Multispored Asci Research Articles

A new connection between wood saprobism and beetle endosymbiosis: the rarely reported saprobic discomycete Tromeropsis is congeneric with the symbiotic yeast Symbiotaphrina (Symbiotaphrinales, Xylonomycetes) and two asexual morphs misplaced in Hyphozyma

The only hitherto known species of the monotypic genus Tromeropsis, the rarely reported T. microtheca, is redescribed from recent collections on mostly little decayed, grayed, xeric, sun-exposed wood of decorticated trunks and branches of different gymnosperms, exceptionally angiosperms, from different humid regions of central Europe and a dry area in Macaronesia. Two further, very similar species are here newly described from decayed xeric wood of different angiosperm trees and shrubs from dry to arid regions of North America, Australia, and Macaronesia. Characteristics of the genus are: black sessile apothecia, dark olivaceous exudate, fissitunicate multi-spored asci, minute, cylindrical to ellipsoid, hyaline ascospores, a yeast-like asexual morph, and, in some species, a synanamorph with allantoid conidia formed on integrated conidiogenous cells reminiscent of the genus Lecythophora but with holoblastic conidiogenesis. A lectotype is designated for the type species of the likewise sexually typified, monotypic, illegitimate genus Microspora, M. dura, which was re-examined from the original material and found to be a later synonym of T. microtheca. Nuclear rDNA data were obtained from two collections of T. microtheca and four collections of the two new species. DNA sequences of T. microtheca match those from asexual morph isolates or environmental samples in public databases. Different misapplied names attributed to sequences from asexual morph isolates gained from coniferous wood from northern Europe, North America, and eastern Asia were re-identified as T. microtheca. A very close relationship between Tromeropsis and the type species of the asexually typified genus Symbiotaphrina, S. buchneri, was observed. Independent molecular phylogenetic analyses of three rDNA regions (partial SSU, ITS, partial LSU) each place Tromeropsis and the type species of Symbiotaphrina in a single supported clade without showing clear limits between the two genera. Based on multigene analysis, Symbiotaphrina was recently placed together with the small order Xylonales in the new class Xylonomycetes. We here validate the order Symbiotaphrinales previously published as nom. nud. and describe the family Symbiotaphrinaceae. Since the name Symbiotaphrina was validated one year before Tromeropsis was published, and is more widely used, it is adopted here and T. microtheca combined into Symbiotaphrina. rDNA data further suggest that two members of the asexually typified genus Hyphozyma, H. lignicola and H. sanguinea, belong to Symbiotaphrina, whereas the type species of Hyphozyma, H. variabilis, clusters in the Thelebolales (Leotiomycetes), where it is a later synonym of Cleistothelebolus nipigonensis, the type species of Cleistothelebolus. The new combinations S. lignicola and S. sanguinea are proposed, to which the newly described species S. desertorum and S. larreae are added. Based on their close relationship and a similar yeast-like asexual morph in pure culture, we hypothesize that the life cycles of all these wood-inhabiting taxa include a symbiotic phase in the gut of arthropods and, conversely, we suppose that the life cycles of S. buchneri and S. kochii include unknown sexual morphs growing on plant substrate.

New and noteworthy species of the lichen genus Lecanora (Ascomycota; Lecanoraceae) from South Korea

AbstractTwo new species, Lecanora hafelliana L. Lü, Y. Joshi & Hur and L. loekoesii Y. Joshi, L. Lü & Hur, are described as new to science from South Korea and eight species, L. campestris (Schaer.) Hue, L. cenisia Ach., L. nipponica H. Miyaw., L. perplexa Brodo, L. plumosa Müll. Arg., L. polytropa (Hoffm.) Rabenh., L. subrugosa Nyl. and L. sulcata (Hue) H. Miyaw., are recorded from South Korea for the first time. Lecanora hafelliana is characterized by the presence of hafellic acid, which is reported for the first time in this genus, while L. loekoesii is characterized by multispored asci and a thallus containing norstictic acid.

Loss of meiotic rereplication block in Saccharomyces cerevisiae cells defective in Cdc28p regulation.

Cdc28p is the major cyclin-dependent kinase in Saccharomyces cerevisiae. Its activity is required for blocking the reinitiation of DNA replication during mitosis. Here, we show that under conditions where Cdc28p activity is improperly regulated--either through the loss of function of the Schizosaccharomyces pombe wee1 ortholog Swe1p or through the expression of a dominant CDC28 allele, CDC28AF--diploid yeast cells are able to complete several rounds of premeiotic DNA replication within a single meiotic cell cycle. Moreover, a percentage of mutant cells exhibit a "multispore" phenotype, possessing the ability to package more than four spores within a single ascus. These multispored asci contain both even and odd numbers of viable spores. In order for meiotic rereplication and multispore formation to occur, cells must initiate homologous recombination and maintain proper chromosome cohesion during meiosis I. Rad9p- or Rad17p-dependent checkpoint mechanisms are not required for multispore formation and neither are the B-type cyclin Clb6p and the cyclin-dependent kinase inhibitor Sic1p. Finally, we present evidence of a possible role for a Cdc55p-dependent protein phosphatase 2A in initiating meiotic replication.

Revision of Trimmatothele (Verrucariaceae), and description of Oevstedalia for Trimmatothelopsis antarctica, a new lichen genus with true ascoconidia

The type species of Trimmatothele is shown to differ from Verrucaria only by the multispored asci. Trimmatothele is consequently regarded as a younger synonym of Verrucaria, and the new combination Verrucaria perquisita proposed. The species is just known from Europe, where it is very rare on calcareous rocks and has a boreo-alpine distribution. Trimmatothelopsis antarctica is a very distinct lichen, not related with Verrucaria, and the new genus Oevstedalia is described to accommodate it. Oevstedalia is characterized by relatively pale perithecia with a hyphal wall, abundant pseudoparaphyses, sparse, thin, basally branched and anastomosed interascal filaments, an I− and K/I− centre, and very large, subcylindrical, entirely thin-walled, K/I+ blue asci containing in the living state 8 conidial balls filled with numerous ascoconidia. Oevstedalia might be related to the Epigloeaceae (family inc. sedis) and represents the first example of a lichenized ascomycete forming true ascoconidia. O. antarctica appears to be endemic in Antarctica, where it seems to be widespread and relatively common. No material is available for Trimmatothele umbellulariae and Lesdainea maritima, and no final conclusion can be given for the taxonomic status of these two species.

Gyalideopsis floridae, sp. nov.a New Lichenicolous Lichen from Florida (Gomphillaceae, Ascomycetes)

Abstract Gyalideopsis floridae, a lichenicolous lichen growing on Parmotrema in Florida (U.S.A.) is described as new. It is distinguished from all hitherto known species of the genus by multispored asci and simple ascospores.

Thelocarpella gordensis gen. et sp. nov. (Ascomycetes lichenisati, Acarosporaceae)

Thelocarpella gordensis Nav.-Ros. et Cl. Roux gen. et sp. nov., a crustose lichen with endolithic thallus, is only known from the type locality, in Provence (south-east of France), on calcareous sandstone. This species is characterized by entirely immersed perithecioid ascomata, a hamathecium consisting of a typical paraphysoid network, multispored asci (more than 1000 spores in optical section), and colourless small oblong spores. The genus Thelocarpella differs from Thelocarpon by having bitunicate asci with a distinctly thicker wall. Heterogeneity of the genus Thelocarpon and the systematic position of Thelocarpella and Thelocarpon are discussed. The genus Trimmatothelopsis Zschacke is considered a synonym of Acarospora A. Massal. and Thelocarpon robustum Eitner identical with Acarospora smaragdula var. murina (Sandst.) H. Magn.Key words: lichens, Thelocarpella, Thelocarpon, taxonomy.

Polyploidy in the haplontic yeast Schizosaccharomyces pombe: construction and analysis of strains.

The fission yeast Schizosaccharomyces pombe has a haplontic life cycle in which the diplophase is confined to the zygote. Through the use of one- and two-step protoplast fusions we show that the ploidy can be increased up to pentaploid. The polyploid fusion products are rather unstable and segregate cells of lower ploidies by gradual loss of chromosomes during mitotic divisions. The polyploid cells conjugate normally but are prone to arrest at various stages of meiosis (1-, 2- and 3-spored asci, binucleate spores) and/or produce inviable, most probably aneuploid, spores. Marker segregation in the complete tetrads indicates the multiple association of homologous chromosomes. In tetra- and penta-ploid meiosis, multispored (6- to 7-spored) asci are also produced, probably by postmeiotic division of the nuclei.

Thaxterina, a new tubeufiaceous genus with multispored asci from India

Thaxterina multispora gen. et sp. nov. is described and illustrated. It is a member of the Tubeufiaceae with dark ascomata. This family is mainly represented by members with hyaline to coloured ascomata but also includes two members, Thaxteriella and Thaxteriellopsis , with dark ascomata. Thaxterina is separated from these two genera by the multispored asci with relatively small ascospores.

Erratum: Sporulation in single-spore isolates from amitrole-induced multispored asci of Saccharomyces cerevisiae

Erratum: Sporulation in single-spore isolates from amitrole-induced multispored asci of Saccharomyces cerevisiae

Sporulation in single-spore isolates from amitrole-induced multispored asci of Saccharomyces cerevisiae

Amitrole treatment causes multispored ascus production by cells of a yeast strain whose asci normally contain two diploid spores. Single spores were isolated from asci containing two to eight spores and their ability to germinate was determined. Cells in colonies grown from single spores sporulated in the same manner as the parent strain indicating that amitrole had not induced meiotic division in the developing asci.

Induction of multispored asci in two-spored strains of Saccharomyces cerevisiae by amitrole

Although growth of two yeast strains characterized by consistent production of two diploid spores per ascus was inhibited in complex presporulation media containing amitrole, a fraction of the cells produced were able to form asci with more than two spores after transfer to acetate sporulation medium. Cells grown in a defined presporulation medium containing amitrole did not acquire this ability. The increase in spore numbers per ascus is attributed either to the induction by amitrole in growth medium of cells with more than one nucleus or to the restoration of normal meioses in the multispored asci.

Dennisiopsis, a New Genus of Discomycetes

Two new coprophilous discomycetes, one with 8-spored asci and the other with multispored asci, are described from India. A new genus, Dennisiopsis, is proposed to accommodate the two species in both of which the ascocarp is a simple fascicle of asci and paraphyses without an ectal excipulum. The taxonomy of the fungi is discussed.

North American species of Coprotus (Thelebolaceae: Pezizales)

The genus Coprotus is a segregate of the coprophilous genus Ascophanus Boud. characterized by minute, translucent, white to yellow apothecia, operculate, non-amyloid, eight- to multi-spored asci, and hyaline, smooth, thin-walled ascospores that contain gas bubbles. Species are distinguished by (1) the number of spores per ascus, (2) the presence or absence of pigments in paraphyses and excipular cells, and (3) the relative size and shape of asci, spores, and sterile elements. Five new combinations are made and six new species are proposed. Keys, descriptions and illustrations are provided for the 18 recognized North American species.

Coprobolus, a new genus of the tribe Theleboleae (Pezizaceae)

Coprobolus poculiformis with hyaline ellipsoid ascospores and multispored asci which split open at the apex is described as a new species and a new genus. It was found on rabbit dung.

CONTRIBUTIONS TO OUR KNOWLEDGE OF AMBROSIA FUNGI. I. ASCOIDEA HYLECOETI SP. NOV. (ASCOMYCETES)

BATRA, LEKH R. (U. Kansas, Lawrence), and HELENE FRANCKE-GROSMANN. Contributions to our knowledge of ambrosia fungi. I. Ascoidea hylecoeti sp. nov. (Ascomycetes). Amer. Jour. Bot. 48(6): 453-456. Illus. 1961.-The genus Ascoidea Bref. & Lindau in Brefeld (1891) belongs to the family Ascoideaceae (Endomycetales, Hemiascomycetidae). Ascoidea differs from all other ascomycetes by its possession of characteristic multispored asci which proliferate, the newer asci being formed through the collar-like wall remnants of older asci. Ascogenous hyphae are absent. The present fungus differs in many ways from the type and the only species of the genus, A. rubescens Bref. & Lindau. Ascoidea hylecoeti reproduces asexually by chlamydospores. The asci are conical and many spored. They are aggregated in thick clusters of 50-200 individual asci. The number of ascospores per ascus is much larger than that of A. rubescens and their size is much smaller. Ascoidea hylecoeti is known to occur only in association with the genus Hylecoetus, one of the ambrosia beetles. AMBROSIA fungi are a group of fungi which live symbiotically with some genera of insects. Most of these fungi live saprophytically on plant and in. sect material. although some may have a rather complex and parasitic role together with the insect partner in the formation of so-called ambrosia galls on some plants. Generally, these fungi serve as a major source of food for the developing larvae. Ambrosia fungi are predominantly ectosymbiotes. They are characterized by having mucilaginous spores and fragrant colonies when grown on common laboratory media or when observed in the field. Some of these fungi cause blue staining of logged timber. resulting in heavy economic losses in some parts of the world. These fungi usually overwinter in the form of oidia, thick-walled chlamydospores, or dried, shiny. and mucilaginous crusts of ascospores. The female ambrosia beetles carry the fungi in special structures and the inocula are deposited during oviposition along with the eggs (FranckeGrosmann 1952, 1956, 1957). Taxonomically, most of the ambrosia fungi belong to the Endomycetales, Ophiostomatales and other ascomycetous orders and Fungi Imperfecti (Batra, 1959). Some unidentified Basidiomycetes have also been isolated by the present authors, although no Phycomycetes have so far been observed. Ascolidea hylecoeti was isolated during our studies of symbiotic relationships between ambrosia fungi and ambrosia beetles. Like many other such fungi, this fungus lives as an ectosymbiote and is

Polyploidy in yeasts.

IN addition to the four strains of Saccharomyces cerevisiae and one strain of Saccharomyces delbrueckii that form asci with more than four spores per ascus1, I have found eight other strains of Saccharomyces cerevisiae that are able to form asci with five, six, seven, eight and nine smooth, round ascospores. One of these strains was obtained some years ago from Seagram's collection in the United States. The other seven strains were recently isolated (one from barley grains, another from prickly pear and five from wine). The shape, size and germination pattern of the spores seem to indicate that the ascospores from multispored asci are haploid. There is thus considerable experimental evidence for the natural occurrence of polyploid yeasts.