Functional Characterization of Kalanchoë Genes Involved in Crassulacean Acid Metabolism

Plants that perform photosynthesis via crassulacean acid metabolism (CAM) pathway have much higher water use efficiency (WUE) than that of C₃ and C₄ plants. Engineering of CAM into C3 plants has great potential for improvement of WUE and drought tolerance in bioenergy and food crops. Understanding of the molecular basis of CAM is a prerequisite for CAM-into-C3 engineering. There are two important biological processes in CAM: nocturnal carboxylation and subsequent daytime decarboxylation. Recently, the genomics resources (i.e., genome and transcriptome) became available for Kalanchoë fedtschenkoi, an emerging model for CAM systems biology and synthetic biology research. Based on these genomics resources, we identified candidate genes that are potentially involved in carboxylation and decarboxylation in K. fedtschenkoi. To characterize the function of these candidate genes, genetic circuits containing different combinations of carboxylation and decarboxylation genes were assembled using synthetic biology tools and introduced into the C₃ model plant Arabidopsis. The transgenic Arabidopsis plants are being characterized.