Distinct Effects of p19 RNA Silencing Suppressor on Small RNA Mediated Pathways in Plants

Kontra, Levente and Csorba, Tibor and Tavazza, Mario and Lucioli, Alessandra and Tavazza, Raffaela and Moxon, Simon and Tisza, Viktória and Medzihradszky, Anna and Turina, Massimo and Burgyán, József (2016) Distinct Effects of p19 RNA Silencing Suppressor on Small RNA Mediated Pathways in Plants. PLoS pathogens. ISSN 1553-7374 (In Press)

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RNA silencing is one of the main defense mechanisms employed by plants to fight viruses. In change, viruses have evolved silencing suppressor proteins to neutralize antiviral silenc- ing. Since the endogenous and antiviral functions of RNA silencing pathway rely on com- mon components, it was suggested that viral suppressors interfere with endogenous silencing pathway contributing to viral symptom development. In this work, we aimed to understand the effects of the tombusviral p19 suppressor on endogenous and antiviral silencing during genuine virus infection. We showed that ectopically expressed p19 sequesters endogenous small RNAs (sRNAs) in the absence, but not in the presence of virus infection. Our presented data question the generalized model in which the sequestra- tion of endogenous sRNAs by the viral suppressor contributes to the viral symptom devel- opment. We further showed that p19 preferentially binds the perfectly paired ds-viral small interfering RNAs (vsiRNAs) but does not select based on their sequence or the type of the 5’ nucleotide. Finally, co-immunoprecipitation of sRNAs with AGO1 or AGO2 from virus- infected plants revealed that p19 specifically impairs vsiRNA loading into AGO1 but not AGO2. Our findings, coupled with the fact that p19-expressing wild type Cymbidium ring- spot virus (CymRSV) overcomes the Nicotiana benthamiana silencing based defense kill- ing the host, suggest that AGO1 is the main effector of antiviral silencing in this host-virus combination.

Item Type: Article
Subjects: Q Science / természettudomány > Q1 Science (General) / természettudomány általában
Depositing User: Dr Tibor Levente Csorba
Date Deposited: 03 Oct 2016 13:30
Last Modified: 07 Oct 2016 23:15

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