Histochemical observations on apothecia, permanently vegetative hyphae, and sclerotia of Pyronema domesticum with special reference to light

Abstract

The Discomycete, Pyronema domesticum (Sow. ex Gray) Saccardo was cultured on an inorganic salts medium, as well as on potato dextrose agar (PDA), and exposed to different light regimens. Permanently vegetative hyphae were obtained on PDA cultures illuminated with cycles of 12 h light: 12 h darkness, while abnormal confluent padlike apothecia were formed on PDA in constant light and sclerotia were formed in PDA cultures that were incubated in the dark. Apothecia were formed on the inorganic salts medium and exposed to different light regimens that favored either overall apothecial development or primarily favored development of the ascogenous or sterile system. Histochemical tests were conducted on permanently vegetative hyphae, sclerotia, and apothecia to localize glycogen, carbohydrates, mucilage, protein, DNA, RNA, lipids, and carotenes. Exposure to light stimulated synthesis of DNA, lipid, glycogen, and other carbohydrates. Favorable development of morphologically normal ascogenous hyphae and asci was positively correlated with moderate to high levels of DNA, RNA, protein, and PAS-positive substances (excluding glycogen). Conversely, favorable development of the morphologically normal sterile system was not positively correlated with higher levels of any components, but excessive accumulation of glycogen was associated with its unfavorable, limited development. Massive accumulations of protein, phospholipids, DNA, glycogen, mucilage, and other carbohydrates were observed in the nonsporulating asci in cultures maintained in the dark for 4 days before being exposed to constant light, or in the permanently vegetative hyphae.

Growth and morphological characteristics of some pyrophilous discomycetes in culture

“…In general, the above-mentioned species, except Pyronema, were poorly studied. Despite the availability of data on the growth of such an important fungus for mycology as P. domesticum in culture (Moore, 1963;Moore & Korf, 1963;Roxon & Batra, 1973), studies of the influence of various factors such as cultural conditions (Moore-Landecker, 1975), culture age and a single photoperiod (Moore-Landecker, 1979b), light regimens and intensities (Moore-Landecker, 1979a;Moore-Landecker, 1981;Moore-Landecker, 1987), ultraviolet, radiation and inhibitory volatile substances (Moore-Landecker, 1984), aeration (Moore-Landecker & Shropshire, 1982), medium composition (Moore-Landecker, 1987) on apothecial and sclerotia morphogenesis in P. domesticum, the lack of modern information should be noted. Besides, there are limitations due to the short period of vegetation of fruit bodies and the fact that they are ephemeral.…”

“…Fuckel (Seaver, 1909;Robinson, 1926), P. domesticum (Sowerby) Sacc. (Moore, 1963;Roxon & Batra, 1973;Moore-Landecker, 1981), Anthracobia melaloma (Alb. & Schwein.)…”