Role of rice stripe virus NSvc4 in cell-to-cell movement and symptom development in Nicotiana benthamiana

Abstract

Our previous work has demonstrated that the NSvc4 protein of Rice stripe virus (RSV) functions as a cell-to-cell movement protein. However, the mechanisms whereby RSV traffics through plasmodesmata (PD) are unknown. Here we provide evidence that the NSvc4 moves on the actin filament and endoplasmic reticulum network, but not microtubules, to reach cell wall PD. Disruption of cytoskeleton using different inhibitors altered NSvc4 localization to PD, thus impeding RSV infection of Nicotiana benthamiana. Sequence analyses and deletion mutagenesis experiment revealed that the N-terminal 125 amino acids (AAs) of the NSvc4 determine PD targeting and that a transmembrane domain spanning AAs 106–125 is critical for PD localization. We also found that the NSvc4 protein can localize to chloroplasts in infected cells. Analyses using deletion mutants revealed that the N-terminal 73 AAs are essential for chloroplast localization. Furthermore, expression of NSvc4 from a Potato virus X (PVX) vector resulted in more severe disease symptoms than PVX alone in systemically infected N. benthamiana leaves. Expression of NSvc4 in Spodoptera frugiperda 9 cells did not elicit tubule formation, but instead resulted in punctate foci at the plasma membrane. These findings shed new light on our understanding of the movement mechanisms whereby RSV infects host plants.

Contribution of Host Intracellular Transport Machineries to Intercellular Movement of Turnip Mosaic Virus

“…Many viruses and individual virus proteins require the actomyosin system for their intracellular and/or intercellular movement [15,16,[18][19][20]22,60]. However, recent studies showed that RNA viruses might have evolved differently in their requirements for actin and the associated myosin motors [22,61].…”

“…In the case of TMV, several studies have shown that microtubules and microfilaments are necessary to anchor and release, or aid the movement of the VRC or MP granules often associated with ER (reviewed in [2,4,14]). Microfilaments influence the intracellular or intercellular transport of other MPs or viruses [15][16][17][18][19][20]. Myosin motors are also required for MP or viral trafficking [6,[21][22][23][24].…”

Rice Stripe Tenuivirus Nonstructural Protein 3 Hijacks the 26S Proteasome of the Small Brown Planthopper via Direct Interaction with Regulatory Particle Non-ATPase Subunit 3

“…SP has also been shown to play a critical role in viral spread in the bodies of insect vectors (13). RSV vcRNA 4 encodes a virus movement protein (MP) involved in cell-to-cell movement and symptom development (14)(15)(16)(17).…”

“…SP has also been shown to play a critical role in viral spread in the bodies of insect vectors (13). RSV vcRNA 4 encodes a virus movement protein (MP) involved in cell-to-cell movement and symptom development (14)(15)(16)(17).RSV is transovarially transmitted by the small brown planthopper (SBPH) in a circulative-propagative manner (5). The virus moves through the midgut, salivary gland, and ovary and is associated with amorphous or filamentous inclusions in the cytoplasm of midgut epithelial cells, salivary glands, and fat bodies (18,19).…”

e-Book on plant virus infection—a cell biology perspective

“…Xu and Zhou (2012) studied NSvc4, the movement protein of rice stripe virus (RSV), the type member of the Tenunivirus genus. They showed that NSvc4 traffics on the actin filament and ER network and that targeting of NSvc4 to PD requires the functional cytoskeleton.…”