title: Infection dynamics in viral spread and interference under the synergism between Cucumber mosaic virus and Turnip mosaic virus.
abstract: Mixed infection of Cucumber mosaic virus (CMV) and Turnip mosaic virus (TuMV) induced more severe symptoms on Nicotiana benthamiana than single infection. To dissect the relationships between spatial infection patterns and the 2b protein (2b) of CMV in single or mixed infections, the CMV vectors expressing enhanced green fluorescent or Discosoma sp. red fluorescent proteins (EGFP [EG] or DsRed2 [Ds], respectively were constructed from the same wild-type CMV-Y and used for inoculation onto N. benthamiana. CMV2-A1 vector (C2-A1 [A1]) has a functional 2b while CMV-H1 vector (C2-H1 [H1]) is 2b deficient. As we expected from the 2b function as an RNA silencing suppressor (RSS), in a single infection, A1Ds retained a high level of accumulation at initial infection sites and showed extensive fluorescence in upper, noninoculated leaves, whereas H1Ds disappeared rapidly at initial infection sites and could not spread efficiently in upper, noninoculated leaf tissues. In various mixed infections, we found two phenomena providing novel insights into the relationships among RSS, viral synergism, and interference. First, H1Ds could not spread efficiently from vasculature into nonvascular tissues with or without TuMV, suggesting that RNA silencing was not involved in CMV unloading from vasculature. These results indicated that 2b could promote CMV to unload from vasculature into nonvascular tissues, and that this 2b function might be independent of its RSS activity. Second, we detected spatial interference (local interference) between A1Ds and A1EG in mixed infection with TuMV, between A1Ds (or H1Ds) and TuMV, and between H1Ds and H1EG. This observation suggested that local interference between two viruses was established even in the synergism between CMV and TuMV and, again, RNA silencing did not seem to contribute greatly to this phenomenon.
authors.affiliation: Kyushu University, Fukuoka, Japan. minorutk@agr.kyushu-u.ac.jp
authors.forename: Minoru
authors.initials: M
authors.lastname: Takeshita
authors.forename: Emiko
authors.initials: E
authors.lastname: Koizumi
authors.forename: Makiko
authors.initials: M
authors.lastname: Noguchi
authors.forename: Kae
authors.initials: K
authors.lastname: Sueda
authors.forename: Hanako
authors.initials: H
authors.lastname: Shimura
authors.forename: Noriko
authors.initials: N
authors.lastname: Ishikawa
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Matsuura
authors.forename: Kazusato
authors.initials: K
authors.lastname: Ohshima
authors.forename: Tomohide
authors.initials: T
authors.lastname: Natsuaki
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kuwata
authors.forename: Naruto
authors.initials: N
authors.lastname: Furuya
authors.forename: Kenichi
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Chikara
authors.initials: C
authors.lastname: Masuta
mesh_terms: D060085:Coinfection; D017799:Cucumovirus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D056265:Microbial Interactions; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000821:virology; D030821:Plants, Genetically Modified; D017800:Potyvirus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D011523:Protoplasts; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013696:Temperature; D014026:Nicotiana / Q000502:physiology / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D000097573:Red Fluorescent Protein
chemical_list: D018076:DNA, Complementary; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D012333:RNA, Messenger; D012367:RNA, Viral; D014764:Viral Proteins; D000097573:Red Fluorescent Protein