scholarly journals A Novel Plant Resistance Inducer for the Protection of European Ash (Fraxinus excelsior L.) against Hymenoscyphus fraxineus—Preliminary Studies

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1072
Author(s):  
Krzysztof Turczański ◽  
Marta Bełka ◽  
Rafal Kukawka ◽  
Maciej Spychalski ◽  
Marcin Smiglak
Keyword(s):  
Cross Section ◽  
Plant Resistance ◽  
Active Substance ◽  
Fraxinus Excelsior ◽  
Site Factors ◽  
Tree Disease ◽  
Hymenoscyphus Fraxineus ◽  
The Cross ◽  
European Ash

Ash tree disease is caused by an ascomycete fungus Hymenoscyphus fraxineus, which first emerged in 1992, eastern Poland. Site factors, genetic predispositions, and resistance to the pathogen have not been fully described yet. The general aim of the study undertaken was to check the effect of using a new active substance representing benzothiadiazoles, a BTH derivative, namely, N-methyl-N-methoxyamide-7-carboxybenzo(1.2.3)thiadiazole (BTHWA), on ash saplings. A total of 41 ash saplings, aged three to five years, were subjected to this experiment in six variants of treatment. The results of the inoculation with H. fraxineus indicated that the treatment with BTHWA resulted in the limitation of the size of necrotic phloem lesions. Although the lesions were detectable in the cross section, the plants showed no visible signs of infection. The results suggest that H. fraxineus development in ash saplings can be slowed down or even completely stopped through triggering plant resistance by BTHWA.

scholarly journals Estimating mortality rates of European ash ( Fraxinus excelsior ) under the ash dieback ( Hymenoscyphus fraxineus ) epidemic

2018 ◽  
Vol 1 (1) ◽  
pp. 48-58 ◽  
Author(s):  
Tim L. R. Coker ◽  
Jiří Rozsypálek ◽  
Anne Edwards ◽  
Tony P. Harwood ◽  
Louise Butfoy ◽  
...  
Keyword(s):  
Mortality Rates ◽  
Fraxinus Excelsior ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
European Ash

scholarly journals The invasive forest pathogen Hymenoscyphus fraxineus boosts mortality and triggers niche replacement of European ash (Fraxinus excelsior)

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Olalla Díaz-Yáñez ◽  
Blas Mola-Yudego ◽  
Volkmar Timmermann ◽  
Mari Mette Tollefsrud ◽  
Ari M. Hietala ◽  
...  
Keyword(s):  
Fraxinus Excelsior ◽  
Forest Pathogen ◽  
Hymenoscyphus Fraxineus ◽  
European Ash

scholarly journals Decline of Fraxinus excelsior L. in parks of Saint Petersburg: Who is to blame – Hymenoscyphus fraxineus or Diplodia spp.?

2020 ◽  
Vol 73 (1) ◽  
pp. 43-51
Author(s):  
Dmitrii A. Shabunin ◽  
Andrey V. Selikhovkin ◽  
Elena Yu. Varentsova ◽  
Dmitry L. Musolin
Keyword(s):  
Light Microscopy ◽  
Fraxinus Excelsior ◽  
Ash Dieback ◽  
Saint Petersburg ◽  
Hymenoscyphus Fraxineus ◽  
Ash Trees ◽  
Fallen Leaves ◽  
European Ash

Abstract The weakening and decline of European ash Fraxinus excelsior L. and other ash species have been recorded at different locations in the suburbs of Saint Petersburg, Russia. During the summer of 2019 and spring of 2020, samples from leaves, petioles, and shoots were collected from the weakened and declining ash trees in three parks in Pushkin and Gatchina and maintained in humid chambers to induce the fructification of fungi. In total, 30 taxa of micromycetes belonging to 23 genera were identified using methods of light microscopy. Hymenoscyphus fraxineus, a putative agent of ash dieback, was not recorded in the samples collected in the crowns of trees, but only on the petioles of the fallen leaves in spring. Out of all the micromycetes recorded, only coelomycetes from the genus Diplodia Fr. (in particular, D. mutila) can damage the branches of ash trees and, thus, be considered pathogenic. It is likely that H. fraxineus opens “the entry of infection” and Diplodia spp. cause the major weakening and decline of branches. The data obtained can significantly change our understanding of the causes of ash dieback and possible methods of ash stand preservation. The reason for the low pathogenicity and activity of H. fraxineus, as well as the possible role of ascomycetes Diplodia spp. in the dieback of ash stands requires further research.

scholarly journals Transformation of European Ash (Fraxinus excelsior L.) Callus as a Starting Point for Understanding the Molecular Basis of Ash Dieback

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2524
Author(s):  
Anna Hebda ◽  
Aleksandra Liszka ◽  
Piotr Zgłobicki ◽  
Katarzyna Nawrot-Chorabik ◽  
Jan J. Lyczakowski
Keyword(s):  
Molecular Basis ◽  
Selection Process ◽  
Pathogenic Fungus ◽  
Fraxinus Excelsior ◽  
Reporter System ◽  
Ash Dieback ◽  
Gus Reporter ◽  
Hymenoscyphus Fraxineus ◽  
Starting Point ◽  
European Ash

The population of European ash (Fraxinus excelsior L.) is currently facing the risk of collapse, mainly due to ash dieback, a disease caused by a pathogenic fungus, Hymenoscyphus fraxineus. To facilitate studies into the molecular basis of ash dieback and design breeding strategies for a generation of resistant trees, it is necessary to develop tools enabling the study of gene function in F. excelsior. Despite this, a method for the genetic engineering of F. excelsior is still missing. Here, we report the first successful genetic transformation of F. excelsior callus and a selection process enabling the formation of stable transgenic callus lines. The protocol relies on the use of Agrobacterium tumefaciens to transform callus tissue derived from embryos of F. excelsior. In our experiments, we used the β-glucuronidase (GUS) reporter system to demonstrate the transformation of callus cells and performed RT-PCR experiments to confirm the stable expression of the transgene. Since ash dieback threatens the long-term stability of many native F. excelsior populations, we hope that the transformation techniques described in this manuscript will facilitate rapid progress in uncovering the molecular basis of the disease and the validation of gene targets previously proposed to be linked to the resistance of trees to H. fraxineus pathogenicity.

scholarly journals Mycobiome of Fraxinus excelsior With Different Phenotypic Susceptibility to Ash Dieback

2021 ◽  
Vol 4 ◽  
Author(s):  
Marta Agostinelli ◽  
Diem Nguyen ◽  
Johanna Witzell ◽  
Michelle Cleary
Keyword(s):  
Large Scale ◽  
Population Decline ◽  
Keystone Species ◽  
Fungal Species ◽  
Fraxinus Excelsior ◽  
Fungal Communities ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
Ash Trees ◽  
European Ash

For the last two decades, large-scale population decline of European ash (Fraxinus excelsior) has occurred in Europe because of the introduction of the alien fungal pathogen, Hymenoscyphus fraxineus, from East Asia. Since European ash is a keystone species having critical importance for biodiversity, and only a small percentage of the ash population appears to show some tolerance against the pathogen, the loss of ash trees means that other associated organisms, especially those with high or obligate associations to ash, are at risk of further species declines. In this study, we used high throughput DNA sequencing and multivariate analysis to characterize: (i) the mycobiome in aerial tissues (i.e., leaf, bark, and xylem) of ash trees showing different phenotypic response to ash dieback, (ii) the temporal variation in fungal communities across the growing season, and (iii) the similarity in fungal community structure between ash and other common trees species that may serve as an ecological niche substitute for ash microfungi. Results showed that fungal communities differed among the three tissue types, susceptibility classes, in time and between sites. Trophic analysis of functional groups using the FUNGuild tool indicated a higher presence of pathotrophic fungi in leaves than in bark and xylem. The share of pathotrophic fungi increased along a gradient of low to high disease susceptibility in both bark and xylem tissue, while the proportion of symbiotrophic fungi correspondingly decreased in both tissue types. Neighboring, alternative host trees did not share all the fungal species found in ash, however, most microfungi uniquely associated to ash in this study are generalists and not strictly host specific. The progressive disappearance of ash trees on the landscape imposes a high risk for extinction of Red-listed macrofungal species, and breeding for resistance against ash dieback should help sustain important biodiversity associated to ash. Microfungal diversity though may be less prone to such demise since most ash-associated endophytes appear to occur on a broad range of host species.

scholarly journals Situation and perspectives of European ash (Fraxinus spp.) in Ukraine: focus on eastern border

2019 ◽  
Vol 25 (2) ◽  
pp. 193-202
Author(s):  
Kateryna V Davydenko ◽  
Valentyna Borysova ◽  
Olena Shcherbak ◽  
Yevhen Kryshtop ◽  
Valentyna Meshkova
Keyword(s):  
Pathogenic Fungus ◽  
Total Mortality ◽  
Fraxinus Excelsior ◽  
Bacterial Disease ◽  
Eastern Region ◽  
Ash Dieback ◽  
Epicormic Shoots ◽  
Hymenoscyphus Fraxineus ◽  
Ash Trees ◽  
European Ash

The health condition of European ash (Fraxinus excelsior) stands in Ukraine has become worse since 2006. Firstly, in 2011 an alien invasive pathogenic fungus Hymenoscyphus fraxineus was identified in the eastern part of the country and, subsequently, its presence was confirmed in the western and central parts. The aims of our research were to evaluate the health of ash trees and identify the main causes of ash decline in different regions of Ukraine with emphasis on ash dieback and its association with collar rots.    Results showed that since 2013 the number of trees with ash dieback symptoms has been gradually increasing, reaching up to 92 % in 2018. Total mortality due to ash dieback was up to 9 % in 2018. Disease intensity remains high in northern and central Ukraine comparing with the east. Branch dieback, collar rots, epicormic shoots and bacterial disease of ash occurred more often in the eastern region, some symptoms were observed simultaneously. Ash bark beetle galleries, as well as foliage browsing insects, were found mostly in weakened and/or dying trees.    It was indicated that collar rots significantly increase the mortality of ash trees. Armillaria spp. fungi were found to be frequently associated with ash dieback on living stems and fallen trees in 2017, causing high rates of mortality in the northern and central regions. For further ash conservation and breeding programmes, resistant trees in severely damaged regions should be selected to preserve genetic diversity in ash populations.                                                       Keywords: Fraxinus excelsior, ash dieback, collar rot, bacterial disease, epicormic shoots, Hymenoscyphus fraxineus, Armillaria spp.

scholarly journals Ash dieback and contributing factors of forest weakening in provenance tests in the Sumy region

2021 ◽  
Vol 67 (2) ◽  
pp. 113-121
Author(s):  
Valentyna Meshkova ◽  
Viacheslav Samoday ◽  
Kateryna Davydenko
Keyword(s):  
Condition Index ◽  
Health Condition ◽  
Fraxinus Excelsior ◽  
Forest Steppe ◽  
Special Focus ◽  
Contributing Factors ◽  
Ash Dieback ◽  
Collar Rot ◽  
Hymenoscyphus Fraxineus ◽  
European Ash

Abstract The aim of this study was to evaluate the health condition of Fraxinus excelsior L. in provenance tests, with special focus on ash dieback (ADB), but taking into account also other causes of its decline. The research was carried out in the provenance tests of F. excelsior in the forest-steppe part of the Sumy region. ADB symptoms were revealed in all provenance tests. For 2012–2019 the health condition index, ADB incidence and severity increased for all provenances except the Steppe. Collar rot was present in all ash provenances. Fungi species were isolated from the stem parts of ash at all provenances. Hymenoscyphus fraxineus induced longest necrotic lesions following wound inoculation of stems of 7–10-years-old plants of European ash in the forest while inoculation with both Cytospora sp. and Diplodia sp. resulted in smaller necroses. The conclusion from other regions about the coincidence the damage of European ash by ADB and collar rots as well as the coincidence the damage of European ash by collar rot and tree colonization by Hylesinus crenatus (Fabricius, 1787) is supported.

Towards silvicultural mitigation of the European ash (Fraxinus excelsior) dieback: the importance of acclimated trees in retention forestry

2015 ◽  
Vol 45 (9) ◽  
pp. 1206-1214 ◽  
Author(s):  
Raul Rosenvald ◽  
Rein Drenkhan ◽  
Taavi Riit ◽  
Asko Lõhmus
Keyword(s):  
Disease Progression ◽  
Secondary Infection ◽  
Fraxinus Excelsior ◽  
Rapid Decline ◽  
Tree Resistance ◽  
Hymenoscyphus Fraxineus ◽  
Retention Forestry ◽  
Ash Trees ◽  
Retention Trees ◽  
European Ash

The European ash (Fraxinus excelsior L.) dieback is an acute forest pathology problem caused by the invasive ascomycete Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz, Hosoya. There are no practical solutions yet, but selection for resistant genotypes and intensive care have been highlighted as options. Our aim was to assess the disease mitigation potential of silvicultural harvests, which influence stress levels in retained trees. We annually monitored 577 retention trees on Estonian cut areas for 13 years, including 9 years impacted by the dieback. Sixty-five percent of the trees survived and 15% retained healthy crown, despite all sampled trees being infected. The damage was smallest in the trees retained near precut edges. Former forest-interior trees that were left in central parts of the cut areas suffered high initial damage but smaller disease progression than trees near postcut edges. Tree size and secondary infection by Armillaria spp. were not related to disease progression, but rapid decline was observed in the region with the highest density of ash trees retained. Our results indicate a significant silvicultural potential for tree resistance. Ash trees tend to be healthiest in open conditions, which probably inhibit the pathogen and provide better resources for the tree. Location near precut edges is an important tree retention criterion, which can mitigate initial harvest-induced stress.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Energy Distribution in Electron Beams

1972 ◽  
Vol 30 ◽  
pp. 568-569
Author(s):  
Tamotsu Ohno
Keyword(s):  
Electron Beam ◽  
Energy Distribution ◽  
Cross Section ◽  
Integral Curve ◽  
Electron Beams ◽  
Electron Gun ◽  
Angular Divergence ◽  
Apparent Increase ◽  
Integral Width ◽  
The Cross

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.

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