title: Altered lignin biosynthesis improves cellulosic bioethanol production in transgenic maize plants down-regulated for cinnamyl alcohol dehydrogenase.
abstract: Cinnamyl alcohol dehydrogenase (CAD) is a key enzyme involved in the last step of monolignol biosynthesis. The effect of CAD down-regulation on lignin production was investigated through a transgenic approach in maize. Transgenic CAD-RNAi plants show a different degree of enzymatic reduction depending on the analyzed tissue and show alterations in cell wall composition. Cell walls of CAD-RNAi stems contain a lignin polymer with a slight reduction in the S-to-G ratio without affecting the total lignin content. In addition, these cell walls accumulate higher levels of cellulose and arabinoxylans. In contrast, cell walls of CAD-RNAi midribs present a reduction in the total lignin content and of cell wall polysaccharides. In vitro degradability assays showed that, although to a different extent, the changes induced by the repression of CAD activity produced midribs and stems more degradable than wild-type plants. CAD-RNAi plants grown in the field presented a wild-type phenotype and produced higher amounts of dry biomass. Cellulosic bioethanol assays revealed that CAD-RNAi biomass produced higher levels of ethanol compared to wild-type, making CAD a good target to improve both the nutritional and energetic values of maize lignocellulosic biomass.
authors.affiliation: Laboratori de Genetica Molecular Vegetal, Centre de Recerca en AgriGenomica (CRAG), Consorci CSIC-IRTA-UAB-UB, Edifici CRAG, Campus UAB, Bellaterra (Cerdanyola del Vallés), Barcelona, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Fornalé
authors.forename: Montserrat
authors.initials: M
authors.lastname: Capellades
authors.forename: Antonio
authors.initials: A
authors.lastname: Encina
authors.forename: Kan
authors.initials: K
authors.lastname: Wang
authors.forename: Sami
authors.initials: S
authors.lastname: Irar
authors.forename: Catherine
authors.initials: C
authors.lastname: Lapierre
authors.forename: Katia
authors.initials: K
authors.lastname: Ruel
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Joseleau
authors.forename: Jordi
authors.initials: J
authors.lastname: Berenguer
authors.forename: Pere
authors.initials: P
authors.lastname: Puigdomènech
authors.forename: Joan
authors.initials: J
authors.lastname: Rigau
authors.forename: David
authors.initials: D
authors.lastname: Caparrós-Ruiz
mesh_terms: D000429:Alcohol Oxidoreductases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D056804:Biofuels; D002473:Cell Wall / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D015536:Down-Regulation / Q000235:genetics*; D000431:Ethanol / Q000378:metabolism*; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism; D008031:Lignin / Q000096:biosynthesis*; D010636:Phenols / Q000737:chemistry / Q000378:metabolism; D018547:Plant Stems / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012995:Solubility; D003313:Zea mays / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D056804:Biofuels; D005419:Flavonoids; D010636:Phenols; D000431:Ethanol; D002482:Cellulose; D008031:Lignin; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase