Leaf colour in autumn

[Jon Monroe]

Char et al.,

To add to your comment:

>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?
>
>Char A. Bezanson (bezanson at stolaf.edu)
>School Nature Area Project
>St. Olaf College
>Northfield,  MN  55057

I also received this similar comment:

[snip]
     Thanks for the summary.  We recently had an internationally known
     carotenoid biosynthesis scientist as a visitor.  He claimed that one
     of the main reasons that chlorophylls are degraded before the leaves
     fall off is so that the magnesium (at the center of chlorophyll) is
     recovered and can be stored in the stem until the following spring.

     Shirley Rodaway
     American Cyanamid
     Princeton, NJ
[snip]

Thanks for all of your input.  If anyone else can add more to the story
please do so.  The TV story went well, but I'm not going to give up my day
job yet...

Jon

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