In C₄ plants, initial carbon dioxide fixation occurs in chloroplasts of

In C₄ plants, initial carbon dioxide fixation occurs in the chloroplasts of Spongy parenchyma.
C₄ carbon fixation is one of three known photosynthetic processes of carbon fixation in plants.
C₄ leaves generally differentiate into two partially isolated compartments called mesophyll cells and bundle-sheath cells. CO₂ is initially fixed in the mesophyll cells by the enzyme PEP carboxylase which reacts with the three carbon. Mesophyll cells are parenchymatous cells.
The CO₂ is fixed by RuBisCo to produce phosphoglycerate (PGA) while the pyruvate is transported back to the mesophyll cell, together with about half of the phosphoglycerate (PGA).