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558 result(s) for "Hyde, Kevin D."
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Ranking higher taxa using divergence times: a case study in Dothideomycetes
The current classification system for the recognition of taxonomic ranks among fungi, especially at high-ranking level, is subjective. With the development of molecular approaches and the availability of fossil calibration data, the use of divergence times as a universally standardized criterion for ranking taxa has now become possible. We can therefore date the origin of Ascomycota lineages by using molecular clock methods and establish the divergence times for the orders and families of Dothideomycetes. We chose Dothideomycetes, the largest class of the phylum Ascomycota, which contains 32 orders, to establish ages at which points orders have split; and Pleosporales , the largest order of Dothideomycetes with 55 families, to establish family divergence times. We have assembled a multi-gene data set (LSU, SSU, TEF1 and RPB2) from 391 taxa representing most family groups of Dothideomycetes and utilized fossil calibration points solely from within the ascomycetes and a Bayesian approach to establish divergence times of Dothideomycetes lineages. Two separated datasets were analysed: (i) 272 taxa representing 32 orders of Dothideomycetes were included for the order level analysis, and (ii) 191 taxa representing 55 families of Pleosporales were included for the family level analysis. Our results indicate that divergence times (crown age) for most orders (20 out of 32, or 63%) are between 100 and 220 Mya, while divergence times for most families (39 out of 55, or 71%) are between 20 and 100 Mya. We believe that divergence times can provide additional evidence to support establishment of higher level taxa, such as families, orders and classes. Taking advantage of this added approach, we can strive towards establishing a standardized taxonomic system both within and outside Fungi. In this study we found that molecular dating coupled with phylogenetic inferences provides no support for the taxonomic status of two currently recognized orders, namely Bezerromycetales and Wiesneriomycetales and these are treated as synonyms of Tubeufiales while Asterotexiales is treated as a synonym of Asterinales . In addition, we provide an updated phylogenetic assessment of Dothideomycetes previously published as the Families of Dothideomycetes in 2013 with a further ten orders and 35 families.
Unambiguous identification of fungi: where do we stand and how accurate and precise is fungal DNA barcoding?
ABSTRACT True fungi ( Fungi ) and fungus-like organisms (e.g. Mycetozoa , Oomycota ) constitute the second largest group of organisms based on global richness estimates, with around 3 million predicted species. Compared to plants and animals, fungi have simple body plans with often morphologically and ecologically obscure structures. This poses challenges for accurate and precise identifications. Here we provide a conceptual framework for the identification of fungi, encouraging the approach of integrative (polyphasic) taxonomy for species delimitation, i.e. the combination of genealogy (phylogeny), phenotype (including autecology), and reproductive biology (when feasible). This allows objective evaluation of diagnostic characters, either phenotypic or molecular or both. Verification of identifications is crucial but often neglected. Because of clade-specific evolutionary histories, there is currently no single tool for the identification of fungi, although DNA barcoding using the internal transcribed spacer (ITS) remains a first diagnosis, particularly in metabarcoding studies. Secondary DNA barcodes are increasingly implemented for groups where ITS does not provide sufficient precision. Issues of pairwise sequence similarity-based identifications and OTU clustering are discussed, and multiple sequence alignment-based phylogenetic approaches with subsequent verification are recommended as more accurate alternatives. In metabarcoding approaches, the trade-off between speed and accuracy and precision of molecular identifications must be carefully considered. Intragenomic variation of the ITS and other barcoding markers should be properly documented, as phylotype diversity is not necessarily a proxy of species richness. Important strategies to improve molecular identification of fungi are: (1) broadly document intraspecific and intragenomic variation of barcoding markers; (2) substantially expand sequence repositories, focusing on undersampled clades and missing taxa; (3) improve curation of sequence labels in primary repositories and substantially increase the number of sequences based on verified material; (4) link sequence data to digital information of voucher specimens including imagery. In parallel, technological improvements to genome sequencing offer promising alternatives to DNA barcoding in the future. Despite the prevalence of DNA-based fungal taxonomy, phenotype-based approaches remain an important strategy to catalog the global diversity of fungi and establish initial species hypotheses.
Towards a natural classification and backbone tree for Sordariomycetes
Sordariomycetes is one of the largest classes of Ascomycota and is characterised by perithecial ascomata and inoperculate unitunicate asci. The class includes many important plant pathogens, as well as endophytes, saprobes, epiphytes, and fungicolous, lichenized or lichenicolous taxa. The class includes freshwater, marine and terrestrial taxa and has a worldwide distribution. This paper provides an updated outline of the Sordariomycetes and a backbone tree incorporating asexual and sexual genera in the class. Based on phylogeny and morphology we introduced three subclasses; Diaporthomycetidae, Lulworthiomycetidae and Meliolomycetidae and five orders; Amplistromatales , Annulatascales , Falcocladiales , Jobellisiales and Togniniales . The outline is based on literature to the end of 2014 and the backbone tree published in this paper. Notes for 397 taxa with information, such as new family and genera novelties, novel molecular data published since the Outline of Ascomycota 2009, and new links between sexual and asexual genera and thus synonymies, are provided. The Sordariomycetes now comprises six subclasses, 28 orders, 90 families and 1344 genera. In addition a list of 829 genera with uncertain placement in Sordariomycetes is also provided.
Microfungi on Tectona grandis (teak) in Northern Thailand
To date there is virtually no information available concerning the fungi associated with Tectona grandis (teak) ( Lamiaceae ) in Thailand. In this study, samples of microfungi were collected from both asymptomatic stems and dead wood, and symptomatic branches, stem and leaves of T. grandis from 27 sites in six provinces (Chiang Mai, Chiang Rai, Phayao, Phitsanulok, Phrae and Uttaradit Provinces). Morphology and combined multi-gene phylogeny (CAL, GAPDH, ITS, LSU, RPB2, SSU, TEF1 and TUB) were used to identify taxa. A total of 270 collections, representing 28 fungal species residing in 12 families, 7 orders and 21 genera, with three species of uncertain taxonomic placement were identified. Of these, one family, three genera and 14 species are new to science. The new family, Pseudocoleodictyosporaceae is introduced based on its distinct lineage in the Dothideomycetes and its unique morphology as compared to Roussoellaceae and Torulaceae . The new genera are Neooccultibambusa , Pseudocoleodictyospora and Subglobosporium . The newly described species are Diaporthe neoraonikayaporum , D. tectonendophytica , D. tectonae , D. tectonigena , Hermatomyces tectonae , H. thailandica , Manoharachariella tectonae , Neooccultibambusa chiangraiensis , Pseudocoleodictyospora sukhothaiensis , Ps. tectonae , Ps. thailandica , Rhytidhysteron tectonae , Subglobosporium tectonae and Tubeufia tectonae . Fourteen species are known published taxa including Alternaria tillandsiae , Berkleasmium talaumae , Boerlagiomyces macrospora , Ceratocladium purpureogriseum , Fusarium solani , Helicoma siamense , Lasiodiplodia theobromae , Macrovalsaria megalospora , Paradictyoarthrinium diffractum , Phaeoacremonium italicum , Sphaeropsis eucalypticola , Stachybotrys levispora , St. renispora and Thaxteriellopsis lignicola . Epitypifications or reference specimens are designated for Boerlagiomyces macrospora and Macrovalsaria megalospora. Macrovalsaria megalospora is transferred from Botryosphaeriaceae to Dothideomycetes genus, incertae sedis based on taxonomy and phylogenetic analysis, which indicate it is distinct from Botryosphaeriaceae . All fungal species represent first reports on T. grandis in Thailand. New taxa and taxa incertae sedis , as well as known taxa which are established as reference specimens or epitypes, are presented with phylogenetic tree analyses, habitat, known distribution, material examined, full descriptions, notes and figures. Information is also provided for known taxa to add to the body of knowledge and to assist those wishing to study fungi occurring on T. grandis in future.
First Report of Colletotrichum fructicola, C. rhizophorae sp. nov. and C. thailandica sp. nov. on Mangrove in Thailand
Colletotrichum, a genus within the phylum Ascomycota (Fungi) and family Glomerellaceae are important plant pathogens globally. In this paper, we detail four Colletotrichum species found in mangrove ecosystems. Two new species, Colletotrichum rhizophorae and C. thailandica, and a new host record for Colletotrichum fructicola were identified in Thailand. Colletotrichum tropicale was collected from Taiwan’s mangroves and is a new record for Rhizophora mucronata. These identifications were established through a combination of molecular analysis and morphological characteristics. This expanded dataset for Colletotrichum enhances our understanding of the genetic diversity within this genus and its associations with mangrove ecosystems. The findings outlined herein provide data on our exploration of mangrove pathogens in Asia.
Taxonomy and phylogeny of dematiaceous coelomycetes
Coelomycetous fungi are an artificial taxonomic group which produce conidia inside a cavity i.e. conidiomata. Coelomycetes comprise about, 1000 genera and 7000 species, which can be endophytic, pathogenic or saprobic. Traditional classification of coelomycetes was previously based on morphology, such as the shape of conidiomata and mode of conidiogenesis, while it was treated as a distinct group i.e. Deuteromycotina. Sequence based taxonomic studies has been used to accommodate asexual fungi in a natural classification system, resolve generic boundaries of polyphyletic genera and species complexes, as well as establish asexual-sexual links. Nevertheless, most of genera lack sequence data, thus, morphology based identification is still important when introducing new genera or species. In this paper we illustrate, describe, and provide taxonomic notes for 235 dematiaceous coelomycetous genera, including five new genera viz. Apiculospora, Didymellocamarosporium, Melanocamarosporium, Melnikia and Paulkirkia. Phylogenetic analyses of combined sequence data are provided to show placements of dematiaceous coelomycetes in Dothideomycetes, Leotiomycetes and Sordariomycetes. One-hundred and fifty-two (65 %) of genera have sequence data, thus, their taxonomic placement in a natural classification system, is listed as an outline. However, 83 genera still lack sequence data, hence, they are treated as Ascomycota, genera incertae sedis. In addition, separate analyses are provided where better taxonomic resolution is needed.
Towards a natural classification and backbone tree for Graphostromataceae, Hypoxylaceae, Lopadostomataceae and Xylariaceae
Species and generic recognition in the order Xylariales has been uncertain due to lack of molecular data from authentic cultures, as well as overlapping morphological characteristics. In this study, we revise the families Graphostromataceae, Hypoxylaceae, Lopadostomataceae and Xylariaceae in Xylariales. Our study is based on DNA sequence data derived from living cultures of fresh isolates, data from GenBank and morphological observation of type and worldwide herbarium specimens. We also collected new specimens from Germany, Italy and Thailand. Combined analyses of ITS, LSU, RPB2 and β-tubulin sequence data were used to reconstruct the molecular phylogeny of the above families. Generic and familiar boundaries between these families are revised and presented in an updated combined phylogenetic tree. We accept six genera in Graphostromataceae, 19 genera in Hypoxylaceae, four in Lopadostomataceae and 37 genera in Xylariaceae. Five genera previously treated in Xylariaceae are placed in Amphisphaeriales genera incertae sedis and seven genera are placed in Xylariales genera incertae sedis. Two genera are placed in Sordariomycetes genera incertae sedis, while four genera are placed as Xylariomycetidae genera incertae sedis. Three genera are considered as doubtful. Barrmaelia and Cannonia, presently included in Xylariaceae are transferred to Diatrypaceae and Coniochaetales respectively, based on their morphology and phylogeny. Areolospora and Myconeesia are excluded from Xylariaceae and synonymized with Phaeosporis and Anthostomella respectively. Updated descriptions and illustrations are provided for all taxa with notes provided on each genus. Excluded and doubtful genera are listed with notes on their taxonomy and phylogeny. Taxonomic keys are provided for all revised families with morphological details for genera within the families.
Importance of Molecular Data to Identify Fungal Plant Pathogens and Guidelines for Pathogenicity Testing Based on Koch’s Postulates
Fungi are an essential component of any ecosystem, but they can also cause mild and severe plant diseases. Plant diseases are caused by a wide array of fungal groups that affect a diverse range of hosts with different tissue specificities. Fungi were previously named based only on morphology and, in many cases, host association, which has led to superfluous species names and synonyms. Morphology-based identification represents an important method for genus level identification and molecular data are important to accurately identify species. Accurate identification of fungal pathogens is vital as the scientific name links the knowledge concerning a species including the biology, host range, distribution, and potential risk of the pathogen, which are vital for effective control measures. Thus, in the modern era, a polyphasic approach is recommended when identifying fungal pathogens. It is also important to determine if the organism is capable of causing host damage, which usually relies on the application of Koch’s postulates for fungal plant pathogens. The importance and the challenges of applying Koch’s postulates are discussed. Bradford Hill criteria, which are generally used in establishing the cause of human disease, are briefly introduced. We provide guidelines for pathogenicity testing based on the implementation of modified Koch’s postulates incorporating biological gradient, consistency, and plausibility criteria from Bradford Hill. We provide a set of protocols for fungal pathogenicity testing along with a severity score guide, which takes into consideration the depth of lesions. The application of a standard protocol for fungal pathogenicity testing and disease assessment in plants will enable inter-studies comparison, thus improving accuracy. When introducing novel plant pathogenic fungal species without proving the taxon is the causal agent using Koch’s postulates, we advise the use of the term associated with the “disease symptoms” of “the host plant”. Where possible, details of disease symptoms should be clearly articulated.
Study of three interesting Amanita species from Thailand: Morphology, multiple-gene phylogeny and toxin analysis
Amanita ballerina and A. brunneitoxicaria spp. nov. are introduced from Thailand. Amanita fuligineoides is also reported for the first time from Thailand, increasing the known distribution of this taxon. Together, those findings support our view that many taxa are yet to be discovered in the region. While both morphological characters and a multiple-gene phylogeny clearly place A. brunneitoxicaria and A. fuligineoides in sect. Phalloideae (Fr.) Quél., the placement of A. ballerina is problematic. On the one hand, the morphology of A. ballerina shows clear affinities with stirps Limbatula of sect. Lepidella. On the other hand, in a multiple-gene phylogeny including taxa of all sections in subg. Lepidella, A. ballerina and two other species, including A. zangii, form a well-supported clade sister to the Phalloideae sensu Bas 1969, which include the lethal \"death caps\" and \"destroying angels\". Together, the A. ballerina-A. zangii clade and the Phalloideae sensu Bas 1969 also form a well-supported clade. We therefore screened for two of the most notorious toxins by HPLC-MS analysis of methanolic extracts from the basidiomata. Interestingly, neither α-amanitin nor phalloidin was found in A. ballerina, whereas Amanita fuligineoides was confirmed to contain both α-amanitin and phalloidin, and A. brunneitoxicaria contained only α-amanitin. Together with unique morphological characteristics, the position in the phylogeny indicates that A. ballerina is either an important link in the evolution of the deadly Amanita sect. Phalloideae species, or a member of a new section also including A. zangii.
Multigene phylogenetic analyses to establish new Valsaria species and taxonomic significance of spore ornamentation
During our studies on fungal diversity from plant substrates, a new species of Valsaria was isolated from dead branches of Ostrya carpinifolia. The taxon is morphologically similar to other taxa in Valsariaceae and is characterized by pseudostromata, apically free pseudoparaphyses, bitunicate asci, and dark brown, 2-celled ascospores. However, it differs from extant species in number of guttules and ornamentation of spore. It is introduced herein as Valsaria ostryae sp. nov. within the family Valsariaceae. Multigene phylogenies based on combined LSU, ITS and RPB2 DNA sequence data generated from maximum likelihood, maximum parsimony and MrBayes analyses indicate that V. ostryae is basal to V. lopadostomoides and V. rudis and its establishment as a new species is strongly supported. No discordance was found between our morphological and phylogenetic species boundaries as postulated by other researchers and our molecular data strongly supports ornamentation of spore as useful for species delineation. Valsaria species do not appear to be host specific. Full morphological details are provided herein and phylogenetic relationships of Valsaria species are also discussed in light with host association.