title: Cell wall modifications triggered by the down-regulation of Coumarate 3-hydroxylase-1 in maize.
abstract: Coumarate 3-hydroxylase (C3H) catalyzes a key step of the synthesis of the two main lignin subunits, guaiacyl (G) and syringyl (S) in dicotyledonous species. As no functional data are available in regards to this enzyme in monocotyledonous species, we generated C3H1 knock-down maize plants. The results obtained indicate that C3H1 participates in lignin biosynthesis as its down-regulation redirects the phenylpropanoid flux: as a result, increased amounts of p-hydroxyphenyl (H) units, lignin-associated ferulates and the flavone tricin were detected in transgenic stems cell walls. Altogether, these changes make stem cell walls more degradable in the most C3H1-repressed plants, despite their unaltered polysaccharide content. The increase in H monomers is moderate compared to C3H deficient Arabidopsis and alfalfa plants. This could be due to the existence of a second maize C3H protein (C3H2) that can compensate the reduced levels of C3H1 in these C3H1-RNAi maize plants. The reduced expression of C3H1 alters the macroscopic phenotype of the plants, whose growth is inhibited proportionally to the extent of C3H1 repression. Finally, the down-regulation of C3H1 also increases the synthesis of flavonoids, leading to the accumulation of anthocyanins in transgenic leaves.
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG) Consorci CSIC-IRTA-UAB-UB Edifici CRAG Campus de Bellaterra de la UAB, 08193 Cerdanyola del Valles, Barcelona, Spain. Electronic address: silvia.fornale@cragenomica.es.
authors.forename: Silvia
authors.initials: S
authors.lastname: Fornalé
authors.affiliation: Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, P.O. Box 1052, 41080-Seville, Spain. Electronic address: jrencoret@irnase.csic.es.
authors.forename: Jorge
authors.initials: J
authors.lastname: Rencoret
authors.affiliation: Área de Fisiología Vegetal, Universidad de León, 24071 León, Spain. Electronic address: lgarc@unileon.es.
authors.forename: Laura
authors.initials: L
authors.lastname: Garcia-Calvo
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG) Consorci CSIC-IRTA-UAB-UB Edifici CRAG Campus de Bellaterra de la UAB, 08193 Cerdanyola del Valles, Barcelona, Spain. Electronic address: montse.capellades@cragenomica.es.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Capellades
authors.affiliation: Área de Fisiología Vegetal, Universidad de León, 24071 León, Spain. Electronic address: a.encina@unileon.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Encina
authors.affiliation: Agrobiología Ambiental, Calidad de Suelos y Plantas (UVIGO) (unidad asociada a la Misión Biológica de Galicia, CSIC), Dpto. Biología Vegetal y Ciencias del Suelo, Facultad de Biología, Universidad de Vigo, Campus As Lagoas Marcosende, 36310, Vigo, Spain. Electronic address: rsantiago@mbg.csic.es.
authors.forename: Rogelio
authors.initials: R
authors.lastname: Santiago
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG) Consorci CSIC-IRTA-UAB-UB Edifici CRAG Campus de Bellaterra de la UAB, 08193 Cerdanyola del Valles, Barcelona, Spain. Electronic address: joan.rigau@cragenomica.es.
authors.forename: Joan
authors.initials: J
authors.lastname: Rigau
authors.affiliation: Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, P.O. Box 1052, 41080-Seville, Spain. Electronic address: anagu@irnase.csic.es.
authors.forename: Ana
authors.initials: A
authors.lastname: Gutiérrez
authors.affiliation: Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, P.O. Box 1052, 41080-Seville, Spain. Electronic address: delrio@irnase.csic.es.
authors.forename: José-Carlos
authors.initials: JC
authors.lastname: Del Río
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG) Consorci CSIC-IRTA-UAB-UB Edifici CRAG Campus de Bellaterra de la UAB, 08193 Cerdanyola del Valles, Barcelona, Spain. Electronic address: david.caparros@cragenomica.es.
authors.forename: David
authors.initials: D
authors.lastname: Caparros-Ruiz
mesh_terms: D000872:Anthocyanins / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D003373:Coumaric Acids / Q000378:metabolism; D015536:Down-Regulation; D008031:Lignin / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
chemical_list: D000872:Anthocyanins; D003373:Coumaric Acids; D010940:Plant Proteins; D008031:Lignin; D006899:Mixed Function Oxygenases
keywords: Cell wall polysaccharides; Degradability; Flavonoids; Lignin; Maize