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SUMMARY:Arabidopsis callus formation requires the activation of the latera
 l root initiation program - Kaoru Sugimoto\, Caltech
DTSTART:20110707T130000Z
DTEND:20110707T140000Z
UID:TALK32007@talks.cam.ac.uk
CONTACT:Jill Harrison
DESCRIPTION:Unlike most animal cells\, plant cells can easily regenerate n
 ew tissues from a wide variety of organs when properly cultured. The commo
 n elements that provide varied plant cells with their remarkable regenerat
 ion ability are still largely unknown. We characterized the initial proces
 s of Arabidopsis in vitro regeneration\, where a pluripotent cell mass ter
 med callus is induced. Using live imaging and whole-genome microarray anal
 ysis\, we found that callus is not an undifferentiated tissue but a somewh
 at differentiated tissue similar to the tip part of a root meristem\, even
  if it is derived from aerial organs such as petals\, which clearly shows 
 that callus formation is not a simple reprogramming process backwards to a
 n undifferentiated state as widely believed. Furthermore\, callus formatio
 n in roots\, cotyledons and petals is blocked in mutant plants incapable o
 f initial cell division of pericycle cells\, a layer of tissue surrounding
  the vasculature whose division is an early step in formation of a lateral
  root. The expression pattern of pericycle markers that characterize later
 al root initiation was observed in the callus-forming region of roots\, co
 tyledons and petals. It thus appears that the ectopic activation of a late
 ral root development program in pericycle-like cells is a common mechanism
  in callus formation from multiple organs. We also tested various media co
 ntaining different levels of plant hormones and confirmed that the conclus
 ions drawn above apply to a wide range of medium conditions.
LOCATION:Tom ap Rees\, Department of Plant Sciences
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