title: A common fungal associate of the spruce bark beetle metabolizes the stilbene defenses of Norway spruce.
abstract: Norway spruce (Picea abies) forests suffer periodic fatal attacks by the bark beetle Ips typographus and its fungal associate, Ceratocystis polonica. Norway spruce protects itself against fungal and bark beetle invasion by the production of terpenoid resins, but it is unclear whether resins or other defenses are effective against the fungus. We investigated stilbenes, a group of phenolic compounds found in Norway spruce bark with a diaryl-ethene skeleton with known antifungal properties. During C. polonica infection, stilbene biosynthesis was up-regulated, as evidenced by elevated transcript levels of stilbene synthase genes. However, stilbene concentrations actually declined during infection, and this was due to fungal metabolism. C. polonica converted stilbenes to ring-opened, deglycosylated, and dimeric products. Chromatographic separation of C. polonica protein extracts confirmed that these metabolites arose from specific fungal enzyme activities. Comparison of C. polonica strains showed that rapid conversion of host phenolics is associated with higher virulence. C. polonica is so well adapted to its host's chemical defenses that it is even able to use host phenolic compounds as its sole carbon source.
authors.affiliation: Max Planck Institute for Chemical Ecology, 07745 Jena, Germany.
authors.forename: Almuth
authors.initials: A
authors.lastname: Hammerbacher
authors.forename: Axel
authors.initials: A
authors.lastname: Schmidt
authors.forename: Namita
authors.initials: N
authors.lastname: Wadke
authors.forename: Louwrance P
authors.initials: LP
authors.lastname: Wright
authors.forename: Bernd
authors.initials: B
authors.lastname: Schneider
authors.forename: Joerg
authors.initials: J
authors.lastname: Bohlmann
authors.forename: Willi A
authors.initials: WA
authors.lastname: Brand
authors.forename: Trevor M
authors.initials: TM
authors.lastname: Fenning
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gershenzon
authors.forename: Christian
authors.initials: C
authors.lastname: Paetz
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000222:Adaptation, Physiological; D000818:Animals; D001203:Ascomycota / Q000378:metabolism* / Q000472:pathogenicity* / Q000502:physiology; D002109:Caffeic Acids / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D001517:Coleoptera / Q000382:microbiology; D005960:Glucosides / Q000378:metabolism; D054884:Host-Pathogen Interactions; D028222:Picea / Q000378:metabolism* / Q000382:microbiology*; D024301:Plant Bark / Q000378:metabolism / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology; D013267:Stilbenes / Q000378:metabolism*
chemical_list: D002109:Caffeic Acids; D005960:Glucosides; D013267:Stilbenes; C121481:astringin; D002244:Carbon; D000217:Acyltransferases; C022674:stilbene synthase; C040048:caffeic acid