title: Improved saccharification and ethanol yield from field-grown transgenic poplar deficient in cinnamoyl-CoA reductase.
abstract: Lignin is one of the main factors determining recalcitrance to enzymatic processing of lignocellulosic biomass. Poplars (Populus tremula x Populus alba) down-regulated for cinnamoyl-CoA reductase (CCR), the enzyme catalyzing the first step in the monolignol-specific branch of the lignin biosynthetic pathway, were grown in field trials in Belgium and France under short-rotation coppice culture. Wood samples were classified according to the intensity of the red xylem coloration typically associated with CCR down-regulation. Saccharification assays under different pretreatment conditions (none, two alkaline, and one acid pretreatment) and simultaneous saccharification and fermentation assays showed that wood from the most affected transgenic trees had up to 161% increased ethanol yield. Fermentations of combined material from the complete set of 20-mo-old CCR-down-regulated trees, including bark and less efficiently down-regulated trees, still yielded ∼ 20% more ethanol on a weight basis. However, strong down-regulation of CCR also affected biomass yield. We conclude that CCR down-regulation may become a successful strategy to improve biomass processing if the variability in down-regulation and the yield penalty can be overcome.
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Van Acker
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Leplé
authors.forename: Dirk
authors.initials: D
authors.lastname: Aerts
authors.forename: Véronique
authors.initials: V
authors.lastname: Storme
authors.forename: Geert
authors.initials: G
authors.lastname: Goeminne
authors.forename: Bart
authors.initials: B
authors.lastname: Ivens
authors.forename: Frédéric
authors.initials: F
authors.lastname: Légée
authors.forename: Catherine
authors.initials: C
authors.lastname: Lapierre
authors.forename: Kathleen
authors.initials: K
authors.lastname: Piens
authors.forename: Marc C E
authors.initials: MC
authors.lastname: Van Montagu
authors.forename: Nicholas
authors.initials: N
authors.lastname: Santoro
authors.forename: Clifton E
authors.initials: CE
authors.lastname: Foster
authors.forename: John
authors.initials: J
authors.lastname: Ralph
authors.forename: Wim
authors.initials: W
authors.lastname: Soetaert
authors.forename: Gilles
authors.initials: G
authors.lastname: Pilate
authors.forename: Wout
authors.initials: W
authors.lastname: Boerjan
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000172:deficiency*; D001530:Belgium; D056804:Biofuels; D018533:Biomass; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005602:France; D008031:Lignin / Q000378:metabolism*; D030821:Plants, Genetically Modified; D032107:Populus / Q000235:genetics / Q000378:metabolism*
chemical_list: D056804:Biofuels; D000431:Ethanol; D008031:Lignin; D000445:Aldehyde Oxidoreductases; C019904:cinnamoyl CoA reductase
keywords: GM; bioethanol; second-generation bioenergy