title: A necrosis-inducing elicitor domain encoded by both symptomatic and asymptomatic Plantago asiatica mosaic virus isolates, whose expression is modulated by virus replication.
abstract: Systemic necrosis is the most destructive symptom induced by plant pathogens. We previously identified amino acid 1154, in the polymerase domain (POL) of RNA-dependent RNA polymerase (RdRp) of Plantago asiatica mosaic virus (PlAMV), which affects PlAMV-induced systemic necrosis in Nicotiana benthamiana. By point-mutation analysis, we show that amino acid 1,154 alone is not sufficient for induction of necrotic symptoms. However, PlAMV replicons that can express only RdRp, derived from a necrosis-inducing PlAMV isolate, retain their ability to induce necrosis, and transient expression of PlAMV-encoded proteins indicated that the necrosis-eliciting activity resides in RdRp. Moreover, inducible-overexpression analysis demonstrated that the necrosis was induced in an RdRp dose-dependent manner. In addition, during PlAMV infection, necrotic symptoms are associated with high levels of RdRp accumulation. Surprisingly, necrosis-eliciting activity resides in the helicase domain (HEL), not in the amino acid 1,154-containing POL, of RdRp, and this activity was observed even in HELs of PlAMV isolates of which infection does not cause necrosis. Moreover, HEL-induced necrosis had characteristics similar to those induced by PlAMV infection. Overall, our data suggest that necrotic symptoms induced by PlAMV infection depend on the accumulation of a non-isolate specific elicitor HEL (even from nonnecrosis isolates), whose expression is indirectly regulated by amino acid 1,154 that controls replication.
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Komatsu
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Kensaku
authors.initials: K
authors.lastname: Maejima
authors.forename: Takuya
authors.initials: T
authors.lastname: Shiraishi
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Neriya
authors.forename: Chihiro
authors.initials: C
authors.lastname: Miura
authors.forename: Nami
authors.initials: N
authors.lastname: Minato
authors.forename: Yukari
authors.initials: Y
authors.lastname: Okano
authors.forename: Kyoko
authors.initials: K
authors.lastname: Sugawara
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamaji
authors.forename: Shigetou
authors.initials: S
authors.lastname: Namba
mesh_terms: D016368:Frameshift Mutation; D015971:Gene Expression Regulation, Enzymologic; D015967:Gene Expression Regulation, Viral; D009336:Necrosis; D010935:Plant Diseases / Q000821:virology; D017354:Point Mutation; D017863:Potexvirus / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology*; D017434:Protein Structure, Tertiary; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D014026:Nicotiana / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D014779:Virus Replication / Q000235:genetics / Q000502:physiology*
chemical_list: D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase