Generation of RNA-Dependent RNA Polymerase Null Arabidopsis through Genome Editing and Artificial MicroRNAs

Science Center, Bent Corridor

RNA silencing is an important mechanism for viral protection in plants. It begins with Dicer, a dsRNA-specific RNase III–class RNA, processing double stranded RNA into 21-24 nucleotide fragments (siRNA) which are then bound by Argonaute proteins to form a RNA-induced silencing complex (RISC). RISC will then bind and degrade RNA that is complementary to this siRNA. This specificity allows the complex to find and destroy viral RNA anywhere in the plant. RNA-dependent RNA Polymerase (RDR) genes amplify the silencing signal which causes RNA silencing to occur throughout the entire plant rather than only at the site of infection. This process grants the plant systemic immunity to viral infection. 6 RDR genes have been identified in Arabidopsis, but only RDR1, RDR2, and RDR6 have been characterized. RDR3a, RDR3b, and RDR3c are linked genes that are not well understood due to the fact they can’t be separated by recombination. Through the combination of T-DNA insertion mutagenesis, artificial microRNA, and CRISPR/Cas9 genome editing this study will create Arabidopsis plants lacking all 6 RDR genes.