Unable to connect to database - 13:36:27 Unable to connect to database - 13:36:27 SQL Statement is null or not a SELECT - 13:36:27 SQL Statement is null or not a DELETE - 13:36:27 Botany & Plant Biology 2007 - Abstract Search
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Abstract Detail


Plant-Pathogen Interactions

Love, Andrew J [1], Laird, Janet [1], Schweiger, Pawel [2], Hamilton, Andrew J [2], Sadanandom, Ari [1], Milner, Joel J [3].

Cauliflower Mosaic Virus Protein P6 is a Suppressor of RNA-Silencing.

RNA-silencing is an important defence mechanism against virus infection, and many plant viruses encode proteins that can counteract the silencing responses enacted by their hosts. CaMV, a caulimovirus with a dsDNA genome, encodes a 66 kDa polypeptide P6 that is the main virus-encoded determinant of pathogenicity. Transgene-mediated expression of P6 induces a symptom-like phenotype in Arabidopsis and profoundly affects both Ethylene and SA-signaling. We tested whether P6 could also act as a suppressor of silencing by crossing transgenic Arabidopsis lines expressing P6 with a line (GxA) that contains an Amplicon-silenced 35S::GFP transgene. Progeny of the crosses showed strong GFP fluorescence in both vascular and non-vascular tissue, indicating that P6 was capable of suppressing both local silencing and systemic movement of the silencing signal. When we inoculated GxA with CaMV, inoculated leaves developed an atypical necrosis, but in systemically infected leaves we observed extensive areas of cells showing strong and extensive GFP fluorescence indicating that virus infection was also capable of suppressing the silencing of GFP. CaMV-infected Arabidopsis accumulate 21 and 24 nt siRNAs derived mainly from the virus 35S RNA leader sequence. We infected P6 transgenic and control plants with mild and severe isolates of CaMV. With mild-isolates, both 21 and 24 nt siRNAs accumulated at much reduced levels in the P6 transgenic lines compared to controls. This is the first report of a silencing suppressor encoded by a plant pararetrovirus. Our results demonstrate that in addition to modulating SA- and Et signaling, P6 is an efficient suppressor of silencing of a GFP transgene and can also suppress virus-induced gene silencing targeted against CaMV.


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1 - University of Glasgow, IBLS
2 - University of Glasgow, Dept. of Pathology
3 - University of Glasgow, Institute of Biomedical and Life Sciences, Bower Building, University Ave, Glasgow, Scotland, G12 8QQ, UK

Keywords:
Silencing Suppressor
Pathogenicity factor.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P15008
Abstract ID:164


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