title: The ER-Membrane Transport System Is Critical for Intercellular Trafficking of the NSm Movement Protein and Tomato Spotted Wilt Tospovirus.
abstract: Plant viruses move through plasmodesmata to infect new cells. The plant endoplasmic reticulum (ER) is interconnected among cells via the ER desmotubule in the plasmodesma across the cell wall, forming a continuous ER network throughout the entire plant. This ER continuity is unique to plants and has been postulated to serve as a platform for the intercellular trafficking of macromolecules. In the present study, the contribution of the plant ER membrane transport system to the intercellular trafficking of the NSm movement protein and Tomato spotted wilt tospovirus (TSWV) is investigated. We showed that TSWV NSm is physically associated with the ER membrane in Nicotiana benthamiana plants. An NSm-GFP fusion protein transiently expressed in single leaf cells was trafficked into neighboring cells. Mutations in NSm that impaired its association with the ER or caused its mis-localization to other subcellular sites inhibited cell-to-cell trafficking. Pharmacological disruption of the ER network severely inhibited NSm-GFP trafficking but not GFP diffusion. In the Arabidopsis thaliana mutant rhd3 with an impaired ER network, NSm-GFP trafficking was significantly reduced, whereas GFP diffusion was not affected. We also showed that the ER-to-Golgi secretion pathway and the cytoskeleton transport systems were not involved in the intercellular trafficking of TSWV NSm. Importantly, TSWV cell-to-cell spread was delayed in the ER-defective rhd3 mutant, and this reduced viral infection was not due to reduced replication. On the basis of robust biochemical, cellular and genetic analysis, we established that the ER membrane transport system serves as an important direct route for intercellular trafficking of NSm and TSWV.
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors: Zhike
authors: Z
authors: Feng
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors: Fan
authors: F
authors: Xue
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors: Min
authors: M
authors: Xu
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors: Xiaojiao
authors: X
authors: Chen
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors: Wenyang
authors: W
authors: Zhao
authors: Departament de Bioquímica i Biologia Molecular, Universitat de València, Burjassot, Spain.
authors: Maria J
authors: MJ
authors: Garcia-Murria
authors: Departament de Bioquímica i Biologia Molecular, Universitat de València, Burjassot, Spain.
authors: Ismael
authors: I
authors: Mingarro
authors: Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, People's Republic of China.
authors: Yong
authors: Y
authors: Liu
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors: Ying
authors: Y
authors: Huang
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors: Lei
authors: L
authors: Jiang
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors: Min
authors: M
authors: Zhu
authors: Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors: Xiaorong
authors: X
authors: Tao
mesh_terms: D004721:Endoplasmic Reticulum / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000821:virology*; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000378:metabolism / Q000821:virology; D053830:Plant Viral Movement Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified; D031425:Plasmodesmata / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D014026:Nicotiana / Q000821:virology; D017865:Tospovirus
chemical_list: D053830:Plant Viral Movement Proteins