differences in the proportions of added RNA which bound to ribosomes in wheat germ extracts. The genome-linked protein was found in initiation complexes. It is therefore located at or near the 5′ end of the RNA molecules and its proteolysis is not a prerequisite for translation.

The LS1 isolate of tomato mosaic virus (a strain of tobacco mosaic virus) replicates and moves from cell to cell in intact tobacco leaves at 22 °C but is restricted in movement when leaves are maintained at 32 °C, although it can replicate at that temperature. Electron microscopy of thin sections revealed a significantly lower number of plasmodesmata between LS1-infected palisade and/or mesophyll cells from leaves held at 32 °C than from those held at 22 °C. There were also substantially fewer plasmodesmata at 32 °C in LS1-infected tissue when compared with tissue infected with the type strain of tomato mosaic virus (L) which moves from cell to cell at the higher temperature. There were no differences in numbers of plasmodesmata in uninfected tissue at either temperature. No qualitative differences in the structure of plasmodesmata were observed under any conditions tested.

Turnip rosette virus (TRosV) and its RNA have been entrapped in multilamellar vesicles (MLVs) composed of phosphatidylcholine and β-sitosterol (neutral MLVs) or of phosphatidylcholine and sterylamine (positively charged MLVs). TRosV RNA was also entrapped in vesicles of phosphatidylcholine, β-sitosterol and dicetylphosphate prepared by the reverse phase evaporation method (REVs). TRosV in positively charged or neutral MLVs will infect turnip protoplasts in the presence of fusogenic agents (polyethylene glycol and/or CaCl2); TRosV RNA in such MLVs did not infect protoplasts. TRosV RNA in REVs infected protoplasts whereas the unentrapped RNA did not.