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[Plant-education] BLC : C3 C4 experiment (Jo Ann Zeman)

David Alan Walker d.a.walker at sheffield.ac.uk
Sat Aug 19 02:56:25 EST 2006

Dear Jo Ann,
Since I am now in my Œanecdotage¹, perhaps I might be permitted to describe
ŒC3C4¹ (ISBN 0-632-00767-2 Pbk) By Edwards & Walker (1983) as a classic book
that everyone seriously interested in this field ought to have on their
shelves. In the spirit of ³open access² this is now available in digital
(PDF) format for free download from

    There are no restrictions in regard to its use other than the now widely
acknowledged concept of ³fair use² although, if you do download it,  E & W
would still appreciate an Email to say that you had done so.
    In the present context it might offer you an opportunity to repeat an
old but still relevant experiment as outlined below.
"You might just as well say," added the Dormouse, who seemed to be talking
in his sleep, "that 'I breathe when I sleep' is the same thing as 'I sleep
when I
The dust-cover of the first edition of ŒC3C4¹was illustrated with a picture
two Atriplex leaves., Edwards and Walker had killed the (pre-illuminated)
leaves, extracted their chlorophyll, and stained with iodine for starch. One
(Atriplex rosea) was C4 the other (Atriplex hastata) was C3. Sadly, the
publisher (Blackwell¹s) forgot to include their explanation of the meaning
the illustration. Now, 25 year¹s later, we have an opportunity to make good
this omission but, ironically, all is not quite as clear as it was then. The
starch distribution in the C4 Atriplex was, and is, characteristic of ŒKranz
anatomy. At the time, there were good grounds for supposing that
ŒKranz type¹ anatomy was structurally synonymous with ŒC4
photosynthesis¹. But the world has taken a few turns since then and
as always, continues. The title of a (much more recent), seminal, letter
to Nature* reads
³Kranz anatomy is not essential for terrestrial C4 plant photosynthesis²
*By Elena V. Voznesenskaya Vincent R. Franceschi—, Olavi Kiirats
Helmut Freitag¯ & Gerald E. Edwards
NATURE 414, 29 543-546

Best regards


>From David Walker, FRS., Emeritus Professor of Photosynthesis, University of
Sheffield, UK.

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