Promoter Architecture and Genomic Control of Gene Expression. The genome interacts with the environment in the regulation of transcription, and changes in promoter architecture play a role in phenotypic variation observed between and within species. Computational methods will be employed to identify DNA motifs (ie. transcription-factor binding sites) in the regulatory sequences upstream of co-expressed/co-regulated genes in Arabidopsis and other plant species with completed genome sequences, including rice and poplar. Molecular, genetic and biochemical approaches will be used to validate the computational predictions, identify interacting transcription factors, and further dissect the transcriptional networks.