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Accueil du site > Equipes de recherche > Génomique fonctionnelle de l’Eucalyptus > Thèmes de recherche > Régulation transcriptionnelle de la formation de la paroi secondaire > Functional characterization of new potential regulators of SCW formation in Eucalyptus

Functional characterization of new potential regulators of SCW formation in Eucalyptus

Another major outcome of our work on the R2R3-MYB, NAC, ARF and Aux/IAA families, is that it allowed us to select the most promising genes possibly involved in the control of wood formation. The choice of the candidate genes (CG) for functional characterization has been performed in the framework of the Plant KBBE project TREE FOR JOULES coordinated by our team. Genes were chosen according to several criteria : (i) preferential expression in cambium and/or differentiating xylem (especially if they were differentially expressed between tension and opposite xylem that exhibit contrasting SCW properties) ; (ii) novelty, meaning that their putative orthologs (if any) in other species were not studied before. In total, we selected 10 CG including MYBs, IAA, ARF and NAC TFs and made overexpressors and dominant repressor constructs. Although Eucalyptus transformation is mastered in the team [Navarro et al. 2011, De la Torres et al. 2014], it is not suitable for analysing a large number of constructions. We generated both Arabidopsis and poplar transgenic lines, which are good alternatives for functional characterization of Eucalyptus CG involved in SCW formation [Legay et al. 2010]. Phenotyping of these lines is in progress.

The availability of an easy and rapid homolog transformation system is obviously desirable. For this reason, we implemented a protocol to transform E. grandis using Agrobacterium rhizogenes, which allowed us to obtain chimeric plants with transformed roots (efficiency >50%). Three months after transformation, transgenic root xylem is similar to that of WT roots at the histological level. We are currently using an antisense CCR construct whose effects on SCW and vessels strength is well known, as a proof of concept. If the preliminary results are confirmed, this system will be widely used to screen the effects of new CG (alone or in combination), and to analyze promoter-driven expression patterns.