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Cinnamoyl CoA reductase, the first committed enzyme of the lignin branch biosynthetic pathway: cloning, expression and phylogenetic relationships

Authors

  • Eric Lacombe,

    1. Signaux et Messages Cellulaires chez les Végétaux, UMR CNRS-UPS No. 5546, Centre de Physiologie Végétale, Université Paul Sabatier, 118 route de Narbonne, 31 062 Toulouse Cédex, France
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  • Simon Hawkins,

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    • Present address: Station d'Amélioration des Arbres Forestiers, INRA, 45160 Orléans, France.

  • Jan Van Doorsselaere ,

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    • Present address: Laboratorium voor Genetica, K.L. Ledeganckstraat 35, B-9000, Gent, Belgium.

  • Joël Piquemal,

    1. Signaux et Messages Cellulaires chez les Végétaux, UMR CNRS-UPS No. 5546, Centre de Physiologie Végétale, Université Paul Sabatier, 118 route de Narbonne, 31 062 Toulouse Cédex, France
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  • Deborah Goffner,

    1. Signaux et Messages Cellulaires chez les Végétaux, UMR CNRS-UPS No. 5546, Centre de Physiologie Végétale, Université Paul Sabatier, 118 route de Narbonne, 31 062 Toulouse Cédex, France
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  • Odile Poeydomenge,

    1. Signaux et Messages Cellulaires chez les Végétaux, UMR CNRS-UPS No. 5546, Centre de Physiologie Végétale, Université Paul Sabatier, 118 route de Narbonne, 31 062 Toulouse Cédex, France
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  • Alain-M. Boudet,

    1. Signaux et Messages Cellulaires chez les Végétaux, UMR CNRS-UPS No. 5546, Centre de Physiologie Végétale, Université Paul Sabatier, 118 route de Narbonne, 31 062 Toulouse Cédex, France
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  • Jacqueline Grima-Pettenati

    Corresponding author
      * For correspondence (fax +33 61 55 62 10; e-mail grima@cict.fr).
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* For correspondence (fax +33 61 55 62 10; e-mail grima@cict.fr).

Summary

Cinnamoyl CoA:NADP oxidoreductase (CCR, EC 1.2.1.44) catalyzes the conversion of cinnamoyl CoA esters to their corresponding cinnamaldehydes, i.e. the first specific step in the synthesis of the lignin monomers. The cloning of a cDNA encoding CCR in Eucalyptus gunnii (EUCCR) is reported here. The identity of the EUCCR cDNA was demonstrated by comparison with peptide sequence data from purified CCR and functional expression of the recombinant enzyme in Escherichia coli. Sequence analysis revealed remarkable homologies with dihydroflavonol-4-reductase (DFR), the first enzyme of the anthocyanin biosynthetic pathway. Moreover, significant similarities were found with mammalian 3β-hydroxysteroid dehydrogenase and bacterial UDP-galactose-4-epimerase, suggesting that CCR shared a common ancestor with these enzymes and can therefore be considered as a new member of the mammalian 3β-hydroxysteroid dehydrogenase/ plant dihydroflavonol reductase superfamily. In Eucalyptus gunnii, CCR is encoded by one gene containing four introns whose positions are similar to those of introns I, II, III and V in DFR genes from dicots. In agreement with the involvement of CCR in lignification, the CCR transcript was shown to be expressed in lignified organs, i.e. root and stem tissues, and was localized mainly in young differentiating xylem. On the other hand, its abundance in Eucalyptus leaves suggests that monolignols may be precursors of end products other than lignins. This first characterization of a gene corresponding to CCR opens new possibilities to genetically engineer plants with lower lignin content. This is particularly important for woody plants such as Eucalyptus which are used for pulp making.

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