Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Khojayori, Farahnoz [1], Zhang, Jingbo [1], Kramer, Elena [2], Davis, Charles C. [3], Zhang, Wenheng [4].

Divergence of CYC2-like genes correlates with reversal to floral actinomorphy in Brachylophon curtisii Oliver (Malpighiaceae).

Recent studies indicate that CYCLOIDEA2- (CYC2-) like genes have likely played an important role in the evolution of floral symmetry in the tropical family Malpighiaceae. Two copies of CYC2, CYC2A and CYC2B, arose as a result of gene duplication in the common ancestor of the family. Those genes are differentially expressed among New World (NW) species exhibiting the typical floral zygomorphy: CYC2A is expressed in the dorsal banner petal and adjacent lateral petals; CYC2B, in contrast, is restricted to the dorsal banner petal. One Old World (OW) lineage, the acridocarpoids, has lost the association with the mutualist oil bee pollinators thought to be necessary for maintaining the typical NW floral morphology. The acridocarpoids thus represent a particularly interesting clade for investigating changes leading to the loss of the broadly conserved floral features characterized by NW members of the family. The acridocarpoids comprise two genera, each displaying divergent and different morphologies. The floral zygomorphy of Acridocarpus, mostly from Africa and Madagascar, consists of two prominent dorsal petals, two lateral petals and one ventral petal; the flowers of Brachylophon, which occurs in Asia, are actinomorphic. We previously demonstrated in Acridocarpus that CYC2B has likely been lost, and that CYC2A expression shifted to the two dorsal petals and two lateral petals coinciding with a shift in its floral morphology. Here, we report on the first investigations of Brachylophon. Our preliminary results suggest that sequence evolution of the CYC2 homologs may have diverged in conjunction with the reversal to actinomorphy in B. curtisii. To illustrate the evolutionary trajectory of CYC2 in biogeographically isolated acridocarpoids between Africa and Asia, further tests of gene expression will be needed to determine whether regulation of CYC2A also changed in B. curtisii.

1 - Virginia Commonwealth University, Biology, 1000 West Cary Street, Richmond, Virginia, 23284, United States
2 - Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138, USA
3 - Harvard University Herbaria, 22 Divinity Ave, Cambridge, MA, 02138
4 - Virginia Commonwealth University, Biology, 1000 West Cary Street, Richmond, VA, 23284, USA

Keywords:
Brachylophon
Malpighiaceae
Reversal
floral evolution
CYCLOIDEA2
Actinomorphy.

Presentation Type: Oral Paper
Session: 2, Evolution and Development
Location: 200/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 8:45 AM
Number: 2004
Abstract ID:669
Candidate for Awards:Katherine Esau Award