The secretory pathway and the actomyosin motility system are required for plasmodesmatal localization of the P7-1 of rice black-streaked dwarf virus

Abstract

Rice black-streaked dwarf virus (RBSDV), a plant-infecting reovirus (genus Fijivirus), generally induces virus-containing tubules in infected cells. The nonstructural protein P7-1, encoded by the first open reading frame of segment 7, is involved in forming the structural matrix of these tubules. In experiments to investigate the subcellular localization of P7-1 in Nicotiana benthamiana epidermal cells, fluorescence of P7-1:eGFP was observed in the nucleus, cytoplasm and cell periphery, and in punctate points along the cell wall of plasmolyzed cells. Co-localization with plasmodesmata-located protein 1 showed that P7-1 formed the punctate points at plasmodesmata. Mutational analysis demonstrated that transmembrane domain 1 and adjacent residues were necessary and sufficient for P7-1 to form punctate structures at the cell wall in the plasmolyzed cells. Chemical drug and protein inhibitor treatments indicated that P7-1 utilized the ER-to-Golgi secretory pathway and the actomyosin motility system for its intracellular transport. The plasmodesmatal localization of RBSDV P7-1 is therefore dependent on the secretory pathway and the actomyosin motility system.

The conundrum of a unique protein encoded by citrus tristeza virus that is dispensable for infection of most hosts yet shows characteristics of a viral movement protein

“…Transport of proteins to PD has been shown to exploit the actin cytoskeleton (Amari et al, 2011;Sun et al, 2013). To investigate the role of actin in p33 intracellular distribution and trafficking, a specific actin marker, GFP:talin (Martin et al, 2009) was coexpressed with the RFP-tagged p33 in N. benthamiana leaves.…”

Abscisic acid negatively modulates plant defence against rice black‐streaked dwarf virus infection by suppressing the jasmonate pathway and regulating reactive oxygen species levels in rice

“…S7‐1 encodes a tubular protein and is localized in the PD of plant cells (Isogai, Uyeda, & Lee, ; Z. Sun, Zhang, et al, ). S7‐2 encodes a component of the SCF (Skp, Cullin, F‐box) complex (Tao et al, ).…”

Nonstructural protein P7-2 encoded by Rice black-streaked dwarf virus interacts with SKP1, a core subunit of SCF ubiquitin ligase

“…Investigating the functions of the viral proteins and elucidating the complicated process of the events in Fijivirus life cycle turn to be the focus of many researchers. Recently, some new functions of several proteins encoded by fijiviruses were reported, such as RBSDV P6, P5-1, P7-1 and their homologs [11,15,33]. However, the biological function of RBSDV P7-2 is still largely unknown, so as their counterparts in other fijiviruses.…”

“…Both S7 and S9 have two non-overlapping ORFs and encode two nonstructural proteins. P7-1 is involved in the formation of tubular structures, and the secretory pathway and actomyosin motility system in plant hosts are required for its plasmodesmatal localization [5,11]. P9-1, a thermostable, α-helical protein, is a major viroplasm matrix protein and plays a key role for the formation of viroplasms [5,12].…”