The gynoecium is the female reproductive structure of angiosperm flowers. In Arabidopsis thaliana the gynoecium is composed of two carpels that are fused into a tube-like structure. As the gynoecial primordium arises from the floral meristem, a specialized meristematic structure, the carpel margin meristem (CMM), develops from portions of the medial gynoecial domain. The CMM is critical for reproductive competence because it gives rise to the ovules, the precursors of the seeds. Here we report a functional role for the transcription factor PERIANTHIA (PAN) in the development of the gynoecial medial domain and the formation of ovule primordia. This function of PAN is revealed in pan aintegumenta (ant) as well as seuss (seu) pan double mutants that form reduced numbers of ovules. Previously, PAN was identified as a regulator of perianth organ number and as a direct activator of AGAMOUS (AG) expression in floral whorl four. However, the seu pan double mutants display enhanced ectopic AG expression in developing sepals and the partial transformation of sepals to petals indicating a novel role for PAN in the repression of AG in floral whorl one. These results indicate that PAN functions as an activator or repressor of AG expression in a whorl-specific fashion. The seu pan double mutants also display enhanced floral indeterminacy, resulting in the formation of “fifth whorl” structures and disruption of WUSCHEL (WUS) expression patterns revealing a novel role for SEU in floral meristem termination.
Keywords: ovule, gynoecium, flowers, agamous, wuschel, organ identity, indeterminate growth
Citation: Wynn AN, Seaman AA, Jones AL and Franks RG (2014) Novel functional roles for PERIANTHIA and SEUSS during floral organ identity specification, floral meristem termination, and gynoecial development. Front. Plant Sci. 5:130. doi: 10.3389/fpls.2014.00130
Received: 09 January 2014; Paper pending published: 08 March 2014;
Accepted: 19 March 2014; Published online: 07 April 2014.
Edited by:Zhongchi Liu, University of Maryland, USA
Reviewed by:Mark Paul Running, University of Louisville, USA
Copyright © 2014 Wynn, Seaman, Jones and Franks. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Robert G. Franks, Department of Plant and Microbial Biology, North Carolina State University, 2548 Thomas Hall, Campus Box 7614, Raleigh, NC 27695-7614, USA e-mail: firstname.lastname@example.org