title: Differential contributions of plant Dicer-like proteins to antiviral defences against potato virus X in leaves and roots.
abstract: Members of the plant Dicer-like (DCL) protein family are the critical components of the RNA-silencing pathway that mediates innate antiviral defence. The distinct antiviral role of each individual DCL protein has been established with mostly based on observations of aerial parts of plants. Thus, although the roots are closely associated with the life cycle of many plant viruses, little is known about the antiviral activities of DCL proteins in roots. We observed that antiviral silencing strongly inhibits potato virus X (PVX) replication in roots of some susceptible Solanaceae species. Silencing of the DCL4 homolog in Nicotiana benthamiana partially elevated PVX replication levels in roots. In Arabidopsis thaliana, which was originally considered a non-host plant of PVX, high levels of PVX accumulation in inoculated leaves were achieved by inactivation of DCL4, while in the upper leaves and roots, it required the additional inactivation of DCL2. In transgenic A. thaliana carrying the PVX amplicon with a green fluorescent protein (GFP) gene insertion in the chromosome (AMP243 line), absence of DCL4 enabled high levels of PVX-GFP accumulation in various aerial organs but not in the roots, suggesting that DCL4 is critical for intracellular antiviral silencing in shoots but not in roots, where it can be functionally compensated by other DCL proteins. Together, the high level of functional redundancies among DCL proteins may contribute to the potent antiviral activities against PVX replication in roots.
authors.affiliation: Institute of Plant Science and Resources (IPSR), Okayama University, 2-20-1, Chuo, Kurashiki, 710-0046, Japan.
authors.forename: Ida Bagus
authors.initials: IB
authors.lastname: Andika
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Maruyama
authors.forename: Liying
authors.initials: L
authors.lastname: Sun
authors.forename: Hideki
authors.initials: H
authors.lastname: Kondo
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Tamada
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Suzuki
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D010935:Plant Diseases / Q000276:immunology* / Q000821:virology; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics; D010942:Plant Viruses / Q000502:physiology; D030821:Plants, Genetically Modified; D017863:Potexvirus / Q000502:physiology*; D034622:RNA Interference; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D014779:Virus Replication
chemical_list: D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D010940:Plant Proteins; C504982:DCL4 protein, Arabidopsis; C511919:DCL2 protein, Arabidopsis; D043244:Ribonuclease III
keywords: Arabidopsis thaliana; Dicer-like protein; Nicotiana benthamiana; RNA silencing; antiviral defence; potato virus X; root