title: Downregulation of cinnamoyl-coenzyme A reductase in poplar: multiple-level phenotyping reveals effects on cell wall polymer metabolism and structure.
abstract: Cinnamoyl-CoA reductase (CCR) catalyzes the penultimate step in monolignol biosynthesis. We show that downregulation of CCR in transgenic poplar (Populus tremula x Populus alba) was associated with up to 50% reduced lignin content and an orange-brown, often patchy, coloration of the outer xylem. Thioacidolysis, nuclear magnetic resonance (NMR), immunocytochemistry of lignin epitopes, and oligolignol profiling indicated that lignin was relatively more reduced in syringyl than in guaiacyl units. The cohesion of the walls was affected, particularly at sites that are generally richer in syringyl units in wild-type poplar. Ferulic acid was incorporated into the lignin via ether bonds, as evidenced independently by thioacidolysis and by NMR. A synthetic lignin incorporating ferulic acid had a red-brown coloration, suggesting that the xylem coloration was due to the presence of ferulic acid during lignification. Elevated ferulic acid levels were also observed in the form of esters. Transcript and metabolite profiling were used as comprehensive phenotyping tools to investigate how CCR downregulation impacted metabolism and the biosynthesis of other cell wall polymers. Both methods suggested reduced biosynthesis and increased breakdown or remodeling of noncellulosic cell wall polymers, which was further supported by Fourier transform infrared spectroscopy and wet chemistry analysis. The reduced levels of lignin and hemicellulose were associated with an increased proportion of cellulose. Furthermore, the transcript and metabolite profiling data pointed toward a stress response induced by the altered cell wall structure. Finally, chemical pulping of wood derived from 5-year-old, field-grown transgenic lines revealed improved pulping characteristics, but growth was affected in all transgenic lines tested.
authors.affiliation: Department of Plant Systems Biology, Flanders Institute for Biotechnology, 9052 Gent, Belgium.
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Leplé
authors.forename: Rebecca
authors.initials: R
authors.lastname: Dauwe
authors.forename: Kris
authors.initials: K
authors.lastname: Morreel
authors.forename: Véronique
authors.initials: V
authors.lastname: Storme
authors.forename: Catherine
authors.initials: C
authors.lastname: Lapierre
authors.forename: Brigitte
authors.initials: B
authors.lastname: Pollet
authors.forename: Annette
authors.initials: A
authors.lastname: Naumann
authors.forename: Kyu-Young
authors.initials: KY
authors.lastname: Kang
authors.forename: Hoon
authors.initials: H
authors.lastname: Kim
authors.forename: Katia
authors.initials: K
authors.lastname: Ruel
authors.forename: Andrée
authors.initials: A
authors.lastname: Lefèbvre
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Joseleau
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Grima-Pettenati
authors.forename: Riet
authors.initials: R
authors.lastname: De Rycke
authors.forename: Sara
authors.initials: S
authors.lastname: Andersson-Gunnerås
authors.forename: Alexander
authors.initials: A
authors.lastname: Erban
authors.forename: Ines
authors.initials: I
authors.lastname: Fehrle
authors.forename: Michel
authors.initials: M
authors.lastname: Petit-Conil
authors.forename: Joachim
authors.initials: J
authors.lastname: Kopka
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
authors.forename: Eric
authors.initials: E
authors.lastname: Messens
authors.forename: Björn
authors.initials: B
authors.lastname: Sundberg
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Mansfield
authors.forename: John
authors.initials: J
authors.lastname: Ralph
authors.forename: Gilles
authors.initials: G
authors.lastname: Pilate
authors.forename: Wout
authors.initials: W
authors.lastname: Boerjan
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000235:genetics*; D002241:Carbohydrates; D002473:Cell Wall / Q000737:chemistry* / Q000648:ultrastructure; D002851:Chromatography, High Pressure Liquid; D015536:Down-Regulation / Q000235:genetics*; D005453:Fluorescence; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007150:Immunohistochemistry; D008031:Lignin / Q000737:chemistry* / Q000378:metabolism*; D010636:Phenols / Q000032:analysis; D010641:Phenotype; D030821:Plants, Genetically Modified; D032107:Populus / Q000166:cytology / Q000201:enzymology* / Q000235:genetics* / Q000648:ultrastructure; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D052584:Xylem / Q000166:cytology / Q000254:growth & development / Q000648:ultrastructure
chemical_list: D002241:Carbohydrates; D010636:Phenols; D008031:Lignin; D000445:Aldehyde Oxidoreductases; C019904:cinnamoyl CoA reductase