Replication and trafficking of a plant virus are coupled at the entrances of plasmodesmata |
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| Authors: | Jens Tilsner Olga Linnik Marion Louveaux Ian M. Roberts Sean N. Chapman Karl J. Oparka |
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| Affiliation: | 1.Biomedical Sciences Research Complex, University of St Andrews, Fife KY16 9ST, Scotland, UK;2.Cell and Molecular Sciences, The James Hutton Institute, Dundee DD2 5DA, Scotland, UK;3.Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK |
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| Abstract: | ![]()
Plant viruses use movement proteins (MPs) to modify intercellular pores called plasmodesmata (PD) to cross the plant cell wall. Many viruses encode a conserved set of three MPs, known as the triple gene block (TGB), typified by Potato virus X (PVX). In this paper, using live-cell imaging of viral RNA (vRNA) and virus-encoded proteins, we show that the TGB proteins have distinct functions during movement. TGB2 and TGB3 established endoplasmic reticulum–derived membranous caps at PD orifices. These caps harbored the PVX replicase and nonencapsidated vRNA and represented PD-anchored viral replication sites. TGB1 mediated insertion of the viral coat protein into PD, probably by its interaction with the 5′ end of nascent virions, and was recruited to PD by the TGB2/3 complex. We propose a new model of plant virus movement, which we term coreplicational insertion, in which MPs function to compartmentalize replication complexes at PD for localized RNA synthesis and directional trafficking of the virus between cells. |
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