Figure 3.

Simplified biochemical pathway of NADP-ME subtype of C4 photosynthesis that is being genetically engineered into indica rice variety by the C4 rice consortium. PEPC does the first carboxylation in the MC producing oxaloacetate which is further converted to malate by MDH. This C4 acid is transported from MC to the BSC chloroplasts where it is decarboxylated by NADP-ME to pyruvate and CO₂ is released to Rubisco to carry out the Calvin cycle reactions. In C4 rice, Rubisco should be expressed in BSC and hence the increased CO₂ levels at its site will reduce its oxygenation activity subsequently reducing the photorespiration. 3-PGA: 3-Phosphoglycarate, CA: Carbonic anhydrase, DiT1: Dicarboxylate translocator1, DiT2: Dicarboxylate translocator2, MEP: Mesophyll envelope protein, NADP-MDH: NADP-Malate dehydrogenase, NADP-ME: NADP-malic enzyme, PEP: Phosphoenol pyruvate, OAA: Oxaloacetate, OMT: Oxoglutarate/malate translocator, PEPC: Phosphoenol pyruvate carboxylase, PPDK: Pyruvate orthophosphate (Pi) dikinase, PPT: Phosphoenol pyruvate phosphate translocator, Rubisco: Ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBP: Ribulose-1,5-bisphosphate, and TPT: Triose-phosphate phosphate translocator.