Question

Is opuntia a C4 plant?

Answer 1

C4 pathway:

1. The C4 pathway is used to efficiently fix $C{O}_{\mathit{2}}$at low concentrations and plants which undergo the C4 pathway are called C4 plants.
2. This pathway occurs in mesophyll cells.
3. The plants can fix CO₂ into a 4-carbon compound (C4) called oxaloacetate.
4. First, CO₂ is fixed to a three-carbon compound called phosphoenolpyruvate to produce the four-carbon compound oxaloacetate.
5. The enzyme catalyzing this reaction, PEP carboxylase, fixes CO₂ very efficiently so the C₄ plants don't need to have their stomata open as much.
6. Opuntia is a succulent plant. They have a modified stem called phylloclades, where photosynthesis occurs.
7. Opuntia fixes their carbon fixation by CAM pathway, i.e. crassulacean acid metabolism.
8. They used this pathway as they are found in arid regions.
9. In arid regions, at higher temperatures, plants tend to close stomata to avoid losing water, which reduces CO₂ availability and traps O₂ which increases photorespiration. C4 plants increase carbon acquisition by adding the C4 pathway to the C3 pathway.
10. And, by increasing the concentration of CO₂ captured in this way, C4 plants reduce the impact the photorespiration cycle has on productivity.