Question

What are apoplast and symplast?

Answer 1

There are two possible pathways for solute movement through plant tissue: the cell wall pathway and the cytoplasmic pathway.

Complete Answer:
Apoplast: It refers to the non-protoplasmic component of a plant including selves and intra-cellular spaces.

Symplast: Symplast refers to the continuous network of protoplast of a plant which are interconnected by plasmodesmata.

- The loss of the water throughout the xylem decreases the water potential in the xylem of a growing primary root. The xylem is directly connected to the apoplast of the stele of that root. Thus low water potential in the xylem pulls in water from the upper apoplast .In turn water in the apoplast is replaced by water flowing into steel from the root cortex and into the cortex from the soil.
- Path of water through the context of the root and into stele involves both the apoplast and symplast, the interconnected cytoplasm of adjacent cells. Because there is no cuticle over the epidermis of a primary root, water can flow in between the cells of the epidermis directly into the apoplast of the cortex and all the way to the endodermis.
- However it cannot cross endodermis in the apoplast because of the casparian strip. The suberized cell wall that separates apoplast of the context from the apoplast of the stele. To move further into the root, water must enter the symplast by crossing the plasma membrane of the endodermal cells.
- Water may also cross the plasma membrane of the cells at the root hairs or in the cortex. Once it does this it can flow from cell to cell through the symplast via the plasmodesmata.

Note: In Apoplast water movement is rapid and in symplastic water movement is slow. Also, the apoplast shows less resistance to water movement and the symplast shows some resistance to the water movement.