title: Localization of phenolics in phloem parenchyma cells of Norway spruce (Picea abies).
abstract: Norway spruce (Picea abies) bark contains specialized phloem parenchyma cells that swell and change their contents upon attack by the bark beetle Ips typographus and its microbial associate, the blue stain fungus Ceratocystis polonica. These cells exhibit bright autofluorescence after treatment with standard aldehyde fixatives, and so have been postulated to contain phenolic compounds. Laser microdissection of spruce bark sections combined with cryogenic NMR spectroscopy demonstrated significantly higher concentrations of the stilbene glucoside astringin in phloem parenchyma cells than in adjacent sieve cells. After infection by C. polonica, the flavonoid (+)-catechin also appeared in phloem parenchyma cells and there was a decrease in astringin content compared to cells from uninfected trees. Analysis of whole-bark extracts confirmed the results obtained from the cell extracts and revealed a significant increase in dimeric stilbene glucosides, both astringin and isorhapontin derivatives (piceasides A to H), in fungus-infected versus uninfected bark that might explain the reduction in stilbene monomers. Phloem parenchyma cells thus appear to be a principal site of phenolic accumulation in spruce bark.
authors.affiliation: Max Planck Institute for Chemical Ecology, Beutenberg Campus, Jena, Germany.
authors.forename: Sheng-Hong
authors.initials: SH
authors.lastname: Li
authors.forename: Nina Elisabeth
authors.initials: NE
authors.lastname: Nagy
authors.forename: Almuth
authors.initials: A
authors.lastname: Hammerbacher
authors.forename: Paal
authors.initials: P
authors.lastname: Krokene
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Niu
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gershenzon
authors.forename: Bernd
authors.initials: B
authors.lastname: Schneider
mesh_terms: D001203:Ascomycota / Q000502:physiology; D001692:Biological Transport; D060467:Disease Resistance; D005960:Glucosides / Q000378:metabolism; D010636:Phenols / Q000378:metabolism*; D052585:Phloem / Q000166:cytology* / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D028222:Picea / Q000166:cytology* / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D024301:Plant Bark / Q000166:cytology / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology; D013267:Stilbenes / Q000378:metabolism
chemical_list: D005960:Glucosides; D010636:Phenols; D013267:Stilbenes; C121481:astringin