Fwd: Phytochrome and hormones

James W. Perry jperry at UWC.EDU
Fri Apr 30 16:07:56 EST 1999


[Plant-eders: 

I (Jim Perry) passed on Grant Cramer's question to my friend Jim Colbert at
Iowa State. Jim is a recognized authority on phytochrome. Here is his
response:]

        Part of the definition of a hormone involves the ability of the
molecule to move from one location in the plant body to another, where the
hormone exerts some effect (e.g., movement of auxin from shoot tips to
axillary buds, where it causes "apical dominance").  There is no evidence,
that I know of, which suggests that phytochrome moves from one portion of a
plant to another.  As far as I know, a molecule of phytochrome functions in
the cell that it was produced.  In addition, hormones made up of amino
acids (of which there are many in animals [i.e., peptide hormones], and at
least one in plants [systemin - at least I think we should elevate systemin
to the status of "hormone", though the new edition of Campbell does not]),
generally are quite small, consisting of relatively few amino acids.
Phytochrome is ~ 1100 amino acids in length - well beyond the "peptide"
category.

Hope that helps,

Jim



Jim Colbert
Department of Botany
447 Bessey Hall
Iowa State University
(515) 294-9330
(515) 294-1337 (FAX)
jtcolber at iastate.edu


"end the suspense......get your feet wet right away"


James. W. Perry, CEO/Campus Dean
Professor, Department of Biological Sciences
University of Wisconsin - Fox Valley
1478 Midway Road, P.O. Box 8002
Menasha, Wisconsin 54952-9002
Office: 920.832.2610
FAX: 920.832.2674
jperry at uwc.edu



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