Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Soza, Valerie L [1], Snelson, Corey [2], Di Stilio, Veronica S [3].

Functional Analysis of E-Class Genes in a Ranunculid.

Floral MADS-box genes have diversified extensively and contribute to the incredible floral diversity of angiosperms. E-class genes from the ABCE model of floral development include the SEPALLATA (SEP) genes. Four SEP genes have been identified in the model core eudicot Arabidopsis thaliana as being redundantly involved in the development of all four floral organs and in meristem determinacy. E-class genes have been examined in other core eudicots and monocots, but have yet to be investigated in non-core eudicots. Our goal was to clone and functionally characterize the E-class genes in the early diverging eudicot Thalictrum thalictroides (Ranunculaceae), which consists of sepals, stamens and carpels (petals have been lost in this genus). Using PCR-based cloning and a transcriptome, we identified three SEP orthologs in T. thalictroides (Tht), which we placed in a phylogenetic context with other E-class genes available from public databases. The Thalictrum genes resulted from a major gene duplication event before the origin of angiosperms (LOFSEP and SEP3 clades) and a subsequent duplication at the origin of the Ranunculales within the LOFSEP clade. We used virus induced gene silencing (VIGS) to knock down the three ThtSEP genes individually and in combination to understand their function in this species and to determine the degree of functional conservation versus divergence to the original model. The two LOFSEP orthologs appear to have subfunctionalized; ThtSEP-1 is required for stamen development whereas ThtSEP-2 is needed for sepal development. ThtSEP-3 (SEP3 clade) has partial redundancies with the other two ThtSEP genes; it is required for sepal, stamen, and carpel development in T. thalictroides. When all three ThtSEP genes are knocked down in T. thalictroides, we do not get the expected complete conversion of all floral organs to leaflike organs, indicating that another potential E-class gene may be required for floral development in this lineage of early eudicots. We are currently investigating the potential role of an additional candidate gene, an AGAMOUS-LIKE 6 (AGL6) ortholog, in E-class function in this ranunculid species.

1 - University Of Washington, Department Of Biology, BOX 351800, SEATTLE, WA, 98195-1800, USA
2 - University of Washington School of Public Health, Public Health Genetics, Box 353410, Seattle, WA, 98195-3410, USA
3 - University of Washington, Biology, Box 351800, Seattle, WA, 98195, USA

Keywords:
floral development
MADS-box genes
Ranunculaceae
SEPALLATA
Thalictrum
Virus Induced Gene Silencing.

Presentation Type: Oral Paper:Papers for Topics
Session: 41
Location: Payette/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 2:00 PM
Number: 41003
Abstract ID:489
Candidate for Awards:None