C4 photosynthesis: from evolutionary analyses to strategies for synthetic reconstruction of the trait

C-4 photosynthesis represents the most productive modes of photosynthesis in land plants and some of the most productive crops on the planet, such as maize and sugarcane, and many ecologically important native plants use this type of photosynthesis. Despite its ecological and economic importance, the genetic basis of C-4 photosynthesis remains largely unknown. Even many fundamental aspects of C-4 biochemistry, such as the molecular identity of solute transporters, and many aspects of C-4 plant leaf development, such as the Kranz anatomy, are currently not understood. Here, we review recent progress in gaining a mechanistic understanding of the complex C-4 trait through comparative evolutionary analyses of C-4 and C-4 species.