title: Inhibition of RNA silencing by the coat protein of Pelargonium flower break virus: distinctions from closely related suppressors.
abstract: Viral-derived double-stranded RNAs (dsRNAs) activate RNA silencing, generating small interfering RNAs (siRNAs) which are incorporated into an RNA-induced silencing complex (RISC) that promotes homology-dependent degradation of cognate RNAs. To counteract this, plant viruses express RNA silencing suppressors. Here, we show that the coat protein (CP) of Pelargonium flower break virus (PFBV), a member of the genus Carmovirus, is able to efficiently inhibit RNA silencing. Interestingly, PFBV CP blocked both sense RNA- and dsRNA-triggered RNA silencing and did not preclude generation of siRNAs, which is in contrast with the abilities that have been reported for other carmoviral CPs. We have also found that PFBV CP can bind siRNAs and that this ability correlates with silencing suppression activity and enhancement of potato virus X pathogenicity. Collectively, the results indicate that PFBV CP inhibits RNA silencing by sequestering siRNAs and preventing their incorporation into a RISC, thus behaving similarly to unrelated viral suppressors but dissimilarly to orthologous ones.
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-UPV), Avenida de los Naranjos, 46022 Valencia, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Martínez-Turiño
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-UPV), Avenida de los Naranjos, 46022 Valencia, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Hernández
mesh_terms: D036022:Capsid Proteins / Q000235:genetics*; D019184:Carmovirus / Q000235:genetics*; D017930:Genes, Reporter; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics; D031316:Pelargonium / Q000821:virology*; D018515:Plant Leaves / Q000821:virology; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics*; D013489:Suppression, Genetic
chemical_list: D036022:Capsid Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D049452:Green Fluorescent Proteins