FUNGAL GEL TISSUE ONTOGENESIS

Conspicuous gelatinous tissues, consisting of gel and hyphae, occur in fungi in the discomycete subfamilies Ombrophiloideae and Leotioideae and in the basidiomycete order Tremellales. The origin and subsequent development of gelatinous tissues in representative species were investigated. Fungal gels may be selectively stained with the mucin stain, mucicarmine, and metachromatically with toluidine blue.. Gel was found to arise in 2 fundamentally different ways, by hyphal disintegration and by direct secretion of mucilage from the protoplasm. With hyphal disintegration a swelling of the hyphal walls may precede the formation of the gel, as occurs in the conidiophores of Coryne cylichnium, or the hyphae may disintegrate directly to form the gel, as occurs in the basidiocarp of Pseudohydnum gelatinosum. Mucilage secretion occurs in the discomycetes Bulgaria inquinans, Coryne cylichnium, Corynella sp., Cudonia lutea, Holwaya leptosperma, Leotia viscosa, Neobulgaria pura, and Neobulgaria sp. Mucilage is secreted directly from the hyphae, except in the imperfect stage of H. leptosperma in which specialized secretory cells occur. Deeply staining material aggregates in the hypha or cell and is then extruded through small pores in the walls. A subsequent change in viscosity occurs and the mucilage becomes gelatinous. If produced in small amounts, the gel ensheaths the hyphae and collects in the interhyphal spaces in a locsely organized tissue, or forms interstitial gel in a compactly organized tissu.e. If gel is produced in largc amounts it will form a continuous gel matrix regardless of the tissue type. Sites of unusually heavy gel production (here termed "gliatopes") may be formed in either rapidly developing or confined tissue. Both rnuci]age secretion and hyphal disintegration to form gel occur in the cupulate coremium of the imperfect stage of C. cylichniuni. PLANT MLTCILAGES are normal products of metabolism which may swell in water to form gels. Mucilages occur widely in higher plants, fungi, and algae. Among the Fungi, mucilages have been detected in representatives of every class (Quillet, 1942). Perhaps the most conspicuous fungal mucilages occur as highly organized gelatinous tissues in apothecia of members of the Ombrophiloideae and Leotioideae of the Helotiales, in Urnula and Sarcosoma of the Pezizales, and in the basidiocarps of the jelly fungi. Fungal gels have been studied little, although there is an extensive literature on the niucilages of higher plants. The role of gel tissues in fungi is unknown, but they have been believed to serve as a water reservoir (Lagerheimn, 1903; Kavina, 1929; Wolf, 1958; Ingold, 1959). Wilson (1948) detected a gelatinous maaterial in the exudate from certain polyporaceous fungi. Farly work on identification and composition of fungus mucilages was based largely on extraction of a gelatinous precipitate or on histochemical I Received for publication July 20, 1964. A portion of a thesis submitted to the Graduate School of Cornell University in partial completion of the requirements for the Ph.D. degree. The author is indebted to Prof. Riehard P. Korf who supervised this work, and to Mr. Howard H. Lyon for the photography. 2Present address: Department of Biology, Monmouth College, West Long Branch, New Jersey. color reactions. Fungus species which have no conspicuous gel were frequently utilized for these studies (Mangin, 1893, 1894, 1899, 1910; Tanret, 1910; Thomas, 1930). Mangin (1890, 1893, 1894) canie to the conclusion that the gel of Bulgaria inquinans (as B. polymnorpha) is of a pectic cornposition. Preliminary biochemical analyses of Phallus inpudicus were made by Colin and Quillet (1931, 1932). Quillet (1942) later made detailed biochemical analyses of the constituents of the nmucilages of Auricularia mesenterica, Tremella mesenterica, and P. impuidicus (as Ithyphallus impudicus). These mucilages consist principally of uronic acids (manno-arabino-uronic, tetramannuronic, and polyglucuronic acids respectively). The uronic acid nucleus is also typically present in the mucilages and gums of higher plants (Norman, 1937; Gill et al., 1946; Laidlaw and Percival, 1949; Percival and Wilcox, 1949; Hough et al., 1950; Hirst, 1951, 1958; Hirst et al., 1951; Rao and Beri, 1951; Joshi and Tewari, 1957), and also in certain algal mucilages (Norman, 1937; Tseng, 1945; Araki, 1958; Nakamnura, 1958a, b). Ulrich (1943) has published a review of fungal membrane constituents, including mucilages. Cytological studies have been conducted by Whelden (1934, 1935a, b, 1937) on various jelly fungi, but he did not discuss the gel in his work. Moore and McAlear (1963) described Golgi