Utilizing heterologous promoters to express green fluorescent protein fromjellyfish in tobacco chloroplasts

The green fluorescent protein (GFP) from the jellyfish (Aequorea victoria) has become a vital reporter not only to identify and screen transformed org anisms including bacteria, animals and plants but also to study gene expres sion. A modified form of the green fluorescent protein was expressed in tob acco (Nicotiana tabacum var, Samsun) chloroplasts using both the bacterial as well as chloroplast specific promoters. A number of species-specific pro moters have been used to express foreign DNA in chloroplasts, but there is no such report where DNA has been expressed in chloroplasts from bacterial promoters. This is the first report of stable expression of reporter gene ( gfp) in chloroplasts using bacterial promoter. The GFP fluorescence was det ected only in transformants where the trc promoter used to regulate gfp. In transformants where gfp was under the control of the chloroplast rrn promo ter, fluorescence was comparable to controls without an introduced gfp gene . The transformed seedlings gave a green fluorescence after illumination wi th long-wave UV light. Fluorescence excitation and emission spectra of leaf extracts from the transformed plants confirmed the presence of GFR Analysi s of high expressing lines was carried out using Confocal Laser Scanning Mi croscopy. Gfp was found as a versatile and sensitive reporter and can be us ed to study promoters. The bacterial trc promoter appeared to be stronger t han the chloroplast rrn promoter in E. coli as well as in chloroplasts of t obacco.