PLANT PHYSIOLOGY , Vol 101, Issue 2 567-572, Copyright © 1993 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Light-Stimulated Apical Hook Opening in Wild-Type Arabidopsis thaliana Seedlings
E. Liscum and R. P. Hangarter
Department of Plant Biology, The Ohio State University, Columbus, Ohio 43210
Apical hook opening and cotyledon unfolding are characteristic responses
that occur during deetiolation of dicotyledonous seedlings.
Light-stimulated apical hook opening and cotyledon unfolding in etiolated
Arabidopsis thaliana seedlings appears to involve the activities of
multiple photosensory systems. Red, far-red, and blue light are all
effective in stimulating these responses in Arabidopsis. Stimulation of
hook opening by red light and low fluence blue light is inductive, far-red
reversible, and exhibits reciprocity, as is characteristic of many low
fluence-dependent phytochrome-mediated responses. Far-red and high-fluence
blue light appear to stimulate hook opening and cotyledon unfolding through
high-irradiance-response systems during long-term light treatments.
Although a phytochrome high-irradiance-response system presumably mediates
the responses in far-red light, the responses to high-fluence blue light
may be mediated by a blue light-specific photosensory system.
