Distinct Mechanisms of Endomembrane Reorganization Determine Dissimilar Transport Pathways in Plant RNA Viruses

Abstract

Plant viruses exploit the endomembrane system of infected cells for their replication and cell-to-cell transport. The replication of viral RNA genomes occurs in the cytoplasm in association with reorganized endomembrane compartments induced by virus-encoded proteins and is coupled with the virus intercellular transport via plasmodesmata that connect neighboring cells in plant tissues. The transport of virus genomes to and through plasmodesmata requires virus-encoded movement proteins (MPs). Distantly related plant viruses encode different MP sets, or virus transport systems, which vary in the number of MPs and their properties, suggesting their functional differences. Here, we discuss two distinct virus transport pathways based on either the modification of the endoplasmic reticulum tubules or the formation of motile vesicles detached from the endoplasmic reticulum and targeted to endosomes. The viruses with the movement proteins encoded by the triple gene block exemplify the first, and the potyviral system is the example of the second type. These transport systems use unrelated mechanisms of endomembrane reorganization. We emphasize that the mode of virus interaction with cell endomembranes determines the mechanism of plant virus cell-to-cell transport.

Interaction between Movement Proteins of Hibiscus green spot virus

“…Transport systems encoded by viruses of distant groups vary considerably in the number of MPs they comprise, in the MP properties, and the mechanisms of MP-mediated virus transport [1,10]. Single MP-based transport systems are exemplified by that of Tobacco mosaic virus (TMV), which codes for the 30-kDa MP capable of PD modification, cell-to-cell transport, RNA binding, and directing VRCs to PD [1,11].…”

Role of Plant Virus Movement Proteins in Suppression of Host RNAi Defense

“…In the first case, the transport form is a virion or vRNP carrying the CI protein at one end, which interacts with P3N-PIPO and/or the CI protein within inclusions at PD. In the second case, the transport form is VRCs formed by the 6K2 protein interacting with CI inclusions at the PD entrances [6].…”

“…In plant virus infections, once a virus genome enters the initial cell(s), the further systemic infection involves cell-to-cell genome movement via plasmodesmata (PD) connecting neighboring cells in plant tissues and subsequent long-distance movement via the vascular system [1][2][3][4][5][6][7][8]. In general, the processes of virus spread from the initially infected cell throughout the plant, as well as viral genome transfer between host organisms, are subject to the major selective forces in the evolution of viruses.…”

Cellular COPI components promote geminivirus infections by facilitating the chloroplast localization of viral C4/AC4 proteins

“…Arf1-GTP subsequently recruits COPI components to assemble into coatomer complexes (Beck et al, 2009). COPI/II pathways were also shown to be involved in viral proteins trafficking during viral infections (Richardson et al, 2014; Barajas and Nagy, 2010; Cabanillas et al, 2018; Agaoua et al, 2021; Solovyev et al, 2022; Sangeetha and Jebasingh, 2021).…”