Introduction

C4 plants are a type of plant that have adapted a specialized mechanism to optimize photosynthesis in hot and dry environments. This adaptation allows them to maximize carbon fixation and minimize water loss. Although only a few cells in a C4 plant carry out the biosynthetic – Calvin pathway, they are highly productive, and this can be attributed to several reasons.

Efficient Carbon Fixation

C4 plants have evolved a two-step process for carbon fixation, which involves the initial capture of carbon dioxide (CO2) by mesophyll cells and the subsequent transfer of CO2 to bundle sheath cells, where the Calvin pathway occurs. This spatial separation of the two steps allows for a more efficient use of resources.

Minimization of Photorespiration

Photorespiration is a process in which oxygen competes with carbon dioxide at the active site of the enzyme RuBisCO, resulting in the release of carbon dioxide and the consumption of energy. C4 plants have a higher concentration of CO2 in the bundle sheath cells, which reduces the likelihood of oxygen binding to RuBisCO and minimizes photorespiration. This allows for more efficient carbon fixation and energy utilization.

Concentration Mechanism

C4 plants have a specialized mechanism known as the C4 pathway, which involves the initial fixation of CO2 into a four-carbon compound called oxaloacetate in the mesophyll cells. This compound is then transported to the bundle sheath cells, where it releases CO2, which enters the Calvin pathway. This concentration mechanism increases the concentration of CO2 in the bundle sheath cells, further reducing the potential for photorespiration and enhancing the efficiency of carbon fixation.

Increased Efficiency in Hot and Dry Environments

C4 plants are particularly well-adapted to hot and dry environments due to their ability to minimize water loss. The spatial separation of carbon fixation and the concentration mechanism reduce the need for stomatal opening, which is responsible for both CO2 uptake and water loss. This allows C4 plants to maintain a higher water use efficiency compared to C3 plants. Additionally, the higher CO2 concentration in the bundle sheath cells reduces the need for stomatal opening even further, conserving water.

Conclusion

In conclusion, although only a few cells in a C4 plant carry out the biosynthetic – Calvin pathway, they are highly productive due to their efficient carbon fixation, minimization of photorespiration, concentration mechanism, and increased efficiency in hot and dry environments. These adaptations allow C4 plants to optimize photosynthesis and maximize productivity, making them well-suited for survival in challenging environmental conditions.

As c4 plant have two different chloroplasts, and photorespiration is absent they are highly productive