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Powdery mildew diseases on crops and ornamental plants are common and cause significant economic losses, by reducing the yield and quality of crops and downgrading the value of ornamentals. In surv...

The introduction, spread, and impact of fungal plant pathogens is a critical concern in ecological systems. In this study, we were motivated by the rather sudden appearance of Acer macrophyllum heavily infected with powdery mildew. We used morphological and genetic analyses to confirm the pathogen causing the epidemic was Sawadaea bicornis. In subsequent field studies, this pathogen was found in several locations in western North America, and in greenhouse studies, A. macrophyllum was found to be significantly more susceptible to S. bicornis than nine other Acer species tested. A genetic analysis of 178 specimens of powdery mildew from freshly collected and old herbarium specimens from 15 countries revealed seven different haplotypes. The high diversity of haplotypes found in Europe coupled with sequence results from a specimen from 1864 provides evidence that S. bicornis has a European origin. Furthermore, sequence data from a specimen from 1938 in Canada show that the pathogen has been present in North America for at least 82 years revealing a considerable lag time between the introduction and current epidemic. This study used old herbarium specimens to genetically hypothesize the origin, the native host, and the invasion time of a detrimental fungal plant pathogen.

The phylogeny and taxonomy of powdery mildews, belonging to the genus Erysiphe, on Lonicera species throughout the world are examined and discussed. Phylogenetic analyses revealed that sequences retrieved from Erysiphe lonicerae, a widespread powdery mildew species distributed in the Northern Hemisphere on a wide range of Lonicera spp., constitutes a complex of two separate species, viz., E. lonicerae (s. str.) and Erysiphe ehrenbergii comb. nov. Erysiphe lonicerae occurs on Lonicera spp. belonging to Lonicera subgen. Lonicera (= subgen. Caprifolium and subgen. Periclymenum ), as well as L. japonica. Erysiphe ehrenbergii comb. nov. occurs on Lonicera spp. of Lonicera subgen. Chamaecerasus. Phylogenetic and morphological analyses have also revealed that Microsphaera caprifoliacearum (≡ Erysiphe caprifoliacearum) should be reduced to synonymy with E. lonicerae (s. str.). Additionally, Erysiphe lonicerina sp. nov. on Lonicera japonica in Japan is described and the new name Erysiphe flexibilis, based on Microsphaera lonicerae var. flexuosa, is introduced. The phylogeny of Erysiphe ehrenbergii and E. lonicerae as well as other Erysiphe species on honeysuckle is discussed, and a survey of all species, including a key to the species concerned, is provided.

Erysiphe adunca s. lat. is a common powdery mildew species, distributed almost worldwide, on hosts of Populus and Salix species. Based on its wide host range and distribution as well as its strong morphological variations, E. adunca s. lat. was previously divided into several species or, alternatively, into varieties. However, comprehensive phylogenetic examinations on the putative monophyly of this species or the existence of a possible E. adunca species complex have not been conducted based on combined morphological and molecular approaches. In this study, we retrieved rDNA (ITS and LSU) sequences of 22 powdery mildew specimens on Populus and Salix spp. collected in China, Germany, Iran, Japan, Russia, and the United States and conducted morphological examinations of these and additional specimens. The morphological and molecular data obtained clearly indicate that E. adunca is a species complex comprised of at least four species., viz., E. adunca s. str. (on Populus spp. in Asia, Europe, and North America), E. capreae, including E. pseudoregularis as a new synonym (on Salix spp., particularly on species in Salix subgen. Vetrix sect. Vetrix in Asia, Europe, and North America), the reinstated E. salicis (on Salix spp. belonging to various subgenera of Salix in Asia and Europe), and E. mandshurica (which has been confirmed as a species of its own on Populus spp., in Asia). In addition to the clear phylogenetic differentiation, the morphology of the asexual and sexual morphs of E. adunca s. str., E. capreae and E. salicis is easily distinguishable. Sequences retrieved from collections on Salix gracilistyla (Uncinula salicis-gracilistylae), a species that was previously considered a variety of Uncinula adunca and Erysiphe adunca, formed a small subclade within the E. salicis clade and are now referred to as Erysiphe salicis var. salicis-gracilistylae comb. nov. Alphitomorpha adunca; Erysiphe capreae and E. salicis are epitypified, and a neotype is designated for Alphitomorpha obtusata, with ex-epitype sequences and, in the latter case, an ex-neotype sequence.

Erysiphe species (powdery mildews) on Corylus and Ostrya hosts (Betulaceae subfam. Coryloideae) in Asia and North America are widespread pathogens on these economically and ecologically valuable nu...

Digitopodium hemileiae was described originally in 1930 as Cladosporium hemileiae; growing as a mycoparasite of the coffee leaf rust (CLR), Hemileia vastatrix, in a sample of diseased leaves of Coffea canephora collected in the Democratic Republic of Congo. No cultures from this material exist. More recently, the type material was re-examined and, based on morphological features, considered to be incorrectly placed in Cladosporium. The new genus Digitopodium was erected to accommodate this species. Interest in fungal antagonists of H. vastarix, as potential biocontrol agents of CLR, led to comprehensive surveys for mycoparasites, both in the African centre of origin of the rust, as well as in its South American exotic range. Among the rust specimens from Ethiopia, one was found to be colonized by a fungus congeneric with, and similar to, D. hemileiae. Pure cultures obtained from the Ethiopian material enabled a molecular study and for its phylogenetic position to be elucidated, based on DNA sequence data from the ITS and LSU regions. Molecular data showed that two members of the recently erected genus Hyalocladosporiella (Herpotrichiellaceae: Chaetothyriales) are congeneric with Digitopodium from Ethiopia and morphologically similar to both D. hemileiae and the two Ethiopian isolates. These isolates were found to be morphologically and genetically identical to H. tectonae, described previously from Brazil. Thus, species of Hyalocladosporiella are re-allocated to Digitopodium here; including D. tectonae, and a novel species, D. canescens, recently found in Brazil growing as a mycoparasite of Puccinia thaliae. The potential use of D. hemileiae and D. tectonae for classical biological control of CLR is discussed.

A worldwide survey of cercosporoid ascomycete species on hosts of the genus Diospyros (persimmon) with key to the species based on characters in vivo is provided. Special emphasis is placed on species of the genus Pseudocercospora, which are in part also phylogenetically analysed, using a multilocus approach. Species of the latter genus proved to be very diverse, with a remarkable degree of cryptic speciation. Seven new species are described (Pseudocercospora diospyri-japonicae, P. diospyriphila, P. ershadii, P. kakiicola, P. kobayashiana, and P. tesselata), and two new names are introduced [P. kakiigena (≡ Cylindrosporium kaki, non Pseudocercospora kaki), and Zasmidium diospyri-hispidae (≡ Passalora diospyri, non Zasmidium diospyri)]. Six taxa are lectotypified (Cercospora atra, C. diospyri, C. diospyri var. ferruginea, C. flexuosa, C. fuliginosa, C. kaki), and Pseudocercospora kaki is epitypified.

The phylogeny and taxonomy of powdery mildew on Viburnum species is evaluated and discussed. Morphological and phylogenetic analyses revealed two new species and demonstrated that Erysiphe hedwigii and E. viburni should be reduced to synonymy and are referred to herein as E. viburni. The two new species, E. viburniphila and E. pseudoviburni, previously hidden under E. viburni (including E. hedwigii), is described on the basis of European, North American, and East Asian powdery mildew collections on Viburnum edule, V. tinus, V. odoratissimum var. awabuki, and V. sieboldii. The sexual morph of E. viburniphila is similar to that of E. viburni; however, morphological differences exist in their asexual morphs. Analyses of sequences from the internal transcribed spacer (ITS) and 28S genomic regions of Erysiphe species obtained on Viburnum species (and other closely allied Eryisphe species) throughout the world reveled that E. viburniphila and E. pseudoviburni are in two different monophyletic groups that are separate from all other Erysiphe species. Erysiphe hedwigii and E. viburni on Viburnum species have often been recognized as separate species based on morphological differences in the size of their chasmothecia and the number of chasmothecial appendages. Taxonomic conclusions based on these morphological distinctions within these species are unreliable (these characters are rather variable and often have overlapping ranges). The present phylogenetic analyses suggest that E. hedwigii has to be reduced to synonymy with E. viburni. To fix the application of the species names E. hedwigii and E. viburni, epitypes have been designated for these taxa with ex-epitype sequences. Additionally, the Asian species E. miranda is phylogenetically confirmed as a species of its own, described in detail and discussed.

Background Previous phylogenetic analyses of species within the genus Golovinomyces (Ascomycota, Erysiphales), based on ITS and 28S rDNA sequence data, revealed a co-evolutionary relationship between powdery mildew species and hosts of certain tribes of the plant family Asteraceae. Golovinomyces growing on host plants belonging to the Heliantheae formed a single lineage, comprised of a morphologically differentiated complex of species, which included G. ambrosiae, G. circumfusus, and G. spadiceus. However, the lineage also encompassed sequences retrieved from Golovinomyces specimens on other Asteraceae tribes as well as other plant families, suggesting the involvement of a plurivorous species. A multilocus phylogenetic examination of this complex, using ITS, 28S, IGS (intergenic spacer), TUB2 (beta-tubulin), and CHS1 (chitin synthase I) sequence data was carried out to clarify the discrepancies between ITS and 28S rDNA sequence data and morphological differences. Furthermore, the circumscription of species and their host ranges were emended. Results The phylogenetic and morphological analyses conducted in this study revealed three distinct species named, viz., (1) G. ambrosiae emend. (including G. spadiceus), a plurivorous species that occurs on a multitude of hosts including, Ambrosia spp., multiple species of the Heliantheae and plant species of other tribes of Asteraceae including the Asian species of Eupatorium; (2) G. latisporus comb. nov. (≡ Oidium latisporum), the closely related, but morphologically distinct species confined to hosts of the Heliantheae genera Helianthus, Zinnia, and most likely Rudbeckia; and (3) G. circumfusus confined to Eupatorium cannabinum in Europe. Conclusions The present results provide strong evidence that the combination of multi-locus phylogeny and morphological analysis is an effective way to identify species in the genus Golovinomyces.

Podosphaera tridactyla (s. lat.) is a powdery mildew species occurring on a wide range of Prunus spp. almost worldwide. We have investigated the phylogeny of the Po. tridactyla complex, with special emphasis on potential aspects of cryptic speciation. The results suggested that Po. tridactyla represents a species complex consisting of at least 12 different species. Based on detailed morphological examinations and molecular sequence analyses, we propose dividing Po. tridactyla s. lat. into 10 species, encompassing 7 new species (Po. ampla, Po. pruni-avium, Po. pruni-cerasoidis, Po. prunigena, Po. pruni-lusitanicae, Po. prunina, and Po. pruni-japonicae) and 3 known species (Po. longiseta, Po. salatai, and Po. tridactyla s. str.). Oidium passerinii on Pr. laurocerasus is confirmed as a synonym of Po. tridactyla s. str. Epitypes are designated for Po. tridactyla and Oidium passerinii.

Recently published phylogenetic analyses of the Golovinomyces orontii complex revealed that three different species of the genus Golovinomyces may occur on cucurbitaceous hosts, viz., G. bolayi, G. orontii s. str., and G. tabaci. Owing to its morphological characteristics, Erysiphe cucurbitacearum (≡ G. cucurbitacearum) was tentatively reduced to synonym with G. tabaci. However, final conclusions on the identity and status of E. cucurbitacearum, described from China on Cucumis sativus, as putative synonym of G. tabaci required a phylogenetic confirmation and epitypification with ex-epitype sequences. Therefore, a sample of G. cucurbitacearum collected on C. sativus in Xinjiang Uygur Autonomous Region, China, in 2014 (HMJAU-PM91862) has been sequenced and is designated as epitype of the latter species, since its holotype material (HMAS 40016, collected in 1954) turned out to be too old for molecular examinations. As a result of morphological examinations and phylogenetic analyses based on ex-epitype ITS and 28S rDNA sequences, the recently assumed synonymy of G. cucurbitacearum, found on C. sativus in China, with G. tabaci could be confirmed. In addition, two new host species of G. tabaci, viz., Trigonotis peduncularis (Boraginaceae) and Rubia cordifolia (Rubiaceae), were concurrently identified. Trigonotis peduncularis is the first verified boraginaceous host for G. tabaci.

The lichenicolous fungi growing onGraphidaleshosts in Florida are revised, mainly based on collections by the second author (R. C.). Twenty-one species are recognized. The new genus and speciesLawreya glyphidiphilais described for a common asexual fungus growing onGlyphis scyphuliferaand more rarelyTrypethelium eluteriae, characterized by black stromatic conidiomata in which subspherical conidiogenous loculi develop, producing aseptate, subglobose, brown conidia. Nine additional new species are described:Amerosporiopsis phaeographidis(onPhaeographis brasiliensis),Arthonia acanthotheciicola(onAcanthothecis floridensis),A. subgraphidicola(onGraphis assimilis),Hemigrapha graphidicola(onG. assimilis),Skyttea graphidicola(onGraphisspp.),Strigula graphidicola(onG. assimilis),S. perparvula(onGraphidales),Talpapellis graphidis(onGraphis caesiella) andTremella wedinii(onGlyphis scyphulifera). Phylogenetic placements ofLawreya glyphidiphila,Skyttea graphidicolaandTremella wediniiare presented. Identification keys are given for the species ofCornutisporaandTalpapellis, and for the 66 species known to grow onGraphidaleshosts worldwide.

A phylogenetic analysis of combined rDNA LSU and ITS sequence data was carried out to determine the phylogenetic placement of specimens identified as Pseudotryblidium neesii. The species forms a distinct clade within Dermateaceae (Helotiales, Leotiomycetes) with Rhizodermea veluwiensis and two Dermea species. The geographical distribution of this species, previously known only from Europe on Abies alba, is extended to north-western North America where it grows exclusively on A. grandis. The name P. neesii is lectotypified in order to disentangle the complicated nomenclature of the species. A new, detailed description of P. neesii with illustrations is provided after comparison of sequenced specimens with the type material. Furthermore, the new combination Pseudographis rufonigra (basionym Peziza rufonigra) is made for a fungus previously known as Pseudographis pinicola.

Powdery mildew of Prunus spp. is a significant disease in most cherry growing regions of Washington, USA. Powdery mildews on Prunus virginiana and Pr. avium were previously assigned to Podosphaera clandestina s. lat. (= Po. oxyacanthae) or Po. prunicola. In this report, we confirm the presence of two distinct Podosphaera species on these hosts. Phylogenetic analyses of nuc rDNA sequences from the internal transcribed spacer region (ITS1-5.8S-ITS2 = ITS) and 28S subunit confirmed the presence of two distinct species. A morphological comparison with type material of Po. prunicola and additional collections demonstrated that the powdery mildew on Pr. virginiana (including var. demissa and var. melanocarpa) is in fact Po. prunicola. The powdery mildew on Pr. avium is genetically, morphologically, and biologically distinct from Po. prunicola and is described here as the new species Po. cerasi. Cross-inoculation experiments confirmed that these two species are host specific. Podosphaera prunicola was unable to colonize Pr. avium, whereas Po. cerasi was unable to colonize Pr. virginiana. Morphological reexamination of numerous specimens identified as Po. prunicola on a broad range of Prunus species suggests that Po. prunicola is probably confined to species in Prunus subgen.Padus (= Prunus subgen. Cerasus sect. Laurocerasus, including sect. Padus), with Pr. virginiana as the principal host. Podosphaera cerasi occurs on hosts in Prunus subgen. Cerasus, and our work confirms a newly described species of powdery mildew on Pr. avium. This work also includes the first documented and genetically proven European record of Po. prunicola on Pr. serotina and its widespread occurrence in the United States.

Golovinomyces orontii is a common plurivorous powdery mildew species with wide host range and worldwide distribution, usually occurring as asexual morph. Ascomata (chasmothecia) are rarely formed on most hosts. Phylogenetic analyses based on rDNA ITS and 28S rDNA data of a wide range of powdery mildew collections of G. orontii s. lat. suggested a high degree of genetic heterogeneity of this species, which is undoubtedly not monophyletic. This study revealed that sequences retrieved from numerous collections referred to as G. orontii (s. lat.) split into three distinct main clusters, previously classified as groups 1 to 3. These groups have been genetically and morphologically analyzed, circumscribed, and named. One cluster (group 2), including a sequence retrieved from powdery mildew on the type host of Erysiphe orontii, Misopates orontium, constitutes G. orontii s. str. G. tabaci comb. nov. (≡ E. tabaci) is introduced for the second cluster in group 1 that is genetically and morphologically clearly distinct from G. orontii s. str. The third assemblage of sequences (group 3) comprises powdery mildews on hosts of the composite tribe Cichorieae, including Cichorium and Lactuca spp., and a wide range of hosts belonging to various other plant families for which the name G. bolayi sp. nov. is proposed. Euoidium longipes and Euoidium lycopersici, two additional powdery mildew species on solanaceous hosts, are briefly discussed and, based on previous phylogenetic analyses, reallocated to Golovinomyces. Oidium lactucae-debilis on Ixeris japonica in Asia is tentatively reduced to synonymy with G. sonchicola, i.e., it does not pertain to the G. orontii s. lat. complex. G. orontii s. lat. on Vinca spp. (Apocynaceae), mostly known as asexual morph, represents a separate species only distantly related to G. orontii s. str., which is described herein as Golovinomyces vincae sp. nov. Some re-examined collections on Vinca major from Germany misidentified as G. orontii turned out to belong to Ramularia vincae and represent first records of this species for Germany. Golovinomyces spadiceus is a further plurivorous Golovinomyces species discussed in this work, which, however, does not belong to the G. orontii complex.

Species of Passalora s. lat. are eminent phytopathogenic fungi that cause generally leaf spot diseases on a broad variety of plants throughout the world. During our investigations exploring cercosporoid fungi associated with leaf spot symptoms of fruit and forest trees in northern and north-western Iran, several passalora-like infections were isolated from symptomatic leaves of different trees belonging to the Fabaceae, Malvaceae, Rosaceae and Ulmaceae. A polyphasic taxonomic approach by applying molecular data, morphological features and host data, was employed to identify the isolates. In a multi-gene phylogenetic analysis (LSU, ITS and RPB2), these isolates clustered in four clades in the Mycosphaerellaceae. The revealed taxa encompass Paracercosporidium microsorum on Tilia platyphyllos, Prathigadoides gleditsiae-caspicae gen. et. sp. nov. on Gleditsia caspica, Pruniphilomyces circumscissus on Prunus avium and Prunus cerasus, and Sirosporium celtidis on Celtis australis. The new genus Prathigadoides and its type species Prathigadoides gleditsiae-caspicae are molecularly distinct from all phylogenetically related genera, and some characteristics of the conidiophores and conidia differs from those of the morphologically similar species Prathigada condensata on the North America Gleditsia triacanthos.

The taxonomy of Oculimacula, Rhynchosporium and Spermospora is re-evaluated, along with that of phylogenetically related genera. Isolates are identified using comparisons of DNA sequences of the internal transcribed spacer ribosomal RNA locus (ITS), partial translation elongation factor 1-alpha (tef1), actin (act), DNA-directed RNA polymerase II largest (rpb1) and second largest subunit (rpb2) genes, and the nuclear ribosomal large subunit (LSU), combined with their morphological characteristics. Oculimacula is restricted to two species, O. acuformis and O. yallundae, with O. aestiva placed in Cyphellophora, and O. anguioides accommodated in a new genus, Helgardiomyces. Rhynchosporium s. str. is restricted to species with 1-septate conidia and hooked apical beaks, while Rhynchobrunnera is introduced for species with 1-3-septate, straight conidia, lacking any apical beak. Rhynchosporium graminicola is proposed to replace the name R. commune applied to the barley scald pathogen based on nomenclatural priority. Spermospora is shown to be paraphyletic, representing Spermospora (type: S. subulata), with three new species, S. arrhenatheri, S. loliiphila and S. zeae, and Neospermospora gen. nov. (type: N. avenae). Ypsilina (type: Y. graminea), is shown to be monophyletic, but appears to be of minor importance on cereals. Finally, Vanderaaea gen. nov. (type: V. ammophilae), is introduced as a new coelomycetous fungus occurring on dead leaves of Ammophila arenaria., Fungal Systematics and Evolution, 7 (1)

The phylogeny and taxonomy of powdery mildew on