Fig. 1
From: CRISPR guides induce gene silencing in plants in the absence of Cas
Cas13 and GIGS reduce viral and endogenous target RNA in N. benthamiana. a Schematic overview of the Cas13 transgene system. Guide crRNA responsible for RNA target specificity contain a single 28-nucleotide (nt) spacer antisense to the target RNA (single-guide, s-guide), multiple 28 nt spacers (multi-guide, m-guide), or lack the spacer (empty-guide). A diagram showing the genome of turnip mosaic virus (TuMV) expressing GFP and indicating the location of the three targeting sites for the guide crRNA. b The accumulation of GFP was assessed at 120 h post inoculation based on GFP fluorescence. Areas of agroinfiltration are shown in dashed white circles. Individual treatments are labeled with numbers and shown schematically below the photographs. c Nanostring RNA quantification for Cas13 and TuMV levels corresponding to labeled treatments for N. benthamiana spot infiltration. Samples expressed Cas13 (+) or not (−). d Representative images of N. benthamiana plants under UV light at 7 days post inoculation. The systemic movement of TuMV is evident based on the accumulation of GFP fluorescence for empty-guide expressing TRV (TRVempty). Single-guide 2 and multi-guide, TRVs-guide 2, and TRVm-guide respectively, stopped systemic TuMV infection. e Quantitative PCR for the endogenous transcript PDS following N. benthamiana leaf spot infiltration. f Representative single leaf images of N. benthamiana following TRV-mediated systemic delivery of guide crRNA targeting the PDS transcript. Empty and non-target guides (NT-guide) did not cause photobleaching (white sectors), while the antisense and multi-guide (m-guide) did induce visible photobleaching