Coordinated transcriptional regulation of two key genes in the lignin branch pathway - CAD and CCR - is mediated through MYB- binding sites

BMC Plant Biology

Research Article

Yves Martinez¹  Jacqueline Grima-Pettenati¹  Valérie Pacquit¹  Anjanirina Rahantamalala¹  Nicole Chaubet-Gigot¹  Philippe Rech² 

[1] Université de Toulouse; UPS; UMR 5546, Surfaces Cellulaires et Signalisation chez les Végétaux; BP 42617, F-31326, Castanet-Tolosan, France;CNRS; UMR 5546; BP 42617, F-31326, Castanet-Tolosan, France;Université de Toulouse; UPS; UMR 5546, Surfaces Cellulaires et Signalisation chez les Végétaux; BP 42617, F-31326, Castanet-Tolosan, France;CNRS; UMR 5546; BP 42617, F-31326, Castanet-Tolosan, France;Université Pierre et Marie Curie Paris 6, EAC7180 CNRS, UR5, Mécanismes de la Régénération des Plantes, F-75252, Paris, cedex 05, France;

关键词: Electrophoretic Mobility Shift Assay;    Secondary Xylem;    Cinnamyl Alcohol Dehydrogenase;    Cambial Cell;    Vascular Cambium;   

DOI  :  10.1186/1471-2229-10-130

 received in 2010-01-27, accepted in 2010-06-28,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundCinnamoyl CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD) catalyze the final steps in the biosynthesis of monolignols, the monomeric units of the phenolic lignin polymers which confer rigidity, imperviousness and resistance to biodegradation to cell walls. We have previously shown that the Eucalyptus gunnii CCR and CAD2 promoters direct similar expression patterns in vascular tissues suggesting that monolignol production is controlled, at least in part, by the coordinated transcriptional regulation of these two genes. Although consensus motifs for MYB transcription factors occur in most gene promoters of the whole phenylpropanoid pathway, functional evidence for their contribution to promoter activity has only been demonstrated for a few of them. Here, in the lignin-specific branch, we studied the functional role of MYB elements as well as other cis-elements identified in the regulatory regions of EgCAD2 and EgCCR promoters, in the transcriptional activity of these gene promoters.ResultsBy using promoter deletion analysis and in vivo footprinting, we identified an 80 bp regulatory region in the Eucalyptus gunnii EgCAD2 promoter that contains two MYB elements, each arranged in a distinct module with newly identified cis-elements. A directed mutagenesis approach was used to introduce block mutations in all putative cis-elements of the EgCAD2 promoter and in those of the 50 bp regulatory region previously delineated in the EgCCR promoter. We showed that the conserved MYB elements in EgCAD2 and EgCCR promoters are crucial both for the formation of DNA-protein complexes in EMSA experiments and for the transcriptional activation of EgCAD2 and EgCCR promoters in vascular tissues in planta. In addition, a new regulatory cis-element that modulates the balance between two DNA-protein complexes in vitro was found to be important for EgCAD2 expression in the cambial zone.ConclusionsOur assignment of functional roles to the identified cis-elements clearly demonstrates the importance of MYB cis-elements in the transcriptional regulation of two genes of the lignin-specific pathway and support the hypothesis that MYB elements serve as a common means for the coordinated regulation of genes in the entire lignin biosynthetic pathway.

【 授权许可】

Unknown   
© Rahantamalala et al; licensee BioMed Central Ltd. 2010. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.