The long-term goal of this research is to understand how plants perceive changes in their light environment, transduce that information, and ultimately alter growth and development to elicit appropriate adaptive responses. In this project, the phototropic response, or directional growth of a plant toward or away from light, is being used as a model response to understand the molecular components underlying plant light responses. In particular, physiological, genetic, biochemical, and molecular approaches will be utilized to study the mechanism(s) by which a specific light receptor, phototropin 1, is capable of converting a directional light signal into a physiological response in the plant. Results from these studies will provide important insights not only into the mechanisms of phototropic signaling but receptor-mediated signaling in general. Because surface and intracellular receptors are utilized by all cells (bacterial, fungal, plant, and animal) to sense environmental cues, results from this work has a potential impact on a variety of human endeavors, from agriculture to medicine. Though such impacts are likely long-term, direct and tangible impact of this project on our nation will be realized through training of young scientists (one technician, at least two PhD students, and three undergraduate students). Moreover, the proposed outreach to local K-12 schools will have a clear and immediate impact on science education.