Emerging model systems for functional genomics analysis of Crassulacean acid metabolism

•Efforts are now underway to decipher the genetic blueprint for CAM.•Several CAM genomes and transcriptomes have recently been published.•Kalanchoë has been established as readily transformable model genus for CAM.•Kalanchoë transgenics demonstrate the importance of key metabolic steps in CAM.•A diverse range of CAM species are being developed as amenable models. Crassulacean acid metabolism (CAM) is one of three main pathways of photosynthetic carbon dioxide fixation found in higher plants. It stands out for its ability to underpin dramatic improvements in plant water use efficiency, which in turn has led to a recent renaissance in CAM research. The current ease with which candidate CAM-associated genes and proteins can be identified through high-throughput sequencing has opened up a new horizon for the development of diverse model CAM species that are amenable to genetic manipulations. The adoption of these model CAM species is underpinning rapid advances in our understanding of the complete gene set for CAM. We highlight recent breakthroughs in the functional characterisation of CAM genes that have been achieved through transgenic approaches.