Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Zhang, Jingbo [1], Cappellari-Rabeling, Simone  [2], Kramer, Elena [3], Davis, Charles [4], Zhang, Wenheng [5].

CYC2 genes and the reversal from floral zygomorphy to actinomorphy in Stigmaphyllon A. Juss. (Malpighiaceae).

The flowers of New World (NW) Malpighiaceae are zygomorphic and possess a single, distinctive banner petal and oil glands on their sepals. This suite of traits has been shown to be important for their mutualism with oil-collecting bees. This plant-pollinator mutualism has been lost nine times principally among the Old World (OW) species, which occur where the NW oil bee pollinators are absent. One such loss occurred among the OW species in the predominantly NW genus Stigmaphyllon. Instead of the standard NW flower, these Australasian species possess actinomorphic flowers with eglandular sepals. To investigate floral morphological evolution in Stigmaphyllon we explored CYCLOIDEA2 (CYC2)-like genes, which we previously showed to play a key role in the evolution of floral symmetry in Malpighiaceae. Here, we cloned CYC2-like genes from a NW and OW species of Stigmaphyllon, S. ellipticum (Kunth) A. Juss. and S. grandifolium (Guillaumin) C. E. Anderson, respectively. The CYC2A and CYC2 B paralogs, which were previously identified in most Malpighiaceae, were isolated. We further identified conserved patterns of CYC2 expression consistent with NW Malpighiaceae in NW Stigmaphyllon. Thus, CYC2A is expressed broadly in the dorsal region of the flower while CYC2B is expressed principally in the banner petal. In contrast, this conserved NW pattern is relaxed in OW Stigmaphyllon. Specifically, the expression of CYC2A and CYC2B is expanded to a broader region with an asymmetrical pattern that is not correlated with the actinomorphic corolla in this OW species. This pattern of asymmetrical expansion raises the hypothesis that downstream regulators of CYC2 have experienced a loss of function such that CYC2 expression is no longer constrained and varies in a manner that is not consistent with morphology.

1 - Department Of Biology, Virginia Commonwealth University, 1000 West Cary Street, Life Science Building 336, Richmond, VA, 23284, United States
2 - Arizona State University, Social Insect Research Group, School of Life Sciences, 427 E Tyler Mall, Tempe, AZ, 85281, USA
3 - Harvard University, Organismic and Evolutionary Biology, 16 Divinity Avenue, Biological Laboratories 1119, Cambridge, MA, 02138, USA
4 - Harvard University Herbaria, Organismic and Evolutionary Biology, 22 Divinity Avenue, Cambridge, Massachusetts, 02138, United States
5 - Virginia Commonwealth University, Department Of Biology, 1000 W Cary Street, Richmond, VA, 23284, United States

Keywords:
CYC2-like genes
development
Floral evolution
floral symmetry
Malpighiaceae
Stigmaphyllon
subg. Ryssopterys
evolutionary reversal.

Presentation Type: Poster
Session: P, Evolutionary Developmental Biology (Evo-Devo)
Location: Grand Ballroom - Exhibit Hall/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PEV005
Abstract ID:826
Candidate for Awards:None