title: A trio of viral proteins tunes aphid-plant interactions in Arabidopsis thaliana.
abstract: BACKGROUND
  Virus-induced deterrence to aphid feeding is believed to promote plant virus transmission by encouraging migration of virus-bearing insects away from infected plants. We investigated the effects of infection by an aphid-transmitted virus, cucumber mosaic virus (CMV), on the interaction of Arabidopsis thaliana, one of the natural hosts for CMV, with Myzus persicae (common names: 'peach-potato aphid', 'green peach aphid').
  
  
  RESULTS
  Infection of Arabidopsis (ecotype Col-0) with CMV strain Fny (Fny-CMV) induced biosynthesis of the aphid feeding-deterrent 4-methoxy-indol-3-yl-methylglucosinolate (4MI3M). 4MI3M inhibited phloem ingestion by aphids and consequently discouraged aphid settling. The CMV 2b protein is a suppressor of antiviral RNA silencing, which has previously been implicated in altering plant-aphid interactions. Its presence in infected hosts enhances the accumulation of CMV and the other four viral proteins. Another viral gene product, the 2a protein (an RNA-dependent RNA polymerase), triggers defensive signaling, leading to increased 4MI3M accumulation. The 2b protein can inhibit ARGONAUTE1 (AGO1), a host factor that both positively-regulates 4MI3M biosynthesis and negatively-regulates accumulation of substance(s) toxic to aphids. However, the 1a replicase protein moderated 2b-mediated inhibition of AGO1, ensuring that aphids were deterred from feeding but not poisoned. The LS strain of CMV did not induce feeding deterrence in Arabidopsis ecotype Col-0.
  
  
  CONCLUSIONS
  Inhibition of AGO1 by the 2b protein could act as a booby trap since this will trigger antibiosis against aphids. However, for Fny-CMV the interplay of three viral proteins (1a, 2a and 2b) appears to balance the need of the virus to inhibit antiviral silencing, while inducing a mild resistance (antixenosis) that is thought to promote transmission. The strain-specific effects of CMV on Arabidopsis-aphid interactions, and differences between the effects of Fny-CMV on this plant and those seen previously in tobacco (inhibition of resistance to aphids) may have important epidemiological consequences.
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Jack H
authors.initials: JH
authors.lastname: Westwood
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Groen
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Zhiyou
authors.initials: Z
authors.lastname: Du
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Alex M
authors.initials: AM
authors.lastname: Murphy
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Damar Tri
authors.initials: DT
authors.lastname: Anggoro
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Trisna
authors.initials: T
authors.lastname: Tungadi
authors.affiliation: Imperial College, London, United Kingdom.
authors.forename: Vijitra
authors.initials: V
authors.lastname: Luang-In
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Mathew G
authors.initials: MG
authors.lastname: Lewsey
authors.affiliation: Imperial College, London, United Kingdom.
authors.forename: John T
authors.initials: JT
authors.lastname: Rossiter
authors.affiliation: Imperial College, London, United Kingdom.
authors.forename: Glen
authors.initials: G
authors.lastname: Powell
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Alison G
authors.initials: AG
authors.lastname: Smith
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: John P
authors.initials: JP
authors.lastname: Carr
mesh_terms: D000818:Animals; D001042:Aphids / Q000502:physiology / Q000821:virology; D017360:Arabidopsis / Q000469:parasitology / Q000821:virology; D017799:Cucumovirus / Q000378:metabolism*; D005247:Feeding Behavior; D006790:Host-Parasite Interactions; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D014764:Viral Proteins