Plant Virus Movement and the Impact ofRNASilencing

Abstract

Plant virus‐encoded movement proteins support the spread of viral genomes through plasmodesmata and thus represent keys to the molecular mechanisms underlying macromolecular trafficking and intercellular communication. Although Tobacco mosaic virus employs a movement mechanism involving the endoplasmic reticulum (ER)/actin network and microtubules, other viruses interact with membranes of the secretory or endocytic pathways. In addition to replication and targeting of plasmodesmata, efficient virus movement depends on the ability of the virus to interact with the ribonucleic acid (RNA) silencing machinery. Viruses generally encode proteins that suppress silencing and, thus, enhance replication and systemic movement. However, new findings suggest that viruses may also be able to subvert the host silencing machinery to manipulate gene expression in cells to be invaded. Thus, successful virus movement relies on orchestrated interactions of virus‐encoded proteins with the cellular transport and RNA silencing immune systems of the plant. Key concepts Viruses and other macromolecules are transported through plasmodesmata. Virus movement requires virus‐encoded proteins and interacting host factors. Viruses use different strategies of movement. Viruses interfere with RNA silencing in complex ways.