Evolution of Development and Physiology
Di Stilio, Verónica S. , Lauri, Andrea , Eiford, Laura L. , Horton, Melissa G. , Zachgo, Sabine .
Conservation and divergence of petal and stamen identity genes between Arabidopsis and Thalictrum, a basal eudicot.
A central goal of evolutionary developmental biology is to understand the connection between changes in developmental control genes and phenotypic variation. Four classes of genes are responsible for producing sepals, petals, stamens and carpels in a predictable manner as described by the “ABC” model of flower development. Extending our knowledge of the role of this type of developmental genes from established model systems to phylogenetically informative taxa is an important step towards understanding the evolution of floral diversity. The focus of our work are the B class genes, MADS box transcription factors responsible for petal and stamen identity, in the basal eudicot Thalictrum (Ranunculaceae).
We have previously shown that there are three members of the APETALA3 (AP3) lineage of B class genes in Thalictrum. To analyze biochemical function after gene duplication, we used a heterologous transgenic approach in an Arabidopsis thaliana AP3 mutant (ap3-1). We looked for complementation by each of the Thalictrum AP3 homologs under the native promoter, and for the effects of over-expression (under CAMV 35S promoter) in wild-type (wt). These experiments have resulted in the rescue of stamens and petals by two of the Thalictrum AP3 homologs; one of the genes did not rescue. This may result from the truncated nature of the predicted protein. However, other possibilities such as a dominant negative role, inability to interact with the Arabidopsis PISTILATA counterpart, or to trigger the positive feedback loop required for its own expression will be discussed. While ectopic expression of the two complementing Thalictrum genes can cause homeotic conversion of sepals into petals, carpels only occasionally showed staminoid characteristics.
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Di Stilio web page at University of Washington
1 - University of Washington, Department of Biology, Box 351800, Seattle, WA, 98195-1800, USA
2 - Max-Planck-Institut für Züchtungsforschung, Carl-von-Linné Weg 10, D-50829 Köln
3 - Max-Planck-Institut für Züchtungsforschung, Carl-von-Linné Weg 10, D-50829 Köln
MADs box genes
B class genes
Presentation Type: ASPB Minisymposium
Location: Continental B/Hilton
Date: Monday, July 9th, 2007
Time: 10:40 AM