PLANT PHYSIOLOGY , Vol 115, Issue 1 79-85, Copyright © 1997 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Photoresponses of Transgenic Arabidopsis Overexpressing the Fern Adiantum capillus-veneris PHY1
H. Okamoto, K. Sakamoto, K. I. Tomizawa, A. Nagatani and M. Wada
Department of Biology, Tokyo Metropolitan University, Minami Osawa 1-1, Hachioji-shi, Tokyo 192-03, Japan (H.O., M.W.)
The phytochrome gene (PHY1) cDNA from the fern Adiantum capillus-veneris
encodes an amino acid sequence that shows equal similarity (50-60%) to all
five Arabidopsis phytochromes (PHYAE). The A. capillus-veneris PHY1 cDNA
was transformed into Arabidopsis ecotype Landsberg erecta to investigate
its activity in angiosperms. Three of the resulting lines contained at
least 8 times more spectrally active phytochrome than the wild type,
indicating that A. capillus-veneris phytochrome can incorporate the
chromophore of the host plants. Hypocotyl growth inhibition of these
transgenic lines was investigated under red and far-red light. The results
indicated dominant negative activity of A. capillus-veneris phy1 on the
phytochrome A response in the host plants under continuous far-red light.
However, the fern phytochrome did not interfere with the red-light
repression of hypocotyl growth mediated by endogenous phytochrome B, and it
failed to complement a phyB mutant phenotype. These observations suggest
that the phy1 phytochrome molecule is too diverged from those of
Arabidopsis to be fully functional.
