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Publikasjoner

NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.

2018

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Sammendrag

Phytophthora cryptogea, P. gonapodyides, P. lacustris, P. megasperma, P. plurivora, P. taxon paludosa and an unknown Phytophthora species were isolated from waterways and soil samples in Christmas tree fields in southern Sweden. In addition, P. megasperma was isolated from a diseased Norway spruce (Picea abies) plant from one of the fields in Svalöv. Inoculation tests were sequentially carried out with one isolate from each of the three species P. cryptogea, P. megasperma, and P. plurivora, all known pathogens on conifers. The same three isolates were used to study a few morphological features to confirm the identification, and temperature-growth relationships were carried out to see how well the organisms fit into Swedish climatic conditions. Seedlings of Norway spruce and Nordmann fir (Abies nordmanniana) were inoculated in the roots and the stems. None of the isolates caused extensive root rot under the experimental conditions, but all three species could be re-isolated from both Norway spruce and Nordmann fir. Phytophthora root rot is currently of minor concern for Christmas tree growers in Sweden. However, the Phytophthora isolations from soil and water indicate the presence of this damaging agent, which may lead to future problems.

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Sammendrag

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.fraxineus, although a minority (~5%) have partial resistance to dieback. Here, we assemble and annotate a H.fraxineus draft genome, which approaches chromosome scale. Pathogen genetic diversity across Europe and in Japan, reveals a strong bottleneck in Europe, though a signal of adaptive diversity remains in key host interaction genes. We find that the European population was founded by two divergent haploid individuals. Divergence between these haplotypes represents the ancestral polymorphism within a large source population. Subsequent introduction from this source would greatly increase adaptive potential of the pathogen. Thus, further introgression of H.fraxineus into Europe represents a potential threat and Europe-wide biological security measures are needed to manage this disease.