kranz anatomy

Kranz’s anatomy can be defined as two separate concentric sheets of chlorenchyma cells, formed by a bundle sheath comprising utmost of the chloroplasts, enclosed by an outer layer comprising of a minor number of mesophyll cells.

The mainly large cells surrounding the vascular bundles of the C4 plants are termed bundle sheath cells and the leaves which have such structure are said to have Kranz anatomy. Kranz means wreath and shows the preparation of cells. The bundle sheath cells may create several sheets around the vascular bundles that are categorized by numerous chloroplasts, impenetrable walls for gaseous exchange, and no intercellular spaces. For example, such anatomy is well-observed in maize.

MEANING OF KRANZ ANATOMY

In the common of plants, together with rice, carbon dioxide is first made static into a compound with three carbons atoms (C3) by the photosynthetic enzyme- ribulose bisphosphate carboxylase oxygenase or simply Rubisco. This is known as C3 photosynthesis. Rubisco is integrally unproductive because it can also catalyze a reaction with oxygen, giving an inefficient method known as photorespiration rather than photosynthesis. To wave off this incompetence, the C4 path primarily fixes carbon dioxide in the atmosphere into C4 acids using the enzyme phosphoenolpyruvate carboxylase which is unresponsive to oxygen. Next, C4 acids release carbon dioxide for re-fixation by Rubisco. In many C4 plants, these two phases of the C4 trail are spatially divided into morphologically different photosynthetic cell categories, allowing a high concentration of carbon dioxide to gather in the area of Rubisco, and better photosynthetic productivity.

In C4 grasses such as maize and some C4 dicots, distended bundle sheath (BS) cells border the veins (V) and the BS cells are then enclosed by mesophyll (M) cells. Each duo of veins is thus parted by two bundle sheaths and two mesophyll cells in a V-BS-M-M-BS-V form denoted as Kranz anatomy. The anatomy of C3 plants is classically a V-BS-M-M-M-M-M-M-M-BS-V form, and the bundle sheath cells are lesser than in C4 plants. An entirely efficient C4 trail, therefore, requires a synchronized alteration in the structure of the tissue and metabolic biochemistry. During development, these variations have happened more than fifty times in an extensive range of blooming plants, representing that, even with being critical, it is a comparatively easy trail to progress.

ADVANTAGES OF KRANZ ANATOMY

Kranz anatomy is a benefit for the reason that it permits plants to prepare their food more capably. The Kranz anatomy moves around the veins in the leaves with a coating of cells that can absorb more light. This lets the plant yield more sugar and oxygen for usage of the plants.

DIAGRAM OF KRANZ ANATOMY

C₄ plants show the Kranz anatomy. The leaves have vascular bundles which are enclosed by bundle sheath cells and mesophyll cells. Bundle sheath cells are thick-walled tubular cells. Chloroplasts of bundle sheath cells are bigger and lack grana while chloroplasts of mesophyll cells are lesser and have grana.

STAGES OF KRANZ ANATOMY

The growth of Kranz anatomy can be measured in three overall stages: 

• beginning of procambium,

• Bundle Sheath and Mesophyll cell description,

• chloroplast expansion and the addition of the C4 cycle. 

CHARACTERISTICS OF KRANZ ANATOMY

The characteristics of Kranz anatomy are the following:

• Mesophyll cells are homogenous and organized in concentric sheets around the vascular bundles.

• The chloroplasts of mesophyll cells are lesser and they lack starch. These have the enzyme structure for C4 photosynthesis.

• The chloroplasts of bundle sheath cells contain starch. These chloroplasts are big. These have an enzyme structure for C3 photosynthesis.

• Mesophyll cells and bundle sheath cells are related by plasmodesmata.

C3 PLANTS LEAF ANATOMY

C3 plants are termed general plants that do not involve any photosynthetic variations to decrease photorespiration. The plants that practice fixation of the carbon dioxide by Rubisco are known as C3 plants. This fixation is completed by the Calvin cycle. C₃ plants cover nearly 85% of total plants, together with rice, wheat, soybeans, and all trees.

DIFFERENCE BETWEEN C3 AND C4 PLANTS

The differences between C3 AND C4 plants are:

Based on Meaning: C3 plants practice the Calvin cycle for the dark reaction of photosynthesis. C4 practices the Hatch-Slack Pathway for the dark reaction of photosynthesis.

Based on Season: C3 plants are plants of the cold season, commonly found in cool and wet areas. C4 plants are plants of the warm season, commonly found in dry areas.

Based on Conditions: C3 plants are plentiful in temperate surroundings. C4 plants are plentiful in tropical surroundings.

Based on Product: The product found in the C3 cycle is a compound composed of 3 carbon atoms– phosphoglyceric acid. The product found in the C4 cycle is a compound composed of 4 carbon atoms– oxaloacetic acid.

Based on Kranz Anatomy: Leaves in C3 do not exhibit Kranz anatomy. Leaves in C4 exhibit Kranz anatomy.

Based on Presence of Chloroplasts: In C3, the bundle sheath cells do not cover chloroplasts. In C4, the bundle sheath cells cover chloroplasts.

Based on Photosynthesis: C3 completes photosynthesis only when stomata are open. C4 completes photosynthesis even when stomata are close.

Based on CO2 fixation: CO2 fixation is slow in C3 plants. It is comparatively rapid in C4 plants.

Based on Mesophyll cells: In C3 plants, the dark reaction occurs only in the mesophyll cells. In C4 plants, mesophyll cells only perform the early steps of the C4 cycle. The key steps are carried out in bundle sheath cells.

Based on Photorespiration: The photorespiration rate in C3 plants is very high. Photorespiration is absent in C4 plants.

Based on Growth: In C3 plants, the growth occurs when the soil temperature is between 4-7 degrees. In C4 plants, the growth occurs when the soil temperature is between 16-21 degrees.

Based on Presence: 95% of total green plants on earth are C3 plants. Around 5% of plants are C4 plants on earth.

Based on Examples: Wheat, Oats, Rice, Sunflower, Cotton are examples of C3 plants. Maize, Sugarcane, Amaranthus are examples of C4 plants.

CONCLUSION

The mainly large cells surrounding the vascular bundles of the C4 plants are termed bundle sheath cells and the leaves which have such structure are said to have Kranz anatomy. Kranz means wreath and shows the preparation of cells. Kranz anatomy is a benefit for the reason that it permits plants to prepare their food more capably. 

The Kranz anatomy moves around the veins in the leaves with a coating of cells that can absorb more light. This lets the plant yield more sugar and oxygen for usage of the plants. In C3 plants, the growth occurs when the soil temperature is between 4-7 degrees. In C4 plants, the growth occurs when the soil temperature is between 16-21 degrees.