Apospory in leaf culture of staghorn fern (Platycerium bifurcatum)

The induction, origin, morphology, and ploidy of aposporous gametophytes produced on juvenile leaves of the fern Platycerium bifurcatum (Cav.) C. Chr. were studied. Leaf explants were grown on modified Murashige and Skoog medium with 0%, 0.01%, 0.1%, 1%, or 2% sucrose. A low sucrose concentration (0.01%) and wounding of the adaxial side of the leaf significantly increased the induction of aposporous gametophytes (90% of leaves produced gametophytes). Regeneration began as a proliferation of mainly epidermal cells on both sides of the leaf; subsequent development was similar to that shown by gametophytes originating from spores. Flow cytometric analysis of sporophytes and aposporous gametophytes revealed that both forms had the same ploidy level. On the basis of these findings, we propose a set of conditions which regularly and reproducibly induces apospory on most of the leaf explants of the fern P. bifurcatum.