PARENT SESSION
Tuesday, August 8, 5:00-6:30 pm
Poster Session 10 - Genetics, evolution, and paleoecology
Exhibit Hall, Ballroom Level, Cook Convention Center

The regulation of gender expression in Ceratopteris richardii gametophytes.

Hamilton, Robert¹, Ainsworth, Adam ^*,1, ¹ Mississippi College, Clinton, MS

ABSTRACT- Gender expression in free sporing plants occurs in the independent sporophyte generation. Some leptosporangiate fern species, such as Ceratopteris richardii, produce two kinds of gametophytes; large meristic hermaphrodites and small ameristic males. In vitro studies have indicated that single-spore cultures result large hermaphrodites. Small males only occur in mulispore cultures. The pheromone antheridiogen is known to induce the small ameristic male phenotype in C. richardii gametophytes. We investigated the effect of competition for nutrients on gender expression and the timing of the appearance of morphological changes associated with the antheridiogen response. Competition for nutrients had a negligible effect on gender expression in our experiment. Morphological changes associated with the antheridiogen response were apparent upon the emergence of a two-dimensional gametophyte from the spore wall. If the antheridiogen response is affected by competition for nutrients, it had only a marginal effect on our results. The appearance of a size dimorphism that is associated with the antheridiogen response in the earliest stages of gametophyte culture suggests that the factors that trigger the antheridiogen response begin to affect gametophyte development at the earliest stages.

Key words: Antheridiogen, Gender regulation, Fern