Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Di Stilio, Veronica S [1].

The ABC model of flower development in non-core eudicots: a functional synthesis from studies in the ranunculid Thalictrum thalictroides.

The elucidation of the “ABC model” of flower development in the 1990’s promised a mechanistic basis for J.W. Goethe’s intuitive idea that all floral organs must have arisen from a leaf bauplan. Yet the first attempts to induce floral organs from leaves by overexpression of B- or C-class genes failed to produce full conversion. The discovery of a fourth gene class, the E-class, filled this gap by elegantly demonstrating the recapitulation of floral organs in seedling leaves via overexpression of all four gene classes. The “extended” ABC model was complete and the ensuing floral quartet model clarified how these transcription factors, belonging mostly to the MADS-box gene family, interacted as tetramers while binding and looping DNA to turn on flower development cascades. As conserved as the ABC model appeared, first among the distinct model systems Arabidopsis thaliana and Antirrhinum majus, later in other eudicots and in monocots, much remained to be elucidated in light of mounting evidence for the importance of gene duplication in the evolution of development. Multiple duplication events affecting the MADS-box gene family and flower morphologies that diverged drastically from those described originally required modifications to the canonical model. As part of this evolutionary journey into the tinkering of the ABC model, be it via gene duplication, changing protein-protein interactions or changes in binding affinities and downstream targets, functional studies in a variety of plant groups began to emerge. In the past few years, my research group has functionally characterized all B, C and E class genes in Thalictrum thalictroides, a representative of the ranunculids (the sister lineage to the rest of the eudicots). Our work contributes to a broader effort to fill the gap in functional knowledge outside of the core eudicots in order to better understand the evolution of this important lineage of floral MADS-box genes. To that end we used Virus Induced gene Silencing, gene expression, protein-protein interactions and mutant analyses. Here, I attempt to summarize these efforts, highlighting particular cases of sub- and neo-functionalization, as well as redundancy, and ending with a proposed ABC model for this plant and its modifications in floral homeotic mutants.

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1 - University Of Washington, Department Of Biology, PO BOX 351800, SEATTLE, WA, 98115-1800, USA

Keywords:
evo-devo
flower development
ABC model
VIGS
non-core eudicots
ranunculid.

Presentation Type: Oral Paper
Session: 2, Evolution and Development
Location: 200/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 8:15 AM
Number: 2002
Abstract ID:826
Candidate for Awards:None