EgMYB2, a new transcriptional activator from Eucalyptus xylem, regulates secondary cell wall formation and lignin biosynthesis
2005
Goicoechea, Monica | Lacombe, Eric | Legay, Sylvain | Mihaljevi, Csnjezana | Rech, Philippe | Jauneau, Alain | Lapierre, Catherine | Pollet, Brigitte | Verhaegen, Daniel | Chaubet-Gigot, Nicole | Grima Pettenati, Jacqueline | Laboratoire de Recherche en Sciences Végétales (LRSV) ; Université Toulouse III - Paul Sabatier (UT3) ; Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Centre National de la Recherche Scientifique (CNRS) | Chimie Biologique (UCB) ; Institut National de la Recherche Agronomique (INRA)-Institut National Agronomique Paris-Grignon (INA P-G) | Département Forêt (Cirad-FORET) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad) | LRSV-Régulation et Dynamique de la Formation du Bois (LRSV-RDFB) ; Laboratoire de Recherche en Sciences Végétales (LRSV) ; Université Toulouse III - Paul Sabatier (UT3) ; Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3) ; Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Centre National de la Recherche Scientifique (CNRS)
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Show more [+] Less [-]English. EgMYB2, a member of a new subgroup of the R2R3 MYB family of transcription factors, was cloned from a library consisting of RNA from differentiating Eucalyptus xylem. EgMYB2 maps to a unique locus on the Eucalyptus grandis linkage map and co-localizes with a quantitative trait locus (QTL) for lignin content. Recombinant EgMYB2 protein was able to bind specifically the cis-regulatory regions of the promoters of two lignin biosynthetic genes, cinnamoyl-coenzyme A reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD), which contain MYB consensus binding sites. EgMYB2 was also able to regulate their transcription in both transient and stable expression assays. Transgenic tobacco plants over-expressing EgMYB2 displayed phenotypic changes relative to wild-type plants, among which were a dramatic increase in secondary cell wall thickness, and an alteration of the lignin profiles. Transcript abundance of genes encoding enzymes specific to lignin biosynthesis was increased to varying extents according to the position of individual genes in the pathway,whereas core phenylpropanoid geneswere not significantly affected. Together these results suggest a role for EgMYB2 in the co-ordinated control of genes belonging to the monolignol-specific pathway, and therefore in the biosynthesis of lignin and the regulation of secondary cell wall formation.
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