9631390 Chory An understanding of the signal transduction pathways controlling light-regulated development of Arabidopsis, with particular emphasis placed on the pathway defined by the negative regulatory gene, DET1, is the major goal of this research. DET1 was cloned and shown to be a novel nuclear protein that does not appear to bind DNA directly. The precise mechanism of action of DET1 in repressing expression of light-regulated promoters will be investigated and targets of DET1 action will be identified and cloned. Specifically, the biochemical function of DET1 will be determined, proteins that functionally interact with DET1 will be identified, any post-translationally modification of DET1 by light or other signals will be determined, DET3, a downstream response gene, will be isolated and characterized and the genetic analysis of suppressors of weak det1 alleles will be genetically analyzed. The data from these experiments will allow construction of mechanistic models for the control of development and gene expression by light and other signals in Arabidopsis thaliana. %%% Light signals are required for the induction and regulation of many developmental processes. Genetic analysis demonstrates that light responses are not simply endpoints of linear signal transduction pathways, but are the result of the integration of a variety of input signals through a complex network of interacting signaling components. The experiments described will integrate genetic, molecular and biochemical approaches in Arabidopsis in an effort to understand the mechanisms involved in plant response to light. Such an understanding in the model plant should form a conceptual framework for how all land plants respond to changes in their environment. ***
