Friday Oct. 25 // Natural Variation in AGO2 determines susceptibility to virus infection

Special time and place, Room 3110 at 10:30 - 11:30

Ayo Adurogbangba
PhD. Candidate
University of Sherbrooke

RNA silencing is a major mechanism of constitutive antiviral defense in plants. Arabidopsis encodes four Dicer-like (DCL) proteins and ten different Argonaute (AGO) proteins that are specialized to function in different RNA silencing-related mechanisms. We have previously shown that AGO2 plays an important role in protecting plants against viruses, including Potato virus X (PVX) in Arabidopsis. However, despite having a functional AGO2 protein, Nicotiana benthiana is highly susceptible to PVX. Using a transient expression system in N. benthamiana leaves, we found that Arabidopsis AGO2 (AtAGO2), but not N. benthamiana (NbAGO2), possesses antiviral activity against PVX. Consistent with this, we find that activity of NbAGO2, but not AtAGO2, is supressed by the PVX suppressor of RNA silencing, P25. Therefore, we generated transgenic tomato and N. benthamiana plants containing AtAGO2 and NbAGO2 constructs. These transgenic lines were inoculated with PVX and viral accumulation levels were assessed. Recent results of these assays will be discussed. In addition, we have observed natural variation in AtAGO2 in naturally occurring Iberian Arabidopsis wild accessions and found that certain polymorphisms correlate with the degree of susceptibility to PVX and to Turnip mosaic virus (TuMV) but not with susceptibility to Cucumber mosaic virus (CMV). Our results indicate that natural variation in AGO2 can have important effects on infection for some, but not all viruses.