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SUMMARY:Three ancient hormonal cues coordinate shoot branching in a moss -
  Yoan Coudert (Harrison Group)
DTSTART:20140207T130000Z
DTEND:20140207T132500Z
UID:TALK49501@talks.cam.ac.uk
CONTACT:Dr Yoan Coudert
DESCRIPTION:Branching was a key innovation in plant evolution that allowed
  plants to colonize larger volumes of space and increase productivity. The
  molecular control of branching has been well studied in Arabidopsis in wh
 ich a main shoot apex interacts with further apices in the leaf axils to d
 etermine which can grow. The interaction between apices is mediated hormon
 ally by auxin and its polar transport\, via plasma membrane canonical PIN 
 proteins\, cytokinins and strigolactones.\n\nThe axillary branching mode o
 f Arabidopsis and other seed plants is evolutionarily derived and has also
  arisen by convergence in mosses like Physcomitrella. However\, recent wor
 k suggests that there is no long range auxin transport in Physcomitrella\,
  that PIN proteins do not localize to the plasma membrane\, and that strig
 olactones do not affect branching in the leafy shoot.\n\nWe have used a co
 mbination of computational and genetic tools to determine what regulates b
 ranching in Physcomitrella. As in Arabidopsis\, and in line with the predi
 ctions of our model\, we find that auxin from an apical source suppresses 
 branching\, cytokinin promotes branching\, and strigolactone from a basal 
 source suppresses branching. However\, our model predicts that a capacity 
 for polar auxin transport is not required to regulate the branching patter
 n\, and mutant analysis reveals that canonical PIN proteins are minor cont
 ributors to the branching pattern.\n\nOur work shows that three conserved 
 and ancient hormonal cues have been recruited independently to regulate th
 e branching pattern in moss and Arabidopsis. It also shows that moss canon
 ical PINs are not necessary for branching to occur and predicts that a non
 -polar auxin transport mechanism is sufficient to effect the auxin transpo
 rt required to generate the branching pattern\, possibly via unknown trans
 porters.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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