We have added a number of targeting sequences to GFP, and checked the subcellular localisation of the fusion proteins in yeast and plants. We have found that localisation of GFP to the endoplasmic reticulum is useful for routinely obtaining brightly fluorescent Arabidopsis transformants.
Chloroplasts are red autofluorescent.
Scale bars are 10 microns. ER localisation may aid the post-translational maturation of GFP, or lessen mild photoxic effects of GFP which are seen with high levels of expression.