Abstract Detail

Recent Topics Posters

Offenheiser, Rachel A [1], Wilcox, Lee W [2], COOK , MARTHA E [3].

Seta development in Coleochaete pulvinata (Streptophyta).

One of the lineages of green algae most closely related to plants is the Coleochaetales, whose members are defined by complex setae (hairs) that are ensheathed at their base by a collar. Because these organisms share common ancestry with plants, elucidating their cell structure may lead to a greater understanding of the evolution of plant cell characters. Previously we reported (Rockwell MS thesis 2015) that the seta collar of Coleochaete is composed of a basal region and a distal region which are composed of different materials. The basal region of the seta collar and the wall of the cell proper stain with calcofluor, while the distal collar does not. Here we report the development of these complex setae in Coleochaete pulvinata. In agreement with work on C. scutata (Wesley 1928, Marchant 1977), seta development begins with a hole in the cell wall, through which additional cell wall material protrudes, forming the collar base. Initially the collar base forms as a small bump that labels with calcofluor. A minute amount of callose, as revealed by aniline blue staining, is present at the tip of the newly formed collar base. The chloroplast spins beneath the base of the collar (Geitler 1961), even in the earliest stages of collar development. A small portion of the chloroplast extends into the collar base as described in C. scutata (McBride 1974, Marchant 1977). The hair begins to form within the collar base early in development. Both hair and collar base label with calcofluor. Regions of the hair also contain callose. The hair grows along with the collar, and both continue to lengthen. The distal collar extends to a length at least as long as, and usually a few times longer than, the collar base before the collar stops growing. The distal collar glows in polarized light when stained with methylene blue and expands when treated with base. Typically the top of the distal collar opens outward. The hair continues to grow well past the tip of the distal collar, and is surrounded by a layer of mucilage.

1 - Illinois State University, Biological Sciences, Campus Box 4120, Normal, IL, 61790-4120, USA
2 - University of Wisconsin-Madison, Department of Botany, 430 Lincoln Drive, Madison, WI, 53706-1381, USA
3 - Illinois State University, Department Of Biological Sciences, CAMPUS BOX 4120, NORMAL, IL, 61790-4120, USA

Keywords:
Coleochaete
seta
development
charophycean
Algae
Streptophyta.

Presentation Type: Recent Topics Poster
Session: P, Recent Topics Posters
Location: Exhibit Hall/Omni Hotel
Date: Monday, June 26th, 2017
Time: 5:30 PM
Number: PRT015
Abstract ID:762
Candidate for Awards:None