Journal of Experimental Botany, Vol 50, 831-836, Copyright © 1999 by Oxford University Press
M Burgin, J Casal, G Whitelam and R Sanchez
The presence of a phytochrome pool down-regulated by light and the
occurrence of high-irradiance responses to far-red light are well
documented in angiosperms but not in gymnosperms. A pool of phytochrome was
identified in Pinus elliottii and
Pseudotsuga menziesii seedlings grown in darkness with
a monoclonal antibody developed against oat phytochrome A. This pool was
barely detectable in light-grown tissues. Dark-grown conifer seedlings
transferred to continuous red light showed a gradual decrease of the levels
of immunodetectable phytochrome. This decrease was significantly slower in
gymnosperms than in angiosperms. Dark-grown seedlings of P.
elliottii and P. menziesii showed enhanced
growth of the cotyledonary whorl and increased anthocyanin pigmentation of
the hypocotyl, but no hypocotyl-growth inhibition in response to continuous
far-red light. Hourly pulses were significantly less effective than
continuos far-red light. The response to far-red light was not observed in
seedlings pretreated with red light to reduce the levels of
immunodetectable phytochrome. Rudiments of phytochrome A-like function and
kinetics are present in P. elliottii and P.
menziesii.Keywords: Gymnosperms,
phytochrome, high irradiance response.
ARTICLES
A light-regulated pool of phytochrome and rudimentary high-irradiance responses under far-red light in Pinus elliottii and Pseudotsuga menziesii
IFEVA, Departamento de Ecologia, Facultad de Agronomia, Universidad de Buenos Aires, Av. San Martin 4453, 1417 Buenos Aires, Argentina; Department of Botany, University of Leicester, University Road, Leicester LE1 7RH, UK; Corresponding author; Fax: +54 1 5148730; E-mail: casal@ifeva.edu.ar
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