Hatch-Slack Pathway or C4-Pathway or Dicarboxylic Acid Pathway

i. C₄ plants possess a characteristic leaf anatomy (Kranz anatomy). In which vascular bundles are surrounded by two rings of cells i.e. inner ring (bundle sheath cells having starch-rich chloroplasts lacking grana) and outer ring (mesophyll cells).

ii. It C₄ plants CO, is picked up by phosphoenol pyruvate (PEP – 3 Compound) in the cytoplasm of mesophyll cells and form oxaloacetate (4C) which is converted to malic- acid or aspartic acid (4-C) for transport to bundle sheath cells.

iii. In bundle sheath cells, CO, is released and is assimilated through Calvin cycle. Pyruvate is released which passes back into mesophyll cells where PEP is regenerated.

iv. The C₄ Pathway is more eftlcicnt than the C₃ pathway due to the absence of photorespiration.