Some ultrastructural features ofRhodosporidium toruloides Banno

Abstract

1972. Some ultrastructural features of Rhodosporidium toruloides Banno. Antonie van Leeuwenhoek 38: 417-435.A 21-day subculture of Rhodosporidium toruloides Banno produced septate mycelium with hook-shaped cells over many septa. In the light microscope these hook-shaped cells appeared to be clamp connections; this feature might suggest that R. toruloides belongs to the basidiomycetes. Electron micrographs, however, demonstrated that the hyphal septum above which the hook cell occurred and the back septum of the hook cell were tapered centripetally, contained a pore in the middle, and were typical of the ascomycete septum. Two electropaque bodies, believed to be similar to Woronin bodies, were observed occluding the pore in one hyphal septum above which was a hook cell.Melanospores in the 21-day subculture were produced terminally on hyphae and laterally above hook cells which occurred over ascomycete-type septa. Proliferating hook ceils appeared similar to repeating croziers found in the ascomycetes.The walls of hyphal cells from the 21-day subculture demonstrated lenticular bodies and alternating electrolucent and electropaque lamellae. The walls of 12-hr dividing yeast cells were observed to be similarly lamellate, a characteristic which has been reported typical of heterobasidiomycetous yeasts.Since R. toruloides exhibited ascomycetous and basidiomycetous features, a reconsideration of its present classification is suggested.The Rhodosporidium observations are a portion of a thesis submitted by JAJ-R in partial fulfillment of the requirements for the Master of Science degree, North Carolina State University. and to whom grateful acknowledgment is made for use of photographic facilities.

Ustomycota, a new division of higher fungi

“…And although generally simple, these septa lack ascomycetous Woronin bodies and the pores are very small. (In Rhodosporidium toruloides, Johnson-Reid and Moore, 1972 did show an instance of paired granules associated with the pore, but these were neither membrane-bound nor crystalline.) The available micrograpbs suggest that, on the one hand, there may be a difference between those septa of Leucosporidium scottii (Fig.…”

“…3), Rhodosporidium sphaerocarpum (Fig. 4), R. toruloides (Johnson-Reid and Moore, 1972), Sporidiobolus johnsonii (Fig. 5), and S. ruinenii (Kreger-van Rij and Veenhuis, 1971a) and those, on the other hand, of the smuts (Figs.…”

“…3) and Rhodosporidium sphaerocarpum (Fig. 4) there is a very small central pore and the pore lip is acute; the septa of R. toruloides (Johnson-Reid and Moore, 1972), Sporidiobohls johnsonii (Fig. 5), and S.ruhTenii (Kreger-van Rij and Veenhuis, 1971a) are comparable.…”

“…At the light-microscope level the smut or brand spore is not satisfactorily a chlamydospore or a teliospore and its germination does not result in basidiospores. At the electron-microscope level it has been shown that while these fungi display layering in the walls (Kreger-van Rij and Veenhuis, 1971a), the septa of Rhodosporidium toruloides (Johnson-Reid and Moore, 1972) and Sporidiobohls ruhwnii (Kreger-van Rij and Veenhuis, 1971a) have a simple pore that lacks dolipores and parenthesomes. The present investigation examines the ultrastructure of a number of these fungi.…”

“…Budding. Kreger-van Rij and Veenhuis (1971a) observed that in those yeasts (Johnson-Reid and Moore, 1972) Entoloma nymphaeae, Graphiola phoenicis (Fig. 19), Spacelotheea destruens, and Ustilago maydis (Fig.…”