Exploiting the engine of C4 photosynthesis

Ever since the discovery of C-4 photosynthesis in the mid-1960s, plant biologists have envisaged the introduction of the C-4 photosynthetic pathway into C-3 crops such as rice and soybeans. Recent advances in genomics capabilities, and new evolutionary and developmental studies indicate that C-4 engineering will be feasible in the next few decades. Furthermore, better understanding of the function of C-4 photosynthesis provides new ways to improve existing C-4 crops and bioenergy species, for example by creating varieties with ultra-high water and nitrogen use efficiencies. In the case of C-4 engineering, the main enzymes of the C-4 metabolic cycle have already been engineered into various C-3 plants. In contrast, knowledge of the genes controlling Kranz anatomy lags far behind. Combining traditional genetics, high-throughput sequencing technologies, systems biology, bioinformatics, and the use of the new C-4 model species Setaria viridis, the discovery of the key genes controlling the expression of C-4 photosynthesis can be dramatically accelerated. Sustained investment in the research areas directly related to C-4 engineering has the potential for substantial return in the decades to come, primarily by increasing crop production at a time when global food supplies are predicted to fall below world demand.