Ranunculales - a Basal Eudicot Perspective of Angiosperm Evolution
Damerval, Catherine , Charon, Celine , Nadot, Sophie .
Evolution of floral architecture in Ranunculales: evolution of floral symmetry and characterization of CYC-like genes in Papaveraceae.
Shifts in floral symmetry have occurred several times independently during Angiosperm evolution. While zygomorphy has evolved recurrently among core eudicots and monocots, it has appeared quite rarely among basal angiosperms and basal eudicots. Among the latter, the Ranunculales are particularly noteworthy, since zygormorphy has evolved in several of its constituting families. We analyzed the evolution of selected floral traits potentially related to symmetry in the Ranunculales, and showed that the evolution of symmetry appears disconnected from changes in merism and stamen number, although zygomorphy has never evolved in the context of an open ground-plan. Our results allowed us to propose an evolutionary scenario for the Papaveraceae.
In the model species Antirrhinum majus (Asterids), a key gene for zygomorphy is CYCLOIDEA (CYC), which belongs to the class II TCP gene family encoding transcriptional activators. Genes homologous to CYC have probably played a role in the emergence of zygomorphy in Rosids, as recently demonstrated in Lotus japonicus. We characterized CYC–like genes in Papaveraceae and examined their potential recruitement in floral development and symmetry in this family. We showed that CYC-like genes have undergone a duplication which is independent from those that have taken place in core eudicots, and that both paralogous lineages (PapaCyL1 and PapaCyL2) are closest to the Arabidopsis AtTCP18 gene. Semi-quantitative RT-PCR and in situ hybridization approaches in three species with different floral symmetry indicate that both PAPACYL paralogues are expressed during floral development. A pattern common to all the three species is observed at organ junctions in flower and inflorescence. Expression in the outer petals is specifically observed in the two species with non-actinomorphic flowers. Hypotheses concerning the ancestral pattern of expression and function of CYC-like genes, and their possible role in floral development of Papaveraceae species leading to bisymmetric buds will be presented.
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1 - Centre National de la Recherche Scientifique, UMR Genetique Vegetale, Ferme du Moulon, Gif-sur-Yvette, 91190, France
2 - Université Paris Sud, Institut de Biotechnologie des Plantes, Université Paris Sud, Orsay, 91405, France
3 - Ecologie, Systematique Et Evolution, Batiment 360, Orsay, F-91405, France
Presentation Type: Symposium or Colloquium Presentation
Location: Stevens 2/Hilton
Date: Wednesday, July 11th, 2007
Time: 1:45 PM