Agave and Kalanchoe Omics for Synthetic Biology to Enhance Water Use Efficiency and Drought Tolerance in Plants

The ongoing and predicted climate change will likely increase drought stress with negative impact on agricultural and bioenergy crop production. Crassulacean acid metabolism (CAM) is a specialized type of photosynthesis that evolved as an adaptation to water-limited environments. CAM plants have much higher water-use efficiency (WUE) than C₃ or C₄ plants due to an inverted day/night pattern of stomatal closure/opening in CAM species relative to C₃ and C₄ species. Engineering of CAM pathway into C₃ crops using synthetic biology approach would have great potential for genetic improvement of WUE and drought tolerance for sustainable production of food and bioenergy in arid, semi-arid and marginal lands. To facilitate CAM-engineering, we generated rich omics resources (e.g., genomics, transcriptomics, proteomics, metabolomics) for Agave spp. and Kalanchoe spp., which are obligate CAM plants in the eudicotyledonous (eudicot) and monocotyledonous (monocot) lineages, respectively. Our integrative analysis of these omics data provides new insight into the evolution of CAM plants and useful knowledge to inform CAM-into-C3 engineering.