Showing papers by "Conrad L. Schoch published in 2011"

Effector diversification within compartments of the Leptosphaeria maculans genome affected by Repeat-Induced Point mutations

Abstract: Fungi are of primary ecological, biotechnological and economic importance. Many fundamental biological processes that are shared by animals and fungi are studied in fungi due to their experimental tractability. Many fungi are pathogens or mutualists and are model systems to analyse effector genes and their mechanisms of diversification. In this study, we report the genome sequence of the phytopathogenic ascomycete Leptosphaeria maculans and characterize its repertoire of protein effectors. The L. maculans genome has an unusual bipartite structure with alternating distinct guanine and cytosine-equilibrated and adenine and thymine (AT)-rich blocks of homogenous nucleotide composition. The AT-rich blocks comprise one-third of the genome and contain effector genes and families of transposable elements, both of which are affected by repeat-induced point mutation, a fungal-specific genome defence mechanism. This genomic environment for effectors promotes rapid sequence diversification and underpins the evolutionary potential of the fungus to adapt rapidly to novel host-derived constraints.

A reappraisal of Microthyriaceae

Abstract: The family Microthyriaceae sensu Lumbsch and Huhndorf 2010 is a poorly known but interesting family comprising 50 genera consisting of foliar epiphytes or saprobes on dead leaves and stems. We re-visited the family based on examinations of generic types where possible. Members are distributed in Aulographaceae, Asterinaceae, Microthyriaceae, Micropeltidaceae and Palmulariaceae and notes are provided on each of these families. Nine genera are transferred from Microthyriaceae to Asterinaceae, and two to Aulographaceae based on the splitting or dissolving nature of the thyriothecia to release ascospores. New sequence data for a number of species and genera are provided. Microthyriaceous members growing on other fungi and lichens differ from Microthyriaceae sensu stricto and the family Trichothyriaceae is reinstated to accommodate these taxa. Other genera of Microthyriaceae belong in Rhytismataceae, Stictidaceae, Venturiales incertae cedis, Dothideomyetes genera incertae cedis,Hypocreales incertae cedis and Ascomycota genera incertae cedis. The family Microthyriaceae is reduced to seven genera characterised by superficial, flattened thyriothecia, with the cells of the upper wall radiating in parallel arrangement from the distinct central ostiolar opening, while the lower peridium is generally poorly developed. Sequence data is provided for five species with thyriothecia and Paramicrothyrium and Neomicrothyrium are described as new genera and Micropeltis zingiberacicola is introduced as a new species. Our phylogenetic analysis underscores the high genetic diversity for thyriotheciate species and there is no clear clade that can be well defined as Microthyriales. Nuclear ribosomal data support multiple polyphyletic lineages within Microthyriaceae and Micropeltidaceae. Some unexpected DNA based phylogenetic relationships such as those between Muyocopron and Saccardoella will require corroboration with more complete taxon sampling as well as additional non ribosomal markers. There are few differences between Aulographaceae, Asterinaceae and Palmulariaceae and these families may need synonymising.

A molecular, morphological and ecological re-appraisal of Venturiales―a new order of Dothideomycetes

Abstract: The Venturiaceae was traditionally assigned to Pleosporales although its diagnostic characters readily distinguish it from other pleosporalean families. These include a parasitic or saprobic lifestyle, occurring on leaves or stems of dicotyledons; small to medium-sized ascomata, often with setae; deliquescing pseudoparaphyses; 8-spored, broadly cylindrical to obclavate asci; 1-septate, yellowish, greenish or pale brown to brown ascospores; and hyphomycetous anamorphs. Phylogenetically, core genera of Venturiaceae form a monophyletic clade within Dothideomycetes, and represent a separate sister lineage from current orders, thus a new order—Venturiales is introduced. A new family, Sympoventuriaceae, is introduced to accommodate taxa of a well-supported subclade within Venturiales, which contains Sympoventuria, Veronaeopsis simplex and Fusicladium-like species. Based on morphology and DNA sequence analysis, eight genera are included in Venturiaceae, viz. Acantharia, Apiosporina (including Dibotryon), Caproventuria, Coleroa, Pseudoparodiella, Metacoleroa, Tyrannosorus and Venturia. Molecular phylogenetic information is lacking for seven genera previously included in Venturiales, namely Arkoola, Atopospora, Botryostroma, Lasiobotrys, Trichodothella, Trichodothis and Rhizogenee and these are discussed, but their inclusion in Venturiaceae is doubtful. Crotone, Gibbera, Lineostroma, Phaeocryptopus, Phragmogibbera, Platychora, Polyrhizon, Rosenscheldiella, Uleodothis and Xenomeris are excluded from Venturiales, and their ordinal placement needs further investigation. Zeuctomorpha is treated as a synonym of Acantharia.

Capnodiaceae

Abstract: In this paper we revisit the Capnodiaceae with notes on selected genera. Type specimens of the ascomycetous genera Aithaloderma, Anopeltis, Callebaea, Capnodaria, Echinothecium, Phragmocapnias and Scorias were re-examined, described and illustrated. Leptoxyphium is anamorphic Capnodiaceae and Polychaeton is a legitimate and earlier name for Capnodium, but in order to maintain nomenclatural stability we propose that the teleomorphic name should be considered for the approved lists of names currently in preparation for fungi. Notes are provided on the ascomycetous genus Scoriadopsis. However, we were unable to locate the type of this genus during the time frame of this study. The ascomycetous genera Aithaloderma, Ceramoclasteropsis, Hyaloscolecostroma and Trichomerium are excluded from Capnodiaceae on the basis of having ascostromata and trans-septate hyaline ascospores and should be accommodated in Chaetothyriaceae. Callebaea is excluded as the ascomata are thyriothecia and the genus is placed in Micropeltidaceae. Echinothecium is excluded as synonym of Sphaerellothecium and is transferred to Mycosphaerellaceae. The type specimen of Capnophaeum is lost and this should be considered as a doubtful genus. The coelomycetous Microxiphium is polyphyletic, while the status of Fumiglobus, Polychaetella and Tripospermum is unclear. Fourteen new collections of sooty moulds made in Thailand were isolated and sequenced. The nuclear large and small rDNA was partially sequenced and compared in a phylogeny used to build a more complete understanding of the relationships of genera in Capnodiaceae. Four new species are described and illustrated, while Phragmocapnias and Scorias are epitypified with fresh collections.

Testing the phylogenetic utility of Mcm7 in the Ascomycota

Abstract: The Ascomycota are a group of filamentous fungi that occur as saprobes, pathogens, and symbionts. They are of immense industrial, medical, ecological, and economical importance. The search for new markers appropriate for molecular phylogenetic analysis of Ascomycota remains a challenging problem. In this study, we explore the phylogenetic utility of a single copy protein-coding gene, MCM7; newly recognized as useful for inferring phylogenetic relationships among the major classes of the Ascomycota. Our specific goals were to: 1) test the phylogenetic utility of MCM7 for estimating phylogenies at various taxonomic ranks (class and below) with an emphasis on non-lichenized ascomycetes; and, 2) compare the congruence, robustness and resolving power of MCM7-based phylogenies with that of nuclear large subunit rDNA (LSU)-based phylogenies for the same taxon set. A dataset of sequence data for MCM7 as well as LSU was assembled for 80 species belonging to 63 genera of lichenized and non-lichenized ascomycetes in the classes Dothideomycetes, Eurotiomycetes, Geoglossomycetes, Lecanoromycetes, Leotiomycetes, and Sordariomycetes. We obtained 93 new sequences of which 65 are MCM7 and 28 are LSU. MaximumLikelihood and Bayesian analyses were performed using single as well as combined gene datasets and partitions. We also assessed substitution saturation for the MCM7 gene. Results indicate that MCM7 can be used successfully for determining phylogenetic relationships of ascomycetes and provided good resolution and support at half the cost compared to LSU. Phylogenetic informativeness profiles showed that MCM7 was more phylogenetically informative than LSU. The MCM7 gene is also a valuable phylogenetic marker for both lower as well as higher level phylogenetic analyses within the Ascomycota, especially when used in

Hypogymnia phylogeny, including Cavernularia, reveals biogeographic structure

Abstract: We inferred phylogenetic relationships using Bayesian and maximum likelihood approaches for two genera of lichenized fungi, Hypogymnia and Cavernularia (Parmeliaceae). Based on the combined ITS and GPD1 dataset from 23 species (49 specimens) of Hypogymnia and two species (8 specimens) of Cavernularia, we conclude that Hypogymnia is paraphyletic, and that it should include Cavernularia to retain its monophyly. Hypogymnia hultenii ( = Cavernularia hultenii) and H. lophyrea ( = C. lophyrea) are accepted here. Five species of Hypogymnia represented by more than a single individual were found to be monophyletic and significantly supported. The phylogeny reflects a statistically significant biogeographic pattern where continental-scale endemic taxa tend to occur within the same phylogenetic group. Sorediate taxa, which have worldwide or broader geographical ranges than affiliated species lacking soredia, are spread across the phylogenetic tree. Hypogymnia contains three species pairs: H. krogiae and ...

Geographic, climatic, and chemical differentiation in the Hypogymnia imshaugii species complex (Lecanoromycetes, Parmeliaceae) in North America

Abstract: Hypogymnia imshaugii is one of the most common, conspicuous and morphologically variable epiphytic lichens of the Pacific coastal states and provinces. The species varies greatly in morphology and chemistry, suggesting multiple closely related species or one or more phenotypically plastic species. We sought to determine whether additional ecologically meaningful species might be present within the H. imshaugii complex. Improving our species concepts could potentially improve ecological inferences based on community sampling. Three relatively well-defined genetic groups and one residual group in the H. imshaugii complex were detected with haplotype networks based on the ITS locus; however, phylogenetic reconstructions on combined ITS, mtSSU, GPD1 and TEF1 loci did not reflect this pattern. At present, we have insufficient evidence to support defining any of these groups as new taxa. The four major chemotypes in H. imshaugii differed in frequency among the genetic groups. None of the genetic groups...

DNA barcoding in fungi

Abstract: The kingdom Fungi, long thought to be primitive plants, are now known to be more closely related to …