Analysis of the parsley chalcone-synthase promoter in response to different light qualities.
We examined the chalcone synthase (chs) promoter from parsley [Petroselinum crispum Miller (A.W. Hill)] for the existence of separate promoter elements responsible for transcriptional activation of the chs gene by UV-B and by blue light. A combination of in-vivo foot-printing in parsley cells and light-induced transient expression assays with different chs promoter constructs in parsley protoplasts was used. Dark controls and blue-light-irradiated cells gave identical in-vivo footprints on the chs promoter. Pre-irradiation with blue light prior to a UV-B-light pulse is known to cause a shift in the timing of UV-B-light-induced increase in chs transcription rates. This shift was also manifested on the DNA template, since UV-B-light-induced in-vivo footprints in cells pretreated with blue light were detected earlier than in cells which had been irradiated with a UV-B-light pulse only. Although there was a clear shift in the timing of footprint appearance, the patterns of footprinting did not change. Light-induced transient-expression assays revealed that the shortest tested chs promoter which retained any light responsiveness, was sufficient for mediating both induction by UV light and the blue-light-mediated kinetic shift. These findings argue against a spatial separation of UV-B- and blue-light-responsive elements on the chs promoter. We interpret these data by postulating that the signal transduction pathways originating from the excitation of UV-B- and blue-light receptors merge at the chs promoter, or somewhere between light perception and protein-DNA interaction.
Merkle
T
T
Institut für Biologie II, Universität Freiburg, Germany.
Frohnmeyer
H
H
Schulze-Lefert
P
P
Dangl
J L
JL
Hahlbrock
K
K
Schäfer
E
E
D000217:Acyltransferases / Q000235:genetics*; D001483:Base Sequence; D002478:Cells, Cultured; D004247:DNA; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects; D008027:Light; D019684:Magnoliopsida; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000528:radiation effects*; D015398:Signal Transduction
D004247:DNA; D000217:Acyltransferases; C020141:flavanone synthetase