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Abstract Detail

Evolution of Flower Development: from Phenotypes to Genes

Theiβen, Günter [1], Mondragón-Palomino, Mariana [1], Simon, Hannelore [1], Melzer, Rainer [1].

Evolutionary developmental genetics of floral organ identity.

Much has been learned during recent years concerning how floral organ identity is specified by homeotic genes and proteins in eudicotyledonous model plants such as Arabidopsis, Antirrhinum and Petunia. These insights have been pulled together in two major hypotheses, termed the ‘ABC model’ and the ‘floral quartet model’. Central players in these models are MIKC-type MADS-box genes and the transcription factors encoded by them, respectively. Here we outline as to how these models are now guiding investigations that help to understand long-standing and central problems of evolutionary biology and botany concerning the origin and diversification of the angiosperm flower. Based on protein-protein and protein-DNA interaction studies we hypothesize that the transition from dimer to tetramer formation of floral homeotic proteins increased the cooperativity of DNA-binding of the transcription factors controlling reproductive growth. That way, we argue, better ‘developmental switches’ originated that facilitated the early evolution of the flower. Studies on tulips and diverse orchid species revealed that heterotopic expression of class B genes conferring petaloidy to outer whorl organs contributed to the diversification of the angiosperm flower. In orchids, duplications of class B genes followed by sub- and neo-functionalization events led to a further diversification of the perianth organs and hence contributed to the origin of the typical orchid flower. The molecular mechanisms underlying these events will be discussed.

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1 - Friedrich-Schiller-Universitaet Jena, Lehrstuhl fuer Genetik, Philosophenweg 12, Jena, Thuringia, D-07743, Germany

ABC model
floral quartet model
MADS-box gene

Presentation Type: Symposium or Colloquium Presentation
Session: SY17
Location: Stevens 4/Hilton
Date: Wednesday, July 11th, 2007
Time: 2:00 PM
Number: SY17008
Abstract ID:1325

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