The Calvin-Benson-Bassham cycle in C 4 and Crassulacean acid metabolism species.

The Calvin-Benson-Bassham (CBB) cycle is the ancestral CO ₂ assimilation pathway and is found in all photosynthetic organisms. Biochemical extensions to the CBB cycle have evolved that allow the resulting pathways to act as CO ₂ concentrating mechanisms, either spatially in the case of C ₄ photosynthesis or temporally in the case of Crassulacean acid metabolism (CAM). While the biochemical steps in the C ₄ and CAM pathways are known, questions remain on their integration and regulation with CBB cycle activity. The application of omic and transgenic technologies is providing a more complete understanding of the biochemistry of C ₄ and CAM species and will also provide insight into the CBB cycle in these plants. As the global population increases, new solutions are required to increase crop yields and meet demands for food and other bioproducts. Previous work in C ₃ species has shown that increasing carbon assimilation through genetic manipulation of the CBB cycle can increase biomass and yield. There may also be options to improve photosynthesis in species using C ₄ photosynthesis and CAM through manipulation of the CBB cycle in these plants. This is an underexplored strategy and requires more basic knowledge of CBB cycle operation in these species to enable approaches for increased productivity.
Competing Interests: Declaration of Competing Interest As corresponding author of the manuscript entitled, “The Calvin-Benson-Bassham cycle in C(4)and Crassulacean acid metabolism species”, I submit this declaration of interest on behalf of all the authors: Martha Ludwig, James Hartwell, Christine A Raines, and Andrew J Simkin. For all the authors, there are no declarations of interest.
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