RNA silencing has evolved as a defense against molecular parasites in plants, such as viruses. It is also useful in regulating gene expression for growth and development. These pathways overlap and operate through the production of small RNAs. Small RNA molecules serve as a guide for complexes to find homologous sequences where they can exert their effect. The biogenesis of small RNAs is diverse and they operate in a variety of phenomena. In the model plant Arabidopsis thaliana, the diversification of small RNAs and gene silencing pathways may be explained by the existence of multiple paralogs of RNA-silencing-associated proteins such as ten AGOs, six RDRs, and four DCLs. Many of these proteins are involved in virus defense. However, viruses also develop strategies to counteract this defense system. As a counterdefense they express silencing suppressor proteins, which efficiently inhibit RNA silencing by interacting with various steps of the different silencing pathways. Insights into the molecular bases of the induction and the suppression of RNA silencing have dramatically improved our knowledge about the intimate interaction of plants and viruses during infection. Furthermore, it has also provided valuable tools to unravel the diversity, regulation, and evolution of RNA-silencing pathways.
ASJC Scopus subject areas
- Immunology and Microbiology(all)