A review of the phylogeny and biology of the Diaporthales

Diversity of cultivable fungal endophytes in Paullinia cupana (Mart.) Ducke and bioactivity of their secondary metabolites

Paullinia cupana is associated with a diverse community of pathogenic and endophytic microorganisms. We isolated and identified endophytic fungal communities from the roots and seeds of P. cupana genotypes susceptible and tolerant to anthracnose that grow in two sites of the Brazilian Amazonia forest. We assessed the antibacterial, antitumor and genotoxic activity in vitro of compounds isolated from the strains Trichoderma asperellum (1BDA) and Diaporthe phaseolorum (8S). In concert, we identified eight fungal species not previously reported as endophytes; some fungal species capable of inhibiting pathogen growth; and the production of antibiotics and compounds with bacteriostatic activity against Pseudomonas aeruginosa in both susceptible and multiresistant host strains. The plant genotype, geographic location and specially the organ influenced the composition of P. cupana endophytic fungal community. Together, our findings identify important functional roles of endophytic species found within the microbiome of P. cupana. This hypothesis requires experimental validation to propose management of this microbiome with the objective of promoting plant growth and protection.

Coniella vitis sp. nov. Is the Common Pathogen of White Rot in Chinese Vineyards

Grape white rot is a common disease and causes considerable yield losses in many grape-growing regions when environmental conditions are favorable. We surveyed grape white rot in five provinces in China and collected 27 isolates from diseased grape tissues. Multigene phylogenetic analyses of the internal transcribed spacer region (ITS1-5.8S-ITS2), the 28S large subunit of nuclear ribosomal RNA (LSU), partial translation elongation factor 1-alpha gene (TEF 1-α), and partial histone 3 gene (HIS), coupled with genealogical concordance phylogenetic species recognition and morphological observations, revealed that Coniella vitis sp. nov. and C. diplodiella are the causal agents of grape white rot in China. Koch's postulates were performed on Vitis vinifera cv. Summer Black in a greenhouse. These results confirmed the pathogenicity on grapes, as symptoms were reproduced, and also indicated significant variations in the virulence among C. vitis isolates. This work provides evidence that C. vitis is the main pathogen of grape white rot in China and also provides an optimized multigene backbone for resolving Coniella species.

Confirmation of independent introductions of an exotic plant pathogen of Cornus species, Discula destructiva, on the east and west coasts of North America

Cornus florida (flowering dogwood) and C. nuttallii (Pacific dogwood) are North American native tree species that belong to the big-bracted group of dogwoods. Cornus species are highly valued for their ornamental characteristics, and have fruits that contain high fat content for animals. Also, they are an important understory tree in natural forests. Dogwood anthracnose, caused by Discula destructiva, was observed in the late 1970s on the east and west coasts of the United States and by 1991 had quickly spread throughout most of the native ranges of C. florida and C. nuttalli. We investigated the genetic diversity and population structure of 93 D. destructiva isolates using 47 microsatellite loci developed from the sequenced genome of the type strain of D. destructiva. Clone-corrected data indicated low genetic diversity and the presence of four genetic clusters that corresponded to two major geographic areas, the eastern United States and the Pacific Northwest, and to the two collection time periods when the isolates were collected (pre- and post-1993). Linkage disequilibrium was present in five out of six subpopulations, suggesting that the fungus only reproduced asexually. Evidence of population bottlenecks was indicated across four identified genetic clusters, and was probably the result of the limited number of founding individuals on both coasts. These results support the hypothesis that D. destructiva is an exotic pathogen with independent introductions on the east and west coasts of North America. We also tested the cross-amplification of these microsatellite primers to other Discula species. Genomic DNA from 17 isolates of four other Discula species and two isolates of Juglanconis species (formerly Melanconis species) were amplified by 17 of 47 primer pairs. These primers may be useful for investigating the genetic diversity and population structure of these Discula species.

Families of Diaporthales based on morphological and phylogenetic evidence

Diaporthales is an important ascomycetous order comprising phytopathogenic, saprobic, and endophytic fungi, but interfamilial taxonomic relationships are still ambiguous. Despite its cosmopolitan distribution and high diversity with distinctive morphologies, this order has received relativelyiaceae, Macrohilaceae, Melanconidaceae, Pseudoplagiostomaceae, Schizoparmaceae, Stilbosporaceae and Sydowiellaceae. Taxonomic uncertainties among genera are also clarified and recurrent discrepancies in the taxonomic position of families within the Diaporthales are discussed. An updated outline and key to families and genera of the order is presented.

Development of qPCR systems to quantify shoot infections by canker-causing pathogens in stone fruits and nut crops

AIMS

To develop real-time PCR assays for quantification of shoot infection levels of canker disease of stone fruits and nut crops caused by six fungal pathogen groups.

METHODS AND RESULTS

This study focused on six major canker-causing fungal pathogen groups: Phomopsis sp., Botryosphaeria dothidea, Lasiodiplodia sp., Cytospora sp., Neofusicoccum sp. and Diplodia sp., occurring in stone fruits and nut crops in California. DNA primers were designed to specifically target each of the six pathogen groups after the specificity tests using canker-causing and non-canker-causing pathogens and by using DNA sequences of other species from GenBank using blast. The quantitative real-time PCR (qPCR) systems were developed and used to quantify the infection levels of inoculated dried plum shoots.

CONCLUSIONS

For Neofusicoccum sp. and Phomopsis sp., which were used in inoculation of walnut shoots, the values of the molecular severity ranged from 5·60 to 6·94 during the 16 days of latent infection period. The qPCR assays were more efficient, accurate and precise to quantify latent infections caused by canker-causing pathogens as compared to the traditional plating methods.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrated the potential of using the developed qPCR systems for epidemiological studies on canker diseases of woody plants.

High genetic variability in endophytic fungi from the genus Diaporthe isolated from common bean (Phaseolus vulgaris L.) in Brazil

AIMS

The goals of the present study were to identify, to analyse the phylogenetic relations and to evaluate the genetic variability in Diaporthe endophytic isolates from common bean.

METHODS AND RESULTS

Diaporthe sp., D. infecunda and D. phaseolorum strains were identified using multilocus phylogeny (rDNA ITS region; EF1-α, β-tubulin, and calmodulin genes). IRAP (Inter-Retrotransposon Amplified Polymorphism) and REMAP (Retrotransposon-Microsatellite Amplified Polymorphism) molecular markers reveal the existence of high genetic variability, especially among D. infecunda isolates.

CONCLUSIONS

It was concluded that the multilocus phylogenetic approach was more effective than individual analysis of ITS sequences, in identifying the isolates to species level, and that IRAP and REMAP markers can be used for studying the genetic variability in the genus Diaporthe particularly at the intraspecific level.

SIGNIFICANCE AND IMPACT OF THE STUDY

The combined use of molecular tools such as multilocus phylogenetic approach and molecular markers, as performed in this study, is the best way to distinguish endophytic strains of Diaporthe isolated from common bean (Phaseolus vulgaris L.).

Citizen science data reveal ecological, historical and evolutionary factors shaping interactions between woody hosts and wood-inhabiting fungi

Woody plants host diverse communities of associated organisms, including wood-inhabiting fungi. In this group, host effects on species richness and interaction network structure are not well understood, especially not at large geographical scales. We investigated ecological, historical and evolutionary determinants of fungal species richness and network modularity, that is, subcommunity structure, across woody hosts in Denmark, using a citizen science data set comprising > 80 000 records of > 1000 fungal species on 91 genera of woody plants. Fungal species richness was positively related to host size, wood pH, and the number of species in the host genus, with limited influence of host frequency and host history, that is, time since host establishment in the area. Modularity patterns were unaffected by host history, but largely reflected host phylogeny. Notably, fungal communities differed substantially between angiosperm and gymnosperm hosts. Host traits and evolutionary history appear to be more important than host frequency and recent history in structuring interactions between hosts and wood-inhabiting fungi. High wood acidity appears to act as a stress factor reducing fungal species richness, while large host size, providing increased niche diversity, enhances it. In some fungal groups that are known to interact with live host cells in the establishment phase, host selectivity is common, causing a modular community structure.

Revising the Schizoparmaceae: Coniella and its synonyms Pilidiella and Schizoparme

The asexual genera Coniella (1918) and Pilidiella (1927), including their sexual morphs in Schizoparme (1923), have a cosmopolitan distribution and are associated with foliar, fruit, leaf, stem and root diseases on a wide variety of hosts. Species of these genera sometimes occur as secondary invaders of plant tissues infected by other organisms or that are injured by other causes. Several studies published over the last few decades had conflicting ideas as to whether Coniella, Pilidiella and Schizoparme should be regarded as synonymous or as separate genera. The present study aims to resolve the generic classification of these genera through phylogenetic analyses of the concatenated alignment of partial LSU nrDNA, rpb2, ITS nrDNA and tef1 sequence data of 117 isolates, combined with their morphology. Results revealed that all strains cluster in a single well-supported clade. Conidial colour, traditionally the distinguishing character between Coniella and Pilidiella, evolved multiple times throughout the clade, and is not a good character at generic level in Schizoparmaceae. The three genera should therefore be regarded as synonymous, with the older name Coniella having priority. Furthermore, this study delineated 13 new species, and new combinations were proposed for a further 15 species.

Complete Genome Sequence of the Endophytic Fungus Diaporthe (Phomopsis) ampelina

Diaporthe ampelina was isolated as an endophytic fungus from the root of Commiphora wightii, a medicinal plant collected from Dhanvantri Vana, Bangalore University, Bangalore, India. The whole genome is 59 Mb, contains a total of 905 scaffolds, and has a G+C content of 51.74%. The genome sequence of D. ampelina shows a complete absence of lovastatin (an anticholesterol drug) gene cluster.

New combinations of plant-associated fungi resulting from the change to one name for fungi

In advancing to one scientific name for each fungus species, a number of name changes are required especially for plant-associated fungi. These include species names that are not in the correct genus. For example, the generic name Elsinoë is used for fungi causing scab diseases but a number of these species were described in the asexually typified genus Sphaceloma and must be placed in Elsinoë. In other cases species names were determined to be unrelated to the type species of the genus in which they are currently placed and are placed in a more appropriate genus. For each new name the history, rationale and importance of the name is discussed. The following new combinations are made: Acanthohelicospora aurea, A. scopula, Bifusella ahmadii, Botryobasidium capitatum, B. rubiginosum, Colletotrichum magnum, Crandallia acuminata, C. antarctica, Elsinoë arachadis, E. freyliniae, E. necator, E. perseae, E. poinsettiae, E. punicae, Entyloma gibbum, Harknessia farinosa, Passalora alocasiae, Protoventuria veronicae, Pseudocercosporella ranunculi, Psiloglonium stygium, Ramularia pseudomaculiformis, Seimatosporium tostum, Thielaviopsis radicicola combs. nov., and Venturia effusa.

Pyrrolocin A, a 3-Decalinoyltetramic Acid with Selective Biological Activity, Isolated from Amazonian Cultures of the Novel Endophyte Diaporthales sp. E6927E

Natural products remain an important source of new therapeutics for emerging drug-resistant pathogens like Candida albicans, which particularly affects immunocompromised patients. A bioactive 3-decalinoyltetramic acid, pyrrolocin A, was isolated from extracts of a novel Amazonian fungal endophyte, E6927E, of the Diaporthales family. The structure of the natural product was solved using NMR and CD spectroscopy and it is structurally related to the fungal setins, equisetin and phomasetin, which are well-characterized tetramic acid antibiotics specific for Gram-positive organisms. We show that the compound inhibits growth of Staphylococcus aureus and Enterococcus faecalis. It shows selective and potent bioactivity against fungal strains, with an MIC of 4 μg/mL for C. albicans, 100 μg/mL for Aspergillus sp. and greater than 100 μg/mL for Saccharomyces cerevisiae. Further, the compound is less toxic to mammalian cells (IC50 = 150 μg/mL), with an inhibitory concentration greater than forty times that for C. albicans. Pyrrolocin A retained potent activity against eight out of seventeen strains of clinical Candida sp. isolates tested.

Diversity of Diaporthe species associated with wood cankers of fruit and nut crops in northern California

Diaporthe ampelina, causal agent of Phomopsis cane and leaf spot of grapevine (Vitis vinifera L.) is isolated frequently from grapevine wood cankers, causing Phomopsis dieback. The latter disease is associated with four other Diaporthe species, three of which also are reported from hosts other than grape. To better understand the role of this Diaporthe community in Phomopsis dieback of grapevine and the potential for infection routes among alternate hosts, 76 Diaporthe isolates were recovered from wood cankers of cultivated grape, pear, apricot, almond and the wild host willow in four California counties. Isolates were characterized morphologically and assigned to species based on multigene sequence analyses. This study identified eight Diaporthe species from grapevine and one novel taxon from willow, D. benedicti. We report the first findings of D. australafricana and D. novem in North America. Our findings also expand the host ranges of D. ambigua to apricot and willow, D. australafricana to almond and willow, D. chamaeropis to grapevine and willow, D. foeniculina to willow and D. novem to almond. The generalists D. ambigua and D. eres were the most genetically diverse species, based on high nucleotide and haplotypic diversity, followed by the grapevine specialist D. ampelina. Analyses based on multilocus linkage disequilibrium could not reject the hypothesis of random mating for D. ambigua, which is further supported by relatively high haplotypic diversity, reports of both mating types and reports of successful matings in vitro. Pathogenicity assays revealed that D. ampelina was the most pathogenic species to grapevine wood.

Secondary Metabolites Isolated from the Amazonian Endophytic Fungus Diaporthe sp. SNB-GSS10

We describe a Sabicea cinerea endophytic fungus closely related to Diaporthe pseudomangiferae that produces two known metabolites, mycoepoxydiene (1) and altiloxin A (2), as well as enamidin (3) and eremofortin F (4), two compounds not previously described in the literature. The structure of these four metabolites was elucidated using spectroscopic analysis, and their cytotoxic activities were measured against the human cell lines KB, MRC-5, and MDA-MB-435.

Endophytic Diaporthe associated with Citrus: A phylogenetic reassessment with seven new species from China

Phytopathogenic species of Diaporthe are associated with melanose, stem-end rot and gummosis diseases of Citrus. However, little is known about the occurrence of species of Diaporthe as endophytes and saprobes. In this study, we obtained 58 strains of Diaporthe, including 44 endophytic isolates from cultivated Citrus in China. The nuclear ribosomal internal transcribed spacer (ITS), partial sequences of translation elongation factor 1-α (EF1-α), beta-tubulin (TUB), and histone-3 (HIS) gene regions were analysed to determine the species of the isolates collected. In combined analysis of four gene regions, these strains grouped in 16 distinct clades in Diaporthe. The isolates were identified in Diaporthe arecae species complex, Diaporthe citri, Diaporthe citriasiana, Diaporthe citrichinensis, Diaporthe endophytica, Diaporthe eres, Diaporthe hongkongensis, and Diaporthe sojae based on molecular phylogeny and morphology. Seven new species are described from Citrus namely, Diaporthe biconispora, Diaporthe biguttulata, Diaporthe discoidispora, Diaporthe multigutullata, Diaporthe ovalispora, Diaporthe subclavata, and Diaporthe unshiuensis with descriptions and illustrations.

Diaporthe species occurring on Lithocarpus glabra in China, with descriptions of five new species

The Diaporthe species include important plant pathogenic fungi with wide host ranges and geographic distributions. In this paper, species associated with Lithocarpus glabra were examined using a multi-locus phylogeny based on a combined rDNA-internal transcribed spacer (ITS), and partial translation elongation factor 1-alpha (TEF1), beta tubulin (TUB), and calmodulin (CAL) regions. The phylogenies inferred from combined multi-locus sequences grouped isolates from L. glabra into seven distinct lineages with high branch support, which corresponded to two previously described species and five novel species described in this paper. Our results indicate a high species diversity of Diaporthe associated with L. glabra, and host association is further proved not reliable for species delimitation. Three species previously described in Phomopsis were transferred to Diaporthe in the present paper. A synopsis of morphological characters of the 14 species currently known from Fagaceae is provided.

The Genera of Fungi: fixing the application of type species of generic names

To ensure a stable platform for fungal taxonomy, it is of paramount importance that the genetic application of generic names be based on their DNA sequence data, and wherever possible, not morphology or ecology alone. To facilitate this process, a new database, accessible at www.GeneraofFungi.org (GoF) was established, which will allow deposition of metadata linked to holo-, lecto-, neo- or epitype specimens, cultures and DNA sequence data of the type species of genera. Although there are presently more than 18 000 fungal genera described, we aim to initially focus on the subset of names that have been placed on the "Without-prejudice List of Protected Generic Names of Fungi" (see IMA Fungus 4(2): 381-443, 2013). To enable the global mycological community to keep track of typification events and avoid duplication, special MycoBank Typification identfiers (MBT) will be issued upon deposit of metadata in MycoBank. MycoBank is linked to GoF, thus deposited metadata of generic type species will be displayed in GoF (and vice versa), but will also be linked to Index Fungorum (IF) and the curated RefSeq Targeted Loci (RTL) database in GenBank at the National Center for Biotechnology Information (NCBI). This initial paper focuses on eight genera of appendaged coelomycetes, the type species of which are neo- or epitypified here: Bartalinia (Bartalinia robillardoides; Amphisphaeriaceae, Xylariales), Chaetospermum (Chaetospermum chaetosporum, incertae sedis, Sebacinales), Coniella (Coniella fragariae, Schizoparmaceae, Diaporthales), Crinitospora (Crinitospora pulchra, Melanconidaceae, Diaporthales), Eleutheromyces (Eleutheromyces subulatus, Helotiales), Kellermania (Kellermania yuccigena, Planistromataceae, Botryosphaeriales), Mastigosporium (Mastigosporium album, Helotiales), and Mycotribulus (Mycotribulus mirabilis, Agaricales). Authors interested in contributing accounts of individual genera to larger multi-authored papers to be published in IMA Fungus, should contact the associate editors listed below for the major groups of fungi on the List of Protected Generic Names for Fungi.

Phylogeny, Morphology, Distribution, and Pathogenicity of Botryosphaeriaceae and Diaporthaceae from English Walnut in California

Species of family Botryosphaeriaceae and genus Diaporthe (anamorph: genus Phomopsis, family Diaporthaceae) were reported and caused diseases on various fruit and nut trees in California. In the last several years, diseases on English walnut (Juglans regia) caused by species of Botryosphaeriaceae and Diaporthe were observed frequently in California. Disease symptoms include stem canker; shoot canker and blight; twig, leaf, and fruit blight; and necrotic leaf lesions. Isolates of the pathogen were collected from English walnut in 13 counties in California. The aims of this study were to identify these isolates and to test their pathogenicity to English walnut cultivars. In total, 159 California isolates were identified based on comparisons of DNA sequence data of the internal transcribed spacer, translation elongation factor 1-α, and β-tubulin gene regions, and combined with the morphological features of the cultures and conidia. Research results revealed that isolates represent 10 species of Botryosphaeriaceae and two species of Diaporthe. These species include Botryosphaeria dothidea, Diplodia mutila, D. seriata, Dothiorella iberica, Lasiodiplodia citricola, Neofusicoccum mediterraneum, N. nonquaesitum, N. parvum, N. vitifusiforme, Neoscytalidium dimidiatum, Diaporthe neotheicola, and D. rhusicola. Pathogenicity on three English walnut cultivars ('Chandler', 'Tulare', and 'Vina') using a mycelium plug inoculation method revealed that all these species are pathogenic to all the tested cultivars, with L. citricola and N. parvum being the most pathogenic species, followed by N. mediterraneum, N. dimidiatum, and B. dothidea. Chandler was more tolerant to infection than Tulare and Vina. Results in this study determined that multiple numbers of the Botryosphaeriaceae fungi and two Diaporthe spp. cause cankers and blights of English walnut and vary in their virulence from highly to slightly virulent, respectively.

Ophiodiaporthe cyatheae gen. et sp. nov., a diaporthalean pathogen causing a devastating wilt disease of Cyathea lepifera in Taiwan

The scaly tree fern, Cyathea lepifera, in Taiwan has been devastated by an ascomycetous pathogen in recent years. This fungus resembles species of Diaporthe, but unlike anamorphs of Diaporthe that produce two types of conidia, its anamorph produces one conidium type. It is described herein as Ophiodiaporthe cyatheae gen. et sp. nov. Through pathogenicity tests, O. cyatheae was demonstrated to be the causal agent of the C. lepifera wilt disease. Of interest, sporulating structures of O. cyatheae have not been found on C. lepifera plants but in culture thus far. The mating system is homothallic. Phylogenetic analyses based on combined sequences of nSSU-rDNA, nLSU-rDNA, EF1-α-1 and RPB2 placed O. cyatheae in Diaporthaceae. Combined sequences of EF1-α-2 and TUB indicated that O. cyatheae had its origin within Diaporthe.

Pilidiella tibouchinae sp. nov. associated with foliage blight of Tibouchina granulosa (quaresmeira) in Brazil

Tibouchina granulosa (Melastomataceae), Brazilian glorytree (Brazilian common name - quaresmeira), a common tree of the Atlantic Forest of Brazil, is widely used as an ornamental for its violet or pink blossoms. Little is known about fungal diseases affecting this species, although these represent a known limitation for its cultivation in nurseries. Among these there is a foliage blight that occurs in combination with distortion of branch apices and die-back. A consistent association of a species of Pilidiella with the diseased tissues was observed. The fungus was isolated in pure culture and based on its morphology and DNA phylogeny, we conclude that it represents a new species, for which the name Pilidiella tibouchinae is introduced.

Aurifilum, a new fungal genus in the Cryphonectriaceae from Terminalia species in Cameroon

Native Terminalia spp. in West Africa provide a popular source of construction timber as well as medical, spiritual and social benefits to rural populations. Very little is, however, known regarding the diseases that affect these trees. During an investigation into possible diseases of Terminalia spp. in Cameroon, orange to yellow fungal fruiting structures, resembling those of fungi in the Cryphonectriaceae, were commonly observed on the bark of native Terminalia ivorensis, and on dead branches of non-native Terminalia mantaly. In this study the fungus was identified based on morphological features as well as DNA sequence data (ITS and beta-tubulin) and its pathogenicity was tested on T. mantaly seedlings. Our results showed that isolates of this fungus represent a previously undescribed genus in the Cryphonectriaceae, which we describe as Aurifilum marmelostoma gen. et sp. nov. Pathogenicity tests revealed that A. marmelostoma is pathogenic on T. mantaly. These tests, and the association of A. marmelostoma with disease symptoms on T. ivorensis, suggest that the fungus is a pathogen of this important tree.

ITS rDNA phylogeny of Iranian strains of Cytospora and associated teleomorphs

Cytospora spp. and associated teleomorphic species (Ascomycota, Diaporthales, Valsaceae) are among the most common and widespread canker- and dieback-causing fungi on trees, shrubs and herbaceous plants worldwide. From specimens collected all over Iran a total of 114 isolates were morphologically identified, representing 20 Cytospora, one Leucostoma and five Valsa species from 38 plant species. Nine of the identified taxa were new records for Iran, and many new hosts were identified. The phylogenetic relationships of the Iranian strains, along with sequences of 13 reference strains from GenBank, were inferred from ITS1-5.8S-ITS2 nuclear rDNA sequences. Parsimony analysis established five distinct major clades and 12 subclades, which represented accepted species and genera. Some of these subclades corresponded to morphologically based taxonomic concepts of single Cytospora species, while others contained more than one morphospecies. Teleomorphic states were present in six subclades, and most clustered with the corresponding anamorphs. This suggests that morphological and phylogenetic species concepts overlap and that in most cases they are meaningful for correct species identification.