Plant viruses traveling without passport

Abstract

All plant viruses were thought to encode in its genome a movement protein that acts as a "passport," allowing active movement within the host. A new study in PLOS Biology characterizes the first plant virus that can colonize its host without encoding this protein.

Fig 1. Schematic representation of plant virus within-host movement.

(A) Viral MP-dependent movement, as required for most plant viruses, in which host proteins (phloem proteins 1 and 2, and/or others) may also be involved. Movement may involve virions (purple hexagons), but for most RNA viruses it involves naked RNA protected from RNases by viral and/or host proteins (ribonucleoprotein complexes) like citrus yellow vein associated virus 1 (CY1) in the adjacent panel. (B) Host MP-dependent movement as shown by Ying and colleagues [5] for CY1 and CY2, which depends on the host protein PP2. Viral (red dots) and host (dark blue shapes) MPs act as “passports” for viral cell-to-cell and long-distance movement through the phloem. Viruses can move as virions (light blue spheres) or as naked genomes (wavy purple lines) that are protected by host proteins like PP2. For clarity, naked CY1 viral RNA is shown as attached to a single PP1/PP2 protein, but these proteins cover the entire molecule to exert their protective role. Phloem also transports other molecules: small RNAs (wavy pink lines), small proteins (green shapes), sugars (blue pentagons), etc., which move freely, and large molecules (orange ovals) that require active transport like viruses. Scheme was constructed using BioRender.