Ascospore development in Ophiostoma piceae (original) (raw)
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Fine structure of ascosporogenesis in Ceratocystiopsis proteae
Canadian Journal of Botany, 1993
VAN WYK, P.W.J., and WINGFIELD, M.J. 1993. Fine structure of ascosporogenesis in Ceratocystiopsis proteae. Can. J . Bot. 71: 1212-1218. The development and ultrastructure of the ascoma, asci, and ascospores in Ceratocystiopsis proteae were studied and compared with that of other genera in Ceratocystis sensu lato. Ascospore delimitation commenced with the formation of double delimiting membranes in the ascus as is true in other species in Ceratocystis s.1. The ascospore wall developed between these membranes. In contrast with three wall layers observed in other species, only two wall layers were observed in C. proteae. Falcate sheaths previously reported in light-microscopic studies were not observed. The falcate appearance of ascospores may be ascribed to the adherence of a matrix to the outermost wall layer during ascospores release. Differences between this species and others in Ceratocystis s.1. illustrate the problems that can arise from the use of single morphological characteristics in the taxonomy of this group. It is accordingly suggested that the genus Ceratocystiopsis requires taxonomic revision.
Ultrastructure of developing ascospores in Sordaria brevicollis
Journal of Bacteriology, 1976
The ultrastructure of ascospore wall formation in the pyrenomycete Sordaria brevicollis was studied in developing asci at progressive time intervals. From early spore delimitation through final stage of maturation, the wall of the ascospore differentiated into four composite layers, the periascosporium the delineation ascosporium, the subascosproium, and the endoascosproium, While ascospores were at the hyaline stage of development,they possessed only the periascosporium and delineation ascosporium as their wall components. At about 7 to 8 days from the initiation of the cross, the spores developed a yellow color, and this coloration was always associated with the elaboration of the subascorsporium just internal to the ascosporium. Asthe spores continued to progressively darken in color, the subascosporium was seen to increase in complexity, electron density, and thickness. Soon after the formation of the subascosporium, the endoascosporium began to develop de novo and was, therefor...
Methods for observing, culturing, and studying living ascospores
2021
Ascospore morphologies provide important characters with which to diagnose and describe taxa in Ascomycota. Ascospore features such as size, shape, color, septation, wall thickness, and guttulation, among others, are provided in identification manuals and descriptions of new species. Yet, by tradition, ascospores are usually described from dead fungarium material, and unfortunately, occasionally from immature or overmature ones. However, living, mature ascospores display a wealth of taxonomically informative morphological features that are lost or obscured when they die. Examples of the severe morphological changes that ascospores undergo when they die are provided here. Data from living ascospores may not be observed and recorded by mycologists because field and laboratory practices do not prioritize the study of freshly collected specimens. In this review, we discuss how to assess ascospore maturity and describe methods to produce an ascospore deposit for the purpose of obtaining ...
ALGAE
Optical microscopy of recently living and cleared material of the fucoid, Ascophyllum nodosum (L.) Le Jolis, revealed novel aspects of its interaction with the ascomycete Mycophycias ascophylli (Cotton) Kohlmeyer and Kohlmeyer (previously Mycosphaerella ascophylli Cotton). Most host cells are associated with hyphae by lateral attachment of cell walls. Hyphae form extensive networks throughout the host thallus and show considerable differentiation in the various host tissues. In the base of epidermal cells, hyphae form multicellular rings around each host cell to produce a continuous network. In medullary regions, long, relatively unbranched and longitudinally aligned hyphae occur, with radial branches extending into cortical regions. Scattered in the inner cortex of host tissue are numerous multicellular nodes of smaller, polygonal to irregular shaped cells with five or more radiating arms of hyphae. Individual hyphal cells show a variety of specializations including swellings and appressoria-like attachments to some host cells. These observations provide the morphological basis for the mutualistic symbiosis supported by recent experimental work. We conclude that this association is best described by the term "symbiotum."
Ascoma development and phylogeny of an apothecioid dothideomycete, Catinella olivacea
American Journal of Botany, 2007
Catinella olivacea is a discomycetous fungus often found fruiting within cavities in rotting logs. Because this habitat would lack the air currents upon which discomycete species normally rely for the dispersal of their forcibly ejected ascospores, we suspected an alternative disseminative strategy might be employed by this species. An examination of the development of the discomycetous ascomata in pure culture, on wood blocks, and on agar showed that the epithecium was gelatinous at maturity and entrapped released ascospores in a slimy mass. We interpreted this as an adaptation for ascospore disperal by arthropods. Developmental data also showed that C. olivacea was unusual among other discomycetes in the Helotiales (Leotiomycetes). For example, the ascoma developed from a stromatic mass of meristematically dividing cells and involved the formation of a uniloculate cavity within a structure better considered an ascostroma than an incipient apothecium. Furthermore, the ascus had a prominent ocular chamber and released its ascospores through a broad, bivalvate slit. These features, along with phylogenetic analyses of large subunit and small subunit rDNA, indicated that this unusual apothecial fungus is, surprisingly, more closely affiliated with the Dothideomycetes than the Leotiomycetes.
The polyphyletic origins of ophiostomatoid fungi
Mycological Research, 1994
Cladistic analysis was performed on partial sequences from the nuclear-encoded small subunit ribosomal DNA. Taxa were sampled from Ceratocystis, Ophiosfoma and Sphaeronaemella to determine the placement of the inferred monophyletic groups among nonfissitunicate perithecial ascomycetes. Eight equally most parsimonious cladograms resulted from the analysis. In a strict consensus of the eight cladograms, the taxa sampled from the three genera did not form a monophyletic group collectively. Ceratocystis and Sphaeronaemella formed a clade, which was a sister group to the taxa sampled from the Microascales. Ophiosfoma was placed in a separate clade of the tree. These results support the convergent evolution of long-necked perithecia, scattered evanescent asci and galeate ascospores. Congruence of anamorph morphology, cycloheximide sensitivity, cell wall carbohydrate composition and centrum anatomy with the molecular data is discussed.