C4 Cycle

Characteristics of C4 Plants

The following are some of the characteristics of C4 plants:...

Examples of C4 Plants

Grasses Millets Sorghum Maize Sugar cane...

Anatomy of C4 Plants

The essential anatomy of C4 plants is Kranz’s anatomy. Its significant highlights of Kranz’s anatomy are –...

Leaves of C4 Plant

Leaves of C4 plants represent Kranz’s anatomy. Mesophyll and BSC form 2 concentric layers across a vascular bundle. Bundle sheaths are close together...

Evolution of C4 Plants

C4 photosynthesis has developed in excess of multiple times which is greater than 60 times as a carbon-concentrating component to expand the C3 photosynthetic pathway. The rate and the effectiveness of photosynthesis are more prominent in the C4 than C3 type under climatic CO2 exhaustion, high light, and temperature, recommending these elements as significant particular agents. This speculation is reliable with similar investigations of grasses, which demonstrate rehashed evolutionary transitions from concealed forests to open territories. Hence, such natural transitions likewise influence emphatically on plant-water relations. The top interest for water transport related to low CO2, high light, and temperature would have been chosen for C4 photosynthesis not exclusively to build the proficiency and pace of photosynthesis, yet additionally as a water-saving system. The C4 pathway permits high rates of photosynthesis at low stomatal conductance, even given low climatic CO2. The hydraulic system is protected by decreasing in transportation and permitting stomata to stay open and photosynthesis to be supported for longer under drying climatic and soil conditions. The development of C4 photosynthesis subsequently will develop plant carbon and water relations, giving solid advantages as atmospheric CO2 declines and a natural interest for water....

Efficiency of C4 Plants

During high temperatures, high light, and the ongoing CO2 concentration in the air, the C4 pathway is more productive than C3 photosynthesis since it builds the CO2 concentration around the significant CO2 fixation enzyme, named Rubisco. The oxygenase response and, likewise, photorespiration is generally suppressed. Because of the high rate of photosynthesis and the reduced rate of photorespiration the C4 plants are more efficient than C3 plants. The photosynthetic efficiency is estimated to be less than 4.6% in C3 plants and in C4 plants the efficiency can be estimated to be 6%. Therefore, there is a great ability to increase photosynthetic efficiency and hence productivity also increases. In C4 plants, the Carbon-dioxide concentration is high at the RuBisCO area and therefore the photorespiration is highly reduced.C4 plants consist of unique leaf anatomy called ‘Kranz anatomy. There is a conversion of oxaloacetic acid to malic acid which is then transferred to bundle sheath cells. In the bundle sheath cells, Carbon dioxide is released and this gets involved in the Calvin cycle....

C4 Cycle

It is another way of the C3 cycle to fix carbon dioxide. The first stable compound in this cycle is a 4-carbon compound called oxaloacetate. Therefore it is known as the C4 cycle. This pathway is also known as the Slack and Hatch pathway as they worked out this pathway in the year 1966. These pathways are generally seen in grasses, sugarcane, and sorghum. C4 pathways involve two carboxylation reactions in which one exists in the chloroplast of bundle sheath cells and another in the chloroplast of mesophyll cells....

Plants that use C4 Carbon Fixation

C3 and C4 pathways vary in the initial product of carbon fixation. In C4 plants the C3 pathway is also utilized in the formation of a glucose molecule. In C4 plants there will be Kranz anatomy in leaves to permit high temperatures. Large bundle sheath cells are located across vascular bundles of leaves. Bundle sheath cells have thick surfaces and there are no intercellular spaces and large chloroplasts will exist. Carbon fixation happens in mesophyll cells. Carbon dioxide acceptor is a 3-carbon compound phosphoenolpyruvate (PEP). The enzyme named phosphoenolpyruvate carboxylase (PEPcase) catalyzes the reaction. The initial product of CO2 fixation is 4 carbon compound Oxaloacetic acid. The oxaloacetic acid is transformed into other 4C acids such as malic acid and aspartic acid. They are transferred to bundle sheath cellsBy the process of decarboxylation in bundle sheath cells, Carbon dioxide is released and involved in the Calvin cycle. The 3-carbon acid is transferred to the mesophyll cells. RuBisCO exists in the bundle sheath cells but  PEPcase is absent....

Steps in C4 Cycle

The C4 cycle consists of two steps they are :...

Need for C4 Pathway

The C4 pathway is intended to effectively fix CO2 at low concentrations and the plants that utilize this pathway are known as C4 plants. These plants connect Carbon dioxide into a four-carbon compound (C4) known as oxaloacetate. This happens in cells that are known to be mesophyll cells. The initial advantage is that the system doesn’t go through photorespiration, an interaction that opposes photosynthesis. The subsequent one is that plants allow their ores to close for longer periods, accordingly staying away from water loss....

Difference Between C3 cycle and C4 cycle:

C3 cycle                    C4 cycle The C3 cycle is generally found almost in all plants. The C4 cycle can be seen only in C4 plants such as maize sorghum etc. The The The The C3 cycle involves granular Granular chloroplasts. The C4 cycle involves both Granular and Agranular chloroplasts. The C3 cycle is carried out by only mesophyll cells.  The C4 cycle is carried out by both mesophyll cells and bundle sheath cells. The first stable product in the C3 cycle is a 3-carbon compound, which is phosphoglyceric acid(PGA).  The first stable product in C4 cycle is 4- the carbon compound, which is oxaloacetic acid(OAA).  3ATP and 2NADPH are required for the fixation of one molecule of CO2.  5ATP and 2NADPH are required for the fixation of one molecule of CO2. The optimum temperature required for the C3 cycle is 10-25 degree Celsius.  The optimum temperature required for the C4 cycle is 30-45 degree Celsius. The C3 cycle is inhibited by oxygen.  The C4 cycle does not require inhibition. The C3 cycle can be saturated with sunlight. The C4 cycle does not saturate with sunlight. In the C3 cycle, only a single carbon fixation happens. In the C4 cycle double carbon fixation happens. Carbon fixation of the C3 cycle is slow and less efficient. Carbon fixation of the C4 cycle is fast and more efficient....

Significance of C4 Cycle

The C4 cycle increases the photosynthetic yield two to three times more than C3 plants. C4 plants perform a high rate of photosynthesis even when stomata are nearly closed. The C4 cycle increases the adaptability of C4 plants to high temperatures and light intensities. They can grow very well in saline soil because of C4 organic acid. CO2 from the atmosphere is fixed by the enzyme PEP carboxylase, which results in the formation of the 4-carbon compound oxaloacetate and hence called the C4 cycle. Plants having the C4 cycle are mainly from tropical and subtropical regions and are able to survive in environments with low CO2 concentrations....

Converting C3 plants to C4

As the population in the world increases, the production of food started to decrease rapidly. To raise food production, mainly rice plants, the development of crops is very crucial and the development in the photosynthetic capacity of rice is also very essential for implanting the C4 photosynthetic pathway in C3 plants for crop yield expansion. The photosynthetic mechanisms which are enhanced by the crops will utilize solar radiation and this solar energy is transformed into biological energy which directly rises the crop yield. The types of pathways include the C4 pathway of photosynthesis, C3 photosynthesis, and CAM pathway of photosynthesis....

Advantages of C4 plants

Photosynthesis is more efficient than C3 plants under high light intensity and high temperatures because carbon dioxide concentration is high, which doesn’t allow it to grab oxygen and undergo photorespiration. It has better water-utilizing efficiency because PEP Carboxylase brings in CO2 faster and hence it does not need to keep stomata open as much (less water lost by transpiration) for the same amount of carbon dioxide gain for photosynthesis....

FAQs on C4 Plant

Question 1: For what reason are C4 plants so unique?...