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Some Effects of Buffers on the Infectivity and Appearance of Virus Inocula used for Tobacco Protoplasts
Abstract
SUMMARY
Inocula of either tobacco rattle (TRV) or raspberry ringspot (RRV) viruses prepared in tris chloride, pH 8.0, were as infective for tobacco mesophyll protoplasts as those prepared in potassium phosphate, pH 6.0. Both types were more infective than inocula prepared in potassium citrate, pH 6.0. However, at sub-optimal concentrations of poly-l-ornithine (< 0.8 µg/ml), tris-chloride buffered inocula of TRV were much more infective than phosphate buffered inocula.
Electron microscopy showed that all inocula contained aggregated virus particles. Aggregates of TRV formed in phosphate or citrate buffers contained 2 to 30 particles whereas those formed in tris chloride were much larger, containing hundreds of virus particles. Such a difference was not evident in TMV inocula, in which virus particles were aggregated into strands of up to 25 µm in length. In contrast aggregates of RRV were approx. spherical, about 150 to 300 nm in diam., with those formed in tris-HCl being more irregular than those formed in citrate or phosphate. These results indicate that the infectivity of an inoculum is not related simply to the type or size of aggregate formed.
- Received:
- Accepted:
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© Journal of General Virology 1979