The Kalanchoë genome provides insights into convergent evolution and building blocks of crassulacean acid metabolism.
Yang X., Hu R., Yin H., Jenkins J., Shu S., Tang H., Liu D., Weighill DA., Cheol Yim W., Ha J., Heyduk K., Goodstein DM., Guo H-B., Moseley RC., Fitzek E., Jawdy S., Zhang Z., Xie M., Hartwell J., Grimwood J., Abraham PE., Mewalal R., Beltrán JD., Boxall SF., Dever LV., Palla KJ., Albion R., Garcia T., Mayer JA., Don Lim S., Man Wai C., Peluso P., Van Buren R., De Paoli HC., Borland AM., Guo H., Chen J-G., Muchero W., Yin Y., Jacobson DA., Tschaplinski TJ., Hettich RL., Ming R., Winter K., Leebens-Mack JH., Smith JAC., Cushman JC., Schmutz J., Tuskan GA.
Crassulacean acid metabolism (CAM) is a water-use efficient adaptation of photosynthesis that has evolved independently many times in diverse lineages of flowering plants. We hypothesize that convergent evolution of protein sequence and temporal gene expression underpins the independent emergences of CAM from C3 photosynthesis. To test this hypothesis, we generate a de novo genome assembly and genome-wide transcript expression data for Kalanchoë fedtschenkoi, an obligate CAM species within the core eudicots with a relatively small genome (~260 Mb). Our comparative analyses identify signatures of convergence in protein sequence and re-scheduling of diel transcript expression of genes involved in nocturnal CO2 fixation, stomatal movement, heat tolerance, circadian clock, and carbohydrate metabolism in K. fedtschenkoi and other CAM species in comparison with non-CAM species. These findings provide new insights into molecular convergence and building blocks of CAM and will facilitate CAM-into-C3 photosynthesis engineering to enhance water-use efficiency in crops.