`star` Apoplast
`star` Symplast
`star` Water Transport to Vascular Cylinder
`star` Mycorrhiza


● The `color{brown}("apoplast")` is the system of adjacent cell walls that is continuous throughout the plant, except at the `color{brown}("casparian strips")` of the `color{violet}("endodermis")` in the `color{violet}("roots.")`

● The `color{violet}("apoplastic movement of water")` occurs exclusively through the `color{brown}("intercellular spaces")` and the walls of the cells.

● Movement through the apoplast does not involve crossing the `color{brown}("cell membrane.")`

● This movement is dependent on the `color{brown}("gradient. ")`

● The apoplast does not provide `color{brown}("any barrier")` to water movement and water movement is through `color{violet}("mass flow.")`

● As water evaporates into the`color{violet}(" intercellular spaces")` or the atmosphere, `color{brown}("tension develop")` in the continuous stream of water in the apoplast, hence `color{brown}("mass flow of water")` occurs due to the `color{brown}("adhesive and cohesive properties")` of water.


● The `color{brown}("symplastic")` system is the system of `color{brown}("interconnected protoplasts.")`

● `color{brown}("Neighbouring cells")` are connected through `color{violet}("cytoplasmic strands")` that extend through `color{brown}("plasmodesmata. ")`

● During symplastic movement, the water travels `color{brown}("through the cells")` – their cytoplasm; intercellular movement is through the plasmodesmata.

● Water has to enter the cells through the `color{brown}("cell membrane")` , hence the movement is relatively slower.

● Movement is again `color{brown}("down a potential gradient.")`

● `color{violet}("Symplastic movement")` may be aided by `color{brown}("cytoplasmic streaming.")`

● One have observed cytoplasmic streaming in cells of the `color{violet}("𝐻𝑦𝑑𝑟𝑖𝑙𝑙𝑎")` leaf; the `color{brown}("movement of chloroplast")` due to streaming is easily visible.


● Most of the `color{violet}("water flow")` in the roots occurs via the apoplast since the `color{brown}("cortical cells")` are loosely packed, and hence offer `color{violet}("no resistance to water movement. ")`

● However, the inner boundary of the cortex, the `color{brown}("endodermis,")` is impervious to water because of a band of `color{brown}("suberised matrix")` called the `color{brown}("casparian strip.")`

● `color{violet}("Water molecules")` are unable to penetrate the layer, so they are directed to wall regions that are not suberised, into the cells proper through the membranes.

● The water then moves through the `color{violet}("symplast")` and again crosses a membrane to reach the `color{violet}("cells of the xylem.")`

● The `color{violet}("movement of water")` through the root layers is `color{brown}("ultimately symplastic")` in the `color{violet}("endodermis.")`

● This is the only way water and other solutes can enter the `color{brown}("vascular cylinder.")`

● Once inside the `color{violet}("xylem, water")` is again free to move between cells as well as through them.

● In young roots, water enters directly into the `color{brown}("xylem vessels")` and/or `color{brown}("tracheids.")`

● These are `color{brown}("non-living conduits")` and so are parts of the `color{violet}("apoplast.")`


● Some plants have `color{brown}("additional structures")` associated with them that help in `color{violet}("water (and mineral)")` absorption.

● A `color{brown}("mycorrhiza")` is a `color{violet}("symbiotic association")` of a fungus with a root system.

● The `color{violet}("fungal filaments")` form a network around the `color{violet}("young root")` or they penetrate the root cells.

● The `color{violet}("hyphae")` have a very `color{brown}("large surface area")` that absorb mineral ions and water from the soil from a much `color{violet}("larger volume of soil")` that perhaps a `color{violet}("root")` cannot do.

● The `color{violet}("fungus")` provides `color{brown}("minerals and water")` to the roots, in turn the roots provide sugars and N-containing compounds to the `color{violet}("mycorrhizae.")`

● Some plants have an `color{brown}("obligate association")` with the `color{violet}("mycorrhizae.")`

● For example, `color{brown}("𝑃𝑖𝑛𝑢𝑠 seeds")` cannot germinate and establish without the presence of mycorrhizae.