February 21, 2017
Written by: Emmanuel G Escobar
Energy conversion in eukaryotes is strictly regulated. In C4 plants, solar energy is converted to chemical energy, driving the carbon fixation engine of C4 photosynthesis—a complex network of finely tuned biochemical reactions, tightly regulated transport networks and underlying regulatory mechanisms . It evolved from the classical C3 pathway, which solely uses ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) as the primary carboxylase for CO2 fixation . During C4 photosynthesis (Fig. 1), CO2 is initially fixed by phosphoenolpyruvate carboxylase (PEPC) in mesophyll cells producing a four-carbon compound that is subsequently transported and decarboxylated in bundle sheath cells, concentrating CO2 around Rubisco, thus maintaining a favourable concentration of CO2 for suppressing rates of photorespiration .