Morphogenetic Studies on the Fern Todea Barbara. Iii. Experimental Embryology

Abstract

DeMaggio, Augustus E. (Rutgers · The State U., Coll. of Pharmacy, Newark, N. J.), and Ralph H. Wetmore. Morphogenetic studies on the fern Todea barbara. III. Experimental embryology. Amer. Jour. Bot. 48(7): 551–565. Illus. 1961.—A study of the various stages in the life history of the fern Todea barbara (L.) Moore has shown that young embryos can be removed from the surrounding prothallial tissue, within which they normally develop, and successfully grown in culture. It was possible, therefore, to investigate the manner in which the embryo develops when it is freed from the restraint of surrounding cells. Embryos excised 20 days after fertilization could be grown to mature sporophytes in a liquid culture containing mineral salts and sugar. Younger embryos, excised 17 days after fertilization, required the addition of whole coconut milk or a mixture of sorbitol and inositol, components of the “neutral” fraction of coconut milk, to complete their development. Embryos excised prior to the appearance of the first division wall, 4–5 days after fertilization, did not develop into the usual, 3‐dimensional, diploid or sporophytic plant. Instead they become irregular, rather 2‐dimensional, thalloid structures, remarkably similar to the early haploid or gametophytic plant. These findings are considered in relation to the environmental conditions of growth with particular reference to nutritional and physical factors.

Sugar Alcohols (Polyols) in Fungi and Green Plants

“…Its presence here suggests its function as a nutrient for embryo development, but polyols have rarely proved very effective in embryo culture. It is nevertheless of interest that, for young embryos of the fern, Todea barbara, which, of course, do not rely on endospermous nutrition, a mixture of sorbitol and inositol could substitute for whole coconut milk as a medium for completion of their development when excised (DeMaggio and Wetmore, 1961). The role of sorhitol as an active component of the neutral fraction of coconut milk may depend on its function as a hydrogen source for reductive events.…”

SCANNING ELECTRON MICROSCOPIC OBSERVATIONS ON THE GAMETOPHYTE AND SPERM OF THE BRACKEN FERN, PTERIDIUM AQUILINUM (L.) KUHN

“…i and 2) and in some previous studies on axenically cultured fern gametophytes these structures were formed primarily on the upper surface (DeMaggio, 1961;Miller, 1968). Aside from the rhizoids, the most conspicuous feature observed on the mature cordate protlialli were the necks of archegonia protruding above the surface.…”

Embryology of Ceratopteris richardii (Pteridaceae, tribe Ceratopterideae), with emphasis on placental development

“…This supports experiments on normally prone embryos where root development was inhibited. Presumably, foot size increased to compensate for the absence of a leaf-root system (Ward and Wetmore 1954;Jayasekera and Bell 1959;DeMaggio and Wetmore 1961).…”

“…The first leaf and primary root develop early from outer octants in C. richardii as in other prone species (Leitgeb 1880;Campbell 1895;Conard 1908, Vladesco 1935Ward and Wetmore 1954;DeMaggio 1961). Early RAM-leaf axis perhaps ensures adequate water and nutrient absorption to facilitate photosynthesis to fuel late embryogenesis and SAM proliferation.…”

“…A second series of divisions in each quadrant produces octant cells in two tiers of four cells. While the order of divisions is not constant, the formation of octants is conserved in leptosporangiate ferns (Vladesco 1935;Wardlaw 1955;DeMaggio 1961). These early divisions may partition long-lived parental mRNAs since embryonic transcription is undetectable until the octant stage (Kuligowski et al 1991).…”