Green Fluorescent Protein Gene.
 The gene coding for green fluorescent protein (GFP), was isolated in the year 1992 from the jelly fish Aequorea victoria. This gene when used for production of transgenic plants, allow non-destructive, real time, in vivoassay. It has been introduced in bacteria, nematodes, fruitfly (Drosophila),mice and several plant species. GFP is a 27 kD monomer, that has the unique characteristic of emitting green light when exposed to ultraviolet or UV light (~ 395 nm) or blue light (~490 nm). This gene differs from other reporter genes, since no substrate or enzyme is needed for detection. Therefore, this will prove to be a universal transgenic marker, because it is species independent. Any plant and its progeny expressitracked  in real time, so that the plants could be easily monitored. When GFP gene is under the control of a constitutive promoter, the leaves fluoresce green when exposed to UV or blue light and viewed under low ambient light, giving contrast to the pinkish hue emitted by non-transgenic plants.