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Background Powdery mildews (Erysiphaceae, Ascomycota) belong to the most important plant pathogenic fungi that cause stress to forest and fruit trees and lead to a considerable loss of economic crops worldwide as well as in Taiwan. The checklist of Erysiphaceae in Taiwan is an important basis to control these pathogens. However, it has been published 25 years ago without any updating, while taxonomic concepts of genera and species changed and many new fungus and host records have been published. We update the checklist of Erysiphaceae by applying new taxonomical concepts and we add several new host records worldwide or for Taiwan based on own, recent collections. Results The updated checklist of powdery mildew in Taiwan is presented including data on 13 species of Erysiphaceae on 28 species of host plants. Doubtful records are marked as such and proposed for further investigation. For agricultural application, information on the usage of host plants was added to the checklist. Besides, over twenty specimens of Erysiphaceae on common plants in Taiwan recently collected by the authors were identified based on ITS sequences and anamorphic morphology. Among the collections, twelve represented new host records worldwide, while seventeen were new host records for Taiwan. Six species of Erysiphaceae were found in Taiwan for the first time. Conclusions The checklist of Erysiphaceae in Taiwan is an important basis for taxonomic and biogeographical studies as well as for quarantine sanctions referring to powdery mildews. Our results reveal that the host spectra of these pathogens are still incompletely known worldwide. Moreover, the list includes some doubtful old records that might be synonyms or wrong identifications. Morphological characteristics and ITS sequences are usually useful for the identification of Erysiphaceae. Several species in certain genera, however, cannot be distinguished since the variation in sequence data of those closely related species is quite low. New collections and re-investigation of old specimens are imperative to clarify some doubtful records.

Foliar fungal communities of plants are diverse and ubiquitous. In grasses endophytes may increase host fitness; in trees, their ecological roles are poorly understood. We investigated whether the genotype of the host tree influences community structure of foliar fungi. We sampled leaves from genotyped balsam poplars from across the species' range, and applied 454 amplicon sequencing to characterize foliar fungal communities. At the time of the sampling the poplars had been growing in a common garden for two years. We found diverse fungal communities associated with the poplar leaves. Linear discriminant analysis and generalized linear models showed that host genotypes had a structuring effect on the composition of foliar fungal communities. The observed patterns may be explained by a filtering mechanism which allows the trees to selectively recruit fungal strains from the environment. Alternatively, host genotype-specific fungal communities may be present in the tree systemically, and persist in the host even after two clonal reproductions. Both scenarios are consistent with host tree adaptation to specific foliar fungal communities and suggest that there is a functional basis for the strong biotic interaction.

Species of the genus Russula are key components of ectomycorrhizal ecosystems worldwide. Nevertheless, their diversity in the tropics is still poorly known. This study aims to contribute to the knowledge of the diversity of Russula species classified in subsection Roseinae based on specimens recently collected in tropical montane rainforests in western Panama. A five gene multilocus phylogeny based on the nuclear markers ITS nrDNA, MCM7 , RPB1 , RPB2 and TEF-1α was constructed to identify the systematic position of 22 collections from Panama. Four new species, Russula cornicolor , Russula cynorhodon , Russula oreomunneae and Russula zephyrovelutipes are formally described and illustrated. None of the four species are sister species and they are more closely related to North American or Asian species. Two of the newly described species were associated with the ectomycorrhizal tree species Oreomunnea mexicana , while the other two species were associated with Quercus species. All four species are so far only known from mountains in western Panama.

Plants associate through their roots with fungal assemblages that impact their abundance and productivity. Non-mycorrhizal endophytes constitute an important component of such fungal diversity, but their implication in ecosystem processes is little known. Using a selection of 128 root-endophytic strains, we defined functional groups based on their traits and plant interactions with potential to predict community assembly and symbiotic association processes. In vitro tests of the strains’ interactions with Arabidopsis thaliana, Microthlaspi erraticum and Hordeum vulgare showed a net negative effect of fungal colonization on plant growth. The effects partly depended on the phylogenetic affiliation of strains, but also varied considerably depending on the plant-strain combination. The variation was partly explained by fungal traits shared by different lineages, like growth rates or melanization. The origin of strains also affected their symbioses, with endophytes isolated from Microthlaspi spp. populations being more detrimental to M. erraticum than strains from other sources. Our findings suggest that plant–endophyte associations are subject to local processes of selection, in which particular combinations of symbionts are favored across landscapes. We also show that different common endophytic taxa have differential sets of traits found to affect interactions, hinting to a functional complementarity that can explain their frequent co-existence in natural communities.

A high number of fungal strains were isolated from roots of Brassicaceae species collected across western and southern Europe, resulting in an unexpectedly rich collection of Cadophora species. These isolates enable us to present a new and comprehensive view of the ecological, morphological, and phylogenetic traits of root-inhabiting members of this helotialean genus. We provide phylogenetic placement of all of our isolates based on a four-gene dataset, analyze their phenotypic traits in relation to their phylogenetic relationships, and infer the potential distribution ranges of the species by sequence comparisons with available databases. We consider seven well supported phylogenetic lineages as species new to science. Six further lineages probably also represent new species but remain undescribed due to the lack of diagnostic morphological characters. Our results show that Cadophora , as currently circumscribed, is paraphyletic and encompasses a broad spectrum of morphologies and lifestyles. Among the new species, only two ( C. ferruginea and C. constrictospora ) form phialides and conidia typical of Cadophora , three species ( C. echinata , C. gamsii and C. variabilis ) produce chains of swollen hyphal segments that may function as holoblastic conidia, and one species ( C. fascicularis ) produces chains of holoblastic ramoconidia and conidia. Ancestral state reconstruction analysis suggests that phialidic conidiogenesis evolved several times in Cadophora s. lat. from a putatively holoblastic common ancestor. Most Cadophora lineages are rare as estimated from the availability of sequence data, in spite of having relatively wide distribution ranges, whereas five lineages may represent endemic relationships given their restricted distributions. Our dataset, probably the most comprehensive available for Cadophora , nevertheless shows knowledge gaps concerning the phylogenetic relationships within this genus and highlights a need for further investigation.

Earliella scabrosa is a pantropical species of Polyporales (Basidiomycota) and well-studied concerning its morphology and taxonomy. However, its pantropical intraspecific genetic diversity and population differentiation is unknown. We initiated this study to better understand the genetic variation within E . scabrosa and to test if cryptic species are present. Sequences of three DNA regions, the nuclear ribosomal internal transcribed spacer (ITS), the large subunit ribosomal DNA (LSU), and the translation elongation factor (EF1α) were analysed for 66 samples from 15 geographical locations. We found a high level of genetic diversity (haplotype diversity, Hd = 0.88) and low nucleotide diversity (π = 0.006) across the known geographical range of E . scabrosa based on ITS sequences. The analysis of molecular variance (AMOVA) indicates that the genetic variability is mainly found among geographical populations. The results of Mantel tests confirmed that the genetic distance among populations of E. scabrosa is positively correlated with the geographical distance, which indicates that geographical isolation is an important factor for the observed genetic differentiation. Based on phylogenetic analyses of combined dataset ITS-LSU-EF1α, the low intraspecific divergences (0–0.3%), and the Automated Barcode Gap Discovery (ABGD) analysis, E. scabrosa can be considered as a single species with five different geographical populations. Each population might be in the process of allopatric divergence and in the long-term they may evolve and become distinct species.

Delimitation of species and the search for a proper threshold for defining phylogenetic species in fungi are under discussion. In this study, morphological and molecular data are correlated to delimit species of Tulasnella, the most important mycobionts of Orchidaceae, which suffer from poor taxonomy. Resupinate basidiomata of Tulasnella species were collected in Ecuador and Germany, and 11 specimens (seven from Ecuador, four from Germany) were assigned to traditional species concepts by use of morphological keys. The specimens were compared by micro-anatomical examination with 75 specimens of Tulasnella borrowed from fungaria to obtain better insights on variation of characters. Sequences of the ITS region (127) were obtained after cloning from the fresh basidiomata and from pure cultures. Proportional variability of ITS sequences was analyzed within and among the cultures and the specimens designated to different morphospecies. Results suggested an intragenomic variation of less than 2%, an intraspecific variation of up to 4% and an interspecific divergence of more than 9% in Tulasnella. Cryptic species in Tulasnella, mostly from Ecuador, were revealed by phylogenetic analyses with 4% intraspecific divergence as a minimum threshold for delimiting species. Conventional diagnostic morphological characters appeared insufficient for species characterization. Arguments are presented for molecular delimitation of the established species Tulasnella albida, T. asymmetrica, T. eichleriana, T. cf. pinicola, T. tomaculum and T. violea.

The diversity within the ectomycorrhizal genus Russula (Basidiomycota) in West Africa is largely unexplored. The study area was Benin, where only ten out of the 159 species endemic to tropical Africa have been previously reported. We focused on “ Afrovirescentinae ”, which is a monophyletic lineage within Russula subgen. Heterophyllidiae sister to subsect. Virescentinae. The phylogenetic placement of this clade was analysed using sequence data from ITS, LSU, mtSSU, tef1 , rpb1 and rpb2 regions. Ten “ Afrovirescentinae ” species are recognised, described and illustrated from Benin. Four of them, R. carmesina , R. hiemisilvae , R. inflata and R. sublaevis , were previously published. Five species, Russula acrialbida sp. nov. , R. beenkenii sp. nov. , R. coronata sp. nov. , R. florae sp. nov. and R. spectabilis sp. nov. , are newly described. Species within this group are characterised by densely reticulated spore ornamentation, but they exhibit considerable variation in field appearance and pileipellis structure. In gallery forests, their basidiomata are ephemeral, small and their basidiospores have prominent ornamentation; while in savannah woodlands, the basidiomata are fleshy, large and basidiospores present low ornamentation. We suggest that these morphological traits may represent evolutionary adaptations to a specific environmental condition. We analysed the species richness, ecological range and distribution of the “ Afrovirescentinae ” clade globally based on data from the UNITE database, estimating a total diversity of 94 species primarily distributed in sub-Saharan Africa, but also in the Neotropics. Four additional previously described species not detected in Benin were assigned to this clade, based on holotype sequencing. Several species are widely distributed across tropical Africa and do not show specificity regarding their associated plant symbionts.

Phytotoxic dioxolanones from Guignardia bidwellii can be described as potential virulence factors which cause the formation of lesions upon an infection by G. bidwellii . The toxin guignardic acid was found in planta of G. bidwellii -infected Vitis vinifera leaves, whereas no phytotoxic dioxolanones were detected in uninfected leaf material. Secondary metabolism analyses of further phytopathogenic fungi from the genus Guignardia led to the observation that all species investigated can produce the phytotoxins known from G. bidwellii . In addition to these studies, it was demonstrated that phenguignardic acid is biosynthetically derived from two molecules of phenylalanine and that phenylalanine is a key precursor in the biosynthesis of the two other phytotoxins – alaguignardic acid and guignardic acid.

In the present study, the mycobiomes of two soils with different ecological conditions located in Benin (West Africa) were investigated by environmental sequencing (Illumina MiSeq) of the ITS2-region of ribosomal DNA to gain information about the influence of pedological stratification on fungal diversity. For each soil depth and horizon, fungal diversity and community composition were analyzed as well as the potential impact of site characteristics, like vegetation, on these traits. The retrieved sequences revealed in all their replicates high similarities between fungal communities of samples from the same site and soil horizon, but differed within one site in their horizons. It was possible to assign a saprotrophic, symbiotrophic, or parasitic lifestyle to 24% of the recorded fungal mOTUs. Plant parasites were found in all samples in similar proportions. The presence of ectomycorrhizal fungi in one site could be linked to the presence of ectomycorrhizal trees. Overall, it was observed that fungal diversity decreased with increasing depth if only one horizon was present, whereas a deeper horizon present at one site contained communities with a distinct composition regarding the taxonomical affiliations and lifestyles of the fungi found compared to the upper layer. Hence, soil horizonation seems to drive differences in the composition of fungal communities, and should be regarded with more attention when analyzing soil mycobiomes.