Gametophyte and sporophyte of tree ferns in vitro culture

Abstract

Experiments had been carried out on gametophytes and very young fronds of sporophytes with application of Murashige and Skoog (1962) medium. The paper described the results of 15 years in vitro experiments on 16 species of tree ferns belonging to various genera: <em>Blechnum</em>, <em>Cibotium</em>, <em>Cyathea</em> and <em>Dicksonia</em>. Genus <em>Cyathea</em> was represented by: <em>C. australis</em> (R.Br.) Domin., <em>C. capensis</em> (L.f.) Sm., <em>C. cooperi</em> (F.Muell.) Domin, <em>C. brownii</em> Domin, <em>C. dealbata</em> (G.Forest) Sw., <em>C. dregei</em> Kunze, <em>C. leichhardtiana</em> (F.Muell.) Copel., <em>C. robertsiana</em> (F.Muell.) Domin., <em>C. schanschin</em> Mart., <em>C. smithii</em> Hook.f. and <em>Cyathea</em> sp. In case of genus <em>Dicksonia</em> only two species were introduced into our experiments: <em>D. fibrosa</em> Colenso and <em>D. sellowiana</em> Hook.. Taxa <em>Blechnum</em> was presented by <em>B. brasiliense</em> Desv. and <em>Cibotium</em> by <em>C. glaucum</em> (Sm.) Hook. and Arn. and <em>C. schiedei</em> Schltdl. and Cham.. The studied species presented various responses on culture conditions depending on the level of stage of development. Time required for spores germination differed between species and took from only a few to 16 weeks. Prothalium formations showed various types of growth presented by marginal meristems. For all investigated species long term gametophyte in vitro cultures was established. Mature gametophyte possessed functional antheridia and archegonia. Spontaneous fertilization helped to establish the culture of young sporophytes. For all species the ex vitro culture in greenhouse collection was established. Manipulation of sucrose content in the medium stimulated the multiplication of gametophytes, but its lack induced formation of gemmae. Apospory was observed when culture of very young fronds was extended for 6 months and new generation of gametophytes was developed. Finally, sporophytes of 12 species were obtained and they have been growing in our greenhouse.