| 1. |
- Schoch, CL, et al.
(författare)
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Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for Fungi
- 2012
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 109:16, s. 6241-6246
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Tidskriftsartikel (refereegranskat)abstract
- Six DNA regions were evaluated as potential DNA barcodes for Fungi, the second largest kingdom of eukaryotic life, by a multinational, multilaboratory consortium. The region of the mitochondrial cytochrome c oxidase subunit 1 used as the animal barcode was excluded as a potential marker, because it is difficult to amplify in fungi, often includes large introns, and can be insufficiently variable. Three subunits from the nuclear ribosomal RNA cistron were compared together with regions of three representative protein-coding genes (largest subunit of RNA polymerase II, second largest subunit of RNA polymerase II, and minichromosome maintenance protein). Although the protein-coding gene regions often had a higher percent of correct identification compared with ribosomal markers, low PCR amplification and sequencing success eliminated them as candidates for a universal fungal barcode. Among the regions of the ribosomal cistron, the internal transcribed spacer (ITS) region has the highest probability of successful identification for the broadest range of fungi, with the most clearly defined barcode gap between inter- and intraspecific variation. The nuclear ribosomal large subunit, a popular phylogenetic marker in certain groups, had superior species resolution in some taxonomic groups, such as the early diverging lineages and the ascomycete yeasts, but was otherwise slightly inferior to the ITS. The nuclear ribosomal small subunit has poor species-level resolution in fungi. ITS will be formally proposed for adoption as the primary fungal barcode marker to the Consortium for the Barcode of Life, with the possibility that supplementary barcodes may be developed for particular narrowly circumscribed taxonomic groups.
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| 2. |
- Zamora, Juan Carlos, et al.
(författare)
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Considerations and consequences of allowing DNA sequence data as types of fungal taxa
- 2018
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Ingår i: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
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Tidskriftsartikel (refereegranskat)abstract
- Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
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| 3. |
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| 4. |
- Schoch, Conrad L., et al.
(författare)
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Finding needles in haystacks: linking scientific names, reference specimens and molecular data for Fungi
- 2014
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Ingår i: Database: The Journal of Biological Databases and Curation. - : Oxford University Press (OUP). - 1758-0463. ; 2014:bau061, s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- DNA phylogenetic comparisons have shown that morphology-based species recognition often underestimates fungal diversity. Therefore, the need for accurate DNA sequence data, tied to both correct taxonomic names and clearly annotated specimen data, has never been greater. Furthermore, the growing number of molecular ecology and microbiome projects using high-throughput sequencing require fast and effective methods for en masse species assignments. In this article, we focus on selecting and re-annotating a set of marker reference sequences that represent each currently accepted order of Fungi. The particular focus is on sequences from the internal transcribed spacer region in the nuclear ribosomal cistron, derived from type specimens and/or ex-type cultures. Re-annotated and verified sequences were deposited in a curated public database at the National Center for Biotechnology Information (NCBI), namely the RefSeq Targeted Loci (RTL) database, and will be visible during routine sequence similarity searches with NR_prefixed accession numbers. A set of standards and protocols is proposed to improve the data quality of new sequences, and we suggest how type and other reference sequences can be used to improve identification of Fungi.
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| 5. |
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| 6. |
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| 7. |
- Myllys, L, et al.
(författare)
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High cyanobiont selectivity of epiphytic lichens in old growth boreal forest of Finland
- 2007
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 173:3, s. 621-629
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Tidskriftsartikel (refereegranskat)abstract
- • Here, cyanobiont selectivity of epiphytic lichen species was examined in an old growth forest area in Finland. • Samples of the eight lichen species were collected from the same aspen (Populus tremula) and adjacent aspens in the same stand. The cyanobionts of these samples were compared with free and symbiotic Nostoc obtained from other habitats and geographic regions. • Our results, based on the phylogenetic analysis of a partial small subunit of the ribosomal DNA (16S rDNA) and the rbcLX gene complex did not show any correlation with the geographic origin of the samples at any spatial scale. Instead, there was a correlation between the cyanobionts and the alleged taxonomy of their mycobionts. • The results indicate that the lichen species examined are highly selective towards their cyanobiont partners. Only Lobaria pulmonaria proved to be more flexible, being able to associate with a wide range of Nostoc. A same Nostoc strain was found to form associations with taxonomically unrelated lichens indicating that the cyanobiont–mycobiont associations as a whole were not highly specific in the examined species.
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| 8. |
- Myllys, L, et al.
(författare)
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New genes for phylogenetic studies of lichenized fungi: glyceraldehyde-3-phosphate dehydrogenase and beta-tubulin genes
- 2002
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Ingår i: Lichenologist. - : Cambridge University Press (CUP). - 0024-2829. ; 34:3, s. 237-246
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Tidskriftsartikel (refereegranskat)abstract
- Primers for amplification and sequencing of partial glyceraldehyde-3-phosphate dehydrogenase (gpd) gene were designed for lichenized fungi. The 5' gpd primer is most probably fungal specific, since a BLAST search in GenBank found identical sequences only from ascomycetous taxa, whereas the 3' gpd primer was more universal. Utility of the gpd primers and previously designed beta-tubulin primers was tested in nine lichen taxa. Both the gpd and beta-tubulin primer pairs amplified in most of the taxa examined: the gpd primers generated a c. 1100 nucleotide fragment, whereas the PCR product obtained from the beta-tubulin primers was c. 900 nucleotides long. The gpd amplification products of Cladonia arbuscula and C. rangiferina were sequenced and both were found to contain three introns, the length of which varied between 49 to 83 nucleotides. To examine the applicability of gpd sequences in resolving relationships within Ascomycota, trees were calculated from 22 fungal gpd sequences obtained from GenBank together with the two Cladonia sequences using parsimony jackknifing. The gpd tree was compared with the SSU rDNA tree of the respective species (or genera). A similar analysis of the beta-tubulin gene was not performed, because only a few beta-tublin sequences from the same taxa were available in GenBank. The gpd tree was well resolved but in conflict with the SSU rDNA tree. In contrast to the SSU rDNA tree, the gpd tree did not support the monophyly of the Ascomycota. Analysis of the combined data set produced a tree very similar to that of the SSU rDNA data. However, the relationship of Lecanorales to the other orders remained unresolved. Even though gpd and beta-tubulin are highly conserved proteins, the third codon positions and introns are variable and both genes have the potential for inferring phylogenetic relationships at the lower taxonomic levels in the lichenized fungi. The two genes may be useful even below species level, depending on the species investigated.
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| 9. |
- Myllys, L, et al.
(författare)
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Phylogenetic relationships of Stereocaulaceae based on simultaneous analysis of beta-tubulin, GAPDH and SSU rDNA sequences
- 2005
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Ingår i: Taxon. - 0040-0262. ; 54:3, s. 605-618
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Tidskriftsartikel (refereegranskat)abstract
- The phylogenetic relationships of the lichenised ascomycete family Stereocaulaceae were investigated with partial beta-tubulin, partial glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and SSU rDNA sequence data. Due to the marked length variation in the SSU rDNA sequences, the analyses were performed with direct optimization. The combined analysis of the beta-tubulin, GAPDH and SSU rDNA sequences as well as the separate analyses of beta-tubulin and GAPDH data recognized the monophyletic group comprising Lepraria, Muhria and Stereocaulon. In the combined analysis Stereocaulon tornense appears as a basal taxon in the Stereocaulon clade, suggesting that the crustose growth form and the absence of cephalodia are primitive features within the genus. Muhria is nested in Stereocaulon and groups with the crustose S. cumulatum and S. leucophaeopsis. The genus Lepraria is monophyletic if Leproloma is included, but species that were represented by several specimens in our study, i.e., Lepraria jackii and Leproloma membranaceun, do not appear as monophyletic entities. The genus Pilophorus is included in Cladoniaceae. Combined analysis of the three data-sets clearly led to an increase in support values compared to the separate analyses, showing high support for the monophyly of families Cladoniaceae and Stereocaulaceae and for the sistergroup relation for the two families. The relationships between higher groupings did not reach high support values probably due to the incongruencies among the three datasets.
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| 10. |
- Myllys, L, et al.
(författare)
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Phylogeny of bipolar Cladonia arbuscula and Cladonia mitis (Lecanorales, Euascomycetes)
- 2003
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Ingår i: Molecular Phylogenetics and Evolution. - 1095-9513. ; 27:1, s. 58-69
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Tidskriftsartikel (refereegranskat)abstract
- Phylogenetic relationships and levels of geographic differentiation of two closely related bipolar taxa, Cladonia arbuscula and Cladonia mitis, were cladistically examined with ITS regions, SSU rDNA introns, partial P-tubulin, and partial glyceraldehyde 3-phosphate dehydrogenase (GAPDH) genes. In the combined analysis of the four genes, C arbuscula was paraphyletic, while C mitis, nested within C arbuscula, formed a strongly supported monophyletic group. C arbuscula samples were divided into three separate clades: "arbuscula I," appearing as basal to the other ingroup taxa, "arbuscula II," and "arbuscula III" (the latter represented by only one specimen), which were not correlated with any morphological trait. Only C mitis specimens formed a morphologically and chemically distinct group. None of the main clades was correlated with geographic origin. The separate analyses were poorly resolved, and in most cases samples from "arbuscula I,'' ''arbuscula, II," and "arbuscula III" clades were intermixed. An incongruence test revealed conflict among the four gene regions in almost all cases. Only ITS regions and introns were not significantly incongruent, suggesting lack of recombination within the ribosomal DNA locus. Incomplete lineage sorting and recombination were considered to be the main reasons accounting for the incongruencies. The high proportion of shared polymorphisms between the "arbuscula F and "arbuscula II" clades, especially found from the beta-tubulin gene and from the ITS regions, and the lack of corroborating morphological characters both indicate a short history of reproductive isolation among the groups. The lack of genetic differentiation among the northern and southern samples within the main clades indicates a relatively recent gene flow, which may have resulted from migrations during the Pleistocene glaciations or from more recent long-distance dispersal. (C) 2002 Elsevier Science (USA). All rights reserved.
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