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Senior Scientist, BioForA
Sabbatical, HTIRC - Purdue University, Indiana USA
Tenured Scientist, INRA - Orléans
Ph.D., Plant biotechnology, Université Lyon I, France
Pre-doctoral, Environmental Horticulture, UC Davis, California, USA
M.S. Differentiation, Genetics and Immunology, Université Lyon I, France
MAIN RESEARCH: Characterization of transcription factors controlling root development and heartwood formation in trees
All over the world and thanks to the wood they produce, trees are major source of biomass. Wood is being used in many areas such as energy, paper and biofuel production, construction, furniture making and green chemistry. As long living organisms, their growth and survival (and consequently, their ability to produce wood) are highly dependent upon the environment they are growing in and will be subjected to in the future. Due to the alarming predictions on global climate changes, many questions can be raised about the sustainability of wood production linked to the adaptation abilities of trees. Beyond a general rise of the average temperatures, the current models also predict greater numbers of extreme climatic events (storms, droughts, late frosts, new or migrating pathogens…) that trees will have to cope with.
The research I conduct aims at putting into relation tree development and adaptation abilities to their wood production capacities while taking into account the forthcoming changing environmental conditions. A better understanding of the physiological, genetic and molecular cues controlling tree development appears to be of great interest in order to set-up efficient selection tools targeted on key aspects of their development that may impact their fitness. To reach these goals, my research focuses on two developmental and differentiation processes that are particularly important for trees:
1) Root development and root architecture are being indirectly considered as key factors for wood production and tree adaptation to the environment. The following illustrations (insert 1) demonstrate the importance of roots and root systems for the adaptation of trees to their environment in various and adverse conditions.
Insert 1 : Roots : The hidden side of tree development and adaptation.
Left : On the Loire bank, the important root system of a black poplar (Populus nigra) has been exposed after a winter flood. These fast growing types of tree stabilize the river banks and allow the settlement of many other vegetal and animal species along rivers (photo credit : Marc Villar, UMR BioForA, INRA Val de Loire – Orléans). Center: Amazing pine tree growing on a montain cliff within rock cracks. Although not visible, the root system of this tree represents its sole survival cause in this hostile environment (photo credit : Marc Villar, UAGPF - INRA Val de Loire – Orléans). Right : In the Landes region, many trees fell down during the storms that occured in decembre 1999. Tree resistance to wind relies upon a great number of factors (trunk resistance and stiffness, root architecture and resistance, soil nature, structure and water content…). In this case, root anchorage gave-up first (photo credit : Gérard Paillard, INRA – Paris).
2) Heartwood formation is studied in terms of quality wood production. Indeed, this last step of the wood differentiation process determines both its natural durability and color that are the main factors affecting the value of the end-products (insert 2).
Insert 2 : Heartwood formation and wood color :
Left : A black walnut (Juglans nigra) tree trunk sliced here for furniture making reveals the major color differences between sapwood and heartwood (photo credit : Christian Jay-Allemand, INRA). Center : Typical walnut tree figured wood. This type of wood is well-appreciated for valuable veneer and furniture making (photo credit : Christian Jay-Allemand, INRA). Right : A black walnut tree trunk observed under U.V. illumination reveals specific metabolic activities linked to heartwood formation. Some fluorescent molecules are specifically synthetized in the sapwood – heartwood transition zone (photo credit : Christian Breton, UMR BioForA, INRA Val de Loire - Orléans).
Both of these research subjects, root and heartwood formation, are being approached through a common strategy aiming at getting a better knowledge of the genes expressed during these developmental process in order to characterize important regulatory genes that would control them. Most of my current experiments are focused on specific types of regulatory genes/proteins: transcription factors (TFs). These regulatory proteins interact within each cell nuclei with the DNA of the target genes they regulate. Briefly, TFs will recognize and bind to specific DNA sites located within the promoter regions of the target genes. Their binding (or release) will lead either to an activation or a repression of the target genes RNA synthesis resulting in the production of more or less quantities of the corresponding proteins. In general, TFs act in a pleiotropic manner on a series of target genes belonging to a same metabolic pathway or developmental process. The knowledge of these genetic interactions and their complex regulation mechanisms allows to determine « Gene Regulatory Networks » (GRNs) governing many physiological or metabolic process.
In the long term, a better characterization of each GRN members and their physiological roles in any developmental or metabolic process should provide new tools for targeted genetic selection. As far as my research is concerned, these tools would rely on a more and more precise genetic description of important phenotypic traits such as root development and heartwood formation.
3) Applied research
Insert 3: Valorization of fluorescent black locust wood extracts (ValRob project): A) Robinia pseudoacacia wood slice with heartwood. ; B) Natural fluorescence of grinded wood used for the extractions (U.V.); C et D) Concentrated wood extractswith fluorescent dye (yellow) (photo credit: Christian Breton, BioForA, INRA Val de Loire - Orléans).
On a more applied point of view, our knowledge of wood extractibles lead us to prospect some industrial uses for some of these molecules highly represented in the heartwood of some species (Insert 3). Our work was centered on the optimization of their extraction, their characterization and on the study of their biological properties that could allow us to target various industrial sectors (e.g. : cosmetics, pharmacy, plant health,...). The ValRob project supported by the Région Centre Val de Loire (2012-2016) and the Cosmetic Valley pole focused on the cosmetic valorization of Robinia pseudoacaciawood extracts due to their important natural fluorescence properties. High contents of a flavonoid (robinetin) present in the extracts allowed us to prospect different cosmetic applications through the development of new formulations (make-up, hair dye,...) as well as some “out of the box” uses such as fluorescent labeling or packaging. The robinetin extraction process has now been adapted to fit the standards of cosmetic raw product extractions and transferred at the industrial level by our partner: Alban Müller International. Many other fluorescent applications can now be investigated in various industrial sectors (clothing, paper printing, packaging, store decoration...).
- Heartwood formation (douglas fir, walnut tree) and root differentiation (poplar): Nathalie Boizot, Jean-Paul Charpentier, Marie-Claude Descauses (Génobois and BioForA, INRA Val de Loire, Orléans), Guy Costa Limoges University (France), Manuela Ruiz-Diaz (University of Misiones, Argentina)
- Black locust wood extract valorization (ValRob Project): Emilie Destandau, Stéphane Bostyn (Orléans University), Jean-Marc Seigneuret, Valérie Serrano (Alban Müller International)
- Black locust improvement: Patrick Pastuszka (Unité Expérimentale Forêt Pierroton, INRA Cestas), Dominique Merzeau (Centre National de la Propriété Forestière, Bordeaux)
- Industrial development organization: Nathalie Schnebelen (INRA Val de Loire), Christophe Masson, Amandine Goubert (Cosmetic Valley, Chartres), Amélie Chaigneau, Emeline Defossez (Végépolys, Angers) and Marina Lopez-Guia (Xylofutur, Gradignan) with the support of the Région Centre Val de Loire.
Montiel G., Breton C., Thiersault M., Burlat V., Jay-Allemand C. and Gantet P. (2007) Transcription factor Agamous-like 12 from Arabidopsis promotes tissue-like organization and alkaloid biosynthesis in Catharanthus roseus suspension cells. Metab Eng. 9: 125-32
Montiel G., Gantet P., Jay-Allemand C. and Breton C. (2004) Transcription factors: Pathways to the knowledge of root development. Plant Physiol. 136: 3478–3485.
Montiel G., Breton C., Doireau P., Jay-Allemand C. and Gantet P. (2003) Transcription factors that regulate secondary metabolism biosynthesis pathways: key actors for plant eco-physiology and ontogeny. Recent Res. Devel. Plant Cell Physiol. 1: 83-98.
Destandau, E., Charpentier, J.-P., Bostyn, S., Zubrzycki, S., Serrano, V., Seigneuret, J.-M., Breton, C. (2016). Gram-Scale Purification of Dihydrorobinetin from Robinia pseudoacacia L. Wood by Centrifugal Partition Chromatography. Separations, 3 (3), 12 p. DOI : 10.3390/separations3030023
Plazanet, I., Zerrouki, R., Lhernould, S., Breton, C., Costa, G. (2015). Direct Immunological Detection of Wood Cell Wall Polysaccharides after Microwave- Assisted Ionic Liquid Disruption. Journal ofGlycobiology, 4 (1), 4 p. DOI: 10.4172/2168- 958X.1000115
Leplé JC., Déjardin A., Laurans F., Pilate G., Goué N., Label P., Beritognolo I., Noizot N. et BretonC. (2004) Physiologie et génomique de la formation du bois. Biofutur 247: 43-48
Beritognolo I., Magel E., A. Abdel-latif, Charpentier J.P., Jay-Allemand C. and BretonC. (2002) Expression of genes encoding chalcone synthase, flavanone 3-hydroxylase, and dihydroflavonol 4-reductase correlates with flavanol accumulation during heartwood formation in Juglans nigra L. Tree Physiol. 22: 291-300.
IN VITRO and FLOWER DEVELOPMENT
Breton C., Cornu D., Chriqui D., Sauvanet A., Capelli P., Germain E. and Jay-Allemand C. (2004) Somatic embryogenesis, micropropagation and plant regeneration of “Early Mature” walnut trees (Juglans regia) that flower in vitro. Tree Physiol. 24: 425-435