Abstract Detail

Systematics Section/ASPT

Ickert-Bond, Stefanie [1], Gerrath, Jean [2], Wen, Jun [3].

Gynoecial structure of Vitales and implications for the evolution of placentation in the rosids.

A survey of gynoecial structure is undertaken within Vitales (the economically important Vitaceae and its sister family Leeaceae) and they are interpreted in light of phylogenetic comparison of placentation types among all angiosperms. Gynoecial structure and architecture in 21 species were studied with light and scanning electron microscopy. Ancestral character reconstruction of gynoecia with axile, parietal, basal, apical, free-central, marginal, or laminar placentae across 640 genera representing all 58 orders of angiosperms was inferred using maximum likelihood to help interpret the evolution of the gynoecium in the Vitales. The syncarpous ovary is bicarpellate in Vitaceae and tricarpellate in Leeaceae; in both the carpels are congenitally fused to form the synascidiate zone. Placentae are located basally on the septum with generally two ovules per carpel. Distally, septa are incomplete, resulting in the ovary being incompletely bilocular in Vitaceae and incompletely trilocular in Leeaceae. Further morphological variations are a result of differential growth of the septa.  In some species of Cyphostemma septa are further reduced and the ovary is clearly unilocular. Ancestral character reconstruction using maximum likelihood across 640 angiosperm taxa infers marginal placentation to be the ancestral condition, while that of the Superrosidae is axile, with basal placentation inferred to be derived within the clade. Placentation state in Vitaceae and Leeaceae with apically incompletely septate gynoecia and basally septate gynoecia is also found in 30 other angiosperm families based on a detailed literature review. These results underscore the labile nature of placentation despite its long use as a character of taxonomic significance. Axile placentation, combined with basally inserted ovules and incompletely septate ovaries, sets the Vitaceae apart from other basal rosids. Uncovering the unique features of a subtle character such as placentation development in a family with such small flowers is difficult, and it may well be that other novel vitaceous characters await discovery. In addition to understanding how some of them may have arisen within a phylogenetic context, these features may also explain the widespread distribution and success of the Vitaceae in both tropical and temperate ecosystems.

1 - University Of Alaska Museum Of The North, Herbarium (ALA) And Dept. Of Biology And Wildlife, University Of Alaska Fairbanks, 907 Yukon Dr., Fairbanks, AK, 99775, USA
2 - University of Guelph, Department of Molecular and Cell Biology, Guelph, ON, N1G 2W1, Canada
3 - Smithsonian Institution, Botany, MRC-166 National Museum Of Natural History, 10th St. & Constitution Ave., NW, MRC 166, Washington/DC, N/A, 20013-7012, USA

Keywords:
Vitaceae
Leeaceae
gynoecial structure
placentation
Superrosidae.

Presentation Type: Oral Paper:Papers for Sections
Session: 44
Location: Firs North/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 2:30 PM
Number: 44005
Abstract ID:235
Candidate for Awards:None