Investigation of constitutive phloem phenolics in European ash (Fraxinus excelsior) with different phenotypic susceptibility to ash dieback
European Ash (Fraxinus excelsior) is an important species for biodiversity through-out Europe. The species is critically threatened due to an alien invasive fungus, Hymenoscyphus fraxineus. Some individual F. excelsior trees however show better resistance to H. fraxineus giving hope that the populat...
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| Formato: | H2 |
| Lenguaje: | Inglés sueco |
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SLU/Southern Swedish Forest Research Centre
2019
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| Sumario: | European Ash (Fraxinus excelsior) is an important species for biodiversity through-out Europe. The species is critically threatened due to an alien invasive fungus, Hymenoscyphus fraxineus. Some individual F. excelsior trees however show better resistance to H. fraxineus giving hope that the population can be saved. The under-lying mechanisms associated with this resistance however are still not clear. In ear-lier work, chemotypes could be clearly distinguished between susceptible and re-sistant ash trees.
The aim of this thesis is to investigate the quantitative and qualitative differences in ash constitutive phenolics that may in part explain the observed resistance in some ash trees. Ash trees of known susceptibility to H. fraxineus from five different European countries were sampled for stem phloem tissue and phenolics were ex-tracted in a butylated hydroxyanisole methanol solution. Chemical analysis using Time-of-Flight Mass spectrometry reveals significant differences in levels of several phenolic compounds, foremost the coumarin fraxin and the secoiridoid ligustroside, which is more prevalent in trees resistant to H. fraxineus than in susceptible ones. Fraxin is also more abundant in the resistant natural host of H. fraxineus, F. mands-hurica, than in susceptible species, such as F. excelsior. This study may help in advancing breeding efforts by identifying potential biomarkers that are associated with resistance. |
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