COMBINATORIAL INTERPLAY OF PROMOTER ELEMENTS CONSTITUTES THE MINIMAL DETERMINANTS FOR LIGHT AND DEVELOPMENTAL CONTROL OF GENE-EXPRESSION INARABIDOPSIS

Higher plants are able to integrate environmental and endogenous signa ls to regulate gene expression for optimal development. To define the minimal sequence requirement sufficient to integrate light and develop mental signals in controlling promoter activity, we carried out a syst ematic analysis of the roles of four well-conserved 'light-responsive elements (LREs)' common to many nuclear-encoded photosynthetic genes, A gain-of-function assay using basal promoter-reporter fusions In-stab le transgenic Arabidopsis was employed to demonstrate that pairwise co mbinations of the LREs, but not the individual elements alone, call co nfer light-inducible expression to the reporter gene independently of the basal promoter contest and the light-triggered morphological chang es, The activity of the synthetic promoters with the paired LREs can b e modulated at least by the phytochrome system. Further, those synthet ic light-regulated promoters confer a photosynthetic cell-specific exp ression pattern and respond to the chloroplast development state, Our data suggest that distinct combinatorial interactions of LREs can serv e as minimal autonomous promoter determinants which integrate light an d developmental signals and modulate promoter activity.