Bob Wise wrote:
>But this begs the question of why would a plant merely replace one pigment
>(chlorophyll) with another (carotenoid or anthocyanin)?
Clarification - only the anthocyanins (reds) are synthesized as
leaves turn color. The carotenoids (yellows) are there all the time
and are simple not seen until the abundant chlorophylls (greens) are
broken down.
This topic seems to come up annually on Plant-ed (I wonder why :-)
and I don't mean to stifle the conversation but past messages on fall
colors can be found in the archives
(http://www.bio.net/hypermail/PLANT-EDUCATION/) by searching with
"fall AND color" or "anthocyanin".
One pertinent message sent to the group in Oct '96 by Sam Beale reads:
>"It is neither for recycling the magnesium (which is plentiful in virtually
>all soils) nor for the trivial amount of nitrogen in chlorophyll that the
>pigment is degraded in the Fall. Rather, chlorophyll is degraded so that
>its potentially interfering photochemical activities are eliminated during
>the physiologically important degradation of proteins and lipids in leaf
>cells and the translocation of their breakdown products for storage.
>>As a student of chlorophyll biosynthesis, it pains me to see all this
>beautiful green stuff get degraded in the Fall. But of course, in the
>Spring, I get renewed by all the chlorophyll biosynthsis going on in the
>New England woods."
Enjoy the colors!
Jon
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Jonathan D. Monroe Associate Professor
Department of Biology, MSC 7801 office: 540-568-6649
James Madison University fax: 540-568-3333
Harrisonburg, VA 22807 email: monroejd at jmu.eduhttp://csm.jmu.edu/biology/monroejd/jmonroe.html
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