BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Towards an interdisciplinary view of shoot apical meristem functio
 n - Professor Jan Traas\, Ecole Normale Supérieure Lyon
DTSTART:20080214T160000Z
DTEND:20080214T170000Z
UID:TALK9398@talks.cam.ac.uk
CONTACT:3901
DESCRIPTION:We are studying the role of physical forces during plant devel
 opment. Pioneering work on plants\, in particular by Green and colleagues\
 , has suggested that physical stress patterns created by differential tiss
 ue expansion are locally interpreted in terms of particular cell growth ch
 aracteristics and patterns of differentiation. So far\, however\, it has b
 een impossible to go beyond the general idea that physical forces are impo
 rtant in morphogenesis. We are re-examining this issue exploiting new imag
 ing technologies combined with genetics\, micro-mechanical approaches and 
 mathematical modelling. Hereby we are focusing on the shoot apical meriste
 m in higher plants. This is a population of stem cells which continuously 
 initiates aerial organs and\, therefore\, is a basic determinant of plant 
 architecture. The link between mechanical constraints and a major structur
 al cellular component\, the microtubules\, receives particular attention. 
 Microtubules are filamentous elements of the cytoskeleton\, which play a m
 ajor role in structuring the extracellular matrix\, or plant cell wall. We
  have found the presence of highly dynamic and stereotypic microtubule ori
 entations in the meristem. The microtubule arrays are aligned to predicted
  stress patterns at the meristem surface and react to externally applied c
 onstraints in a cell autonomous way. We show\, using mathematical modeling
 \, that a cell autonomous reaction to stress patterns would be sufficient 
 to generate the observed behaviour of microtubules. When microtubules are 
 depolymerized using drug treatments\, the cells loose their capacity to gr
 ow anisotropically. As a result\, the meristematic cells adopt a number of
  growth properties usually observed in foams and the tissue is no longer a
 ble to carry out certain morphogenetic processes such as tissue folding. W
 e are currently testing the hypothesis that microtubules react to physical
  stress vectors that arise during anisotropic growth. Via directing cellul
 ose synthase complexes in the membrane they would subsequently structure t
 he cell wall in such a way that the cells would resist to stress. This\, i
 n turn\, would allow specific events such as directional organ outgrowth a
 nd tissue folding to happen. \n\nhttp://www.ens-lyon.fr/RDP/index.php?lang
 =en
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
END:VEVENT
END:VCALENDAR