ABSTRACT
The tymovirus group was organized by the ICTV in 1971. The group name is derived from the type member, furnip yellow mosaic virus. Properties of the group have been reviewed by Matthews, Koenig and Lesemann, Francki and co-workers, and Hirth and Givord. Tymovirus particles are icosahedral, ca. 28 nm in diameter, containing one molecule of ssRNA. Tymoviruses exhibit a high cytosine content. In tymovirus-infected cells, chloroplasts contain nonperipheral vacuoles and flask-shaped double-membrane-bound vesicles at their peripheries. Desmodium yellow mottle virus (DeYMV) was described by Walters and Scott, and its properties were reviewed by Scott. DeYMV has been classified as a member of the tymovirus group by the ICTV. Lesemann describes chloroplasts in DeYMV-infected cells as containing peripheral vesicles but lacking the vacuoles which occur in other tymovirus infections. Kennedia yellow mosaic virus has been classified as a member of the tymovirus group by the ICTV.
