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SUMMARY:The endodermis - a selective and protective interface between plan
 t and soil - Niko Geldner\, Lausanne
DTSTART:20111124T160000Z
DTEND:20111124T170000Z
UID:TALK31550@talks.cam.ac.uk
CONTACT:Jill Harrison
DESCRIPTION:My lab investigates the molecular and developmental basis of e
 ndodermal structure and polarity. The endodermis is an invariable barrier 
 within the root of all vascular plants. Its barrier function is mediated b
 y the Casparian Strips\, ring-like hydrophobic cell wall thickenings that 
 are coordinated between endodermal cells and form a supracellular network.
  Casparian Strips effectively blocks passage of nutrients and pathogens th
 rough the extracellular space\, while still allowing for signal perception
  and nutrient uptake. This very much resembles the dual\, protective/uptak
 e function of polarised gut epithelia in animals\, for example. The molecu
 lar players and mechanisms that underlie this intricately structured cell 
 layer have remained obscure. Our group has recently described the developm
 ental events leading to a differentiated endodermis. Its initial different
 iation\, less than 1 mm away from the root tip\, occurs in a switch-like 
 “burst” of events rather than as a gradual maturation. We have visuali
 sed a strict polarity within the endodermis\, with proteins being distribu
 ted exclusively to the outer domain of the plasma membrane (facing the roo
 t cortex) or the inner domain (facing the cells of the stele). The two pol
 ar domains are separated by a central membrane diffusion-barrier. We ident
 ified an unknown protein family that forms this central membrane barrier a
 nd predicts the site of Casparian Strip formation. Mutants in these CASP g
 enes display disorganized deposition of Casparian Strips. In addition\, we
  have obtained a number of mutants in Casparian Strip development\, both b
 y forward and reverse genetic approaches\, which display interrupted\, or 
 strongly delayed\, deposition of Casparian Strips\, some by interfering wi
 th CASP localization. These mutants now provide the unprecedented opportun
 ity to directly test the many supposed roles of the Casparian Strips and I
  will report on our latest results from the analysis of these mutants.  
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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