Isolation and analysis of plant RNA-dependent RNA polymerases

RNA-dependent RNA polymerases (RDRPs) are encoded by RNA viruses as well as eukaryotic organisms such as plants. The function of these cellular RDRPs has been associated with the synthesis of short interfering RNAs (siRNAs), which are essential regulators of genomic integrity and plant viral defense. The multiple gene copies, and functional diversities, of the plant RDRPs raise the question of whether their intrinsic properties differ. This chapter describes protocols to extract and test in vitro, the activity of plant RDRPs.