Caspary Band

Caspary Band

In the field of cell biology and botany there is much talk about the caspary band and its importance. It is a thickening of the cell walls that plays a fundamental role in the support tissues of vascular plants and in some algae. We know that the cell wall is made up of lignin and suberin and that it helps protect the plant. The Caspary band is formed at the same time as the primary cell walls in the primary root and from there is of great importance for the development of the plant.

In this article we are going to tell you everything you need to know about the formation and importance of Caspary's band.

Key features

apoplast

We know that the endodermis of the cell walls has a thickness, hardness, impermeability resistance that helps to protect the cells of the plants. The thickening of the radial and transverse cell walls is caused by natural polymers known as the Caspary band. It plays a fundamental role in the support tissues of vascular plants and some algae. There is a band in each cell infiltrated by organic substances or polymers and it marks a great differentiation between the primary walls of the cells.

The Caspary band extends across all the walls in a discontinuous manner. That is, it does not appear simultaneously in all cells of the endodermis. Its name comes from the production of a kind of waterproof layer that it generates. What begins with a deposition of phenolic and fatty substances on the radial walls of the cells in the end ends up becoming a belt that joins the plasma membrane to increase its thickness. We can observe Caspary's gang through the microscope using a biological dye called Safranin. This band can be said to be a belt where the primary walls are embedded.

Caspary band function

caspary band under microscope

We are going to know what the function of Caspary's band is. It is composed mainly of suberin and constitutes an alternating structure that serves as a barrier between plants and the environment. We know that plants need a certain protection to not be damaged by natural agents that exist in the environment. In addition, one of its functions is to intervene in the transport of water and ions through the apoplast of the root. It also prevents the substances from flowing through this medium and forces the intermembrane transport by the simplistic way.

Suberin is made up of hydroxy, epoxy, and dicarboxylic fatty acids. These fatty acids fill the space of the extracellular part on the periphery of plant cells. That is, it blocks the passage of substances between the walls of the endodermis and the liquid from the soil ends up passing through the cytoplasm. In this way, a rather interesting selective permeability is created for the plant. This is how the plant can control the flow of ions, control the entry of water and other mineral substances.

If we go to the endodermis of the cell, we can see that it is the only cell layer that prevents the passage of substances from the soil to the vascular bundles. The endodermis is covered by the cortex and although the substance ions can easily diffuse between the rhizodermis and the vascular cylinder, they cannot access the latter. For this reason, the pathway is the plant syplast or the cytoplasm of the epidermis.

Caspary band and water transport

via the sympathetic

In most plants the water entered the roots naturally. It is not necessary to have an extra expenditure of energy for the water to enter through the roots. However, the movement of water through the crust and the entire interior layer does use up more energy and undergo various processes. The movement of water to the xylem can occur in two ways: the apoplast and the syplast. Caspary's gang is present at both. We are going to study in depth which are these two routes of which the Caspary band is found:

Apoplast pathway

It is the region of the plant that is not occupied by the protoplast. In them are the empty spaces apparently located between the cell walls and between the different cells. The apoplast constitutes one of the access zones for water and other substances that are incorporated into the interior of the plant. This pathway serves as a conduit for carbon dioxide to the chloroplast. to contribute to the fixation of carbon during the photosynthesis process. They also intervene after the resistance of the plant to various phytopathogenic organisms that can stress the cellular metabolism.

It must be taken into account that the spaces between cell walls and between cells fill up as organic polymers whose main nature is fat. These organic polymers are what make up the Caspary band and prevent the diffusion of water and ions. The transport of these elements through the apoplast is null, much lower than that which occurs in the sympathetic pathway.

Sympathetic pathway

The suberification of the endodermis means that the only route for transport is the syplast. It is here that water passes through the cytoplasmic membranes and protoplasts of cells. It is considered as the most active transport and It goes from cell to cell using the differentiation of water potentials. We have seen that he had apoplast has a movement of water through the dynamics of perspiration. This occurs mainly after the loss of water through the opening of the stomata.

The syplast is the interconnected protoplasts that give rise to the cytoplasm of the cell. At the same time we can see that they are linked by plasmodesmata. It is through here that water flows easily as well as other low molecular weight molecules and substances.

I hope that with this information you can learn more about the Caspary band and the importance it has for plants.


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