Fungal Communities in Leaves and Roots of Healthy-Looking and Diseased Ulmus glabra

The aim of this study was to investigate fungal communities associated with leaves and roots of healthy-looking and declining U. glabra trees. The study was expected to demonstrate whether and how the diversity and composition of fungal communities change in these functional tissues following the infection by Dutch elm disease-causing fungi. The study sites included six U. glabra sites in Lithuania, where leaves and roots were sampled. DNA was isolated from individual samples, amplified using ITS2 rRNA as a marker, and subjected to high-throughput sequencing. The sequence analysis showed the presence of 32,699 high-quality reads, which following clustering, were found to represent 520 non-singleton fungal taxa. In leaves, the fungal species richness was significantly higher in healthy-looking trees than in diseased ones (p  0.05). The most common fungi in all samples of roots were Trichocladium griseum (32.9%), Penicillium restrictum (21.2%), and Unidentified sp. 5238_7 (12.6%). The most common fungi in all samples of leaves were Trichomerium sp. 5238_8 (12.30%), Aureobasidium pullulans (12.03%), Cladosporium sp. 5238_5 (11.73%), and Vishniacozyma carnescens (9.86%). The results showed that the detected richness of fungal taxa was higher in samples collected from healthy-looking trees than from diseased ones, thereby highlighting the negative impact of the Dutch elm disease on the overall fungal diversity

Mycobiota Associated with Symptomatic and Asymptomatic Fraxinus excelsior in Post-Dieback Forest Stands

In Lithuania, the dieback of European ash (Fraxinus excelsior L.), caused by alien ascomycete Hymenoscyphus fraxineus, started in the mid-1990s, resulting in a large-scale decline of F. excelsior and its dominated forest habitats. Nevertheless, the recent inventories show the presence of several hundred hectares of naturally regenerated F. excelsior stands. We used seven naturally regenerated sites and three planted progeny trials of F. excelsior to collect leaves, shoots, roots, and the surrounding soil to study ash-associated fungal communities based on high-throughput sequencing. Results showed that fungal communities associated with F. excelsior in re-emerging stands in post-dieback areas were composed of 1487 fungal taxa. Among these, 60.5% were Ascomycota, 37.5%-Basidiomycota, 1.7%-Zygomycota, and 0.2% were Chytridiomycota. Revealed mycobiota was largely composed of endophytic fungal communities as these were dominated by Cladosporium sp., Fraxinicola fraxini (syn. Venturia fraxini) and Vishniacozyma foliicola. Identified mycobiota also included a range of ash-specific fungal taxa. Hymenoscyphus fraxineus occurred in all stands but was not frequent. Cladosporium sp. showed strongest negative correlation with the presence of H. fraxineus. This ascomycete, given its dominance in leaves, shoots and in the organic soil layer, might be the limiting factor for the infection rate or spread of H. fraxineus. Although fungal communities in asymptomatic and symptomatic samples of F. excelsior differed significantly from each other, the majority of the most frequently found fungal taxa were not host-specific, suggesting that these were negligibly affected by ash dieback. Investigated stands in natural F. excelsior habitats exhibited larger diversity of fungal taxa (especially ash-specific), than progeny trials planted on former grasslands, indicating the importance of natural habitats in F. excelsior restoration programs

Identifying Fraxinus excelsior tolerant to ash dieback: Visual field monitoring versus a molecular marker

Ash dieback (ADB) caused by the pathogen Hymenoscyphus fraxineus is the cause of massive mortality of Fraxinus spp. in Europe. The aim of this work was to check for the presence of the molecular marker for ADB tolerance in mapped healthy-looking F. excelsior trees, and to compare its occurrence in trees exhibiting severe ADB symptoms. Monitoring of 135 healthy-looking F. excelsior on the island of Gotland, Sweden, showed that after 3-4 years 99.3% of these trees had 0%-10% crown damage, thus remaining in a similar health condition as when first mapped. After 5-6 years, 94.7% of these trees had 0%-10% crown damage. Molecular analysis of leaf tissues from 40 of those showed the presence of the molecular marker in 34 (85.0%) trees, while it was absent in 6 (15.0%) trees. Analysis of leaf tissues from 40 severely ADB-diseased trees showed the presence of the molecular marker in 17 (42.5%) trees, but its absence in 23 (57.5%) trees (p < .0001). The results demonstrated that monitoring of healthy-looking F. excelsior is a simple and straightforward approach for the selection of presumably ADB-tolerant ash for future breeding. The cDNA-based molecular marker revealed moderate capacity on its own to discriminate between presumably ADB-tolerant and susceptible F. excelsior genotypes

Fungal Communities in Re-Emerging Fraxinus excelsior Sites in Lithuania and Their Antagonistic Potential against Hymenoscyphus fraxineus

Fifty-nine fungal taxa, isolated from re-emerging Fraxinus excelsior sites in Lithuania, were in vitro tested against three strains of Hymenoscyphus fraxineus on agar media to establish their biocontrol properties. All tested fungi were isolated from leaves and shoots of relatively healthy Fraxinus excelsior trees

Adaptive potential of ash (Fraxinus excelsior) populations against the novel emerging pathogen Hymenoscyphus pseudoalbidus

An emerging infectious pathogen Hymenoscyphus pseudoalbidus has spread across much of Europe within recent years causing devastating damage on European common ash trees (Fraxinus excelsior) and associated plant communities. The present study demonstrates the presence of additive genetic variation in susceptibility of natural F. excelsior populations to the new invasive disease. We observe high levels of additive variation in the degree of susceptibility with relatively low influence of environmental factors (narrow-sense heritability = 0.37–0.52). Most native trees are found to be highly susceptible, and we estimate that only around 1% has the potential of producing offspring with expected crown damage of <10% under the present disease pressure. The results suggest that the presence of additive genetic diversity in natural F. excelsior populations can confer the species with important ability to recover, but that low resistance within natural European populations is to be expected because of a low frequency of the hypo-sensitive trees. Large effective population sizes will be required to avoid genetic bottlenecks. The role of artificial selection and breeding for protection of the species is discussed based on the findings

Data Descriptor: Ash leaf metabolomes reveal differences between trees tolerant and susceptible to ash dieback disease

CMS was funded by the ‘Nornex’ project jointly by UK BBSRC (BBS/E/J/000CA5323) and DEFRA and a BBSRC Tools and Resources grant (BB/N021452/1) awarded to M.G. and D.J.S

Dieback of Fraxinus excelsior in the Baltic Sea Region

This thesis is comprised of three main studies: (1) the wood-inhabiting fungi found in declining European ash (Fraxinus excelsior L.) and their pathogenicity; (2) the relationship between F. excelsior phenology, site density and the susceptibility to the dieback; and (3) the potential of natural regeneration of dieback affected ash stands. The studies that are presented here were conducted in Denmark, Lithuania and Sweden. Combination of different sampling and detection methods revealed a high diversity of fungi in both healthy looking and symptomatic tissues of declining F. excelsior. The most frequently detected fungal taxa were Alternaria alternata, Armillaria cepistipes, Aureobasidium pullulans, Botryosphaeria stevensii, Cladosporium cladosporioides, Cryptococcus foliicola, Epicoccum nigrum, Gibberella avenacea, Hymenoscyphus pseudoalbidus, Lewia sp., Phoma spp. and Phomopsis sp. In pathogenicity tests nine fungal taxa caused symptomatic discoloration of bark and cambium on F. excelsior saplings, though only H. pseudoalbidus infected substantial proportion (50-100%) of tested trees. The seasonal pattern of ash dieback severity, attributed to crown damage of F. excelsior trees, significantly increased towards the end of the investigated growth season. Severity of dieback symptoms was more pronounced in the unthinned stands, but otherwise was not related with stand density. However, susceptibility of F. excelsior to the disease was found to be dependent on the flushing (bud-bursting) phenology of the trees - late-flushing F. excelsior were most severely affected. Our study demonstrated that vigorous natural regeneration of F. excelsior in examined clear-felled sites cannot be expected. Regenerating F. excelsior exhibited abundant dieback symptoms. The species composition in sites with long disease history is likely to shift away from F. excelsior to early successional pioneer species such as Alnus incana, Betula spp., and in some instances Populus tremula

Automatic usability evaluation of website

This work describe InChecking systems prototype, wich goal is to test and evaluate a specified page usability. Description includes system design and functionality. As the functionality of the system is based on the heuristic evaluation method, which consists of 10 principles, so main part of the work is about how to implement these principles in the system. The result may not be as expected, because the prototype is difficult to fully implement some of the principles. This is due to the fact that the heuristic evaluation method is designed for people evaluators and it is imposible to fully implement all of the principles when system is using only the code checking. However the prototype is able to verify the usability of the pages, only some of the principles estimates are inaccurate

Fandraisan’anjara amin’ny fandalinana ny fampianarana algorithmika amin’ny mpianatra amin’ny ambaratonga faharoa amin’ny fampiasana sava atontan’isa misy fitarihana araka ny MGK

Noting the current version of the school curriculum in Madagascar which ignores the true meaning of computer science, this thesis, located in the field of Didactics of Mathematics and Computer Science, proposes a relatively effective proven strategy to integrate algorithmic education through the teaching of the discipline of mathematics in secondary school using its various problem-solving techniques. Pedagogical experiments including evaluation sessions followed by comparative analysis in the presence of a control populationwere carried out during this thesis to study and identify the implicative links contained in the database collected from this occasion. An optimized implementation of the association rule extraction algorithms has been made; which led to the design and implementation of a computer tool for Implicative Statistical Analysis based on the measure MGK in the context of binary data mining. Which made it possible to extract implicative links or association rules of the type "if behavior (condition) A, then behavior B".Constatant la version actuelle du programme scolaire de Madagascar qui ignore le sens véritable de l’informatique, cette thèse, située dans le domaine de Didactiques des Mathématiques et de l’Informatique, propose une stratégie avérée relativement efficace d’intégrer l’éducation algorithmique à travers l’enseignement de la discipline des mathématiques au secondaire à l’aide de ses différentes techniques de résolution de problème. Des expérimentations pédagogiques comprenant des séances d’évaluation suivies d’analyse comparative en présence de population témoin ont été réalisées durant cette thèse pour étudier et identifier les liens implicatifs contenus dans la base de données collectées à cette occasion. Une implémentation optimisée des algorithmes d’extraction des règles d’association a été faite ; ce qui a conduit à la conception et à la réalisation d’un outil informatique d’Analyse Statistique Implicative basé sur la mesure MGK dans le contexte de la fouille de données binaires. Ce qui a permis d’extraire des liens implicatifs ou des règles d’association de type « si comportement (condition) A, alors comportement B ».Fahitana ny votoatiny fandaharam-pianarana ankehitriny eto Madagasikara izay tsy miraharaha ny tena dikan’ny siansa momba ny informatika, ity tezy ity, izay ao anatin’ny sehatry ny Didaktikan’ny Matematika sy informatika, dia manolotra paikady mahomby sy azo antoka hampidirana ny fampianarana algoritmika amin’ny alàlan’ny fampianarana ny taranja matematika amin’ny sekoly ambaratonga faharoa mifototra amin’ny fampiasana ireo tetika famahana olana isankarazany.Fanandramana andakilasy izay nisy fotoam-panombanana narahin’ny famakafakana fampitahana amin’ny fisian’ny kilasy vavolombelona, no natao nandritra ity asa fikarohana ity, mba ho fandalinana sy famantarana ireo rohy manjavozavo amin’ny angon-drakitra voaangona tamin’ireo kilasy nokendrena. Nisy ny fampiharana sy fanatsarana ny algoritma momba ny fitrandrahana fitsipiky ny fifandraisana misy fitarihana ; izay nitarika ho amin’ny famolavolana sy ny famokarana ny fitaovana informatika mikasika ny sava atontan’isa mifototra amin’ny refy MGK ao anatin’ny tontolon’ny fitrandrahana angon-drakitra mimari-droa mba hahazoana rohy na fitsipiky ny fifandraisana misy fitarihana « raha toa kafitondrantena (fepetra) A, dia ny fitondrantena B »