Inhibition of Tobacco Mosaic Virus Reproduction in Isolated Tobacco Protoplasts by Means of Pancreatic Ribonuclease

Abstract

Treatment of protoplasts with RNase solutions (1 — 100 μg/ml) sharply reduced their ability to support TMV reproduction. Treatment of protoplasts with RNase both prior to and after inoculation with the virus, and also treatments of varying duration, had approximately the same effect on inhibiting TMV reproduction; however, the effect became sharply intensified with higher RNase concentrations. The authors assume that the RNase inhibitive effect in protoplasts is ensured by the specific structure of this relatively small positively‐charged macromolecule, not by its enzymic properties. The RNase molecules apparently have a damaging effect on the plasmalemma and possibly on other cell membranes with which the initial stages of TMV reproduction are associated. The development of the RNase damaging effect can be prevented by bivalent metal ions in the incubation medium, especially by calcium and manganese. The protective effect of cations is presumably caused not only by the charge, but by their steric configuration since K+ and Mg++ are ineffective in protecting the protoplasts.

The plastochron index: Still useful after nearly six decades

“…Zhuravlev et al (1983) standardized tobacco protoplast sources in studies on tobacco mosaic virus to LPI 1–3 leaves from PI 16–18 plants. The PI and LPI has been used to standardize experimental and control plants inoculated with tobacco mosaic virus (Burundukova et al, 2009) as well as follow the progression of viral diseases in intact (Derrick et al, 1997) and grafted (Malinovskii et al, 1994) plants, and tissue and cell cultures obtained from inoculated plants (Malinovskii et al, 1993).…”