Cell-to-cell movement of plant viruses via plasmodesmata: a current perspective on potyviruses

Plant viruses have evolved efficient mechanisms to move cell-to-cell through plasmodesmata (PD) for systemic infection. Potyviruses including many economically important viruses constitute the largest group of known plant-infecting RNA viruses. Potyviral intercellular movement is accomplished by the coordinated action of at least three viral proteins and diverse host components. It requires the viral coat protein and is interlinked with active virus replication that generates, through RNA-polymerase slippage, a small percentage of frameshift viral RNA for the production of another essential movement protein named P3N-PIPO. This PD-located protein targets the virus-encoded cylindrical inclusion protein to PD to form special conical structures for potyviral passage, possibly in the form of virion. Here, I highlight and discuss major advances of potyviral intercellular trafficking.