Explanation

The process of photosynthesis in $C_{4}$-plants and CAM (crassulacean Acid Metabolism) is same. But instead of spatial separation of initial PEP case fixation and final RUBISCO fixation of carbon dioxide, the two steps occurs in the same cells but at different times, night and day, e.g.,Opuntia, pineapple, Vanilla. PEP (Phosphoenol Pyruvic Acid) is the first acceptor of carbon dioxide in CAM-plants like $C_{4}$-plants.