Short-circuiting the fern life cycle: apospory in Ceratopteris richardii
Sexual plant life cycles are typically characterized by a distinct alternation of generations. This involves the presence of two generations or phases within the life cycle, sporophytes and gametophytes. Alternation between the gametophyte and sporophyte involves a corresponding change in chromosome number, from n to 2n. Ceratopteris is a genus of homosporous ferns found in most tropical and subtropical areas of the world. In some environments Ceratopteris sporophytes can become an aggressive weed by clogging up freshwater streams and drainage systems. Like all homosporous ferns, Ceratopteris richardii has two independent, autotrophic phases: a developmentally simple haploid gametophyte and a vascular diploid sporophyte. Ceratopteris richardii gametophytes and sporophytes can be grown in a simple mineral nutrient medium. After sporophyte production, leaves harvested from sporophytes should be cultured on basic C-Fern medium supplemented with 10 μnM gibberellic acid (GA). GA should be added by sterile filtration after autoclaving.