J. Biol. Chem., Vol. 264, Issue 34, 20175-20176, Dec, 1989
Light to dark transition modulates the phase of antenna chlorophyll protein gene expression
E Lam and NH Chua
Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021.
The genes coding for the light-harvesting chlorophyll a/b-binding protein
of photosystem II (cab) in wheat are regulated by phytochrome and an
endogenous circadian clock. The regulation by these factors has been shown
to be at the transcriptional level. Here we show that the phase of cab gene
expression is reset by light to dark transition of the previous day. The
time of light to dark transition is linearly related to the time of maximal
cab gene expression under free running conditions in darkness. We propose
that in nature the onset of darkness resets the phase of the circadian
clock, which regulates the timing of cab gene expression, so as to
anticipate the time of sunrise in the following day.