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| 2. |
- Agostinelli, Marta, et al.
(författare)
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Mycobiome of Fraxinus excelsior With Different Phenotypic Susceptibility to Ash Dieback
- 2021
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Ingår i: Frontiers in Forests and Global Change. - : Frontiers Media S.A.. - 2624-893X. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Agostinelli, Marta, et al.
(författare)
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Pedunculate Oaks (Quercus robur L.) Differing in Vitality as Reservoirs for Fungal Biodiversity
- 2018
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Ecological significance of trees growing in urban and peri-urban settings is likely to increase in future land-use regimes, calling for better understanding of their role as potential reservoirs or stepping stones for associated biodiversity. We studied the diversity of fungal endophytes in woody tissues of asymptomatic even aged pedunculate oak trees, growing as amenity trees in a peri-urban setting. The trees were classified into three groups according to their phenotypic vitality (high, medium, and low). Endophytes were cultured on potato dextrose media from surface sterilized twigs and DNA sequencing was performed to reveal the taxonomic identity of the morphotypes. In xylem tissues, the frequency and diversity of endophytes was highest in oak trees showing reduced vitality. This difference was not found for bark samples, in which the endophyte infections were more frequent and communities more diverse than in xylem. In general, most taxa were shared across the samples with few morphotypes being recovered in unique samples. Leaf phenolic profiles were found to accurately classify the trees according to their phenotypic vitality. Our results confirm that xylem is more selective substrate for endophytes than bark and that endophyte assemblages in xylem are correlated to the degree of host vitality. Thus, high vitality of trees may be associated with reduced habitat quality to wood-associated endophytes.
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| 4. |
- Albrectsen, Benedicte R, 1960-, et al.
(författare)
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Large scale geographic clines of parasite damage to Populus tremula L
- 2010
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 33:3, s. 483-493
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Tidskriftsartikel (refereegranskat)abstract
- In conclusion, clines of Phyllocnistis were stronger and more persistent compared to Melampsora, which showed contrasting clines of varying strength. Our data thus support the assumption of the GMTC model that clines exist in the border between hot and cold spots and that they may be less persistent for parasites with an elevated gene flow, and/or for parasites which cover relatively larger hot spots surrounded by fewer cold spots.
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| 5. |
- Anderbrant, O., et al.
(författare)
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Feeding by Scolytus bark beetles to test for differently susceptible elm varieties
- 2017
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Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 141:5, s. 417-420
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Tidskriftsartikel (refereegranskat)abstract
- Dutch elm disease (DED), caused by the fungi Ophiostoma ulmi and O. novo-ulmi, has reduced elm populations severely in Europe and North America. Breeding programmes are in action to find less susceptible elm varieties suitable for re-establishing elm stands. Bark beetles, mainly Scolytus spp., are the only known natural vectors of DED. During twig feeding, beetles transfer Ophiostoma spores to healthy elms. Thus, less palatable elms should run a lower risk of DED infections. In feeding preference bioassays, we offered twigs from elms exhibiting different degree of susceptibility to O. novo-ulmi, together with non-host trees to Scolytus beetles. Scolytus multistriatus preferred wych elm, Ulmus glabra, to 100% in two-choice tests, whereas S. laevis did not discriminate between a tolerant and a susceptible variety of field elm, U. minor. We suggest that the feeding assay is useful as a low-tech method in breeding programmes for evaluating the suitability of promising elm genotypes to vector insects.
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| 6. |
- Benavent-Celma, Clara, et al.
(författare)
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Current practices and emerging possibilities for reducing the spread of oomycete pathogens in terrestrial and aquatic production systems in the European Union
- 2022
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Ingår i: Fungal Biology Reviews. - : Elsevier. - 1749-4613 .- 1878-0253. ; 40, s. 19-36
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Tidskriftsartikel (refereegranskat)abstract
- Diseases caused by oomycete pathogens are a global threat to forestry, agriculture and aquaculture. Because of their complex life cycles, characterised by dormant resting structures that enable their survival for years under hostile environmental conditions, reducing the spread of oomycetes is a challenging task. In this review, we present an overview of this challenge, starting from the need to understand the natural and anthropogenic dispersal pathways of these pathogens. Focusing on the European Union, we explore current legislation that forms a backbone for biosecurity protocols against the spread of oomycetes through trade and transport. We discuss the options for prevention, containment and long-term management of oomycetes in different production settings, emphasising the importance of prevention as the most cost-efficient strategy to reduce the spread of these pathogens. Finally, we highlight some of the new and emerging technologies and strategies as potential tools in the integrated pest management of animal and plant diseases caused by oomycetes. We emphasise the urgency of actions to halt the global spread of these pathogens.
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| 7. |
- Bengtsson, Therese, et al.
(författare)
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Activation of defence responses to Phytophthora infestans in potato by BABA
- 2014
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Ingår i: Plant Pathology. - : Wiley. - 0032-0862 .- 1365-3059. ; 63, s. 193-202
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Tidskriftsartikel (refereegranskat)abstract
- Late blight caused by Phytophthora infestans is one of the most devastating diseases of the potato crop. Resistance breeding and current fungicides are unable to control the rapidly evolving P. infestans and new control strategies are urgently needed. This study examined mechanisms of dl-β-aminobutyric acid (BABA)-induced resistance (IR) in the potato-P. infestans system. Leaves from two cultivars that differ in their degree of resistance, Bintje and Ovatio, were analysed after foliar treatment with BABA. Rapid activation of various defence responses and a significant reduction in P. infestans growth were observed in leaves treated with BABA. In the more resistant cultivar, Ovatio, the activation was both faster and stronger than in Bintje. Microscopic analysis of leaves treated with BABA revealed induction of small hypersensitive response (HR)-like lesions surrounded by callose, as well as production of hydrogen peroxide (H2O2). Molecular and chemical analyses revealed soluble phenols such as arbutin and chlorogenic acid and activation of PR-1. These results show a direct activation of defence responses in potato, rather than priming as reported for other plant species. They also show that the efficiency of BABA-IR differs between cultivars, which highlights the importance of taking all aspects into consideration when establishing new methods for disease management.
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| 8. |
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| 9. |
- Blumenstein, Kathrin, et al.
(författare)
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Diversidad de endófitos del olmo y relación con la resistencia a la grafiosis
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Los endófitos activan en sus hospedantes mecanismos defensivos similares a los activados por patógenos. Se plantea la hipótesis de que estos mecanismos limitan el establecimiento de endófitos en olmos resistentes a la grafiosis. Asimismo, ciertos endófitos proporcionan a sus hospedantes mecanismos epigenéticos de protección ante patógenos. Planteamos como segunda hipótesis que determinados endófitos están implicados en la resistencia ambiental a la grafiosis. Se ha estudiado la frecuencia y diversidad de endófitos en olmos genéticamente resistentes a la grafiosis y se ha comparado con la encontrada en olmos susceptibles. Además, se han aislado endófitos de olmos que en campo muestran resistencia fenotípica a la grafiosis, pese a que son susceptibles a la enfermedad. Su antagonismo hacia la grafiosis se ha evaluado mediante ensayos in vitro e in vivo. Olmos resistentes muestran una menor frecuencia y diversidad de endófitos en el xilema, lo que confirma la primera hipótesis. Ciertos endófitos produjeron metabolitos extracelulares que inhibieron el crecimiento del hongo de la grafiosis in vitro. El efecto protector de los tratamientos con endófitos ante la grafiosis ha sido en general poco notable, si bien ciertas cepas mostraron un efecto significativo, aunque dependiente del genotipo de olmo.
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| 10. |
- Blumenstein, Kathrin, et al.
(författare)
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Nutritional niche overlap potentiates the use of endophytes in biocontrol of a tree disease
- 2015
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Ingår i: BioControl (Dordrecht). - : Springer Science and Business Media LLC. - 1386-6141 .- 1573-8248. ; 60:5, s. 655-667
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Tidskriftsartikel (refereegranskat)abstract
- Asymptomatic endophytic fungi are often regarded as potent biocontrol agents in plants, but the competitive interactions between endophytes and other microbes within the same host plant are poorly understood. We tested a hypothesis that as compared to asymptomatic endophytes, an aggressive pathogen inhabiting the same host is able to utilize carbon substrates more efficiently. Using phenotype microarray, we determined the carbon utilization profiles of the highly virulent Dutch elm disease (DED) pathogen Ophiostoma novo-ulmi, and four asymptomatic elm (Ulmus spp.) endophyte isolates that were selected based on their differential association to the DED-susceptibility pattern of the host elms. The competitive interactions between isolates were evaluated using a niche overlap index. In contrast to our hypothesis, the studied endophytes exhibited extensive niche overlap with the pathogen, suggesting that some endophyte strains might protect elms against DED-pathogen through competition for substrates and provide new tools for biocontrol of DED.
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