The versatility of RNA-dependent RNA polymerases (RDRPs) in eukaryotic gene silencing is perhaps best illustrated in the kingdom Fungi. Biochemical and genetic studies of Schizosaccharomyces pombe and Neurospora crassa show that these types of enzymes are involved in a number of fundamental gene-silencing processes, including heterochromatin regulation and RNA silencing in S. pombe and meiotic ...

RNA silencing plays a critical role in plant resistance against viruses, with multiple silencing factors participating in antiviral defense. Both RNA and DNA viruses are targeted by the small RNA-directed RNA degradation pathway, with DNA viruses being also targeted by RNA-directed DNA methylation. To evade RNA silencing, plant viruses have evolved a variety of counter-defense mechanisms such a...

RNA silencing is a newly discovered mechanism of genetic regulation in eukaryotes. It is based on an immune system that protects eukaryotes against viruses and transposons and in some respects it is conceptually similar to classical humoral immunity. However RNA silencing is distinct from humoral immunity in that it only targets nucleic acids and has a specificity mechanism based on nucleic aci...