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SUMMARY:A Division in PIN-Mediated Auxin Patterning During Organ Initiatio
 n in Grasses - Devin O'Connor (Leyser Group)
DTSTART:20140117T130000Z
DTEND:20140117T132500Z
UID:TALK49498@talks.cam.ac.uk
CONTACT:Dr Yoan Coudert
DESCRIPTION:The hormone auxin plays a crucial role in plant morphogenesis.
   In the shoot apical meristem\, the PIN-FORMED1 (PIN1) efflux carrier con
 centrates auxin into local maxima in the epidermis which localize incipien
 t leaf or floral primordia.  From these maxima\, PIN1 transports auxin int
 o internal tissues along emergent paths that pattern leaf and stem vascula
 ture.  In Arabidopsis thaliana\, these functions are attributed to a singl
 e PIN1 protein.  Using phylogenetic and gene synteny analysis we identifie
 d an angiosperm PIN clade sister to PIN1\, here termed Sister-of-PIN1 (SoP
 IN1)\, which is present in all sampled angiosperms except for in the Brass
 icaceae\, including Arabidopsis.  Additionally\, we identified a conserved
  duplication of PIN1 in the grasses: PIN1a and PIN1b.  In Brachypodium dis
 tachyon\, SoPIN1 is highly expressed in the epidermis and is consistently 
 polarized toward regions of high expression of the DR5 auxin-signaling rep
 orter\, which suggests that SoPIN1 functions in the localization of new pr
 imordia.  In contrast\, PIN1a and PIN1b are highly expressed in internal t
 issues\, suggesting a role in vascular patterning.  PIN1b is expressed in 
 broad regions spanning the space between new primordia and previously form
 ed vasculature\, suggesting a role in connecting new organs to auxin sinks
  in the older tissues.  Within these regions\, PIN1a forms narrow canals t
 hat likely pattern future veins.  Using a computer model\, we reproduced t
 he observed spatio-temporal expression and localization patterns of these 
 proteins by assuming that SoPIN1 is polarized up the auxin gradient\, and 
 PIN1a and PIN1b are polarized to different degrees with the auxin flux.  O
 ur results suggest that examination and modeling of PIN dynamics in plants
  outside of Brassicaceae will offer insights into auxin-driven patterning 
 obscured by the loss of the SoPIN1 clade in Brassicaceae.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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