Plant virus: Tobacco mosaic virus
The tobacco mosaic virus is an RNA virus that infects the tobacco plant (N. tabacum) and closely related species. It is one of the best-studied plant viruses.
The virus causes patchy discolouration on infected leaves.
The tobacco virus is a single-stranded positive sense RNA virus and lacks a lipid envelope, like most plant viruses.
Its capsid (protein coat) is rod shaped and made up of repeating protein subunits that form a helical pattern around the genetic material.