It was Eduard Tangl who discovered the plasmodesmata in 1879, and it was Eduard Strasburger who developed the name “plasmodesmata” in 1901 to describe the symplastic transport. Hanstein was the first to use the term symplast, which was first used in 1880.Munch coined the terms apoplast and symplast, which are diametrically opposed to one another.
In plants, symplast is a structural component that makes up the inside region of the plasma membrane. It is in this environment that water and other low-molecular solutes such as amino acids, carbohydrates, and several other ions can freely circulate between cells. The protoplast is a term used to refer to the protoplast in plants. Simplast’ cells have more than one nucleus, indicating that they are multicellular. While the plasmodesmata allow for the free movement of all tiny molecules, they also allow for the dispersion of larger molecules such as plant viruses or transcription factors, which can be disseminated with their active structures.
Symplast
It is the inner portion of a plant’s plasma membrane, where water and light molecules can freely pass across the membrane. All nutrients are transported from the soil to the root systems using this technique. With the help of the cortex, it moves these solutes from the cells of the epidermis to those of the endodermis.
When the transport process begins, the solutes are transported to the endodermal cells by the apoplastic transport mechanism. The presence of the Casparian strip causes these solutes to be forced into the Symplastic pathway as a result of its occupancy. Following tranquil processing of all of the solutes, they arrive at the pericycle for further processing. It is through the pericycle that they are transported to the xylem, where long-distance transport takes place. In comparison to apoplastic flow, xylem transport differs significantly since it relies on cell wall transfer.
Symplast pathway
The symplastic path is a term used to describe the ion and water pathways that are formed by symplast. This pathway provides resistance to the passage of water because the selective plasma membrane of the root cells is responsible for the intake of ions and water into the root cells themselves. The endodermis contains a suberised band known as the Casparian strip, which is a suberised band. Because the Casparian strip is resistant to water, water is channelled through the non-suberised wall portions of the plant and through the cell membrane to reach the xylem through the xylem. As a result, water and other solutes reach the vascular bundle by the symplastic pathway by crossing the endodermis, because apoplastic water migration beyond the cortex is prevented by the Casparian strip, which is located in the vascular bundle.
Apoplast
The apoplast is a region outside of the plasma membrane that is made up of intercellular spaces in which material can freely diffuse. Rather than protoplasm in plant tissues, it involves non-living components of the plant, such as the cell wall and intercellular gaps. Apoplast is a discontinuous structure that is divided into two parts. One region is made up of the cortex and tissues that are not part of the endodermis. The other region is made up of the tissues of the stele, such as the tracheids and vessels, which are located within the endodermis itself. The endodermis is responsible for the discontinuity in the apoplast.
Water moves from the root hair to the xylem via passing through the walls of intervening cells, without touching any membranes or cytoplasm, in this instance. The pathway offers the least amount of impediment to the movement of the water. In the walls of endodermal cells, however, the presence of impermeable lignosuberin casparian strips prevents the passage of water.
Apoplast pathway
The apoplast path transports water from the root hair to the xylem by passing through the cell walls of intermediate cells on the way. The Casparian strip of endodermal cells prevents apoplast water transport beyond the cortex from occurring beyond the cortex.
Thus, the symplastic pathway is used to transfer water and ions past the cortex’s protective membranes. Because the apoplast is composed entirely of non-living components, the apoplast pathway is the least affected by the metabolic status of the plant’s root.
Conclusion
plasmodesmata are channels that allow tiny molecules such as sugars, amino acids and ions to pass directly between cells without passing through a cell membrane. Actin structures are also capable of transporting larger molecules, such as transcription factors and plant viruses, through the body of the cell.The direct movement of water and other nutrients from one cell to another along concentration gradients is enabled as a result. Symplast flow is very effective at transporting nutrients from the soil into plant root systems.