1. Movement of Water at the
Tissue/Organ Level
From Cell to Cell, Through the Root
to the Stem
Apoplast
Symplast
2. Water Absorption by Roots
• Surface is increased by:
– Root hairs
– Mycorrhizae - 90% of terrestrial plants
• Fungus attached to roots
– Hyphae form a mycelium
– Hyphae grow into the root , between plant’s cells
3. Apoplast Symplast
• Water and minerals are passed from the root
epidermis through the cortex to the stele via apoplast
or symplast
4.
5. Water Movement Through Tissues
• Symplast – pathway through the cytosol of
adjacent cells via plasmodesmata
• Apoplast – water movement through the cell walls
• Transmembrane - slow
6. Symplast Pathway
• Central vacuole – stores water/minerals
– Tonoplast - membrane
• Proton pumps in the
tonoplast, pump H+ into the
vacuole
• Other active transport moves
soil minerals into the vacuole
(K+)
• Makes the cytosol hyposmotic
(increases Ψs )
7. Apoplast Pathway
• Materials flowing along the apoplastic route are
blocked by the waxy (suberin) Casparian strip at
the endoderm
• Must enter endodermal
cells to move into the xylem
– Enables endodermal cells
to extract (active transport)
minerals from soil
8. Movement Through Tissues
• Water passes through the cortex to the stele
(xylem – tracheids/vessel elements)
