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P W Crous - One of the best experts on this subject based on the ideXlab platform.
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the rise of ramularia from the Mycosphaerella labyrinth
Fungal Biology, 2015Co-Authors: S I R Videira, P W Crous, Uwe Braun, J Z Groenewald, Gerard J M VerkleyAbstract:In this study we aimed to resolve the Ramularia endophylla species-complex by applying a polyphasic approach involving morphology and multi-gene phylogeny. Eleven partial genes were targeted for amplification and sequencing for a total of 81 isolates representing R. endophylla s. lat. and 32 isolates representing 11 Ramularia species that were previously linked to a Mycosphaerella sexual morph in literature. A Bayesian phylogenetic analysis, as well as a parsimony analysis, was performed on a combined five-locus dataset and the resulting trees showed significant support for three species within the complex, including the previously described R. endophylla and R. vizellae, and one novel species, Ramularia unterseheri. A parsimony analysis was also separately performed with mating-type gene sequences (MAT1-1-1 and MAT1-2-1) and the resulting tree topologies were in accordance with that of the multigene analysis. A bibliographic review of the proposed links between Ramularia spp. and their purported Mycosphaerella sexual morphs is also presented, confirming six connections in Ramularia. In spite of more than 10 000 species having been described in Mycosphaerella, the majority is shown to belong to other genera, suggesting that the taxa identified as Mycosphaerella in much of the plant pathology literature needs to be revisited.
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zymoseptoria gen nov a new genus to accommodate septoria like species occurring on graminicolous hosts
Persoonia, 2011Co-Authors: W Quaedvlieg, Johannes Z Groenewald, G H J Kema, G J M Verkley, S Seifbarghi, Mohammad Razavi, Mirzadi A Gohari, Rahim Mehrabi, P W CrousAbstract:The Mycosphaerella complex is both poly- and paraphyletic, containing several different families and genera. The genus Mycosphaerella is restricted to species with Ramularia anamorphs, while Septoria is restricted to taxa that cluster with the type species of Septoria, S. cytisi, being closely related to Cercospora in the Mycosphaerellaceae. Species that occur on graminicolous hosts represent an as yet undescribed genus, for which the name Zymoseptoria is proposed. Based on the 28S nrDNA phylogeny derived in this study, Zymoseptoria is shown to cluster apart from Septoria. Morphologically species of Zymoseptoria can also be distinguished by their yeast-like growth in culture, and the formation of different conidial types that are absent in Septoria s.str. Other than the well-known pathogens such as Z. tritici, the causal agent of septoria tritici blotch on wheat, and Z. passerinii, the causal agent of septoria speckled leaf blotch of barley, both for which epitypes are designated, two leaf blotch pathogens are also described on graminicolous hosts from Iran. Zymoseptoria brevis sp. nov. is described from Phalaris minor, and Z. halophila comb. nov. from leaves of Hordeum glaucum. Further collections are now required to elucidate the relative importance, host range and distribution of these species.
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evolutionary dynamics of mating type loci of Mycosphaerella spp occurring on banana
Eukaryotic Cell, 2010Co-Authors: P W Crous, Mahdi Arzanlou, Luteharm ZwiersAbstract:The devastating Sigatoka disease complex of banana is primarily caused by three closely related heterothallic fungi belonging to the genus Mycosphaerella: M. fijiensis, M. musicola, and M. eumusae. Previous phylogenetic work showing common ancestry led us to analyze the mating-type loci of these Mycosphaerella species occurring on banana. We reasoned that this might provide better insight into the evolutionary history of these species. PCR and chromosome-walking approaches were used to clone the mating-type loci of M. musicola and M. eumusae. Sequences were compared to the published mating-type loci of M. fijiensis and other Mycosphaerella spp., and a novel organization of the MAT loci was found. The mating-type loci of the examined Mycosphaerella species are expanded, containing two additional Mycosphaerella-specific genes in a unique genomic organization. The proteins encoded by these novel genes show a higher interspecies than intraspecies homology. Moreover, M. fijiensis, M. musicola, and M. eumusae contain two additional mating-type-like loci, containing parts of both MAT1-1-1 and MAT1-2-1. The data indicate that M. fijiensis, M. musicola, and M. eumusae share an ancestor in which a fusion event occurred between MAT1-1-1 and MAT1-2-1 sequences and in which additional genes became incorporated into the idiomorph. The new genes incorporated have since then evolved independently in the MAT1-1 and MAT1-2 loci. Thus, these data are an example of the evolutionary dynamics of fungal MAT loci in general and show the great flexibility of the MAT loci of Mycosphaerella species in particular.
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unravelling Mycosphaerella do you believe in genera
Persoonia, 2009Co-Authors: P W Crous, Michael J. Wingfield, Brett A. Summerell, Angus J. Carnegie, Treena I Burgess, P A Barber, G C Hunter, Vera Andjic, J Z GroenewaldAbstract:Many fungal genera have been defined based on single characters considered to be informative at the generic level. In addition, many unrelated taxa have been aggregated in genera because they shared apparently similar morphological characters arising from adaptation to similar niches and convergent evolution. This problem is aptly illustrated in Mycosphaerella. In its broadest definition, this genus of mainly leaf infecting fungi incorporates more than 30 form genera that share similar phenotypic characters mostly associated with structures produced on plant tissue or in culture. DNA sequence data derived from the LSU gene in the present study distinguish several clades and families in what has hitherto been considered to represent the Mycosphaerellaceae. In some cases, these clades represent recognisable monophyletic lineages linked to well circumscribed anamorphs. This association is complicated, however, by the fact that morphologically similar form genera are scattered throughout the order (Capnodiales), and for some species more than one morph is expressed depending on cultural conditions and media employed for cultivation. The present study shows that Mycosphaerella s.s. should best be limited to taxa with Ramularia anamorphs, with other well defined clades in the Mycosphaerellaceae representing Cercospora, Cercosporella, Dothistroma, Lecanosticta, Phaeophleospora, Polythrincium, Pseudocercospora, Ramulispora, Septoria and Sonderhenia. The genus Teratosphaeria accommodates taxa with Kirramyces anamorphs, while other clades supported in the Teratosphaeriaceae include Baudoinea, Capnobotryella, Devriesia, Penidiella, Phaeothecoidea, Readeriella, Staninwardia and Stenella. The genus Schizothyrium with Zygophiala anamorphs is supported as belonging to the Schizothyriaceae, while Dissoconium and Ramichloridium appear to represent a distinct family. Several clades remain unresolved due to limited sampling. Mycosphaerella, which has hitherto been used as a term of convenience to describe ascomycetes with solitary ascomata, bitunicate asci and 1-septate ascospores, represents numerous genera and several families yet to be defined in future studies.
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molecular diagnostics in the Mycosphaerella leaf spot disease complex of banana and for radopholus similis
Proceedings of the International Symposium on Recent Advances in Banana Crop Protection for Sustainable Production and Improved Livelihoods White Rive, 2009Co-Authors: Mahdi Arzanlou, Cees Waalwijk, Gert H J Kema, I Carlier, P M De Vries, Mauricio Guzman, Araya M Vargas, Johannes Helder, P W CrousAbstract:Mycosphaerella leaf spots and nematodes threaten banana cultivation worldwide. The Mycosphaerella disease complex involves three related ascomycetous fungi: Mycosphaerella fijiensis, M. musicola and M. eumusae. The exact distribution of these three species and their disease epidemiology remain unclear, since their symptoms and life cycles are rather similar. Diagnosing these diseases and the respective causal agents is based on the presence of host symptoms and fungal fruiting structures, but is time consuming and not conducive to preventive management. In the present study, we developed rapid and robust species-specific diagnostic tools to detect and quantify M. fijiensis, M. musicola and M. eumusae. Conventional species-specific PCR primers were developed based on the actin gene that detected as little as 100, 1 and 10 pg/µl DNA from, respectively, M. fijiensis, M. musicola and M. eumusae. Furthermore, TaqMan real-time quantitative PCR assays that were developed based on the s-tubulin gene detected quantities as low as 1 pg/µl DNA of each species from pure cultures and 1.6 pg/µl DNA/mg of M. fijiensis from dry leaf tissue. The efficacy of the tests was validated using naturally infected banana leaves. Similar technology has been used to develop a quantitative PCR assay for the banana burrowing nematode, Radopholus similis, which is currently being validated
Michael J. Wingfield - One of the best experts on this subject based on the ideXlab platform.
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Mycosphaerella and Teratosphaeria diseases of Eucalyptus; easily confused and with serious consequences
Fungal Diversity, 2011Co-Authors: Gavin C. Hunter, Pedro W. Crous, Angus J. Carnegie, Treena I Burgess, Michael J. WingfieldAbstract:The Mycosphaerella complex accommodates thousands of taxa. Many of these species are economically important plant pathogens, notably on native and commercially propagated Eucalyptus species where they cause a wide range of disease symptoms including leaf spot, leaf blotch, shoot blight and stem cankers. Some of these diseases represent major impediments to sustainable Eucalyptus forestry in several countries where infection by Mycosphaerella and Teratosphaeria species can result in reduction of wood volume and in severe cases tree death. Extensive research has been conducted on these disease complexes over the past 40 years. The incorporation of DNA-based molecular techniques has made it possible to define and to better understand the differences between the Mycosphaerella and Teratosphaeria species occurring on Eucalyptus . These studies have also enabled refinement of anamorph and teleomorph generic concepts for the genera and thus facilitated the more accurate identification of species. They have also promoted a more lucid understanding of the biology, life cycles, population biology and epidemiology of the most important pathogens in the group.
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unravelling Mycosphaerella do you believe in genera
Persoonia, 2009Co-Authors: P W Crous, Michael J. Wingfield, Brett A. Summerell, Angus J. Carnegie, Treena I Burgess, P A Barber, G C Hunter, Vera Andjic, J Z GroenewaldAbstract:Many fungal genera have been defined based on single characters considered to be informative at the generic level. In addition, many unrelated taxa have been aggregated in genera because they shared apparently similar morphological characters arising from adaptation to similar niches and convergent evolution. This problem is aptly illustrated in Mycosphaerella. In its broadest definition, this genus of mainly leaf infecting fungi incorporates more than 30 form genera that share similar phenotypic characters mostly associated with structures produced on plant tissue or in culture. DNA sequence data derived from the LSU gene in the present study distinguish several clades and families in what has hitherto been considered to represent the Mycosphaerellaceae. In some cases, these clades represent recognisable monophyletic lineages linked to well circumscribed anamorphs. This association is complicated, however, by the fact that morphologically similar form genera are scattered throughout the order (Capnodiales), and for some species more than one morph is expressed depending on cultural conditions and media employed for cultivation. The present study shows that Mycosphaerella s.s. should best be limited to taxa with Ramularia anamorphs, with other well defined clades in the Mycosphaerellaceae representing Cercospora, Cercosporella, Dothistroma, Lecanosticta, Phaeophleospora, Polythrincium, Pseudocercospora, Ramulispora, Septoria and Sonderhenia. The genus Teratosphaeria accommodates taxa with Kirramyces anamorphs, while other clades supported in the Teratosphaeriaceae include Baudoinea, Capnobotryella, Devriesia, Penidiella, Phaeothecoidea, Readeriella, Staninwardia and Stenella. The genus Schizothyrium with Zygophiala anamorphs is supported as belonging to the Schizothyriaceae, while Dissoconium and Ramichloridium appear to represent a distinct family. Several clades remain unresolved due to limited sampling. Mycosphaerella, which has hitherto been used as a term of convenience to describe ascomycetes with solitary ascomata, bitunicate asci and 1-septate ascospores, represents numerous genera and several families yet to be defined in future studies.
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a multi gene phylogeny for species of Mycosphaerella occurring on eucalyptus leaves
Studies in Mycology, 2006Co-Authors: G C Hunter, Brenda D Wingfield, P W Crous, Michael J. WingfieldAbstract:Species of the ascomycete genus Mycosphaerella are regarded as some of the most destructive leaf pathogens of a large number of economically important crop plants. Amongst these, approximately 60 Mycosphaerella spp. have been identified from various Eucalyptus spp. where they cause leaf diseases collectively known as Mycosphaerella Leaf Disease (MLD). Species concepts for this group of fungi remain confused, and hence their species identification is notoriously difficult. Thus, the introduction of DNA sequence comparisons has become the definitive characteristic used to distinguish species of Mycosphaerella. Sequences of the Internal Transcribed Spacer (ITS) region of the ribosomal RNA operon have most commonly been used to consider species boundaries in Mycosphaerella. However, sequences for this gene region do not always provide sufficient resolution for cryptic taxa. The aim of this study was, therefore, to use DNA sequences for three loci, ITS, Elongation factor 1-alpha (EF-1α) and Actin (ACT) to reconsider species boundaries for Mycosphaerella spp. from Eucalyptus. A further aim was to study the anamorph concepts and resolve the deeper nodes of Mycosphaerella, for which part of the Large Subunit (LSU) of the nuclear rRNA operon was sequenced. The ITS and EF-1α gene regions were found to be useful, but the ACT gene region did not provide species-level resolution in Mycosphaerella. A phylogeny of the combined DNA datasets showed that species of Mycosphaerella from Eucalyptus cluster in two distinct groups, which might ultimately represent discrete genera.
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phylogenetic reassessment of Mycosphaerella spp and their anamorphs occurring on eucalyptus ii
Studies in Mycology, 2006Co-Authors: P W Crous, Michael J. Wingfield, Acelino C Alfenas, Pedro J Mansilla, J Z GroenewaldAbstract:Species of Eucalyptus are widely planted as exotics in the tropics and Southern Hemisphere and to some extent in southern Europe, for timber and fibre production. Species of Mycosphaerella are commonly associated with leaves and twigs of Eucalyptus and can result in defoliation, dieback, and even tree death. In the present study, numerous isolates of Mycosphaerella species were collected from leaf litter, living leaves exhibiting leaf spot symptoms or severe Mycosphaerella leaf blotch symptoms. Isolates were compared based on DNA sequence data for the internal transcribed spacer region (ITS1 & ITS2) and the 5.8S gene. These data, together with characteristics of the fungal growth on three different media, morphology of the anamorph and teleomorph structures as well as ascospore germination patterns were used to describe 21 new species.
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first record of colletogloeopsis zuluense comb nov causing a stem canker of eucalyptus in china
Fungal Biology, 2006Co-Authors: Marianoel Cortinas, Brenda D Wingfield, P W Crous, T Burgess, B Dell, Michael J. WingfieldAbstract:Coniothyrium zuluense causes a serious canker disease of Eucalyptus in various parts of the world. Very little is known regarding the taxonomy of this asexual fungus, which was provided with a name based solely on morphological characteristics. In this study we consider the phylogenetic position of C. zuluense using DNA-based techniques. Distance analysis using 18S and ITS regions revealed extensive sequence divergence relative to the type species of Coniothyrium, C. palmarum and species of Paraconiothyrium. Coniothyrium zuluense was shown to be an anamorph species of Mycosphaerella, a genus that includes a wide range of Eucalyptus leaf and stem pathogens. Within Mycosphaerella it clustered with taxa having pigmented, verruculose, aseptate conidia that proliferate percurrently and sympodially from pigmented conidiogenous cells arranged in conidiomata that vary from being pycnidial to acervular. The genus Colletogloeopsis is emended to include species with pycnidial conidiomata, and the new combination Colletogloeopsis zuluense is proposed. This is also the first report of the pathogen from China where it is associated with stem cankers on Eucalyptus urophylla.
J Z Groenewald - One of the best experts on this subject based on the ideXlab platform.
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the rise of ramularia from the Mycosphaerella labyrinth
Fungal Biology, 2015Co-Authors: S I R Videira, P W Crous, Uwe Braun, J Z Groenewald, Gerard J M VerkleyAbstract:In this study we aimed to resolve the Ramularia endophylla species-complex by applying a polyphasic approach involving morphology and multi-gene phylogeny. Eleven partial genes were targeted for amplification and sequencing for a total of 81 isolates representing R. endophylla s. lat. and 32 isolates representing 11 Ramularia species that were previously linked to a Mycosphaerella sexual morph in literature. A Bayesian phylogenetic analysis, as well as a parsimony analysis, was performed on a combined five-locus dataset and the resulting trees showed significant support for three species within the complex, including the previously described R. endophylla and R. vizellae, and one novel species, Ramularia unterseheri. A parsimony analysis was also separately performed with mating-type gene sequences (MAT1-1-1 and MAT1-2-1) and the resulting tree topologies were in accordance with that of the multigene analysis. A bibliographic review of the proposed links between Ramularia spp. and their purported Mycosphaerella sexual morphs is also presented, confirming six connections in Ramularia. In spite of more than 10 000 species having been described in Mycosphaerella, the majority is shown to belong to other genera, suggesting that the taxa identified as Mycosphaerella in much of the plant pathology literature needs to be revisited.
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unravelling Mycosphaerella do you believe in genera
Persoonia, 2009Co-Authors: P W Crous, Michael J. Wingfield, Brett A. Summerell, Angus J. Carnegie, Treena I Burgess, P A Barber, G C Hunter, Vera Andjic, J Z GroenewaldAbstract:Many fungal genera have been defined based on single characters considered to be informative at the generic level. In addition, many unrelated taxa have been aggregated in genera because they shared apparently similar morphological characters arising from adaptation to similar niches and convergent evolution. This problem is aptly illustrated in Mycosphaerella. In its broadest definition, this genus of mainly leaf infecting fungi incorporates more than 30 form genera that share similar phenotypic characters mostly associated with structures produced on plant tissue or in culture. DNA sequence data derived from the LSU gene in the present study distinguish several clades and families in what has hitherto been considered to represent the Mycosphaerellaceae. In some cases, these clades represent recognisable monophyletic lineages linked to well circumscribed anamorphs. This association is complicated, however, by the fact that morphologically similar form genera are scattered throughout the order (Capnodiales), and for some species more than one morph is expressed depending on cultural conditions and media employed for cultivation. The present study shows that Mycosphaerella s.s. should best be limited to taxa with Ramularia anamorphs, with other well defined clades in the Mycosphaerellaceae representing Cercospora, Cercosporella, Dothistroma, Lecanosticta, Phaeophleospora, Polythrincium, Pseudocercospora, Ramulispora, Septoria and Sonderhenia. The genus Teratosphaeria accommodates taxa with Kirramyces anamorphs, while other clades supported in the Teratosphaeriaceae include Baudoinea, Capnobotryella, Devriesia, Penidiella, Phaeothecoidea, Readeriella, Staninwardia and Stenella. The genus Schizothyrium with Zygophiala anamorphs is supported as belonging to the Schizothyriaceae, while Dissoconium and Ramichloridium appear to represent a distinct family. Several clades remain unresolved due to limited sampling. Mycosphaerella, which has hitherto been used as a term of convenience to describe ascomycetes with solitary ascomata, bitunicate asci and 1-septate ascospores, represents numerous genera and several families yet to be defined in future studies.
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species of Mycosphaerella and related anamorphs on eucalyptus leaves from thailand
Persoonia, 2008Co-Authors: Ratchadawan Cheewangkoon, P W Crous, J Z Groenewald, Kevin D Hyde, C ToananAbstract:Species of Mycosphaerella and their related anamorphs represent potentially serious foliar pathogens of Eucalyptus. The fungi treated in the present study were isolated from symptomatic Eucalyptus leaves collected in Thailand during June-October 2007. Species were initially identified based on morphological and cultural charac- teristics. Identifications were confirmed using comparisons of DNA sequence data of the internal transcribed spacers (ITS1, 5.8S nrDNA, ITS2) and the 28S nrDNA (LSU) regions. To help distinguish species of Pseudocercospora, the dataset was expanded by generating partial sequences of the translation elongation factor 1-α and actin genes. By integrating the morphological and molecular datasets, five new taxa were distinguished, namely Mycosphaerella irregulari, M. pseudomarksii, M. quasiparkii, Penidiella eucalypti and Pseudocercospora chiangmaiensis, while M. vietnamensis represents a new record for Thailand.
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multiple gene genealogies and phenotypic characters differentiate several novel species of Mycosphaerella and related anamorphs on banana
Persoonia, 2008Co-Authors: Mahdi Arzanlou, M F Zapater, J Carlier, Edwin C A Abeln, J Z Groenewald, R A Fullerton, I W Buddenhagen, Altus Viljoen, P W CrousAbstract:Three species of Mycosphaerella, namely M. eumusae, M. fijiensis, and M. musicola are involved in the Sigatoka disease complex of bananas. Besides these three primary pathogens, several additional species of Mycosphaerella or their anamorphs have been described from Musa. However, very little is known about these taxa, and for the majority of these species no culture or DNA is available for study. In the present study, we collected a global set of Mycosphaerella strains from banana, and compared them by means of morphology and a multi-gene nucleotide sequence data set. The phylogeny inferred from the ITS region and the combined data set containing partial gene sequences of the actin gene, the small subunit mitochondrial ribosomal DNA and the histone H3 gene revealed a rich diversity of Mycosphaerella species on Musa. Integration of morphological and molecular data sets confirmed more than 20 species of Mycosphaerella (incl. anamorphs) to occur on banana. This study reconfirmed the previously described presence of Cercospora apii, M. citri and M. thailandica, and also identified Mycosphaerella communis, M. lateralis and Passalora loranthi on this host. Moreover, eight new species identified from Musa are described, namely Dissoconium musae, Mycosphaerella mozambica, Pseudocercospora assamensis, P. indonesiana, P. longispora, Stenella musae, S. musicola, and S. queenslandica.
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Mycosphaerella is polyphyletic
Studies in Mycology, 2007Co-Authors: P W Crous, Uwe Braun, J Z GroenewaldAbstract:Mycosphaerella, one of the largest genera of ascomycetes, encompasses several thousand species and has anamorphs residing in more than 30 form genera. Although previous phylogenetic studies based on the ITS rDNA locus supported the monophyly of the genus, DNA sequence data derived from the LSU gene distinguish several clades and families in what has hitherto been considered to represent the Mycosphaerellaceae. Several important leaf spotting and extremotolerant species need to be disposed to the genus Teratosphaeria, for which a new family, the Teratosphaeriaceae, is introduced. Other distinct clades represent the Schizothyriaceae, Davidiellaceae, Capnodiaceae, and the Mycosphaerellaceae. Within the two major clades, namely Teratosphaeriaceae and Mycosphaerellaceae, most anamorph genera are polyphyletic, and new anamorph concepts need to be derived to cope with dual nomenclature within the Mycosphaerella complex.
Pedro W. Crous - One of the best experts on this subject based on the ideXlab platform.
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Mycosphaerella and Teratosphaeria diseases of Eucalyptus; easily confused and with serious consequences
Fungal Diversity, 2011Co-Authors: Gavin C. Hunter, Pedro W. Crous, Angus J. Carnegie, Treena I Burgess, Michael J. WingfieldAbstract:The Mycosphaerella complex accommodates thousands of taxa. Many of these species are economically important plant pathogens, notably on native and commercially propagated Eucalyptus species where they cause a wide range of disease symptoms including leaf spot, leaf blotch, shoot blight and stem cankers. Some of these diseases represent major impediments to sustainable Eucalyptus forestry in several countries where infection by Mycosphaerella and Teratosphaeria species can result in reduction of wood volume and in severe cases tree death. Extensive research has been conducted on these disease complexes over the past 40 years. The incorporation of DNA-based molecular techniques has made it possible to define and to better understand the differences between the Mycosphaerella and Teratosphaeria species occurring on Eucalyptus . These studies have also enabled refinement of anamorph and teleomorph generic concepts for the genera and thus facilitated the more accurate identification of species. They have also promoted a more lucid understanding of the biology, life cycles, population biology and epidemiology of the most important pathogens in the group.
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Host specificity and speciation of Mycosphaerella and Teratosphaeria species associated with leaf spots of Proteaceae.
Persoonia, 2008Co-Authors: Pedro W. Crous, Brett A. Summerell, Lizel Mostert, Johannes Z GroenewaldAbstract:Species of Mycosphaerella and Teratosphaeria represent important foliicolous pathogens of Proteaceae. Presently approximately 40 members of these genera (incl. anamorphs) have been recorded from Proteaceae, though the majority are not known from culture, and have never been subjected to DNA sequence analysis. During the course of this study, epitypes were designated for several important species, namely Batcheloromyces leucadendri, B. proteae, Catenulostroma macowanii, Mycosphaerella marksii, Teratosphaeria bellula, T. jonkershoekensis, T. parva, and T. proteae-arboreae. Several species were also newly described, namely Batcheloromyces sedgefieldii, Catenulostroma wingfieldii, Dissoconium proteae, Teratosphaeria persoonii, T. knoxdavesii, and T. marasasii. Although accepted as being highly host specific, some species were shown to have wider host ranges, such as M. communis (Eucalyptus, Protea), M. konae (Leucospermum, Eucalyptus), M. marksii (Eucalyptus, Leucadendron), T. associata (Eucalyptus, Protea), and T. parva (Eucalyptus, Protea), which in most cases were found to co-occur with other species of Mycosphaerella or Teratosphaeria on Proteaceae. Furthermore, earlier records of T. jonkershoekensis on Proteaceae in Australia were shown to be representative of two recently described species, T. associata and T. maxii. A phenomenon of underdeveloped, or micro-ascospores was also newly observed in asci of T. maculiformis and T. proteae-arboreae. The exact purpose of asci with two distinct types of ascospores remains to be clarified, as both types were observed to germinate on agar.
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Foliicolous Mycosphaerella spp. and their anamorphs on Corymbia and Eucalyptus
Fungal Diversity, 2007Co-Authors: Pedro W. Crous, Brett A. Summerell, Angus J. Carnegie, Caroline Mohammed, W. Himaman, Johannes Z GroenewaldAbstract:The genus Eucalyptus is host to numerous species of Mycosphaerella, several of which are only known as anamorphs, and for which no Mycosphaerella state is known. In this study new Mycosphaerella teleomorph states are described for Nothostrasseria dendritica and Trimmatostroma excentrica. Two new hyphomycete genera are introduced. Of these, Cibiessia gen. nov., with three new species accommodates an arthoconidial synanamorph of Readeriella. Phaeothecoidea gen. nov. is described for species with brown, thick-walled endoconidia. Four additional new species of Mycosphaerella are introduced with several new anamorph species described in Dissoconium, Phaeophleospora, Pseudocercospora, Ramularia and Stenella. Furthermore, an epitype is designated for Mycosphaerella molleriana. This study also presents new Eucalyptus host and distribution records including M. mexicana from Hawaii, M. ohnowa from Australia, M. acaciigena from Australia and Venezuela, M. heimii from Venezuela and Thailand, M. konae from Venezuela, and M. thailandica from Thailand.
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Phylogeny and taxonomy of Cladosporium-like hyphomycetes, including Davidiella gen. nov., the teleomorph of Cladosporium s. str.
Mycological Progress, 2003Co-Authors: Uwe Braun, Pedro W. Crous, Frank Dugan, J. Z. (ewald) Groenewald, G. Sybren De HoogAbstract:A phylogenetic study employing sequence data from the internal transcribed spacers (ITS1, ITS2) and 5.8S gene, as well as the 18S rRNA gene of various Cladosporium -like hyphomycetes revealed Cladosporium s. lat. to be heterogeneous. The genus Cladosporium s. str. was shown to represent a sister clade to Mycosphaerella s. str. , for which the teleomorph genus Davidiella is proposed. The morphology, phylogeny and taxonomy of the cladosporioid fungi are discussed on the basis of this phylogeny, which consists of several clades representing Cladosporium -like genera. Cladosporium is confined to Davidiella (Mycosphaerellaceae) anamorphs with coronate conidiogenous loci and conidial hila. Pseudocladosporium is confined to anamorphs of Caproventuria (Venturiaceae). Cladosporium -like anamorphs of the Venturia (conidia catenate) are referred to Fusicladium . Human-pathogenic Cladosporium species belong in Cladophialophora ( Capronia , Herpotrichiellaceae) and Cladosporium fulvum is representative of the Mycosphaerella/Passalora clade (Mycosphaerellaceae). Cladosporium malorum proved to provide the correct epithet for Pseudocladosporium kellermanianum (syn. Phaeoramularia kellermaniana, Cladophialophora kellermaniana ) as well as Cladosporium porophorum . Based on differences in conidiogenesis and the structure of the conidiogenous loci, further supported by molecular data, C. malorum is allocated to Alternaria .
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A phylogenetic redefinition of anamorph genera in Mycosphaerella based on ITS rDNA sequence and morphology
Mycologia, 2001Co-Authors: Pedro W. Crous, Ji-chuan Kang, Uwe BraunAbstract:Anamorph genera associated with Mycos- phaerella are separated on a combination of charac- ters such as conidiomatal structure, the nature and arrangement of conidiophores, conidiogenesis, de- hiscence scars and pigmentation. To date 27 genera have been reported as anamorphs of Mycosphaerella, 19 of which were included in this study. Based on the phylogeny of the ITS1, 5.8S, and ITS2 rDNA se- quence data, Mycosphaerella proved to be monophy- letic. The major group consisted of several small clus- ters correlating to specific anamorph genera, as well as other clusters containing an assemblage of ana- morph genera. Although Mycosphaerella is monophy- letic, it appears that many of the morphological char- acters defining different anamorph genera evolved more than once and for the most part do not rep- resent true groups within Mycosphaerella. Neverthe- less, the anamorph generic concepts contain valuable information of practical use to plant pathologists and mycologists working with these organisms. Based on these results, as well as a re-evaluation of the criteria upon which anamorph genera are distinguished in
Mahdi Arzanlou - One of the best experts on this subject based on the ideXlab platform.
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evolutionary dynamics of mating type loci of Mycosphaerella spp occurring on banana
Eukaryotic Cell, 2010Co-Authors: P W Crous, Mahdi Arzanlou, Luteharm ZwiersAbstract:The devastating Sigatoka disease complex of banana is primarily caused by three closely related heterothallic fungi belonging to the genus Mycosphaerella: M. fijiensis, M. musicola, and M. eumusae. Previous phylogenetic work showing common ancestry led us to analyze the mating-type loci of these Mycosphaerella species occurring on banana. We reasoned that this might provide better insight into the evolutionary history of these species. PCR and chromosome-walking approaches were used to clone the mating-type loci of M. musicola and M. eumusae. Sequences were compared to the published mating-type loci of M. fijiensis and other Mycosphaerella spp., and a novel organization of the MAT loci was found. The mating-type loci of the examined Mycosphaerella species are expanded, containing two additional Mycosphaerella-specific genes in a unique genomic organization. The proteins encoded by these novel genes show a higher interspecies than intraspecies homology. Moreover, M. fijiensis, M. musicola, and M. eumusae contain two additional mating-type-like loci, containing parts of both MAT1-1-1 and MAT1-2-1. The data indicate that M. fijiensis, M. musicola, and M. eumusae share an ancestor in which a fusion event occurred between MAT1-1-1 and MAT1-2-1 sequences and in which additional genes became incorporated into the idiomorph. The new genes incorporated have since then evolved independently in the MAT1-1 and MAT1-2 loci. Thus, these data are an example of the evolutionary dynamics of fungal MAT loci in general and show the great flexibility of the MAT loci of Mycosphaerella species in particular.
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molecular diagnostics in the Mycosphaerella leaf spot disease complex of banana and for radopholus similis
Proceedings of the International Symposium on Recent Advances in Banana Crop Protection for Sustainable Production and Improved Livelihoods White Rive, 2009Co-Authors: Mahdi Arzanlou, Cees Waalwijk, Gert H J Kema, I Carlier, P M De Vries, Mauricio Guzman, Araya M Vargas, Johannes Helder, P W CrousAbstract:Mycosphaerella leaf spots and nematodes threaten banana cultivation worldwide. The Mycosphaerella disease complex involves three related ascomycetous fungi: Mycosphaerella fijiensis, M. musicola and M. eumusae. The exact distribution of these three species and their disease epidemiology remain unclear, since their symptoms and life cycles are rather similar. Diagnosing these diseases and the respective causal agents is based on the presence of host symptoms and fungal fruiting structures, but is time consuming and not conducive to preventive management. In the present study, we developed rapid and robust species-specific diagnostic tools to detect and quantify M. fijiensis, M. musicola and M. eumusae. Conventional species-specific PCR primers were developed based on the actin gene that detected as little as 100, 1 and 10 pg/µl DNA from, respectively, M. fijiensis, M. musicola and M. eumusae. Furthermore, TaqMan real-time quantitative PCR assays that were developed based on the s-tubulin gene detected quantities as low as 1 pg/µl DNA of each species from pure cultures and 1.6 pg/µl DNA/mg of M. fijiensis from dry leaf tissue. The efficacy of the tests was validated using naturally infected banana leaves. Similar technology has been used to develop a quantitative PCR assay for the banana burrowing nematode, Radopholus similis, which is currently being validated
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multiple gene genealogies and phenotypic characters differentiate several novel species of Mycosphaerella and related anamorphs on banana
Persoonia, 2008Co-Authors: Mahdi Arzanlou, M F Zapater, J Carlier, Edwin C A Abeln, J Z Groenewald, R A Fullerton, I W Buddenhagen, Altus Viljoen, P W CrousAbstract:Three species of Mycosphaerella, namely M. eumusae, M. fijiensis, and M. musicola are involved in the Sigatoka disease complex of bananas. Besides these three primary pathogens, several additional species of Mycosphaerella or their anamorphs have been described from Musa. However, very little is known about these taxa, and for the majority of these species no culture or DNA is available for study. In the present study, we collected a global set of Mycosphaerella strains from banana, and compared them by means of morphology and a multi-gene nucleotide sequence data set. The phylogeny inferred from the ITS region and the combined data set containing partial gene sequences of the actin gene, the small subunit mitochondrial ribosomal DNA and the histone H3 gene revealed a rich diversity of Mycosphaerella species on Musa. Integration of morphological and molecular data sets confirmed more than 20 species of Mycosphaerella (incl. anamorphs) to occur on banana. This study reconfirmed the previously described presence of Cercospora apii, M. citri and M. thailandica, and also identified Mycosphaerella communis, M. lateralis and Passalora loranthi on this host. Moreover, eight new species identified from Musa are described, namely Dissoconium musae, Mycosphaerella mozambica, Pseudocercospora assamensis, P. indonesiana, P. longispora, Stenella musae, S. musicola, and S. queenslandica.
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cryptic speciation and host specificity among Mycosphaerella spp occurring on australian acacia species grown as exotics in the tropics
Studies in Mycology, 2004Co-Authors: P W Crous, W. Himaman, Mahdi Arzanlou, J Z Groenewald, K Pongpanich, M J WingfieldAbstract:Species of Mycosphaerella and their anamorphs represent serious pathogens of two phyllodenous species of Acacia, A. mangium and A. crassicarpa. In recent years, these fungi have been collected during surveys in South America and South- East Asia, where these trees are widely planted as exotics. In this study, the Mycosphaerella spp. and their anamorphs were identified based on morphological and cultural characteristics. Identifications were confirmed using comparisons of DNA sequences for the internal transcribed spacers (ITS1 & ITS2), the 5.8S rRNA gene, elongation factor 1-α, histone 3, actin and calmodulin gene regions. The data revealed six new taxa, of which three are named in this study, along with their anamorphs. Cercospora acaciae-mangii, which is morphologically part of the C. apii sensu lato species complex, is distinguished based on its distinct phylogeny. Mycosphaerella acaciigena, collected in Venezuela, is distinguished from M. konae and M. heimii, and described as new. Mycosphaerella thailandica, a new species occurring on Acacia and Musa, is shown to be a sibling species to M. colombiensis , a foliar pathogen of Eucalyptus. Mycosphaerella citri, an important leaf and fruit pathogen of Citrus (Rutaceae), is shown to also occur on Musa (Musaceae) and Acacia (Leguminosae). Taxonomic novelties: Cercospora acaciae-mangii Crous, Pongpanich & M.J. Wingf. sp. nov., Mycosphaerella acaciigena Crous & M.J. Wingf. sp. nov. (anamorph Pseudocercospora acaciigena Crous & M.J. Wingf. sp. nov.), Mycosphaerella thailandica Crous, Himaman & M.J. Wingf. sp. nov. (anamorph Pseudocercospora thailandica Crous, Himaman & M.J. Wingf. sp. nov.).
