oxidation in C4

[Janice M. Glime]

Dear Plant-edders,
  One of my graduate students asked a very good question and I don't have
an answer.  If C4 plants benefit by being able to continue photosynthesis
while keeping their guard cells closed, what happens to the excess CO2
during that time?  
  My added question, can it be going to the closely aligned mitochondria,
and if so, what prevents loss of photosynthate through photorespiration,
especially at higher temperatures?
Thanks for any insight or references.
Janice
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 Janice M. Glime, Professor  
 Department of Biological Sciences
 Michigan Technological University
 Houghton, MI 49931-1295
 jmglime at mtu.edu
 906-487-2546
 FAX 906-487-3167 
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