Ali H. Bahkali

Families of Dothideomycetes

Dothideomycetes comprise a highly diverse range of fungi characterized mainly by asci with two wall layers (bitunicate asci) and often with fissitunicate dehiscence. Many species are saprobes, with many asexual states comprising important plant pathogens. They are also endophytes, epiphytes, fungicolous, lichenized, or lichenicolous fungi. They occur in terrestrial, freshwater and marine habitats in almost every part of the world. We accept 105 families in Dothideomycetes with the new families Anteagloniaceae, Bambusicolaceae, Biatriosporaceae, Lichenoconiaceae, Muyocopronaceae, Paranectriellaceae, Roussoellaceae, Salsugineaceae, Seynesiopeltidaceae and Thyridariaceae introduced in this paper. Each family is provided with a description and notes, including asexual and asexual states, and if more than one genus is included, the type genus is also characterized. Each family is provided with at least one figure-plate, usually illustrating the type genus, a list of accepted genera, including asexual genera, and a key to these genera. A phylogenetic tree based on four gene combined analysis add support for 64 of the families and 22 orders, including the novel orders, Dyfrolomycetales, Lichenoconiales, Lichenotheliales, Monoblastiales, Natipusillales, Phaeotrichales and Strigulales. The paper is expected to provide a working document on Dothideomycetes which can be modified as new data comes to light. It is hoped that by illustrating types we provide stimulation and interest so that more work is carried out in this remarkable group of fungi.

The genus Phomopsis: biology, applications, species concepts and names of common phytopathogens

The genus Phomopsis (teleomorph Diaporthe) comprises phytopathologically important microfungi with diverse host associations and a worldwide distribution. Species concepts in Phomopsis have been based historically on morphology, cultural characteristics and host affiliation. This paper serves to provide an overview of the current status of the taxonomy in Phomopsis with special reference to biology, applications of various species, species concepts, future research perspectives and names of common pathogens, the latter being given taxonomic reappraisal. Accurate species identification is critical to understanding disease epidemiology and in developing effective control measures for plant diseases. Difficulties in accurate species identification using morphology have led to the application of alternative approaches to differentiate species, including virulence and pathogenicity, biochemistry, metabolites, physiology, antagonism, molecular phylogenetics and mating experiments. Redefinition of Phomopsis/Diaporthe species has been ongoing, and some species have been redefined based on a combination of molecular, morphological, cultural, phytopathological and mating type data. Rapid progress in molecular identification has in particular revolutionized taxonomic studies, providing persuasive genetic evidence to define the species boundaries. A backbone ITS based phylogenetic tree is here in generated using the sequences derived from 46 type, epitype cultures, and vouchers and is presented as a rough and quick identification guide for species of Phomopsis. The need for epitypification of taxonomic entities and the need to use multiple loci in phylogenies that better reflect species limits are suggested. The account of names of phytopathogens currently in use are listed alphabetically and annotated with a taxonomic entry, teleomorph, associated hosts and disease symptoms, including brief summaries of taxonomic and phylogenetic research. Available type culture information and details of gene sequences derived from type cultures are also summarized and tabulated.

The genomes of the fungal plant pathogens Cladosporium fulvum and Dothistroma septosporum reveal adaptation to different hosts and lifestyles but also signatures of common ancestry.

We sequenced and compared the genomes of the Dothideomycete fungal plant pathogens Cladosporium fulvum (Cfu) (syn. Passalora fulva) and Dothistroma septosporum (Dse) that are closely related phylogenetically, but have different lifestyles and hosts. Although both fungi grow extracellularly in close contact with host mesophyll cells, Cfu is a biotroph infecting tomato, while Dse is a hemibiotroph infecting pine. The genomes of these fungi have a similar set of genes (70% of gene content in both genomes are homologs), but differ significantly in size (Cfu >61.1-Mb; Dse 31.2-Mb), which is mainly due to the difference in repeat content (47.2% in Cfu versus 3.2% in Dse). Recent adaptation to different lifestyles and hosts is suggested by diverged sets of genes. Cfu contains an α-tomatinase gene that we predict might be required for detoxification of tomatine, while this gene is absent in Dse. Many genes encoding secreted proteins are unique to each species and the repeat-rich areas in Cfu are enriched for these species-specific genes. In contrast, conserved genes suggest common host ancestry. Homologs of Cfu effector genes, including Ecp2 and Avr4, are present in Dse and induce a Cf-Ecp2- and Cf-4-mediated hypersensitive response, respectively. Strikingly, genes involved in production of the toxin dothistromin, a likely virulence factor for Dse, are conserved in Cfu, but their expression differs markedly with essentially no expression by Cfu in planta. Likewise, Cfu has a carbohydrate-degrading enzyme catalog that is more similar to that of necrotrophs or hemibiotrophs and a larger pectinolytic gene arsenal than Dse, but many of these genes are not expressed in planta or are pseudogenized. Overall, comparison of their genomes suggests that these closely related plant pathogens had a common ancestral host but since adapted to different hosts and lifestyles by a combination of differentiated gene content, pseudogenization, and gene regulation.

The Faces of Fungi database: fungal names linked with morphology, phylogeny and human impacts

Taxonomic names are key links between various databases that store information on different organisms. Several global fungal nomenclural and taxonomic databases (notably Index Fungorum, Species Fungorum and MycoBank) can be sourced to find taxonomic details about fungi, while DNA sequence data can be sourced from NCBI, EBI and UNITE databases. Although the sequence data may be linked to a name, the quality of the metadata is variable and generally there is no corresponding link to images, descriptions or herbarium material. There is generally no way to establish the accuracy of the names in these genomic databases, other than whether the submission is from a reputable source. To tackle this problem, a new database (FacesofFungi), accessible at www.facesoffungi.org (FoF) has been established. This fungal database allows deposition of taxonomic data, phenotypic details and other useful data, which will enhance our current taxonomic understanding and ultimately enable mycologists to gain better and updated insights into the current fungal classification system. In addition, the database will also allow access to comprehensive metadata including descriptions of voucher and type specimens. This database is user-friendly, providing links and easy access between taxonomic ranks, with the classification system based primarily on molecular data (from the literature and via updated web-based phylogenetic trees), and to a lesser extent on morphological data when molecular data are unavailable. In FoF species are not only linked to the closest phylogenetic representatives, but also relevant data is provided, wherever available, on various applied aspects, such as ecological, industrial, quarantine and chemical uses. The data include the three main fungal groups (Ascomycota, Basidiomycota, Basal fungi) and fungus-like organisms. The FoF webpage is an output funded by the Mushroom Research Foundation which is an NGO with seven directors with mycological expertise. The webpage has 76 curators, and with the help of these specialists, FoF will provide an updated natural classification of the fungi, with illustrated accounts of species linked to molecular data. The present paper introduces the FoF database to the scientific community and briefly reviews some of the problems associated with classification and identification of the main fungal groups. The structure and use of the database is then explained. We would like to invite all mycologists to contribute to these web pages.

Pestalotiopsis—morphology, phylogeny, biochemistry and diversity

The genus Pestalotiopsis has received considerable attention in recent years, not only because of its role as a plant pathogen but also as a commonly isolated endophyte which has been shown to produce a wide range of chemically novel diverse metabolites. Classification in the genus has been previously based on morphology, with conidial characters being considered as important in distinguishing species and closely related genera. In this review, Pestalotia, Pestalotiopsis and some related genera are evaluated; it is concluded that the large number of described species has resulted from introductions based on host association. We suspect that many of these are probably not good biological species. Recent molecular data have shown that conidial characters can be used to distinguish taxa; however, host association and geographical location is less informative. The taxonomy of the genera complex remains confused. There are only a few type cultures and, therefore, it is impossible to use gene sequences in GenBank to clarify species names reliably. It has not even been established whether Pestalotia and Pestalotiopsis are distinct genera, as no isolates of the type species of Pestalotia have been sequenced, and they are morphologically somewhat similar. When selected GenBank ITS accessions of Pestalotiopsis clavispora, P. disseminata, P. microspora, P. neglecta, P. photiniae, P. theae, P. virgatula and P. vismiae are aligned, most species cluster throughout any phylogram generated. Since there appears to be no living type strain for any of these species, it is unwise to use GenBank sequences to represent any of these names. Type cultures and sequences are available for the recently described species P. hainanensis, P. jesteri, P. kunmingensis and P. pallidotheae. It is clear that the important species in Pestalotia and Pestalotiopsis need to be epitypified so that we can begin to understand the genus/genera. There are numerous reports in the literature that various species produce taxol, while others produce newly discovered compounds with medicinal potential and still others cause disease. The names assigned to these novel compound-producing taxa lack an accurate taxonomic basis, since the taxonomy of the genus is markedly confused. Until the important species have been epitypified with living strains that have been sequenced and deposited in public databases, researchers should refrain from providing the exact name of species.

Naming and outline of Dothideomycetes-2014 including proposals for the protection or suppression of generic names

Article 59.1, of the International Code of Nomenclature for Algae, Fungi, and Plants (ICN; Melbourne Code), which addresses the nomenclature of pleomorphic fungi, became effective from 30 July 2011. Since that date, each fungal species can have one nomenclaturally correct name in a particular classification. All other previously used names for this species will be considered as synonyms. The older generic epithet takes priority over the younger name. Any widely used younger names proposed for use, must comply with Art. 57.2 and their usage should be approved by the Nomenclature Committee for Fungi (NCF). In this paper, we list all genera currently accepted by us in Dothideomycetes (belonging to 23 orders and 110 families), including pleomorphic and non-pleomorphic genera. In the case of pleomorphic genera, we follow the rulings of the current ICN and propose single generic names for future usage. The taxonomic placements of 1261 genera are listed as an outline. Protected names and suppressed names for 34 pleomorphic genera are listed separately. Notes and justifications are provided for possible proposed names after the list of genera. Notes are also provided on recent advances in our understanding of asexual and sexual morph linkages in Dothideomycetes. A phylogenetic tree based on four gene analyses supported 23 orders and 75 families, while 35 families still lack molecular data.

Fungal diversity notes 1–110: taxonomic and phylogenetic contributions to fungal species

This paper is a compilation of notes on 110 fungal taxa, including one new family, 10 new genera, and 76 new species, representing a wide taxonomic and geographic range. The new family, Paradictyoarthriniaceae is introduced based on its distinct lineage in Dothideomycetes and its unique morphology. The family is sister to Biatriosporaceae and Roussoellaceae. The new genera are Allophaeosphaeria (Phaeosphaeriaceae), Amphibambusa (Amphisphaeriaceae), Brunneomycosphaerella (Capnodiales genera incertae cedis), Chaetocapnodium (Capnodiaceae), Flammeascoma (Anteagloniaceae), Multiseptospora (Pleosporales genera incertae cedis), Neogaeumannomyces (Magnaporthaceae), Palmiascoma (Bambusicolaceae), Paralecia (Squamarinaceae) and Sarimanas (Melanommataceae). The newly described species are the Ascomycota Aliquandostipite manochii, Allophaeosphaeria dactylidis, A. muriformia, Alternaria cesenica, Amphibambusa bambusicola, Amphisphaeria sorbi, Annulohypoxylon thailandicum, Atrotorquata spartii, Brunneomycosphaerella laburni, Byssosphaeria musae, Camarosporium aborescentis, C. aureum, C. frutexensis, Chaetocapnodium siamensis, Chaetothyrium agathis, Colletotrichum sedi, Conicomyces pseudotransvaalensis, Cytospora berberidis, C. sibiraeae, Diaporthe thunbergiicola, Diatrype palmicola, Dictyosporium aquaticum, D. meiosporum, D. thailandicum, Didymella cirsii, Dinemasporium nelloi, Flammeascoma bambusae, Kalmusia italica, K. spartii, Keissleriella sparticola, Lauriomyces synnematicus, Leptosphaeria ebuli, Lophiostoma pseudodictyosporium, L. ravennicum, Lophiotrema eburnoides, Montagnula graminicola, Multiseptospora thailandica, Myrothecium macrosporum, Natantispora unipolaris, Neogaeumannomyces bambusicola, Neosetophoma clematidis, N. italica, Oxydothis atypica, Palmiascoma gregariascomum, Paraconiothyrium nelloi, P. thysanolaenae, Paradictyoarthrinium tectonicola, Paralecia pratorum, Paraphaeosphaeria spartii, Pestalotiopsis digitalis, P. dracontomelon, P. italiana, Phaeoisaria pseudoclematidis, Phragmocapnias philippinensis, Pseudocamarosporium cotinae, Pseudocercospora tamarindi, Pseudotrichia rubriostiolata, P. thailandica, Psiloglonium multiseptatum, Saagaromyces mangrovei, Sarimanas pseudofluviatile, S. shirakamiense, Tothia spartii, Trichomerium siamensis, Wojnowicia dactylidicola, W. dactylidis and W. lonicerae. The Basidiomycota Agaricus flavicentrus, A. hanthanaensis, A. parvibicolor, A. sodalis, Cantharellus luteostipitatus, Lactarius atrobrunneus, L. politus, Phylloporia dependens and Russula cortinarioides are also introduced. Epitypifications or reference specimens are designated for Hapalocystis berkeleyi, Meliola tamarindi, Pallidocercospora acaciigena, Phaeosphaeria musae, Plenodomus agnitus, Psiloglonium colihuae, P. sasicola and Zasmidium musae while notes and/or new sequence data are provided for Annulohypoxylon leptascum, A. nitens, A. stygium, Biscogniauxia marginata, Fasciatispora nypae, Hypoxylon fendleri, H. monticulosum, Leptosphaeria doliolum, Microsphaeropsis olivacea, Neomicrothyrium, Paraleptosphaeria nitschkei, Phoma medicaginis and Saccotheciaceae. A full description of each species is provided with light micrographs (or drawings). Molecular data is provided for 90 taxa and used to generate phylogenetic trees to establish a natural classification for species.

Horizontal gene and chromosome transfer in plant pathogenic fungi affecting host range

Plant pathogenic fungi adapt quickly to changing environments including overcoming plant disease resistance genes. This is usually achieved by mutations in single effector genes of the pathogens, enabling them to avoid recognition by the host plant. In addition, horizontal gene transfer (HGT) and horizontal chromosome transfer (HCT) provide a means for pathogens to broaden their host range. Recently, several reports have appeared in the literature on HGT, HCT and hybridization between plant pathogenic fungi that affect their host range, including species of Stagonospora/Pyrenophora, Fusarium and Alternaria. Evidence is given that HGT of the ToxA gene from Stagonospora nodorum to Pyrenophora tritici-repentis enabled the latter fungus to cause a serious disease in wheat. A nonpathogenic Fusarium species can become pathogenic on tomato by HCT of a pathogenicity chromosome from Fusarium oxysporum f.sp lycopersici, a well-known pathogen of tomato. Similarly, Alternaria species can broaden their host range by HCT of a single chromosome carrying a cluster of genes encoding host-specific toxins that enabled them to become pathogenic on new hosts such as apple, Japanese pear, strawberry and tomato, respectively. The mechanisms HGT and HCT and their impact on potential emergence of fungal plant pathogens adapted to new host plants will be discussed.

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.

From morphology to molecular biology: can we use sequence data to identify fungal endophytes?

Isolation followed by morphological identification was the traditional basis of all earlier endophyte studies. However, the use of molecular phylogenetics has become increasingly common in the identification of fungal endophytes, and during the period of 2007–2010 there were approximately 200 publications that reported data obtained using this approach. This new methodology involves using sequence data from isolates or whole DNA from plant substrates, which are amplified using fungus- specific primers. The data obtained are compared with sequences downloaded from public databases such as GenBank and then used to construct phylogenetic trees. The major problem with this approach is that much of the sequence data in these databases has been shown to be from isolates that were incorrectly named. In some species, as much as 86% of the sequences available are not from the organism whose name has been applied to the sequence in question. The use of these GenBank sequences to identify endophytic isolates by sequence similarity simply perpetuates the problem of wrong species identification, and any lists of endophytes established by such methods are likely to be highly erroneous. It is recommended that comparisons of sequence data be made using sequences from type species, and if such sequences are not available, then the data must be treated with caution.