PLANT PHYSIOLOGY , Vol 103, Issue 4 1115-1121, Copyright © 1993 by American Society of Plant Biologists
|
MOLECULAR BIOLOGY AND GENE REGULATION |
Effects of Blue and Red Light on Expression of Nuclear Genes Encoding Chloroplast Glyceraldehyde-3-Phosphate Dehydrogenase of Arabidopsis thaliana
J. Dewdney, T. R. Conley, M. C. Shih and H. M. Goodman
Department of Genetics, Harvard Medical School, and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114 (J.D., H.M.G.)
We have characterized the effects of different light spectra on expression
of the nuclear genes (GapA and GapB) encoding chloroplast
glyceraldehyde-3-phosphate dehydrogenase in Arabidopsis thaliana.
Steady-state mRNA levels for both genes in etiolated seedlings increased
after a short exposure to red or blue light. However, these increases could
not be reversed by immediate far-red light following the initial light
treatment. In mature plants, a short light pulse, regardless of its
spectrum, had no apparent effect on GapA or GapB mRNA levels in
dark-adapted plants. In contrast, continuous exposure to red, blue, or
white light resulted in increases of GapA and GapB mRNA levels, with blue
and white light being far more efficient than red light. Similarly,
continuous exposure of etiolated seedlings to red, blue, or white light
also resulted in increased GapA and GapB mRNA levels. In addition, we show
that illumination of red light-saturated Arabidopsis plants with continuous
blue light results in further increases of GapA and GapB mRNA levels. Based
on these results, we conclude that both blue light photoreceptor- and
phytochrome-mediated pathways are involved in light regulation of GapA and
GapB genes in Arabidopsis, with blue light acting as the dominant
regulator.
