Specificity of the Antheridogen from Ceratopteris thalictroides (L.) Brongn

Characteristics of the fern antheridogen from Ceratopteris thalictroides (L.) Brongn. are investigated. These are: (a) determination of molecular size (it is readily dialyzable), (b) pK_a (about 5), (c) movement in thin layer chromatography, and (d) ability to induce dark germination of fern spores. These four characteristics are compared to the same characteristics of three other antheridogens (antheridogens A and B or GA). Molecular size and pK_a are similar, but, the antheridogens are separable from each other using thin layer chromatography. It was also shown that spore germination is not induced by the Ceratopteris antheridogen, even in its own spores, a characteristic not reported as shared by the other antheridogens. However, the inconsistency of spore germination as an assay for antheridogen is demonstrated. The presence of gametophyte-produced allelopathic substances is also shown.