Difference Between C3 and C4 Plants
When it comes to plants, there is more to them than just their appearance. Scientists have classified plants into different groups, one of which is based on the photosynthesis process. The two major categories are C3 and C4 plants. The distinction between the two lies in their structural and biochemical adaptations for photosynthesis. In this article, we will discuss the differences between C3 and C4 plants.
C3 Plants
C3 plants are the most common type of plant on earth, and they include nearly 98% of all plant species. C3 plants are named after the first product of photosynthesis, which is a three-carbon compound called 3-phosphoglyceric acid (PGA). C3 plants are found in various habitats, including temperate grasslands and forests, and operate efficiently in mild temperatures and under normal atmospheric conditions. However, the efficiency of C3 plants in terms of photosynthetic productivity is limited.
One of the major factors that limit photosynthetic productivity is the oxygenation of Rubisco enzyme, which results in the production of a toxic molecule called glycolate. C3 plants are sensitive to this toxic molecule and must dispose of it immediately through a process called photorespiration. This process reduces the productivity of C3 plants by removing up to 25% of the fixed carbon.
C4 Plants
C4 plants are a group of plants with a unique photosynthetic pathway. They are named after the four-carbon molecule that is produced during the CO2 uptake process, which is called oxaloacetate (OAA). C4 plants are adapted to warmer climates and environments with high light intensity, and they are mainly found in the tropics and subtropics.
Unlike C3 plants, C4 plants have two types of photosynthetic cells: mesophyll and bundle-sheath cells. Mesophyll cells are the primary site of CO2 uptake, while bundle-sheath cells are responsible for carbon fixation. C4 plants use a different enzyme called PEP carboxylase, which has a higher affinity for CO2 than Rubisco. This higher affinity for CO2 reduces the oxygenation of Rubisco and helps minimize photorespiration, leading to increased photosynthetic productivity.
Conclusion
In summary, C3 and C4 plants differ in their adaptation to varying environmental conditions. C3 plants are more prevalent and operate efficiently under normal atmospheric conditions, while C4 plants are more efficient in hotter climates and high light conditions. Understanding the differences between these plant types is essential for crop breeding, ecology, and climate research.
Table difference between c3 and c4 plants
| Feature | C3 plants | C4 plants |
|---|---|---|
| Carbon fixation process | Calvin cycle | Hatch-Slack pathway |
| Anatomy | Mesophyll cells | Bundle sheath cells and mesophyll cells |
| Catalyst for carbon fixation | Rubisco | Phosphoenolpyruvate carboxylase |
| CO2 uptake | Low efficiency in low CO2 | High efficiency in low CO2 |
| Productivity | Lower in high temperature and dry climate | Better in high temperature and dry climate |
| Examples | Rice, wheat, soybeans | Corn, sugar cane, sorghum |