Potato Y virus. Coloured transmission electron micrograph (TEM) of virus particles (virions) of the potato y virus (PVY). This plant virus is a potyvirus, and has an RNA (ribonucleic acid) genome. It was first identified in 1931 in the potato plant (Solanum tuberosum), one of the world's major food crops. This virus also infects tomato, bell pepper and tobacco plants. Symptoms are mild to severe leaf mottling. The virus is transmitted by several species of aphids. Magnification: x125,000 when printed 10cm high.