Photo-Reactivation of Tobacco Mosaic Virus in vivo

Abstract

TOBACCO mosaic virus, inactivated in vitro by ultra-violet irradiation, could not be photo-reactivated by exposing plants, inoculated with the inactivated virus, to light^1,2. However, ribonucleic acid preparations from tobacco mosaic virus could be photo-reactivated in this manner, following inactivation by ultra-violet light^1,3. Siegel et al.⁴ investigated the effects of ultra-violet light on tobacco mosaic virus and tobacco mosaic virus nucleic acid, at different times after inoculation of Nicotiana glutinosa plants, on which local necrotic lesions are formed. They interpreted their results to suggest that the nucleic acid of tobacco mosaic virus is freed from its protein moiety during a lag period of approximately 2.5 hr. following inoculation and before the infective centre begins to increase in resistance to ultra-violet light. If this model is correct, and the nucleic acid of tobacco mosaic virus separates from the protein, then it should be possible to photo-reactivate the nucleic acid during the period when the separation occurs.