Effect of Light Quality and Light Intensity and Various Sugars on the Sexual Expression and Some Observations on the Red Pigment in Equisetum Gametophytes

John Joseph Thompson, University of Rhode Island


The purpose of this study were to explore what effect light quality and light intensity and various sugars have on the sexual expression of Equisetum gametophytes and to determine some characteristics of the red pigment in Equisetum gametophytes.

Light quality and light intensity were employed to seek the presence of a morphogenetic factor involved in the sexual expression of Equisetum gametophytes. The gametophytes were grown in mass culture in petri dishes and singly in test tubes under red light and white light or under high light intensity and low light intensity. Light quality was employed when the Equisetum species was Equisetum hyemale. When the species was Equisetum arvense, light intensity was employed. A higher percentage of antheridial gametophytes in mass culture in petri dishes than sinlgy in test tubes under either red light or high light intensity would indicate an interaction among the gametopphytes due to a diffusible substance and thus would indicate that light quality or light intensity was probably involved in a mechanism which activated a morphogenetic factor determining the sex of Equisetum gametophytes. In mass culture in petri dishes, the morphogenetic factor activated by either red light or light intensity would influence the sexual expression of other gametophytes in the same petri dish; whereas, singly in test tubes the gametophytes are isolated from each other so that any morphogenetic actor that is produced could not influence the sexual expression of the gametophytes. The factor would probably be some sort of diffusible substance comparable to the antheridogens of ferns. The results were ambiguous.

Mannitol, sucrose and glucose were added separately to Bold's basal medium to determine what effect these sugars have on the sexual expression of Equisetum gametophytes. The result were ambiguous.

The red pigment often associated with Equisetum antheridial production was isolated by column chromatography and some characteristics were determined using visible light spectrophotometry. It is definitely not rhodoxanthin, as reported, but could not be identified other than to be a carotenoid.

This study showed that Equisetum gametophytes are a difficult system with which to experiment. It seems the sensitivity of Equisetum spores to light quality and light intensity can vary.