Definition and functional implications of gibberellin and abscisic acid cis-acting hormone response complexes.
The mechanisms by which cis-acting hormone response elements affect transcription is unclear. In this study, we demonstrated that a second "coupling element," identified as O2S, must be present to allow a single copy of either the gibberellin response element (GARE) or the abscisic acid response element (ABRE) to mediate their hormonal effects in the barley Amy32b alpha-amylase gene promoter. The interactive effects of the O2S and the GARE are constrained positionally and spatially; thus, together they form a gibberellin response complex (GARC). The absolute requirement of the O2S for function of the ABRE demonstrates that these together form an abscisic acid response complex (ABRC). A second copy of the GARE can substitute for the O2S in the GARC, but only in one orientation. By expressing the GARC-containing and ABRC-containing promoters in developing aleurone tissue, we showed that hormonal effects prevent alpha-amylase gene expression during the second half of grain development, but other mechanisms suppress expression earlier. Our results suggest that the specific sequence serving as a coupling element in a given gene promoter will greatly affect where and when the GARE or ABRE will be able to regulate transcription.
Rogers
J C
JC
Division of Hematology-Oncology, Washington University School of Medicine, St. Louis, Missouri 63110.
Rogers
S W
SW
D000040:Abscisic Acid / Q000494:pharmacology*; D001483:Base Sequence; D004252:DNA Mutational Analysis; D004274:DNA, Recombinant; D005812:Genes, Switch; D005875:Gibberellins / Q000494:pharmacology*; D001467:Hordeum / Q000187:drug effects / Q000235:genetics*; D008969:Molecular Sequence Data; D012045:Regulatory Sequences, Nucleic Acid / Q000187:drug effects / Q000235:genetics*; D012639:Seeds / Q000196:embryology; D014158:Transcription, Genetic / Q000187:drug effects*
D004274:DNA, Recombinant; D005875:Gibberellins; D000040:Abscisic Acid