Apoplast and symplast are used in transmembrane pathways. They are components of the root cortex in plants.
Apoplasts symbolize the opening between plant cells and the wall of those cells, while symplasts are known as cytoplasm cells. The symplast contains cytosol and plasmodesmata.
Apoplast and symplast are water tubes and solutes throughout a plant’s root system. The apoplast and symplast routes are responsible for the transfer of water and solutes (dissolved minerals in structure ions and amino acids) via the root cortex and to the xylem.
The apoplast pathway is called the apoplastic pathway, while the symplast pathway is called the symplastic pathway.
The apoplast and symplast share the same features but are unique in diverse ways. Filtration of water solution occurs in both the apoplast and symplast.
The difference is that in apoplast, the water moves via capillary action or diffusion, while in symplast, the water goes via osmosis.
What Are Apoplast And Symplast?
Apoplast and Symplast are elements of the root cortex in plants.
The growth of a plant is dependent on its capacity to take up water and dissolved minerals from the soil. The root system of any plant is provided with important tissues to speed up water and solute penetration.
This plant tissue has two major components called Apoplast and symplast.
There are three pathways namely the apoplastic, symplastic, or transmembrane routes. The apoplastic route entails the activity of water and melted minerals along cell walls and extracellular openings, while in the symplastic route, the water and solutes flow along the cytosol.
In this route, materials are required to cross the plasma membrane when flowing from one cell to another cell close by through plasmodesmata.
Alternatively, in the transmembrane pathway, the melted minerals and water flow from cell to cell and to the next. However, these three routes are not mutually exclusive, as some solutes may use extra routes.
Additionally, there is another potential route called the vascular route, but it is mostly limited to water molecule flow.
In this route, water crosses through the vacuoles of plant cells via osmosis. It is almost the same with the symplastic route, only that water transport is via vacuoles instead of cytosol.
Apoplast
Apoplast is a term formed in 1930 by Munch to separate the living symplast from the dead apoplast. The apoplast is the opening outside the plasma membrane within which material can scatter freely.
It is smashed by the Casparian strip in roots, by air openings between plant cells and by the plant cuticle. It contains cell walls, xylem, phloem, extracellular openings, and tracheids.
The apoplast pathway speeds up the transfer of water and solutes across a tissue or organ. This procedure is called apoplastic transport.
Apoplastic Pathway
This is a vital pathway for the absorption and movement of water nutrients in plants and plays a fundamental function in the adequate functioning and improvement of the plant.
This pathway starts in the root hairs, which are tiny, hair-like extensions of the root which increase the surface area for absorption. Root hairs absorb water and nutrients from the soil via diffusion.
Diffusion is the flow of substances from a region of higher concentrations to a region of lower concentration.
When water and nutrients are soaked up by the root hairs, they flow via the cell walls of the root cells and move into the extracellular opening.
This opening is the one outside the cells but within the plant tissue. From the opening, the substances flow through the cell of the root cells and move into the opening outside the stem.
This is where they are moved upwards via the plant. It is essential you know that this pathway does not need energy to move substances.
Additionally, this pathway allows the movement of any substance through the cell wall and extracellular opening.
Symplast
Symplast is the internal side of the plasma membrane through which water and low molecular weight solutes diffuse freely. Its cells have more than a nucleus.
The movement of water in a symplastic route is supported by cytoplasmic streaming. It contains the whole cytosol and plasmodesmata which are known as the cytoplasmic channel.
Symplastic Pathway
This pathway involves the movement of water and solutes through the cytoplasm and cell-to-cell connections of plants.
It is essential in the distribution of nutrients and water throughout the plant. It is also vital in the flow of signaling molecules and hormones.
This pathway encompasses the flow of substances via plasmodesmata which are tiny channels that attach the cytoplasm of plant cells.
This plasmodesmata enables the flow of substances between cells without passing over the cell membrane.
The cell membrane only allows certain substances to pass through while inhibiting others from crossing over. This pathway needs energy to carry substances through it.
It is also crucial in conveying substances in the phloem. The phloem is the tissue responsible for the transfer of sugars and other substances from leaves to the rest of the plant.
Generally, the pathway is crucial in the proper functioning and improvement of the plant.
Differences Between Apoplast And Symplast
They are differentiated based on subheadings
1. Types Of Cell
Apoplast consists of non-living cells of the plants while Symplast consists of the living cells of the plant.
2. Flow of water
In apoplast, water flows via capillary action or free diffusion along the gradient while in symplast, the water flow is via Osmosis along the gradient.
3. System Elements
Apoplast contains cell walls and intracellular openings while Symplast contains cytoplasm of cells connected with plasmodesmata.
4. Resistance To Waterflow
In Apoplast, the water flow happens via bulk or mass flow and does not give any impediment to water flow while in Symplast, the water flow happens from one cell to another cell via plasmodesmata, but it impedes water flow.
The suberin of the Casparian lines in the endodermis prevents the progression of water via the cell walls forcing it through the route.
5. Rate Of Pathways
In apoplastic, its route is quick While in symplastic, its route is slower than the latter.
6. Transportation
In apoplast, more ions and water are transferred via the apoplastic route while in symplast, ions, and water are transferred via the symplastic route.
7. Metabolic state
In apoplast, during water transport, the root cortex of the cell does not influence the metabolic rate in the apoplastic channel Whilec in Symplastic, during water transport, the root cortex of the cell is heavily affected by the metabolic status of the cells.
8. Implication
In Apoplast, during the root’s secondary growth, the apoplastic channel transfers the bulk of the water While in symplast, water travels via the route beyond the cortex.
Similarities Between Apoplast And Symplast.
- They both live within the cortex of plants.
- Apiplast and symplast are the two means water flows from the root hair cell to the xylem.
- Appplast and symplast convey water and solutes to the stele apoplast and xylem.
- Filtration occurs in both although in different stages of the process.
Final Word
Apoplast and symplast are the elements of the root cortex in plants. The development of plants is dependent on their capacity to carry water and dissolved minerals from the soil.
Each of these elements has specific pathways that perform this activity. Though the pathway functions in different ways, it still has similar functions.
