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Pteridological Section/AFS

Rebert, April [1], DeVol, Joe [1], Dietrich, Margaret [1], Greer, Gary [1].

Blocking the Gibberillin Pathway Inhibits Morphological Development of the Gametophyte of the Fern Osmunda regalis.

An important milestone in fern gametophyte development occurs when a gametophyte transitions from a paddle-shape to a heart-shape and production of archegonia is initiated.  Production and insensitivity of antheridiogen also occurs at this time.  Antheridiogen is a gibberellin-based compound that induces precocious maleness in neighboring gametophytes, a mechanism promoting outcrossing.  Gibberellins are a group of hormones found in all vascular plants that induce cell division and elongation and, in many species, influence gender expression.  To investigate the role of gibberellin-class compounds in gametophyte development, we blocked synthesis of the gibberellin precursor ent-kaurene using Apogee®.  Spores from the royal fern, Osumunda regalis, were grown on basal nutrient media (control) and media with 1nM, 1µM, and 1mM concentrations of Apogee®;.  After five weeks, gametophytes were mounted on semi-permanent slides, gametangia counted, and whole gametophyte images digitally captured.  We analyzed each image for size, sphericity and notch-depth: length ratio.  Size, notch depth: length ratio, and number of archegonia corrected for notch depth: length ratio (an indicator of onset or rate of notch-meristem development) were reduced with increasing concentration of Apogee®.  Sphericity and number of antheridia corrected for size were not significantly affected.  Our results indicate that interruption of biosynthesis of the gibberellin class of compounds delays onset of notch formation and/or the rate of notch development and retards production of archegonia.  These observations are consistent with: (1) the hypothesis that the gibberellin class of compounds stimulates notch-formation by increasing the rate of anticlinal division in the meristem, and (2) the hormone-pheromone hypothesis that antheridiogen is a hormone involved in notch formation as well as a gender influencing pheromone.

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1 - Grand Valley State University, Biology Department, 1 Campus Drive, Allendale, Michigan, 49401, USA

Osmunda regalis
Gametophyte development
Gibberellin biosynthesis.

Presentation Type: Poster
Session: 33-73
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM
Abstract ID:154

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