Targeting of plasmodesmal proteins requires unconventional signals.

Effective cellular signaling relies on precise spatial localization and dynamic interactions among proteins in specific subcellular compartments or niches, such as cell-to-cell contact sites and junctions. In plants, endogenous and pathogenic proteins gained the ability to target plasmodesmata, membrane-lined cytoplasmic connections, through evolution to regulate or exploit cellular signaling across cell wall boundaries. For example, the receptor-like membrane protein PLASMODESMATA-LOCATED PROTEIN 5 (PDLP5), a potent regulator of plasmodesmal permeability, generates feed-forward or feed-back signals important for plant immunity and root development.

Evidence for reduced plasmodesmata callose accumulation in Nicotiana benthamiana leaves with increased symplastic cell-to-cell communication caused by RNA processing defects of chloroplasts.

RNA processing defects in chloroplasts were previously associated with increased plasmodesmata (PD) permeability. However, the underlying mechanisms for such association are still unknown. To provide insight into this, we silenced the expression of chloroplast-located INCREASED SIZE EXCLUSION LIMIT 2 (ISE2) RNA helicase in Nicotiana benthamiana leaves and determined an increase in PD permeability which is caused by a reduction of PD callose deposition.

In vivo imaging of tagged mRNA in plant tissues using the bacterial transcriptional antiterminator BglG.

RNA transport and localization represent important post-transcriptional mechanisms to determine the subcellular localization of protein synthesis. Plants have the capacity to transport messenger (m)RNA molecules beyond the cell boundaries through plasmodesmata and over long distances in the phloem. RNA viruses exploit these transport pathways to disseminate their infections and represent important model systems to investigate RNA transport in plants.

An evolutionarily conserved motif is required for Plasmodesmata-located protein 5 to regulate cell-to-cell movement.

Numerous cell surface receptors and receptor-like proteins (RLPs) undergo activation or deactivation via a transmembrane domain (TMD). A subset of plant RLPs distinctively localizes to the plasma membrane-lined pores called plasmodesmata. Those RLPs include the Arabidopsis thaliana Plasmodesmata-located protein (PDLP) 5, which is well known for its vital function regulating plasmodesmal gating and molecular movement between cells.

Interplay between potato virus X and RNA granules in Nicotiana benthamiana.

Cytoplasmic RNA granules consist of microscopic agglomerates of mRNAs and proteins and occur when the translation is reversibly and temporally halted (stress granules, SGs) or mRNAs are targeted for decapping (processing bodies, PBs). The induction of RNA granules formation by virus infection is a common feature of mammalian cells. However, plant-virus systems still remain poorly characterized.

Citrus Psorosis Virus Movement Protein Contains an Aspartic Protease Required for Autocleavage and the Formation of Tubule-Like Structures at Plasmodesmata.

Plant virus cell-to-cell movement is an essential step in viral infections. This process is facilitated by specific virus-encoded movement proteins (MPs), which manipulate the cell wall channels between neighboring cells known as plasmodesmata (PD). Citrus psorosis virus (CPsV) infection in sweet orange involves the formation of tubule-like structures within PD, suggesting that CPsV belongs to "tubule-forming" viruses that encode MPs able to assemble a hollow tubule extending between cells to allow virus movement.

ICTV Virus Taxonomy Profile: Ophioviridae.

The Ophioviridae is a family of filamentous plant viruses, with single-stranded negative, and possibly ambisense, RNA genomes of 11.3-12.5 kb divided into 3-4 segments, each encapsidated separately.

Identification and characterization of two RNA silencing suppressors encoded by ophioviruses.

Citrus psorosis virus and Mirafiori lettuce big-vein virus are two members of the genus Ophiovirus, family Ophioviridae. So far, how these viruses can interfere in the antiviral RNA silencing pathway is not known. In this study, using a local GFP silencing assay on Nicotiana benthamiana, the 24K-25K and the movement protein (MP) of both viruses were identified as RNA silencing suppressor proteins.

Bioinformatic and mutational analysis of ophiovirus movement proteins, belonging to the 30K superfamily.

Ophioviridae is a family of segmented, negative-sense, single-stranded RNA plant viruses. We showed that their cell-to-cell movement protein (MP) is an isolated member of the 30K MP superfamily with a unique structural organization. All 30K MPs share a core domain that contains a nearly-invariant signature aspartate.

Citrus psorosis virus 24K protein interacts with citrus miRNA precursors, affects their processing and subsequent miRNA accumulation and target expression.

Sweet orange (Citrus sinensis), one of the most important fruit crops worldwide, may suffer from disease symptoms induced by virus infections, thus resulting in dramatic economic losses. Here, we show that the infection of sweet orange plants with two isolates of Citrus psorosis virus (CPsV) expressing different symptomatology alters the accumulation of a set of endogenous microRNAs (miRNAs). Within these miRNAs, miR156, miR167 and miR171 were the most down-regulated, with almost a three-fold reduction in infected samples.

Ophioviruses CPsV and MiLBVV movement protein is encoded in RNA 2 and interacts with the coat protein.

Citrus psorosis virus (CPsV) and Mirafiori lettuce big-vein virus (MiLBVV), members of the Ophioviridae family, have segmented negative-sense single-stranded RNA genomes. To date no reports have described how ophioviruses spread within host plants and/or the proteins involved in this process. Here we show that the 54K protein of CPsV is encoded by RNA 2 and describe its subcellular distribution.

Citrus psorosis and Mirafiori lettuce big-vein ophiovirus coat proteins localize to the cytoplasm and self interact in vivo.

Citrus psorosis (CPsV) and Mirafiori lettuce big-vein virus (MiLBVV) belong to the family Ophioviridae, plant viruses with filamentous nucleocapsids and segmented genomes of negative polarity, causing the worldwide distributed citrus psorosis and lettuce big-vein diseases, respectively. To gain insight into the replication cycle of these viruses, the subcellular localization of the viral coat proteins (CP) was studied. Immunoblot analysis of fractionated extracts derived from natural and experimental infected hosts indicated that the CP of CPsV occurs in the soluble cytoplasmic fraction.