Fungal succession in decomposing ash leaves colonized by the ash dieback pathogen or its harmless relative .

Introduction: The ascomycete , originating from Asia, is currently threatening common ash () in Europe, massive ascospore production from the saprotrophic phase being a key determinant of its invasiveness.

Methods: To consider whether fungal diversity and succession in decomposing leaf litter are affected by this invader, we used ITS-1 metabarcoding to profile changes in fungal community composition during overwintering. The subjected ash leaf petioles, collected from a diseased forest and a healthy ash stand hosting the harmless ash endophyte , were incubated in the forest floor of the diseased stand between October 2017 and June 2018 and harvested at 2-3-month intervals.

Five new species from hardwood trees in Poland.

species form a well-supported monophyletic lineage within the Microascales (Ascomycota). Members of this genus can be found in association with bark beetles, as well as on tree wounds and in soils. During surveys of bark and ambrosia beetle-associated fungi and cavities made by woodpeckers on hardwood trees in Poland, many isolates with an affinity to were recovered.

The Native and the Invasive Are Similar in Their Necrotrophic Growth Phase in Ash Leaves.

The populations of European ash and its harmless fungal associate are in decline owing to ash dieback caused by the invasive , a fungus that in its native range in Asia is a harmless leaf endophyte of local ash species. To clarify the behavior of and its spatial and temporal niche overlap with the invasive relative, we used light microscopy, fungal species-specific qPCR assays, and PacBio long-read amplicon sequencing of the ITS1-5.8S-ITS2 region to examine fungal growth and species composition in attached leaves of European ash.

Seasonal Dynamics of Fungi Associated with Healthy and Diseased Needles in Northern Europe.

The relationship between the ecological success of needle pathogens of forest trees and species richness of co-inhabiting endophytic fungi is poorly understood. One of the most dangerous foliar pathogens of pine is , which is a widely spread threat to northern European forests. We sampled two sites in Estonia and two in Norway in order to analyse the relations between the abundance of and overall fungal richness, specific fungal species composition, time of season, needle age and position in the canopy.

Highly Clonal Structure and Abundance of One Haplotype Characterise the Populations in Europe and Western Asia.

is a cosmopolitan endophyte and opportunistic pathogen having occurred on several conifer species in Europe for at least 200 years. In Europe, disease outbreaks have increased on several spp. in the last few decades.

Six new species of from hardwood trees in Poland.

(, ) is a well-supported monophyletic lineage within the , species of which occur in a diverse range of habitats including on forest trees, in the soil, associated with bark beetles and mites as well as on the fruiting bodies of some . Several species have also been reported as important human and animal pathogens. During surveys of insect- and wound-associated from hardwood trees in Poland, many isolates with affinity to were recovered.

First Report of Fusarium oxysporum f. sp. lactucae Race 1 Causing Fusarium Wilt of Lettuce in Norway.

Lettuce (Lactuca sativa L.) is produced in Norway both in field and greenhouses. In Norway, greenhouse lettuce is one of the most important vegetables grown year-round.

Worldwide Genetic Structure Elucidates the Eurasian Origin and Invasion Pathways of , Causal Agent of Dothistroma Needle Blight.

, the primary causal agent of Dothistroma needle blight, is one of the most significant foliar pathogens of pine worldwide. Its wide host and environmental ranges have led to its global success as a pathogen and severe economic damage to pine forests in many regions. This comprehensive global population study elucidated the historical migration pathways of the pathogen to reveal the Eurasian origin of the fungus.

The Relationship between Fungal Diversity and Invasibility of a Foliar Niche-The Case of Ash Dieback.

European ash () is threatened by the invasive ascomycete originating from Asia. Ash leaf tissues serve as a route for shoot infection but also as a sporulation substrate for this pathogen. Knowledge of the leaf niche partitioning by indigenous fungi and is needed to understand the fungal community receptiveness to the invasion.

Seven new species of from conifers in Norway, Poland, and Russia.

During surveys of insect-associated mycobiomes in Norway, Poland, and Russia, isolates with affinity to (Ophiostomatales, Ascomycota) were recovered. In this study, eight known species as well as the newly collected isolates were compared based on morphology and DNA sequence data for four gene regions. The results revealed seven new species, described here as , and .

Two new species of Ophiostomatales (Sordariomycetes) associated with the bark beetle from Poland.

Bark beetles belonging to the genus (Coleoptera, Curculionidae, Scolytinae) are known vectors of fungi, such as the pathogenic species involved in alpine fir () mortality. Associations between hardwood-infesting species and fungi in Europe have received very little research attention. Ectosymbiotic fungi residing in and (Ophiostomatales, Sordariomycetes, Ascomycota) were commonly detected in previous surveys of the -associated mycobiome in Poland.

Priming of inducible defenses protects Norway spruce against tree-killing bark beetles.

Plants can form an immunological memory known as defense priming, whereby exposure to a priming stimulus enables quicker or stronger response to subsequent attack by pests and pathogens. Such priming of inducible defenses provides increased protection and reduces allocation costs of defense. Defense priming has been widely studied for short-lived model plants such as Arabidopsis, but little is known about this phenomenon in long-lived plants like spruce.

Four new Ophiostoma species associated with hardwood-infesting bark beetles in Norway and Poland.

Ophiostoma spp. (Ophiostomatales, Ascomycota) are well-known fungi associated with bark and ambrosia beetles (Curculionidae: Scolytinae, Platypodinae). Fungi in the Ophiostomatales include serious tree pathogens as well as agents of timber blue-stain.

Propagule Pressure Build-Up by the Invasive Following Its Introduction to an Ash Forest Inhabited by the Native .

Dieback of European ash, caused by the ascomycete originating from Asia, has rapidly spread across Europe, and is threatening this keystone tree at a continental scale. High propagule pressure is characteristic to invasive species. Consistently, the enormous production of windborne ascospores by in an ash forest with epidemic level of disease obviously facilitates its invasiveness and long distance spread.

Three new Leptographium spp. (Ophiostomatales) infecting hardwood trees in Norway and Poland.

Species of Leptographium are characterized by mononematous or synnematous conidiophores and are commonly associated with different arthropods. Some of them also produce a sexual state characterised by globose ascomata with elongated necks. Compared to investigations on coniferous trees, the occurrence of Leptographium species on hardwood trees has been poorly studied in Europe.

The ash dieback invasion of Europe was founded by two genetically divergent individuals.

Accelerating international trade and climate change make pathogen spread an increasing concern. Hymenoscyphus fraxineus, the causal agent of ash dieback, is a fungal pathogen that has been moving across continents and hosts from Asian to European ash. Most European common ash trees (Fraxinus excelsior) are highly susceptible to H.

Invasive forest pathogens in Europe: Cross-country variation in public awareness but consistency in policy acceptability.

Political action can reduce introductions of diseases caused by invasive forest pathogens (IPs) and public support is important for effective prevention. The public's awareness of IP problems and the acceptability of policies aiming to combat these pathogens were surveyed in nine European countries (N = 3469). Although awareness of specific diseases (e.

Looking for relationships between the populations of Dothistroma septosporum in northern Europe and Asia.

Dothistroma septosporum, a notorious pine needle pathogen with an unknown historical geographic origin and poorly known distribution pathways, is nowadays found almost in all areas inhabited by pines (Pinus spp.). The main aim of this study was to determine the relationship between North European and East Asian populations.

Two new Leptographium spp. reveal an emerging complex of hardwood-infecting species in the Ophiostomatales.

Species of Leptographium are generally characterized by mononematous conidiophores and are commonly associated with bark beetles and weevils. These species are responsible for sapstain and in some cases serious diseases on a range of primarily coniferous trees. In comparison with coniferous trees, the occurrence of Leptographium species on hardwood trees has been poorly studied in Europe.

Insights into the phylogeny of Northern Hemisphere Armillaria: Neighbor-net and Bayesian analyses of translation elongation factor 1-α gene sequences.

Armillaria possesses several intriguing characteristics that have inspired wide interest in understanding phylogenetic relationships within and among species of this genus. Nuclear ribosomal DNA sequence-based analyses of Armillaria provide only limited information for phylogenetic studies among widely divergent taxa. More recent studies have shown that translation elongation factor 1-α (tef1) sequences are highly informative for phylogenetic analysis of Armillaria species within diverse global regions.

Fungal diversity and seasonal succession in ash leaves infected by the invasive ascomycete Hymenoscyphus fraxineus.

High biodiversity is regarded as a barrier against biological invasions. We hypothesized that the invasion success of the pathogenic ascomycete Hymenoscyphus fraxineus threatening common ash in Europe relates to differences in dispersal and colonization success between the invader and the diverse native competitors. Ash leaf mycobiome was monitored by high-throughput sequencing of the fungal internal transcribed spacer region (ITS) and quantitative PCR profiling of H.

The Ophiostoma clavatum species complex: a newly defined group in the Ophiostomatales including three novel taxa.

Two species of blue-stain fungi with similar morphologies, Ophiostoma brunneo-ciliatum and Ophiostoma clavatum, are associates of bark beetles infesting Pinus spp. in Europe. This has raised questions whether they represent distinct taxa.

Using laser micro-dissection and qRT-PCR to analyze cell type-specific gene expression in Norway spruce phloem.

The tangentially oriented polyphenolic parenchyma (PP) and radially organized ray parenchyma in the phloem are central in the defense of conifer stems against insects and pathogens. Laser micro-dissection enables examination of cell-specific defense responses. To examine induced defense responses in Norway spruce stems inoculated with the necrotrophic blue-stain fungus Ceratocystis polonica, RNA extracted from laser micro-dissected phloem parenchyma and vascular cambium was analyzed using real-time RT-PCR (qRT-PCR) to profile transcript levels of selected resistance marker genes.