Characterization of Structure, Divergence and Regulation Patterns of Plant Promoters

Abstract

Plant promoters have attracted increasing attention because of their irreplaceable role in modulating the spatio-temporal expression of genes interacting with transcription factors (TFs). Despite their importance, the basic characteristics of plant promoters are not well understood. In order to determine sequence diversity within promoter regions, evolutionary divergence of promoters between plant species, and the general structural characteristics of promoter sequences, we downloaded and analyzed 3922 plant promoter sequences from a wide range of plant species. The average plant promoter GC content was lower in dicotyledons than in monocotyledons, which might suggest different evolutionary pressures for promoter sequences between the two clades. Approximately 3.3% of plant promoters harbored minisatellite sequences, and 15.4% of plant promoters harbored microsatellite sequences (also called simple sequence repeats). Very few transposable elements were detected within the plant promoters. The most common transcription factor binding site (TFBS) motif was AGAGAGAGA, followed by TTAGGGTTT and then GCCGCC. Transcribed gene regions with promoters containing the corresponding TFBSs were predicted to be most commonly involved in metabolic processes, biological regulation, and stimulus response in plants. These results reveal some basic structural characteristics of plant promoters and clarify the evolutionary forces shaping plant promoters. This data might facilitate cloning of plant promoter sequences and aid in our understanding of gene spatio-temporal expression patterns in plants.