Visualizing nuclear‐localized RNA using transient expression system in plants

By modifying the existing cytosolic RNA visualization tool pioneered by Schönberger, Hammes, and Dresselhaus (2012), we developed a method to visualize nuclear‐localized RNA . Our method uses (i) an RNA component that consists of an RNA of interest that is fused to a bacteriophage‐derived MS 2 sequence; and (ii) GFP fused to MS 2 coat protein ( MSCP ), which binds specifically to MS 2 as is also the case in the method for cytosolic RNA visualization. The nuclear localization sequence ( NLS ) at the C‐terminal of MSCP ‐ GFP tethers the probe to the nucleus. To reduce background signals in the nucleus, we replaced the NLS with a nuclear export sequence ( NES ) that anchors the MSCP ‐ GFP probe in the cytosol. Our nuclear RNA visualization method differs from previous methods in two aspects: (i) We used an NES to reduce nuclear background signal so that the MSCP ‐ GFP probe localizes in the cytosol by default; (ii) We added mC herry as a visual marker in the RNA component to increase its efficient usage in a transient system.