title: CINNAMYL ALCOHOL DEHYDROGENASE-C and -D are the primary genes involved in lignin biosynthesis in the floral stem of Arabidopsis.
abstract: During lignin biosynthesis in angiosperms, coniferyl and sinapyl aldehydes are believed to be converted into their corresponding alcohols by cinnamyl alcohol dehydrogenase (CAD) and by sinapyl alcohol dehydrogenase (SAD), respectively. This work clearly shows that CAD-C and CAD-D act as the primary genes involved in lignin biosynthesis in the floral stem of Arabidopsis thaliana by supplying both coniferyl and sinapyl alcohols. An Arabidopsis CAD double mutant (cad-c cad-d) resulted in a phenotype with a limp floral stem at maturity as well as modifications in the pattern of lignin staining. Lignin content of the mutant stem was reduced by 40%, with a 94% reduction, relative to the wild type, in conventional beta-O-4-linked guaiacyl and syringyl units and incorportion of coniferyl and sinapyl aldehydes. Fourier transform infrared spectroscopy demonstrated that both xylem vessels and fibers were affected. GeneChip data and real-time PCR analysis revealed that transcription of CAD homologs and other genes mainly involved in cell wall integrity were also altered in the double mutant. In addition, molecular complementation of the double mutant by tissue-specific expression of CAD derived from various species suggests different abilities of these genes/proteins to produce syringyl-lignin moieties but does not indicate a requirement for any specific SAD gene.
authors.affiliation: Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Sainte-Foy, QC G1V 4C7, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Sibout
authors.forename: Aymerick
authors.initials: A
authors.lastname: Eudes
authors.forename: Gregory
authors.initials: G
authors.lastname: Mouille
authors.forename: Brigitte
authors.initials: B
authors.lastname: Pollet
authors.forename: Catherine
authors.initials: C
authors.lastname: Lapierre
authors.forename: Lise
authors.initials: L
authors.lastname: Jouanin
authors.forename: Armand
authors.initials: A
authors.lastname: Séguin
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D015536:Down-Regulation / Q000502:physiology; D035264:Flowers / Q000201:enzymology* / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D008031:Lignin / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010636:Phenols / Q000378:metabolism; D010641:Phenotype; D010666:Phenylpropionates / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D013055:Spectrophotometry, Infrared; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D018744:DNA, Plant; D010636:Phenols; D010666:Phenylpropionates; D020033:Protein Isoforms; C434468:sinapyl alcohol dehydrogenase; C496130:sinapyl alcohol; D008031:Lignin; C010559:coniferyl alcohol; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase