Perspectives on the basic and applied aspects of crassulacean acid metabolism (CAM) research

Due to public concerns about the decreasing supply of blue water and increasing heat and drought stress on plant growth caused by urbanization, increasing human population and climate change, interest in crassulacean acid metabolism (CAM), a specialized type of photosynthesis enhancing water-use efficiency (WUE) and drought tolerance, has increased markedly. Significant progress has been achieved in both basic and applied research in CAM plants since the beginning of this century. Here we provide a brief overview of the current status of CAM research, and discuss future needs and opportunities in a wide range of areas including systems biology, synthetic biology, and utilization of CAM crops for human benefit, with a focus on the following aspects: 1) application of genome-editing technology and high-throughput phenotyping to functional genomics research in model CAM species and genetic improvement of CAM crops, 2) challenges for multi-scale metabolic modeling of CAM systems, 3) opportunities and new strategies for CAM pathway engineering to enhance WUE and drought tolerance in C3 (and C4) photosynthesis crops, 4) potential of CAM species as resources for food, feed, natural products, pharmaceuticals and biofuels, and 5) development of CAM crops for ecological and aesthetic benefits.