Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Boyden, Geraldine S. [1], Donoghue, Michael J. [2], Howarth, Dianella G. [1].

Duplications in the floral symmetry gene RADIALIS in Dipsacales and Pentapetalae are similar to those of other floral transcription factors.

The greatest diversity of angiosperm species and floral form is found in the Pentapetalae clade. This diversity, however, is superimposed on a basic conserved ground plan, which resulted from a shift from the dimerous flowers with spiral phyllotaxy of “basal” eudicot lineages to pentamerous flowers with whorled floral phyllotaxy. The switch to pentamery entails the differentiation of dorsal and ventral portions of the flower in relation to the axis. The shift to clearly demarcated floral whorls involves the function of the members of the ABCE model of MADS-box genes. It is possible, therefore, that the shift in floral morphology that marks the Pentapetalae clade is at least in part the result of the subfunctionalization and neofunctionalization (following the duplication) of genes from three separate transcription factor gene families (MADS-box, TCP, and MYB) that are of known importance in flower development. Members of all four MADS-box classes and two floral symmetry genes lineages (CYCLOIDEA and DIVARICATA) duplicated near the divergence of the Pentapetalae and additionally duplicated in each of these paralogous lineages in different Dipsacales clades. We discuss our findings from the third known floral symmetry gene lineages, the MYB gene RADIALIS in Dipsacales and the placement of their duplications in the phylogenetic context of the Pentapetalae. The RAD-like genes fall into a small clade of the I-box-like subfamily of MYB genes, which are a different subgroup than the R-R-type MYB genes, which include DIV. It appears from our data that RAD-like genes may contain three eudicot clades, with at least one duplication near the divergence of the Pentapetalae paralogs. There are additional duplications within Dipsacales as well. These data will provide the necessary backbone for other researchers to clearly determine the orthology of their genes of interest. This data set compliments the phylogenies from MADS-box and floral symmetry genes, adding to our understanding of the floral symmetry pathway, and helping us uncover the floral ground plan patterning of the Pentapetalae.

Broader Impacts:

1 - St. John's University, Biological Sciences, 8000 Utopia Parkway, SAH RM 257, Jamaica, NY, 11439, USA
2 - Yale University, Department Ecology & Evolutionary Biology, Po Box 208105, New Haven, Connecticut, 06520-8105, USA

Keywords:
RADIALIS
Dipsacales
Pentapetalae
Flower symmetry genes 
gene duplication.

Presentation Type: Oral Paper:Papers for Topics
Session: 5
Location: 554A/Convention Center
Date: Monday, August 2nd, 2010
Time: 11:00 AM
Number: 5010
Abstract ID:725