The effect of freezing on the structure of turnip yellow mosaic virus and a number of other simple plant viruses: An ultracentrifugal analysis

Abstract

Turnip yellow mosaic virus (TYMV), a simple, icosahedral, RNA-containing plant virus, is structurally severely injured by in vitro freezing of its water solutions. An ultracentrifugal analysis revealed that the virus is completely degraded into its RNA, which remains intact, and its protein component, which becomes predominantly fragmented. The effect of a large number of chemicals on the extent of freezing injury incurred by TYMV has also been determined. Most of the chemicals tested conferred complete or almost complete protection from freezing injury that was ultracentrifugally detectable. Notable exceptions were KCl and Naformate, which failed to prevent freezing injury to TYMV. Structural resistance to freezing injury in vitro was also tested with tobacco mosaic virus, southern bean mosaic virus, cucumber mosaic virus strain S, tomato bushy stunt virus, and tobacco ringspot virus. It was found that none of these viruses, with the possible exception of tomato bushy stunt virus, was degraded after freezing and thawing.