a Principle of the CytoRP technology showing that endogenous plant PRORP enzymes localizations are restricted to mitochondria, chloroplasts, and the nucleus. Because the two PRORP enzymes which are present in Arabidopsis nuclei, have redundant functions10, it can be envisaged to relocate one of them (PRORP2) to the cytosol, where virus RNA translation/replication takes place. Nuclear PRORP proteins are shown in blue, organellar PRORP1 in yellow, and the cytosolic CytoRP in red. b CytoRP proteins obtained by two different deletions, i.e. of the first 24 amino acids or of residues 11–26, accumulate in the cytosol while PRORP2 and PRORP1 accumulate in the nucleus and organelles, respectively. NLS and OTS show the nuclear localization signal and organellar targeting sequences localized upstream of the functional PPR and NYN domains of PRORP enzymes. The subcellular localization of CytoRP and PRORP protein was analyzed by confocal microscopy of proteins fused to eYFP. Independent observations were performed three times. C indicates the autofluorescence of chlorophyll for CytoRP as well as PRORP1 and DAPI staining for PRORP2. T are transmitted light images of Arabidopsis protoplasts transformed with the respective constructs. Scale bars correspond to 5 μm. Source data underlying b are provided as a Source Data file.