03.14.2017 // Peter Moffett, Département de Biologie, Université de Sherbrooke

3/8/2017

Molecular mechanisms of anti-viral defences in plants

Plants defend against viruses using several mechanisms including RNA silencing and by the recognition of specific viral proteins by NB-LRR proteins. Most plants encode at least four Dicer-like (DCL) proteins and ten different Argonaute (AGO) proteins, which 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 resistance to Potato virus X (PVX) in Arabidopsis. Further investigation has shown that natural variation in the AGO2 gene plays a very important role in susceptibility to viruses and to determining virus host range. Although AGO2 appears to be a central actor in defence against viruses, additional AGO proteins also play roles in antiviral. However, the efficacy of these other AGO proteins differs against different viruses, suggesting that the ability of different AGO proteins to target viral RNA may be affected by viral replication and/or silencing suppression strategies. Induced defence against viruses is conferred by nucleotide-binding, leucine-rich repeat (NB-LRR) proteins, which make up an important branch of the plant innate immune system. Elicitation of NB-LRR proteins results in the repression of translation of viral transcripts and, in many cases, the eventual activation of programmed cell death. Using several experimental systems we have investigated the role of translational control in NB-LRR signalling. This approach has uncovered a link between translational control and the growth-to-defence switch as well as identifying a number of new actors involved in plant defence.

Seminar series of the Molecular, Cellular & Integrative Biology
research groups at Queen's University