Describe Crassulacean Acid Metabolism (CAM Cycle).

Explanation

1. It is one of the carbon pathways identified in succulent plants growing in semi-arid or xerophytic condition.
2. First observed in Crassulaceae family plants like Bryophyllum, Sedum, Kalanchoe and is the reason behind the name of this cycle .
3 . Also noticed in plants from other families Eg.., Agave , Opuntia , Pineapple , Orchids , etc.
4 . The stomata are closed during day and are open during night ( Scotoactive) . This reverse stomatal rhythm helps to conserve water loss through transpiration and will stop the fixation of `CO_(2)` during the day time .
5. At night time CAM plants fix `CO_(2)` with the help of Phospho Enol Pyruvic acid (PEP) and produce Oxalo Acetic Acid (OAA) .
5. Subsequently OAA is converted into Malic acid like `C_(4)` Cycle and gets accumulated in vacuole increasing the acidity .
6. During the day time stomata are closed and Malic acid is decarboxylated into Pyruvic acid resulting in the decrease of acidity . `CO_(2)` thus formed enters into Calvin Cycle and produces carbohydrates .
Significance of CAM Cycle .
1 It is advantageous for succulent plants to obtain `CO_(2)` from malic acid when stomata are closed.
2 During day time stomata are closed and `CO_(2)` is not taken but continue their photosynthesis .
3. Stomata closed during the day time and help the plants to avoid transpiration and water loss .