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

PLoS Pathogens

Raffaela Tavazza¹  Alessandra Lucioli¹  Simon Moxon¹  Levente Kontra²  Mario Tavazza²  Massimo Turina²  Anna Medzihradszky²  József Burgyán³  Viktória Tisza⁴  Tibor Csorba⁵ 

[1] Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), C.R. Casaccia, Rome, Italy;National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllő, Hungary;National Research Council, Institute for Sustainable Plant Protection, Torino, Italy;School of Biological Sciences, University of East Anglia, Norwich, Norfolk, United Kingdom;Szent István University, Gödöllő, Hungary

关键词: MicroRNAs;    Small interfering RNAs;    Genetically modified plants;    Nicotiana;    RNA interference;    Leaves;    Immunoprecipitation;    RNA viruses;   

DOI  :  10.1371/journal.ppat.1005935

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

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 silencing. Since the endogenous and antiviral functions of RNA silencing pathway rely on common 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 sequestration of endogenous sRNAs by the viral suppressor contributes to the viral symptom development. 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 ringspot virus (CymRSV) overcomes the Nicotiana benthamiana silencing based defense killing the host, suggest that AGO1 is the main effector of antiviral silencing in this host-virus combination.

【 授权许可】

CC BY