9604528 Stewart The proposed research will develop green fluorescent protein (GFP) as a whole-plant fluorescent marker for use in subsequent physiological and ecological research. GFP when engineered into plants cause the plants glow green in the presence of an ultraviolet or blue light, thereby enabling them to be distinguished from wild-type pink plants. This system would allow researchers to detect GFP-genetically engineered plants very easily in vivo and in real time in a mixed population containing non-GFP plants. Also plant responses to biological or environmental stimuli could also be studied using such an in vivo marker. The PI (Nature Biotechnology 14:682, 1996) has demonstrated the feasibility of using GFP technology for ecological work. However, many of the details controlling expression and fluorescence of GFP in whole plant applications are unknown. Some of the unknown factors revolve around the following questions: Which GFP gene is most useful in whole plant studies? What is the threshold expression/fluorescent level necessary for visual observation: What are the environmental controls of expression and fluorescence? How stable is GFP in plant cells, and what is the response time for induced expression? Are there any fitness costs associated with high expression and fluorescence in GFP transgenics? What are fluorescence patterns in the field? Experiments are proposed that will directly answer all these questions in 2 years. These questions must be answered before this powerful technology may be used effectively in physiological ecology research.
