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http://purl.uniprot.org/citations/23799112http://www.w3.org/1999/02/22-rdf-syntax-ns#typehttp://purl.uniprot.org/core/Journal_Citation
http://purl.uniprot.org/citations/23799112http://www.w3.org/2000/01/rdf-schema#comment"

Background

RNA-dependent RNA polymerases (RDRs) function in anti-viral silencing in Arabidopsis thaliana and other plants. Salicylic acid (SA), an important defensive signal, increases RDR1 gene expression, suggesting that RDR1 contributes to SA-induced virus resistance. In Nicotiana attenuata RDR1 also regulates plant-insect interactions and is induced by another important signal, jasmonic acid (JA). Despite its importance in defense RDR1 regulation has not been investigated in detail.

Methodology/principal findings

In Arabidopsis, SA-induced RDR1 expression was dependent on 'NON-EXPRESSER OF PATHOGENESIS-RELATED GENES 1', indicating regulation involves the same mechanism controlling many other SA-defense-related genes, including pathogenesis-related 1 (PR1). Isochorismate synthase 1 (ICS1) is required for SA biosynthesis. In defensive signal transduction RDR1 lies downstream of ICS1. However, supplying exogenous SA to ics1-mutant plants did not induce RDR1 or PR1 expression to the same extent as seen in wild type plants. Analysing ICS1 gene expression using transgenic plants expressing ICS1 promoter:reporter gene (β-glucuronidase) constructs and by measuring steady-state ICS1 transcript levels showed that SA positively regulates ICS1. In contrast, ICS2, which is expressed at lower levels than ICS1, is unaffected by SA. The wound-response hormone JA affects expression of Arabidopsis RDR1 but jasmonate-induced expression is independent of CORONATINE-INSENSITIVE 1, which conditions expression of many other JA-responsive genes. Transiently increased RDR1 expression following tobacco mosaic virus inoculation was due to wounding and was not a direct effect of infection. RDR1 gene expression was induced by ethylene and by abscisic acid (an important regulator of drought resistance). However, rdr1-mutant plants showed normal responses to drought.

Conclusions/significance

RDR1 is regulated by a much broader range of phytohormones than previously thought, indicating that it plays roles beyond those already suggested in virus resistance and plant-insect interactions. SA positively regulates ICS1."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.org/dc/terms/identifier"doi:10.1371/journal.pone.0066530"xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/author"Palukaitis P."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/author"Smith A.G."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/author"Macfarlane S.A."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/author"Westwood J.H."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/author"Carr J.P."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/author"Heath G."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/author"Hunter L.J."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/author"Macaulay K."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/date"2013"xsd:gYear
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/name"PLoS One"xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/pages"e66530"xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/title"Regulation of RNA-dependent RNA polymerase 1 and isochorismate synthase gene expression in Arabidopsis."xsd:string
http://purl.uniprot.org/citations/23799112http://purl.uniprot.org/core/volume"8"xsd:string
http://purl.uniprot.org/citations/23799112http://www.w3.org/2004/02/skos/core#exactMatchhttp://purl.uniprot.org/pubmed/23799112
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