Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Ascomycota”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed2004

A phylogenetic study of the Lecanora rupicola group (Lecanoraceae, Ascomycota).

A molecular phylogeny of the Lecanora rupicola group is presented, based on ITS sequence analyses. The study includes saxicolous and corticolous members of the Lecanora rupicola group as well as other Lecanora species with pruinose apothecia. A phylogenetic hypothesis for species in Lecanora s. lat. and various other genera in Lecanoraceae, based on an alignment-free distance estimation technique, shows that the Lecanora rupicola group forms a monophyletic clade within Lecanoraceae. Affinities to the core group of Lecanora are not well supported, likewise the monophyly of Lecanora s. str. with other species groups in Lecanora, such as the lobate taxa (and Rhizoplaca) is not supported. A more detailed analysis involving Lecanora species with pruinose apothecial discs was carried out with model-based Bayesian Markov chain Monte Carlo (B/MCMC) tree sampling. The results suggest the monophyly of the Lecanora species that are characterized by the presence of chromones. Corticolous as well as saxicolous species are included. Lepraria flavescens is closely related to the Lecanora swartzii subgroup, and the new name Lecanora rouxii nom. nov. is introduced for that species. Other Lecanora species with pruinose discs are not closely related to the Lecanora rupicola group.

Ascomycota↗
PubMed2004

Evolution and taxonomy of the marine Collemopsidium species (lichenized Ascomycota) in north-west Europe.

The taxonomy of the marine species of Collemopsidium in northwest Europe was investigated using morphological and molecular evidence. 210 specimens were collected from the west coasts of Norway and Ireland, and morphological and ecological variables recorded. ITS1 rDNA sequences were obtained from 24 specimens. A phylogenetic analysis, resulting in a single optimal tree, was performed under the unweighted least squares optimality criterion based on maximum likelihood distances obtained from unaligned sequences. Principal components analysis (PCA) was performed on morphological variables of the sequenced specimens, and classification was carried out by maximizing agreement between the phylogenetic tree and the PCA. Thallus immersion, and perithecial immersion and size, were the most important characters for discriminating between taxa. Apart from substratum, niche separation between taxa was small but statistically significant as shown by a redundancy analysis (RDA). Variance partitioning indicated that genetic variation is vastly more important than ecology for explaining phenotypic variation. Five species of marine Collemopsidium are recognized, including two new combinations: C. foveolatum (syn. Arthopyrenia foveolata) and C. ostrearum (syn. Lecanactis ostrearum) combs. nov.

Ascomycota↗
PubMed2006

Evolutionary history of vegetative reproduction in Porpidia s.L. (Lichen-forming ascomycota).

The evolutionary history of gains and losses of vegetative reproductive propagules (soredia) in Porpidia s.l., a group of lichen-forming ascomycetes, was clarified using Bayesian Markov chain Monte Carlo (MCMC) approaches to monophyly tests and a combined MCMC and maximum likelihood approach to ancestral character state reconstructions. The MCMC framework provided confidence estimates for the reconstructions of relationships and ancestral character states, which formed the basis for tests of evolutionary hypotheses. Monophyly tests rejected all hypotheses that predicted any clustering of reproductive modes in extant taxa. In addition, a nearest-neighbor statistic could not reject the hypothesis that the vegetative reproductive mode is randomly distributed throughout the group. These results show that transitions between presence and absence of the vegetative reproductive mode within Porpidia s.l. occurred several times and independently of each other. Likelihood reconstructions of ancestral character states at selected nodes suggest that--contrary to previous thought--the ancestor to Porpidia s.l. already possessed the vegetative reproductive mode. Furthermore, transition rates are reconstructed asymmetrically with the vegetative reproductive mode being gained at a much lower rate than it is lost. A cautious note has to be added, because a simulation study showed that the ancestral character state reconstructions were highly dependent on taxon sampling. However, our central conclusions, particularly the higher rate of change from vegetative reproductive mode present to absent than vice versa within Porpidia s.l., were found to be broadly independent of taxon sampling.

Ascomycota↗
PubMed2002

Quantitative analysis of phytopathogenic ascomycota on leaves of pedunculate oaks (Quercus robur L.) by real-time PCR.

Leaves of oak trees are often infected by various pathogenic fungi. As it is difficult to remove such organisms quantitatively from the leaf surface and as it is often impossible to grow these organisms independently from their host, there are almost no molecular data available from these oak leaf specific pathogens. For the quantitative removal of the microorganisms a procedure was developed combining a wax and microorganism freezing method with a DNA extraction technique. For the development of a species specific detection, DNA of pathogenic filamentous fungi was isolated from hyphae of the upper leaf surface of Quercus robur. Three different species could be identified as (i) Cladosporium sp., (ii) Ramularia sp. and (iii) Microsphaera alphitoides by amplifying and sequencing an 18S-28S segment of their rDNA. For the final quantification a real-time PCR protocol was established allowing the species specific quantification of the three pathogenic filamentous fungi. The whole procedure was successfully applied to quantify the amount of the three species on oak leaves collected in autumn.

Ascomycota↗
PubMedDate not supplied

Molecular phylogeny of parmotremoid lichens (Ascomycota, Parmeliaceae).

Parmotrema is one of the larger genera segregated from Parmelia s. lat. Additional genera recently have been segregated from this large genus based mainly on morphological and chemical features. We have employed molecular data from three genes to continue a revision of the generic concept within the parmelioid lichens. A Bayesian analysis of nuclear ITS, LSU rDNA and mitochondrial SSU rDNA sequences was performed. The genera Canomaculina, Concamerella, Parmelaria and Rimelia appear nested within Parmotrema. Alternative hypotheses to maintain the independence of Canomaculina, Concamerella and Rimelia are shown to be highly unlikely and are rejected. As a consequence these three genera are reduced to synonymy with Parmotrema. An alternative topology segregating Parmelaria from Parmotrema s. lat. cannot be rejected with the dataset at hand. However we have established that this genus is closely related to Parmotrema rather than to cetrarioid species as was considered previously. The revised genus Parmotrema includes species that have an upper cortex consisting of a palisade plectenchyma or rarely paraplectenchyma with vaults, have a pored or fenestrated epicortex, lack pseudocyphellae, have or lack cilia, have laminal, perforate or eperforate apothecia, usually have simple rhizines and filiform, cylindrical, bacilliform or sublageniform conidia. It is closely related to Flavoparmelia but the status of these genera requires further investigation. Nineteen new combinations are made.

Ascomycota↗
PubMed2004

[Growth in species of the genus Ascobolus. II. (Pezizales-Ascomycota)].

The kinetics of growth of six heterothallic species of the genus Ascobolus was studied in liquid culture media. The results obtained showed variation among the species in the duration of the different phases of the growth cycle. Four groups can be recognized considering the extension of the exponential phase of growth. The stationary phase, which differs in its length, is frequently very short, entering quickly in the phase of death, accompanied by the autolysis of the mycelium.

Ascomycota↗
PubMed2006

The mycorrhizal status of Pseudotulostoma volvata (Elaphomycetaceae, Eurotiales, Ascomycota).

Pseudotulostoma volvata (O. K. Mill. and T. W. Henkel) is a morphologically unusual member of the otherwise hypogeous Elaphomycetaceae due to its epigeous habit and exposed gleba borne on an elevated stalk at maturity. Field observations in Guyana indicated that P. volvata was restricted to rain forests dominated by ectomycorrhizal (EM) Dicymbe corymbosa (Caesalpiniaceae), suggesting an EM nutritional mode for the fungus. In this paper, we confirm the EM status of P. volvata with a combination of morphological, molecular, and mycosociological data. The EM status for P. volvata corroborates its placement in the ectotrophic Elaphomycetaceae.

Ecosystem↗
PubMed2006

Isolation of Paecilomyces lilacinus (Thom) Samson (Ascomycota: Hypocreales) from the Chagas disease vector, Triatoma infestans Klug (Hemiptera: Reduviidae) in an endemic area in Argentina.

A survey for entomopathogenic fungi of the Chagas disease vector Triatoma infestans was conducted in two provinces of Argentina from March-December 2003. Field-collected insects that died in the laboratory were individually maintained in moist chamber and incubated at 22 degrees C. Triatominae adults infected with the fungus Paecilomyces lilacinus were found at El Quebracho (27 degrees 34'S-64 degrees 31'W), Santiago del Estero province, Argentina, in December 2003. Paecilomyces lilacinus was cultured and isolated from infected insects in SDAY, PYG and MEA media. Pathogenicity tests were conducted and positive results were recorded. The median survival time (MST) of T. infestans exposed to a P. lilacinus conidial suspension was 12.8 days, and 100% mortality occurred at 30 days post-treatment. This is the first record of natural infection caused by P. lilacinus in T. infestans in the world.

Animals↗
PubMed2006

Phylogenetic significance of morphological characters in the tropical Hypotrachyna clade of parmelioid lichens (Parmeliaceae, Ascomycota).

Lichen-forming ascomycetes exhibit often complex morphologies of the vegetative thallus that are usually not found in non-lichenized fungi. This includes the thallus organization and appendical structures associated with the main thallus, such as cilia and rhizines. Such morphological characters are widely employed in the taxonomy of parmelioid lichens, especially at generic level. Within parmelioid lichens, several monophyletic groups can be distinguished, the Hypotrachyna clade being one of them, which includes mostly tropical taxa. In this first molecular study focused specifically on the Hypotrachyna clade, we used maximum parsimony and Bayesian analyses of a combined data set of nuclear ITS and mitochondrial SSU rDNA sequences to (1) test the monophyly of genera presently accepted within the clade and (2) evaluate the phylogenetic value of the morphological characters used to circumscribe genera in parmelioid lichens. Out of the 89 mtSSU and 88 nuITS sequences included in the present study, 121 sequences were newly obtained. Our results show that the taxa within the clade fall into two major groups and that the genus Hypotrachyna is polyphyletic. Everniastrum and Parmelinopsis are nested within Hypotrachyna sensu stricto, the latter being also polyphyletic. Bulbothrix is paraphyletic with Parmelinella nested within and is basal to the second major Hypotrachyna clade. Monophylies of Bulbothrix and Hypotrachyna are significantly rejected. The phylogenetic analysis demonstrates that morphological characters currently used to circumscribe genera in parmelioid lichens, such as cortical anatomy, lobe configuration, cilia, and rhizines have been overestimated and have only minor value in identifying monophyletic groups.

Lichens↗
PubMed2001

Gene genealogies, cryptic species, and molecular evolution in the human pathogen Coccidioides immitis and relatives (Ascomycota, Onygenales).

Previous genealogical analyses of population structure in Coccidioides immitis revealed the presence of two cryptic and sexual species in this pathogenic fungus but did not clarify their origin and relationships with respect to other taxa. By combining the C. immitis data with those of two of its closest relatives, the free-living saprophytes Auxarthron zuffianum and Uncinocarpus reesii, we show that the C. immitis species complex is monophyletic, indicating a single origin of pathogenicity. Cryptic species also were found in both A. zuffianum and U. reesii, indicating that they can be found in both pathogenic and free-living fungi. Our study, together with a few others, indicates that the current list of known fungal species might be augmented by a factor of at least two. However, at least in the C. immitis, A. zuffianum, and U. reesii complexes, cryptic species represent subdivisions at the tips of deep monophyletic clades and thus well within the existing framework of generic classification. An analysis of silent and expressed divergence and polymorphism values between and within the taxa identified by genealogical concordance did not reveal faster evolution in C. immitis as a consequence of adaptation to the pathogenic habit, nor did it show positive Darwinian evolution in a region of a dioxygenase gene (tcrP gene coding for 4-HPPD) known to cause antigenic responses in humans. Instead, the data suggested relative stasis, indicative of purifying selection against mostly deleterious mutations. Two introns in the same gene fragment were considerably more divergent than exons and were unalignable between species complexes but had very low polymorphism within taxa.

4-Hydroxyphenylpyruvate Dioxygenase↗
PubMed2002

Allelic variation of a Beauveria bassiana (Ascomycota: Hypocreales) minisatellite is independent of host range and geographic origin.

The minisatellite locus, BbMin1, was isolated from a partial Beauveria bassiana genomic library that consisted of poly(GA) flanked inserts. Polymerase chain reaction (PCR) of the BbMin1 repeat demonstrated allele size variation among 95 B. bassiana isolates. Amplification was also observed from single isolates of Beauveria amorpha, Beauveria brongniartii, and Beauveria caledonica. Eight alleles were identified at the haploid locus, where repeat number fluctuated between one and fourteen. AMOVA and theta (Fst) indicated that fixation of repeat number has not occurred within pathogenic ecotypes or geographically isolated samples of B. bassiana. Selective neutrality of allele size, the rate of BbMin1 mutation, and the age of the species may contribute to host and geographic independence of the marker. Presence of alleles with a large number of repeat units may be attributed to the rare occurrence of somatic recombination or DNA replication error. The molecular genetic marker was useful for the identification of genetic types of B. bassiana and related species.

Analysis of Variance↗
PubMedDate not supplied

Establishment of the fungal entomopathogen Beauveria bassiana (Ascomycota: Hypocreales) as an endophyte in cocoa seedlings (Theobroma cacao).

The fungal entomopathogen Beauveria bassiana became established as an endophyte in in vitro-grown cocoa seedlings tested for up to 2 mo after inoculation to the radicle with B. bassiana suspensions. The fungus was recovered in culture from stems, leaves and roots. B. bassiana also was detected as an epiphyte 1 and 2 mo postinoculation. Penicillium oxalicum and five bacterial morphospecies also were detected, indicating that these were present as endophytes in the seed.

Animals↗
PubMed2001

Major fungal lineages are derived from lichen symbiotic ancestors.

About one-fifth of all known extant fungal species form obligate symbiotic associations with green algae, cyanobacteria or with both photobionts. These symbioses, known as lichens, are one way for fungi to meet their requirement for carbohydrates. Lichens are widely believed to have arisen independently on several occasions, accounting for the high diversity and mixed occurrence of lichenized and non-lichenized (42 and 58%, respectively) fungal species within the Ascomycota. Depending on the taxonomic classification chosen, 15-18 orders of the Ascomycota include lichen-forming taxa, and 8-11 of these orders (representing about 60% of the Ascomycota species) contain both lichenized and non-lichenized species. Here we report a phylogenetic comparative analysis of the Ascomycota, a phylum that includes greater than 98% of known lichenized fungal species. Using a Bayesian phylogenetic tree sampling methodology combined with a statistical model of trait evolution, we take into account uncertainty about the phylogenetic tree and ancestral state reconstructions. Our results show that lichens evolved earlier than believed, and that gains of lichenization have been infrequent during Ascomycota evolution, but have been followed by multiple independent losses of the lichen symbiosis. As a consequence, major Ascomycota lineages of exclusively non-lichen-forming species are derived from lichen-forming ancestors. These species include taxa with important benefits and detriments to humans, such as Penicillium and Aspergillus.

Ascomycota↗
PubMed1999

Phylogenetic relationships among ascomycetes: evidence from an RNA polymerse II subunit.

In an effort to establish a suitable alternative to the widely used 18S rRNA system for molecular systematics of fungi, we examined the nuclear gene RPB2, encoding the second largest subunit of RNA polymerase II. Because RPB2 is a single-copy gene of large size with a modest rate of evolutionary change, it provides good phylogenetic resolution of Ascomycota. While the RPB2 and 18S rDNA phylogenies were highly congruent, the RPB2 phylogeny did result in much higher bootstrap support for all the deeper branches within the orders and for several branches between orders of the Ascomycota. There are several strongly supported phylogenetic conclusions. The Ascomycota is composed of three major lineages: Archiascomycetes, Saccharomycetales, and Euascomycetes. Within the Euascomycetes, plectomycetes, and pyrenomycetes are monophyletic groups, and the Pleosporales and Dothideales are distinct sister groups within the Loculoascomycetes. We confirm the placement of Neolecta within the Archiascomycetes, suggesting that fruiting body formation and forcible discharge of ascospores were characters gained early in the evolution of the Ascomycota. These findings show that a slowly evolving protein-coding gene such as RPB2 is useful for diagnosing phylogenetic relationships among fungi.

Ascomycota↗
PubMed2006

Loss of the flagellum happened only once in the fungal lineage: phylogenetic structure of kingdom Fungi inferred from RNA polymerase II subunit genes.

BACKGROUND: At present, there is not a widely accepted consensus view regarding the phylogenetic structure of kingdom Fungi although two major phyla, Ascomycota and Basidiomycota, are clearly delineated. Regarding the lower fungi, Zygomycota and Chytridiomycota, a variety of proposals have been advanced. Microsporidia may or may not be fungi; the Glomales (vesicular-arbuscular mycorrhizal fungi) may or may not constitute a fifth fungal phylum, and the loss of the flagellum may have occurred either once or multiple times during fungal evolution. All of these issues are capable of being resolved by a molecular phylogenetic analysis which achieves strong statistical support for major branches. To date, no fungal phylogeny based upon molecular characters has satisfied this criterion. RESULTS: Using the translated amino acid sequences of the RPB1 and RPB2 genes, we have inferred a fungal phylogeny that consists largely of well-supported monophyletic phyla. Our major results, each with significant statistical support, are: (1) Microsporidia are sister to kingdom Fungi and are not members of Zygomycota; that is, Microsporidia and fungi originated from a common ancestor. (2) Chytridiomycota, the only fungal phylum having a developmental stage with a flagellum, is paraphyletic and is the basal lineage. (3) Zygomycota is monophyletic based upon sampling of Trichomycetes, Zygomycetes, and Glomales. (4) Zygomycota, Basidiomycota, and Ascomycota form a monophyletic group separate from Chytridiomycota. (5) Basidiomycota and Ascomycota are monophyletic sister groups. CONCLUSION: In general, this paper highlights the evolutionary position and significance of the lower fungi (Zygomycota and Chytridiomycota). Our results suggest that loss of the flagellum happened only once during early stages of fungal evolution; consequently, the majority of fungi, unlike plants and animals, are nonflagellated. The phylogeny we infer from gene sequences is the first one that is congruent with the widely accepted morphology-based classification of Fungi. We find that, contrary to what has been published elsewhere, the four morphologically defined phyla (Ascomycota, Basidiomycota, Zygomycota and Chytridiomycota) do not overlap with one another. Microsporidia are not included within kingdom Fungi; rather they are a sister-group to the Fungi. Our study demonstrates the applicability of protein sequences from large, slowly-evolving genes to the derivation of well-resolved and highly supported phylogenies across long evolutionary distances.

Amino Acid Sequence↗
PubMed2005

Manganese superoxide dismutase in pathogenic fungi: an issue with pathophysiological and phylogenetic involvements.

Manganese-containing superoxide dismutases (MnSODs) are ubiquitous metalloenzymes involved in cell defence against endogenous and exogenous reactive oxygen species. In fungi, using this essential enzyme for phylogenetic analysis of Pneumocystis and Ganoderma genera, and of species selected among Ascomycota, Basidiomycota and Zygomycota, provided interesting results in taxonomy and evolution. The role of mitochondrial and cytosolic MnSODs was explored in some pathogenic Basidiomycota yeasts (Cryptococcus neoformans var. grubii, Cryptococcus neoformans var. gattii, Malassezia sympodialis), Ascomycota filamentous fungi (Aspergillus fumigatus), and Ascomycota yeasts (Candida albicans). MnSOD-based phylogenetic and pathogenic data are confronted in order to evaluate the roles of fungal MnSODs in pathophysiological mechanisms.

Ascomycota↗