Is CAM an answer to photorespiration?

Jonathan B. Marder MARDER at
Thu Dec 5 10:16:26 EST 1996

In article <1996Dec5.093217.1 at>,
   joaroyo at wrote:
>Hi, I have a question concerning plant phisiology, are CAM plants primarily
>an answer to photorespiration, like C4 plants, or are they basically an
>adaption to arid ambients, reduction of photorespiration being a welcome

The answer is yes, and yes. C4 itself can be considered a water-saving 
feature. While C3 plants have to keep their stomata wide open to maintain
a sufficient internal concentration of CO2 for optimum photosynthesis.
C4 plants can go on fixing CO2 even when its concentration in the mesophyll
is very low. Thus, they can happily photosynthesize with stomata almost 

Jonathan B. Marder             ,      Department of Agricultural Botany
E-mail: MARDER at |      The Hebrew University of Jerusalem
Phone: (08 or +9728) 9481918   | /\/  Faculty of Agriculture
Fax:   (08 or +9728) 9467763   |/  \  P.O.Box 12, Rehovot 76100, ISRAEL

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