Autofluorescence in non-transformed Poinsettia vs. Arabidopsis protoplasts. Excitation with a filter for red fluorescence detection triggers strong autofluorescence in (chloroplast-rich) Arabidopsis protoplasts (bottom row), but not in Poinsettia protoplasts (top row). Interference of chlorophyll autofluorescence with red fluorescent protein detection (e.g. mCherry) can be overcome in Poinsettia (Figure 5e). Left: brightfield,middle: UV image, right: overlay.