Leaf colour in autumn

Ross Koning Koning at ECSUC.CTSTATEU.EDU
Fri Oct 25 14:26:14 EST 1996


Here in CT we are just at peak color
and I have been enjoying the "give and
take" on this subject.

The comment about sugar availability
and lack of carotenoids in Euonymus alatus
(burning bush) was fascinating.  Today I
was turning in MT grades and walked past
some of these plants in our campus landscape.

Indeed if the leaves are any color, they are
either red or pure white.  The white leaves
are on the interior of the shrub and on the
north side of the exterior.  The red leaves
are on the exterior only and are rare on the
north side of the shrub (exclusive of the top).
This distribution would be consistent with
leaves that do not import photosynthate and
are significantly below compensation point
for long periods.

So here is an interesting idea...we have plenty
of red burning bush, but a specimen that was defective
in anthocyanin synthesis genes would go pure
white at this time of year.  That would be an
interesting plant to study sugar content using
the usual color reagents and paper chromatography
with students (without the anthocyanin complication)
AND would be an interesting contrast for the red
specimens on campus...the better to show off the
opening capsules and orange seeds too!

That could lead to a comparison of bird feeding
rates on the two seed types...hmm.  Anyone know
how to defeat the anthocyanin synthesis enzyme
genes?  It might be good to keep an eye out for
any branches that sport in those genes and do
some vegetative propagation.  I'm checking out
the plants in our local landscape this week to
see if there are any such sports.

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
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                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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