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Abstract Detail



Phycological Section

Rockwell, Timothy [1], Wilcox, Lee [2], Cook, Martha [1].

Seta structure in the Coleochaetales (Streptophyta).

The Coleochaetales are among the closest relatives of land plants. A distinctive character among this clade of streptophyte green algae is the presense of a complex hair (seta) with a sheath that encompasses its base. Previous reports on the structure and growth of setae in Coleochaete scutata are in conflict, while the details of structure and growth of hairs in Chaetosphaeridium have not been reported. We are attempting to resolve the structure of sheathed hairs in these taxa. We have demonstrated with calcofluor staining that, in agreement with one report of hairs in Coleochaete scutata, the hairs of Coleochaete orbicularis, Coleochaete irregularis, and Chaetosphaeridium globosum are composed of cellulose, and grow from the base. Observations of chlorophyll autofluorescence in UV light demonstrated that in Chaetosphaeridium the single seta cell chloroplast may extend into the sheath of the seta as was shown for Coleochaete scutata by McBride. It was found with differential interference contrast optics that in Coleochaete orbicularis as well as in Coleochaete pulvinata the setae exhibit internal structures similar to those described by Marchant in Coleochaete scutata. These structures were not observed in setae of the most basal members of the Coleochaetales that we studied, Coleochaete irregularis and Chaetosphaeridium globosum. Understanding development in members of the Coleochaetales may lead to greater insight into the evolution of plant structure and growth from a common ancestor of plants and Coleochaetales.

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1 - Illinois State University, Biological Sciences, Campus Box 4120, Normal, IL, 61790-4120, USA
2 - University of Wisconsin-Madison, Botany, 430 Lincoln Drive, Madison, WI, 53706, USA

Keywords:
Chaetosphaeridium
Coleochaete
Algae
streptophyte
Development
Evolution
seta.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PPC006
Abstract ID:925
Candidate for Awards:None


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