C4 and CAM Plants

C4 photosynthesis evolved as an upgrade for hot, dry climates. Plants like corn and sugarcane concentrate CO2 in special bundle-sheath cells, boosting the Calvin cycle and cutting wasteful photorespiration.

CAM plants (such as cacti and pineapples) take a different route. They open their pores only at night to take in CO2, store it as malic acid, then close up by day to save water and release that CO2 for photosynthesis.

Scientists are now trying to engineer C4 traits into rice, which still uses the less efficient C3 pathway. Success could raise rice yields by up to 50% — a breakthrough that might help feed billions in a warming climate.