Abstract Detail

Development and Structure

Mustacchio, Theresa [1], Savriama, Yoland [2], Berger, Brent [3], Tong, Jingjing [1], Howarth, Dianella [4].

Knockdown of floral symmetry in Fedia graciliflora.

Shifts between radial symmetry (actinomorphy) and bilateral symmetry (zygomorphy) in flowers have occurred multiple times independently within angiosperms. These morphological shifts are commonly associated with increased pollinator specialization and speciation rates. Evidence from studies across angiosperms indicate that the CYCLOIDEA (CYC)-like genes play a role in patterning bilaterally symmetrical flowers. Three core eudicot clades of CYC-like genes have been identified: CYC1, CYC2 and CYC3, with CYC2-like genes being the most involved in dorsal specialization. To further investigate the CYC-like genes and the regulation of bilateral symmetry we used the non-model plant, Fedia graciliflora (Caprifoliaceae). Fedia species have strongly bilaterally symmetrical flowers with morphologically distinct dorsal (upper), lateral, and ventral (lower) petals and only two functional stamens. Fedia has evolved within the Valerianella, a group with pseudo-radially symmetric flowers with three functional stamen, providing a model for studying the evolution of strong bilateral symmetry. In this study, VIGS was used to study morphological differences in floral symmetry by knocking down each of these separately: FgCYC2A, FgCYC2B, FgCYC3A, and FgCYC3B. The down-regulated plants were assayed using geometric morphometrics combined with tools of multivariate statistical shape analysis to quantify shape changes, using a combination of landmarks and semilandmarks to trace the petal lobes. We analyze these data with canonical variate analysis (CVA) and show the overlapping effects of each gene copy. Our general findings indicate that CYC2 paralogs do not shift in the location of lateral and ventral petals, but the dorsal petals become more splayed out, this is most prominent in CYC2A. CYC2A knockdowns develop elongated ventral petals and wider lateral petals which are not as prominent in the CYC2B knockdowns. The CYC3 paralogs, on the other hand, do not shift their dorsal petal location, but their lateral petals become more splayed, this is the most prominent in CYC3B.

1 - St. John's University, Biological Sciences, 8000 Utopia Pkwy, Jamaica, NY, 11439, United States
2 - Max Planck Institute, Evolutionary Biology, August-Thienemann-Straße 2, Plön , 24306 , Germany
3 - St. John's University, 8000 Utopia Parkway, Queens, NY, 11439, United States
4 - St. John's University, Department Of Biological Sciences, St. Albert Hall Rm 257, 8000 Utopia Pkwy, Jamiaca, NY, 11439, United States

Keywords:
Cycloidea 
Geometric Morphometrics
EvoDevo
Floral Development
Floral morphology
Fedia graciliflora.

Presentation Type: Oral Paper
Number: DS1002
Abstract ID:223
Candidate for Awards:Katherine Esau Award,Maynard F. Moseley Award,Developmental and Structural Section Graduate Student Registration Award