9408166 Hangarter Plant development is influenced by many environmental stimuli, including light, temperature and gravity. Of these stimuli, light is of particular importance because it regulates nearly all stages of development in addition to supplying energy for photosynthesis. Examples of light-regulated development include germination, stem growth, leaf and root development, tropic responses, chloroplast development, branching, and flower induction. Plants respond to different qualities of light through the action of multiple photosensory systems. The long-term objective of this proposal is to determine at the cellular and molecular level how blue light in particular is perceived by plants and converted into modified growth responses. The research will focus on the Arabidopsis blue light photomorphogenic mutants blu1, blu2 and blu3 which have been shown to be deficient in several important blue light responses. The major objective of the proposed research is to identify the nature and mechanism of action of the gene products required for blue light-dependent signal transduction. A second objective is to continue conducting physiological and genetic experiments using various double mutants between the three blu mutants and other photomorphogenic mutants, including phytochrome-deficient mutants, in order to identify functional interactions between different photosensory systems. This work will provide significant new knowledge about the complex network of regulatory events that control photomorphogenesis and will help elucidate the mechanisms by which light, and possibly other environmental stimuli, control plant development. ***
