Overexpression of rice phytochrome A partially complements phytochrome B deficiency in Arabidopsis |
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Authors: | Karen J Halliday Cordelia Bolle Nam-Hai Chua Garry C Whitelam |
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Institution: | (1) Department of Biology, Leicester, University, University Road, Leicester, LE1 7RH, UK, GB;(2) Laboratory of Plant Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10021-6399, USA, US |
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Abstract: | The red/far-red reversible phytochromes play a central role in regulating the development of plants in relation to their
light environment. Studies on the roles of different members of the phytochrome family have mainly focused on light-labile,
phytochrome A and light-stable, phytochrome B. Although these two phytochromes often regulate identical responses, they appear
to have discrete photosensory functions. Thus, phytochrome A predominantly mediates responses to prolonged far-red light,
as well as acting in a non-red/far-red-reversible manner in controlling responses to light pulses. In contrast, phytochrome
B mediates responses to prolonged red light and acts photoreversibly under light-pulse conditions. However, it has been reported
that rice (Oryza sativa L.) phytochrome A operates in a classical red/far-red reversible fashion following its expression in transgenic tobacco plants.
Thus, it was of interest to determine whether transgenic rice phytochrome A could substitute for loss of phytochrome B in
phyB mutants of Arabidopsis thaliana (L.) Heynh. We have observed that ectopic expression of rice phytochrome A can correct the reduced sensitivity of phyB hypocotyls to red light and restore their response to end-of-day far-red treatments. The latter is widely regarded as a hallmark
of phytochrome B action. However, although transgenic rice phytochrome A can correct other aspects of elongation growth in
the phyB mutant it does not restore other responses to end-of-day far-red treatments nor does it restore responses to low red:far-red
ratio. Furthermore, transgenic rice phytochrome A does not correct the early-flowering phenotype of phyB seedlings.
Received: 12 July 1998 / Accepted: 13 August 1998 |
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Keywords: | :Arabidopsis (transgenic) Mutant (Arabidopsis) Oryza (PHYA) Phytochrome A (PHYA cDNA) Phytochrome B phyB mutant |
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