BIOL 2242 Lecture Notes - Lecture 14: Casparian Strip, Suberin, Endodermis

• School: University of Manitoba
• Department: Biological Sciences
• Course: BIOL 2242
• Professor: Isobel Waters

Document Summary

30. 16, p. 718: apoplastic, between living cells via intercellular spaces and ii) inside dead cells, path of least resistance, symplastic, between living cells via plasmodesmata, transcellular, between living cells by crossing plasma membranes and walls. Controlling movement into stele: i) root hair zone (fig. 24. 13, p. 568: endodermis is critical control point, casparian strip is suberin layer on 4 of 6 walls. On anticlinal walls only (at right angles to organ exterior) Periclinal (face) walls are unsuberized: forces water, minerals to exit apoplastic route and enter via transcellular (most) or symplastic route. Most cellular control by i) manipulating solute concentration; and ii) presence of transport proteins for specific substances: older root regions. In mature root portions, water uptake is minimal. Endodermis now prevents water outflow en route to shoot: more suberin and cellulose on all walls (cid:523)c. strip (cid:498)plus(cid:499)(cid:524) Blocks transcellular route; only symplastic entry now possible: no casparian strip plus on passage cells in endodermis.