Respiratory Metabolism in CAM Plants

Abstract

CAM metabolism involves a CO2 concentration mechanism in which organic acids are used as transitory carbon storage. The substrate on which CO2 is fixed derives from sugars via glycolysis. Therefore, CAM metabolism is intrinsically linked to enzymatic steps of catabolism and respiration. Respiration is essential to recycle products of malate metabolism (pyruvate) or to provide energy and reductive power sustaining malate synthesis and accumulation. Despite this importance, many aspects of CAM respiration are not well known, including flux quantitation, regulation and possible alternative pathways. The present Chapter summarizes key concepts and known enzymatic actors and emphasizes the need for a greater precision in CAM respiratory pathways.