Vectors of Dutch Elm Disease in Northern Europe

Jürisoo, Liina; Süda, Ilmar; Agan, Ahto; Drenkhan, Rein

doi:10.3390/insects12050393

Cited by 12 publications

(2 citation statements)

References 87 publications

(132 reference statements)

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“…The PCR products were sequenced using PacBio platform at the University of Oslo, Norway. PacBio has been recently used successfully in metabarcoding analysis of microorganisms in different plant, tree, and insect species, with the lesson that the long DNA barcodes (500–1500 bp) enabled by the platform substantially improve the resolution in species identification ( Loit et al, 2019 ; Tedersoo and Anslan, 2019 ; Tedersoo et al, 2019 ; Agan et al, 2020 , 2021 ; Jürisoo et al, 2021 ). The primer ITS1catta was originally designed to differentiate H. albidus from H. fraxineus , and to avoid amplification of plant DNA and the long intron in the 3′ end of the rRNA 18S gene of Hymenoscyphus species (see Tedersoo and Anslan, 2019 ; Agan et al, 2020 ).…”

Section: Methodsmentioning

confidence: 99%

The Native Hymenoscyphus albidus and the Invasive Hymenoscyphus fraxineus Are Similar in Their Necrotrophic Growth Phase in Ash Leaves

et al. 2022

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The populations of European ash and its harmless fungal associate Hymenoscyphus albidus are in decline owing to ash dieback caused by the invasive Hymenoscyphus fraxineus, a fungus that in its native range in Asia is a harmless leaf endophyte of local ash species. To clarify the behavior of H. albidus 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. The plant material was collected from a healthy stand in central Norway, where ash saplings in late autumn showed leaflet vein necrosis like that commonly related to H. fraxineus. For reference, leaflet samples were analyzed from stands with epidemic level of ash dieback in southeastern Norway and Estonia. While H. albidus was predominant in the necrotic veins in the healthy stand, H. fraxineus was predominant in the diseased stands. Otherwise, endophytes with pathogenic potential in the genera Venturia (anamorph Fusicladium), Mycosphaerella (anamorph Ramularia), and Phoma, and basidiomycetous yeasts formed the core leaflet mycobiome both in the healthy and diseased stands. In necrotic leaf areas with high levels of either H. albidus or H. fraxineus DNA, one common feature was the high colonization of sclerenchyma and phloem, a region from which the ascomata of both species arise. Our data suggest that H. albidus can induce necrosis in ash leaves, but that owing to low infection pressure, this first takes place in tissues weakened by autumn senescence, 1–2 months later in the season than what is characteristic of H. fraxineus at an epidemic phase of ash dieback. The most striking difference between these fungi would appear to be the high fecundity of H. fraxineus. The adaptation to a host that is phylogenetically closely related to European ash, a tree species with high occurrence frequency in Europe, and the presence of environmental conditions favorable to H. fraxineus life cycle completion in most years may enable the build-up of high infection pressure and challenge of leaf defense prior to autumn senescence.

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Section: Methodsmentioning

confidence: 99%

The Native Hymenoscyphus albidus and the Invasive Hymenoscyphus fraxineus Are Similar in Their Necrotrophic Growth Phase in Ash Leaves

et al. 2022

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“…Twelve years after plantation, no clone has been lost and the test can be used for education purposes and possibly for seed collection. This good situation, however, may be challenged by DED in the future because prevalence may increase dramatically with the vectors' population dynamics (Jürisoo et al 2021). If many clones are lost and/or most of the trees offer a severely diseased appearance, the conservatory role of the plantation may come to an end.…”

Section: Practical Implications Of Results For the Conservation Of Ge...mentioning

confidence: 99%

Monitoring of the incidence of Dutch Elm Disease and mortality in experimental plantations of French Ulmus minor clones

Collin¹,

Pozzi²,

Joyeau³

et al. 2022

iForest

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The results of 16 experimental plantations of Ulmus minor clones of the French national collection are presented as a complement to a previous work (Collin et al. 2020) on the outcome of the French Programme for the Conservation of Native Elm Genetic Resources. A total of 710 elms from 38 clones were planted in three different regions of France using two types of experimental designs and exposed to natural infection by Dutch Elm Disease (DED). DED infection and subsequent mortality were monitored in rectangular monospecific plantations ("plot-tests"), comprising at least 100 elms (10 clones). Linear plantations of 15 to 36 elms intermixed with other trees and shrubs ("hedge-tests") investigated the feasibility of using native field elm clones in hedge reconstruction projects. After at least 9 (up to 17) years of experimentation, overall DED infection frequency was 33%, with scores above 63% in the oldest plantation and in two fast-growing tests. The overall mortality in the 232 diseased trees was 21%, reaching 29% in the oldest plantation and 64% in a hedge-test on high quality soil, suggesting a possible effect of the very fast growth of the trees. A few clones showed an interesting lower infection frequency or some ability to recover, whereas some others were found quickly infected in several tests and could serve in future experiments on clone attractiveness for DED vectors. Practical conclusions for genetic resources conservation consist of recommendations for the establishment of conservation plantations using regional clones.

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Soil fungal diversity of birch plantations on former agricultural land resembles naturally regenerated birch stands on agricultural and forest land

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Riit

Agan

et al. 2023

Forest Ecology and Management

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Vectors of Dutch Elm Disease in Northern Europe

Cited by 12 publications

References 87 publications

The Native Hymenoscyphus albidus and the Invasive Hymenoscyphus fraxineus Are Similar in Their Necrotrophic Growth Phase in Ash Leaves

The Native Hymenoscyphus albidus and the Invasive Hymenoscyphus fraxineus Are Similar in Their Necrotrophic Growth Phase in Ash Leaves

Monitoring of the incidence of Dutch Elm Disease and mortality in experimental plantations of French Ulmus minor clones

Soil fungal diversity of birch plantations on former agricultural land resembles naturally regenerated birch stands on agricultural and forest land

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