Subcellular Localization Of Rice Stripe Virus NSvc2 Proteins In N.Benthamiana Cells

Rice stripe diease is caused by Rice stripe virus (RSV) which is a member of Tenuivirus and caused significant losses in fields in China. RSV is transmitted by Laodelphax striatellus in a persistent, circulative-propagative manner. RSV particles are filamentous and have no membrane. RSV has very close phylogenetic relationship with the members of Bunyaviridae. The NSvc2 glycoproteins encoded by RSV share common characteristics with the GP glycoproteins found in the viruses of Bunyaviridae. In Bunyaviridae, the targeting of glycoproteins to the Golgi apparatus plays a pivotal role in the maturation of the enveloped spherical particles. In the cells of the host, GP glycoproteins of Bunyaviridae are processed into two mature glycoproteins:Gn (the amino-termina of glycoproteins) and Gc (the carboxyl-termina of glycoproteins), and Gn targets to the Golgi while Gc in the ER when expressed espectively. Gn redirects Gc from the ER to the Golgi upon co-expression. RSV also has glycoproteins NSvc2, but the particles are not spherical with membrane. There was no much study about the behavior characteristics of RSV in cells of its host. To answer this question, the subcellular localization of RSV NSvc2 glycoproteins was researched in Nicotiana benthamiana cells in this study. Firstly, yellow fluorescent protein (YFP) was fused to the carboxyl-terminal of NSvc2-N, NSvc2-C and NSvc2, and then these constructions were co-expressed with ER marker mCherry-HDEL or Golgi marker Man49-mCherry in N. benthamiana cells. The results showed that the amino-terminal NSvc2 (NSvc2-N) targeted to the Golgi apparatus in N. benthamiana cells, whereas the carboxyl-terminal NSvc2 (NSvc2-C) accumulated in the ER. Upon co-expression, NSvc2-N could redirect NSvc2-C from the ER to the Golgi. Lastly, Split-ubiquitin membrane yeast two-hybrid system also indicated that NSvc2-N and NSvc2-C interact with each other. Targeting of the NSvc2 glycoproteins to the Golgi was strictly dependent on functional COP Ⅰ or COP Ⅱ vesicae.Our findings demonstrate for the first time that the glycoproteins from an unenveloped Tenuivirus could target into Golgi bodies in plant cells.In light of the evidence from viruses in Bunyavidae that targeting into Golgi is important for the viral particle assembly and vector transmission, we propose that targeting of RSV glycoproteins into Golgi in plant cells represents a physiologically relevant mechanism in the maturation of RSV particle complex for insect vector transmission, which provide a new idea to study why the particles of RSV is filamentous and the mechanism of vector transmission of RSV.