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Bark beetle (Ips typographus) is the most serious killer of Norway spruce trees (Picea abies) in Europe. The blue stain fungus (Endoconidiophora polonica) is closely associated with I.typographus and is transmitted from tree to tree by bark beetle. Spruce trees synthesize various phenolic compounds and the biosynthesis of these compounds is up-regulated in response to bark beetle attack and fungus infection. Interestingly, the concentration of phenolic compounds decreases during the course of infection possibly due to fungal metabolism. It has been shown that successful virulent strains that produce large lesions in tress can detoxify phenolic compounds at much higher rate than less virulent strains. This shows that there is a correlation between fungal biotransformation of phenolics and fungal fitness during infection. Analysis of fungal biotransformation of phenolic substrates in the medium shows various intermediates like ring opened lactones, aglycones and dimeric products. Several candidate genes were identified to be involved in detoxification steps from a transcriptome of E. polonica that was grown on polyphenols.

The main aim of this thesis is to identify, characterize and study the regulation of different enzymes involved in detoxification of phenolic compounds. I am also interested in comparing the genes involved in detoxification from different E. polonica isolates in an attempt to answer the question why some of the E. polonica isolates are less virulent.
last updated on 2019-04-15