Cryphonectria carpinicola discovered in Japan: first report of the sexual state on Carpinus tree.

Cryphonectria carpinicola is an ascomycetous fungus that has been regularly found in its asexual form on European hornbeam (Carpinus betulus) in Europe over the past two decades. Here we describe the discovery of C. carpinicola in Japan and report for the first time its sexual state on Carpinus species. No symptomatic trees were observed, but stromata were found saprotrophically on broken branches of Carpinus species on the forest floor. The sexual structures of C. carpinicola resembled that of other Cryphonectria species and strongly resembled those of the closely related species C. radicalis. A phylogenetic tree based on the internal transcribed spacer sequences showed monophyly for the Japanese and European isolates of C. carpinicola. Further studies on the distribution and host range of C. carpinicola in Japan and on the life history strategies of this fungus are needed.

Diversity, migration routes, and worldwide population genetic structure of Lecanosticta acicola, the causal agent of brown spot needle blight.

Lecanosticta acicola is a pine needle pathogen causing brown spot needle blight that results in premature needle shedding with considerable damage described in North America, Europe, and Asia. Microsatellite and mating type markers were used to study the population genetics, migration history, and reproduction mode of the pathogen, based on a collection of 650 isolates from 27 countries and 26 hosts across the range of L. acicola. The presence of L. acicola in Georgia was confirmed in this study. Migration analyses indicate there have been several introduction events from North America into Europe. However, some of the source populations still appear to remain unknown. The populations in Croatia and western Asia appear to originate from genetically similar populations in North America. Intercontinental movement of the pathogen was reflected in an identical haplotype occurring on two continents, in North America (Canada) and Europe (Germany). Several shared haplotypes between European populations further suggests more local pathogen movement between countries. Moreover, migration analyses indicate that the populations in northern Europe originate from more established populations in central Europe. Overall, the highest genetic diversity was observed in south-eastern USA. In Europe, the highest diversity was observed in France, where the presence of both known pathogen lineages was recorded. Less than half of the observed populations contained mating types in equal proportions. Although there is evidence of some sexual reproduction taking place, the pathogen spreads predominantly asexually and through anthropogenic activity.

Biotic threats for 23 major non-native tree species in Europe.

For non-native tree species with an origin outside of Europe a detailed compilation of enemy species including the severity of their attack is lacking up to now. We collected information on native and non-native species attacking non-native trees, i.e. type, extent and time of first observation of damage for 23 important non-native trees in 27 European countries. Our database includes about 2300 synthesised attack records (synthesised per biotic threat, tree and country) from over 800 species. Insects (49%) and fungi (45%) are the main observed biotic threats, but also arachnids, bacteria including phytoplasmas, mammals, nematodes, plants and viruses have been recorded. This information will be valuable to identify patterns and drivers of attacks, and trees with a lower current health risk to be considered for planting. In addition, our database will provide a baseline to which future impacts on non-native tree species could be compared with and thus will allow to analyse temporal trends of impacts.

Molecular characterization and phylogenetic analyses of Lophodermella needle pathogens (Rhytismataceae) on Pinus species in the USA and Europe.

Increasing prevalence of conifer needle pathogens globally have prompted further studies on pathogen identification and a better understanding of phylogenetic relationships among needle pathogens. Several Lophodermella species can be aggressive pathogens causing needle cast in natural pine forests in the USA and Europe. However, their relationships with other Rhytismataceae species have historically been based on similarities of only limited phenotypic characters. Currently, no molecular studies have been completed to elucidate their relationships with other Lophodermella needle pathogens. This study collected and sequenced three gene loci, namely: internal transcribed spacer, large ribosomal subunit, and translation elongation factor 1-alpha, from five Lophodermella needle pathogens from North America (L. arcuata, L. concolor, L. montivaga) and Europe (L. conjuncta and L. sulcigena) to distinguish phylogeny within Rhytismatacaeae, including Lophophacidium dooksii. Phylogenetic analyses of the three loci revealed that all but L. conjuncta that were sampled in this study consistently clustered in a well-supported clade within Rhytismataceae. The multi-gene phylogeny also confirmed consistent nesting of L. dooksii, a needle pathogen of Pinus strobus, within the clade. Potential synapomorphic characters such as ascomata position and ascospore shape for the distinct clade were also explored. Further, a rhytismataceous species on P. flexilis that was morphologically identified as L. arcuata was found to be unique based on the sequences at the three loci. This study suggests a potential wider range of host species within the genus and the need for genetic characterization of other Lophodermella and Lophophacidium species to provide a higher phylogenetic resolution.

Cryphonectria carpinicola sp. nov. Associated with hornbeam decline in Europe.

Since the early 2000s, reports on declining hornbeam trees (Carpinus betulus) are spreading in Europe. Two fungi are involved in the decline phenomenon: One is Anthostoma decipiens, but the other etiological agent has not been identified yet. We examined the morphology, phylogenetic position, and pathogenicity of yellow fungal isolates obtained from hornbeam trees from Austria, Georgia and Switzerland, and compared data with disease reports from northern Italy documented since the early 2000s. Results demonstrate distinctive morphology and monophyletic status of Cryphonectria carpinicola sp. nov. as etiological agent of the European hornbeam decline. Interestingly, the genus Cryphonectria splits into two major clades. One includes Cry. carpinicola together with Cry. radicalis, Cry. decipiens and Cry. naterciae from Europe, while the other comprises species known from Asia-suggesting that the genus Cryphonectria has developed at two evolutionary centres, one in Europe and Asia Minor, the other in East Asia. Pathogenicity studies confirm that Car. betulus is a major host species of Cry. carpinicola. This clearly distinguished Cry. carpinicola from other Cryphonectria species, which mainly occur on Castanea and Quercus.

Insect herbivory facilitates the establishment of an invasive plant pathogen.

Plants can be severely affected by insect herbivores and phytopathogenic fungi, but interactions between these plant antagonists are poorly understood. We analysed the impact of feeding damage by the abundant herbivore Orchestes fagi on infection rates of beech (Fagus sylvatica) leaves with Petrakia liobae, an invasive plant pathogenic fungus. The fungus was not detected in hibernating beetles, indicating that O. fagi does not serve as vector for P. liobae, at least not between growing seasons. Abundance of the fungus in beech leaves increased with feeding damage of the beetle and this relationship was stronger for sun-exposed than for shaded leaves. A laboratory experiment revealed sun-exposed leaves to have thicker cell walls and to be more resistant to pathogen infection than shaded leaves. Mechanical damage significantly increased frequency and size of necroses in the sun, but not in shade leaves. Our findings indicate that feeding damage of adult beetles provides entry ports for fungal colonization by removal of physical barriers and thus promotes infection success by pathogenic fungi. Feeding activity by larvae probably provides additional nutrient sources or eases access to substrates for the necrotrophic fungus. Our study exemplifies that invasive pathogens may benefit from herbivore activity, which may challenge forest health in light of climate change.

Linosporopsis, a new leaf-inhabiting scolecosporous genus in Xylariaceae.

Based on molecular phylogenetic and morphological evidence, the new genus Linosporopsis (Xylariales) is established for several species previously classified within Linospora (Diaporthales). Fresh collections of Linospora ischnotheca from dead overwintered leaves of Fagus sylvatica and of L. ochracea from dead overwintered leaves of Malus domestica, Pyrus communis, and Sorbus intermedia were isolated in pure culture, and molecular phylogenetic analyses of a multi-locus matrix of partial nuITS-LSU rDNA, RPB2 and TUB2 sequences as well as morphological investigations revealed that both species are unrelated to the diaporthalean genus Linospora, but belong to Xylariaceae sensu stricto. The new combinations Linosporopsis ischnotheca and L. ochracea are proposed, the species are described and illustrated, and their basionyms lecto- and epitypified. Linospora faginea is synonymized with L. ischnotheca. Based on similar morphology and ecology, Linospora carpini and Linospora magnagutiana from dead leaves of Carpinus betulus and Sorbus torminalis, respectively, are also combined in Linosporopsis. The four accepted species of Linosporopsis are illustrated, a key to species is provided and their ecology is discussed.

Morphological and molecular analyses of fungal endophytes of achlorophyllous gametophytes of Diphasiastrum alpinum (Lycopodiaceae).

PREMISE OF THE STUDY: To understand the early evolution of mycorrhizal symbioses, it is important to know the fungal partners of gametophytes and sporophytes for basal lineages of vascular plants. Subterranean mycotrophic gametophytes of the clubmoss Diphasiastrum alpinum found at three localities gave an opportunity to study their morphology and anatomy and to identify and describe their hitherto unknown fungal endophytes. In addition, sporophytes were screened for fungal partners. METHODS: Gametophytes with attached young sporophytes were excavated, and their anatomy and their associated fungi were studied by light microscopy. DNA was isolated and amplified with both universal and group-specific fungal primers for the ITS region, the large subunit and small subunit of the nuclear rDNA, respectively, to identify the fungal partner. KEY RESULTS: Gametophytes were uniformly colonized by a fungus with septate hyphae forming coils and vesicles. Its morphology resembles that of the sebacinoid genus Piriformospora. Both ITS and LSU sequences were identified as Sebacinales group B, a basal clade of the Agaricomycetes (Basidiomycota). This fungus was detected in 11 gametophytes from two localities and in rootlets of adjacent Calluna vulgaris (Ericaceae) plants, but was absent in roots of sporophytes. In addition, several ascomycetes and glomeromycetes were found by DNA sequencing. CONCLUSIONS: Our study suggests a fungus belonging to Sebacinales group B as the main fungal host of the D. alpinum gametophytes. However, Sebacinales group B fungi occur as well in adjacent Ericaceae plants; therefore, we assume the mycoheterotrophic gametophyte to be epiparasitic on Ericaceae, which would explain the steady association of these plants.

Rust fungi on Annonaceae II: the genus Dasyspora Berk. & M.A. Curtis.

Dasyspora gregaria, the single species of the allegedly monotypic rust genus Dasyspora (Basidiomycota, Pucciniales), was investigated by light microscopy and DNA sequencing (ITS1-5.8S-ITS2 region, partial LSU and SSU of the nuclear rDNA, mt cytochrome oxidase subunit 3). Both methods indicated that D. gregaria is not a single species but can be split in 11 distinct taxa, each of which appear confined to a single Xylopia species (Annonaceae) host. Herein nine of these are described as new. Both the phylogenetic analyses and morphology show that the species are grouped into two main clades designated Dasyspora gregaria and D. winteri. The first comprises D. gregaria, the type species of the genus, which is restricted to X. cayennensis, two new species on X. aromatica, D. segregaria from northern South America and D. echinata from Brazil. The second clade is formed by D. winteri, recombined from Puccinia winteri on X. sericea, and the new species D. amazonica on X. amazonica, D. emarginatae on X. emarginata, D. frutescentis on X. frutescens, D. ferrugineae on X. frutescens var. ferruginea, D. guianensis on X. benthamii, D. mesoamericana on X. frutescens, and D. nitidae on X. nitida. Dasyspora frutescentis and D. mesoamericana were not clearly distinguishable by their morphology and host associations but differed from another in their sequences and geographic distributions. They are considered cryptic species. An identification key and the distributions are given for all recognized species. Along with molecular data we discuss the systematic position of Dasyspora in the Pucciniales.

Rust fungi on Annonaceae: the genus Sphaerophragmium.

Seven species of the rust genus Sphaerophragmium occur on members of the tropical plant family Annonaceae. Uropyxis gerstneri is recombined to S. gerstneri. A new species, S. xylopiae, is described from Xylopia acutiflora. The host plant of S. boanense is identified as Mitrella sp. Sphaerophragmium pulchrum is transferred to Dicheirinia. The anatomy of telia with teliospores and parasitizing mycelium is described and illustrated in detail. A new type of M-haustorium, which emanates laterally from intracellular hypha, is detected in S. monodorae. An identification key is given.

Anatomical and molecular characterization of Lactarius aff. omphaliformis, Russula alnijorullensis and Cortinarius tucumanensis ectomycorrhizae on Alnus acuminata.

Ectomycorrhizae (ECM) of Lactarius aff. omphaliformis Romagn., Russula alnijorullensis (Sing.) Sing. and Cortinarius tucumanensis Mos. on Andean alder (Alnus acuminata Kunth) were characterized and identified. The identification of the fungal symbionts was achieved by morpho-anatomical observations of mycorrhizae and by comparison of ITS-RFLP patterns obtained from ECM and fruitbodies. L. aff omphaliformis ECM differed in some morphological details such as ramification and mantle type from ECM of the same species on A. glutinosa. L. aff omphaliformis ECM show an orange to ochre mantle containing latex cells, which stain with sulpho-vanillin, emanating hyphae without clamps. R. alnijorullensis ECM represent a typical Russula-type-ECM, light yellow to pinkish, the outer mantle being composed of triangular latex-filled cells staining with sulpho-vanillin, emanating hyphae without clamps. C. tucumanensis ECM exhibit a white (silvery) to yellowish brown mantle covered with soil particles, emanating hyphae with clamps.