Interactions Between Nutrients and Crassulacean Acid Metabolism

Abstract

CAM expression is under the control of an intricate signaling network involving numerous interconnected environmental cues strongly linked to nutrient accessibility for plants. Mineral nutrients are essential elements for conferring plant resistance to drought or salinity while both these abiotic stresses can disturb the nutritional relations and modulate the photosynthetic pathway of CAM plants. Hypothetical connections between CAM photosynthesis and mineral nitrogen metabolism have been suggested as possible mechanisms conferring physiological advantages for plant survival under severe environment conditions. Although the mineral nutrition of CAM plants has received relatively scarce attention, some studies have consistently demonstrated that different degrees of nutrient fertilization can influence CAM expression. In addition, the nutritional aspect of CAM regulation is frequently related to the action of other environmental factors, especially light and water availability. Among all the essential macronutrients, variation in nitrogen content usually shows the strongest correlation with CAM activity. Some evidence indicates that specific effects of nitrate and ammonium ions are crucial in the CAM modulation rather than an influence of nitrogen status itself. Therefore, future research is required to unravel the effects and the respective metabolic and signaling mechanisms of interaction between mineral nutrients and other environmental signals on CAM photosynthesis.