The ability to adjust to changes in the external light environment is especially important to plant survival because, unlike animals, plants depend on sunlight for photosynthesis and they do not have a neuromuscular system which allows them to move to a more optimum light environment. Plants therefore possess the unique light-sensing photoreceptor molecule phytochrome which enables them to perceive the frequent fluctuations of intensity, direction and spectral quality of light in their environment. Experiments outlines in this proposal seek to provide new information on phytochrome structure and to address the hypothesis that phytochrome is a light-regulated enzyme. The long tern goal of these studies is to define the structural basis for phytochrome function. For a number of our studies, we will; employ the unicellular green alga Mesotaenium caldariorum as a model system. Identification of the components of the phytochrome signal transduction pathway in this algal should produce useful tools for analysis of phytochrome response pathways in considerably more complex higher plant tissues. %%% The ability to adjust to changes in the external light environment is especially important to plant survival because, unlike animals, plants depend on sunlight for photosynthesis and they do not have a neuromuscular system which allows them to move to a more optimum light environment. This project focuses on phytochrome, a light-sensing protein found in all plants which perceives the direction, intensity and color of light that impinges on the plant. Specifically, we are interested in how this information is received by phytochrome, how it passed on to other molecules, and ultimately how these processes lead to changes in plant growth and development (e.g. seed germination, flowering and growth rate). Since all life on earth depends on photosynthesis by green plants, a basic understanding of the biochemical processes which enable plants to adapt to their light environment is of great importance.
