Crassulacean Acid Metabolism: A Pathway for Photosynthetic CO2 Fixation in Arid Habitats

A.A. IGLESIAS, D.H. GONZÁLEZ, C.S. ANDREO

BIOCHEMICAL EDUCATION

Año: 1987 vol. 15 p. 111 - 115

0307-4412

Several higher plants achieve fixation of atmospheric CO2 in the dark, therebysynthesizing malic acid which then in turn is decarboxylated during the light period. Thereleased CO2 then is refixed through the Calvin cycle. This metabolic route is known asCrassulacean Acid Metabolism (CAM). This pathway was first discovered in the succulentfamily Crassulaceae, but later it was established that it occurs also in other families ofhigher plants. In this respect, one can distinguish between plants exhibiting CAM activityonly under certain external conditions (facultative or inducible) and those which performthis metabolic route at all times (obligate or constitutive). 1 Although only a few speciesperforming CAM seem to be of economical significance (eg pineapple), the study of thisroute is interesting since it represents an efficient mechanism for the adaptation ofphotosynthetic CO2 fixation in arid habitats.