title: Clustering and cellular distribution characteristics of virus particles of Tomato spotted wilt virus and Tomato zonate spot virus in different plant hosts.
abstract: BACKGROUND
  Tomato spotted wilt virus (TSWV) and Tomato zonate spot virus (TZSV) are the two dominant species of thrip-transmitted tospoviruses, cause significant losses in crop yield in Yunnan and its neighboring provinces in China. TSWV and TZSV belong to different serogroup of tospoviruses but induce similar symptoms in the same host plant species, which makes diagnostic difficult. We used different electron microscopy preparing methods to investigate clustering and cellular distribution of TSWV and TZSV in the host plant species.
  
  
  RESULTS
  Negative staining of samples infected with TSWV and TZSV revealed that particles usually clustered in the vesicles, including single particle (SP), double particles clustering (DPC), triple particles clustering (TPC). In the immunogold labeling negative staining against proteins of TZSV, the antibodies against Gn protein were stained more strongly than the N protein. Ultrathin section and high pressure freeze (HPF)-electron microscopy preparations revealed that TSWV particles were distributed in the cisternae of endoplasmic reticulum (ER), filamentous inclusions (FI) and Golgi bodies in the mesophyll cells. The TSWV particles clustered as multiple particles clustering (MPC) and distributed in globular viroplasm or cisternae of ER in the top leaf cell. TZSV particles were distributed more abundantly in the swollen membrane of ER in the mesophyll cell than those in the phloem parenchyma cells and were not observed in the top leaf cell. However, TZSV virions were mainly present as single particle in the cytoplasm, with few clustering as MPC.
  
  
  CONCLUSIONS
  In this study, we identified TSWV and TZSV particles had the distinct cellular distribution patterns in the cytoplasm from different tissues and host plants. This is the first report of specific clustering characteristics of tospoviruses particles as well as the cellular distribution of TSWV particles in the FI and globular viroplasm where as TZSV particles inside the membrane of ER. These results indicated that tospoviruses particles possessed specific and similar clustering in the saps of diseased plants. Furthermore, the results of this study will also provide a basis for further study on the tospoviruses assembling, maturation and movement.
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, P.R. China. zhongkai99@sina.com.|Key Lab of Southwestern Crop Gene Resources and Germplasm Innovation, Ministry of Agriculture, Yunnan Provincial Key Laboratory of Agricultural Biotechnology, Biotechnology and Germplasm Resources Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650223, Yunnan, P.R. China. zhongkai99@sina.com.
authors.forename: Zhongkai
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Key Lab of Southwestern Crop Gene Resources and Germplasm Innovation, Ministry of Agriculture, Yunnan Provincial Key Laboratory of Agricultural Biotechnology, Biotechnology and Germplasm Resources Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650223, Yunnan, P.R. China. zhengkuanyu@126.com.
authors.forename: Kuanyu
authors.initials: K
authors.lastname: Zheng
authors.affiliation: Key Lab of Southwestern Crop Gene Resources and Germplasm Innovation, Ministry of Agriculture, Yunnan Provincial Key Laboratory of Agricultural Biotechnology, Biotechnology and Germplasm Resources Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650223, Yunnan, P.R. China. dongjhn@126.com.
authors.forename: Jiahong
authors.initials: J
authors.lastname: Dong
authors.affiliation: Key Lab of Southwestern Crop Gene Resources and Germplasm Innovation, Ministry of Agriculture, Yunnan Provincial Key Laboratory of Agricultural Biotechnology, Biotechnology and Germplasm Resources Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650223, Yunnan, P.R. China. 324474381@qq.com.
authors.forename: Qi
authors.initials: Q
authors.lastname: Fang
authors.affiliation: Center of Analysis and Measurement, Zhejiang University, Hangzhou, 310058, P.R. China. jhong@zju.edu.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Hong
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, P.R. China. xfwang@ippcaas.cn.
authors.forename: Xifeng
authors.initials: X
authors.lastname: Wang
mesh_terms: D001692:Biological Transport; D054884:Host-Pathogen Interactions; D018551:Solanum lycopersicum / Q000821:virology; D010935:Plant Diseases / Q000821:virology; D010944:Plants / Q000821:virology*; D014026:Nicotiana / Q000821:virology; D017865:Tospovirus / Q000502:physiology* / Q000648:ultrastructure*; D014771:Virion / Q000648:ultrastructure*