At 12:44 PM 10/20/96 -0700, Char A Bezanson wrote:
>Thanks for the summary. Just one question- I've always been under the
>impression that it was the Mg ion in the center of each chorophyll
>molecule that is the primary object of recycling by trees before
>leaf-drop. Since Mg++ occupies essentially the same position as Fe++ in
>hemoglobin, its lack would cause the plant equivalent of "iron-poor
>blood"...although I'm sure N is worth retrieving as well. Do any of the
>plant physiologists out there have any comment on the relative scarcity of
>Mg and N, and of their fate and storage over winter?
One physiologist's perspective...
I cannot say from personal measurements of Mg in plants
and soils, but I was always taught it was the Mg ion
that was the "goal" of the recycling. I wonder where
the data are that support that idea? I would guess
that someone HAS done the measurements...perhaps decades
ago. The nitrogen recycling is likely important too.
I have always considered the hydrocarbon and hydroxycarbon
skeletons as dispensable, explaining the lack of selective
pressure to retrieve the carotenoids and anthocyanins
from leaves. I have speculated that the rise in the
anthocyanins was a by-product of "mineral mining" in the
leaves. I like the light-protection theory, though. I
wish someone would resolve all this in a clearcut "Botanical
Review."
I think it would be great to have a modern study of this
whole phenomenon. The University of Vermont would be a
natural location...
ross
______________________________________________________________
|
Ross Koning | Koning at ecsu.ctstateu.edu
Biology Department | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | Phone: 860-465-5327
Willimantic, CT 06226 USA | Fax: 860-465-5213
____________________________|_________________________________
Plant Physiology is Phun!
/\|___/\ //\______COOH NH-CH2-CH=C-CH2OH \/OH
| | | | | | || //\___ \CH3 /\|/\\/\\COOH
\/ \/|\/| \\/ \ / N || N | |
/\ | |__|= NH | || || //\//\
| COOH \\ /\ / O
COOH H2C=CH2 N NH
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