Éditeur(s) : HAL CCSD CRC Press
Résumé : Among the ecosystem services provided by forests, wood provisioning takes a central position. Wood and derived products have played a critical role in the evolution of human kind and demand for raw material is increasing in a foreseeable future. Wood is used for energy production, construction and a wide variety of products for which different properties are required. Anatomical, chemical and physical properties of wood are determined through a complex process called xylogenesis controlled by internal and external signals and occurring during the life of the tree. In this chapter we describe i/how wood is formed and ii/the different factors controlling this developmental process with emphasis on the molecular machinery involved, iii/the functions of wood and iv/the biotechnology approaches developed to improve wood biomass production and properties genetically.
Tree Biotechnology

ISBN : 978-1466597143
hal-01032436
https://hal.archives-ouvertes.fr/hal-01032436

Éditeur(s) : HAL CCSD
Résumé : International audience
Trees can control their shape and resist gravity thanks to their ability to produce wood under tensile stress. This stress is known to be produced during the maturation of wood fibres but the mechanism of its generation remains unclear. This study focuses on the formation of the secondary wall in tension wood produced in artificially tilted poplar saplings. Thickness of secondary wall layer (SL) and gelatinous layer (GL) were measured from cambium to mature wood in several trees sampled at different times after tilting. Measurements on wood fibres produced before tilting show the progressive increase of secondary wall thickness during the growing season. After the tilting date, SL thickness decreased markedly from normal wood to tension wood while the total thickness increased compared to normal wood, with the development of a thick GL. However, even after GL formation, SL thickness continues to increase during the growing season. GL thickening was observed to be faster than SL thickening. The development of the unlignified GL is proposed to be a low cost, efficient strategy for a fast generation of tensile stress in broadleaved trees.
IAWA journal / International Association of Wood Anatomists.

hal-01229277
https://hal.archives-ouvertes.fr/hal-01229277
https://hal.archives-ouvertes.fr/hal-01229277/document
https://hal.archives-ouvertes.fr/hal-01229277/file/AbediniClair-Iawa-TensionCellWallThickening_preprint_HAL.pdf
DOI : 10.1163/22941932-00000084

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : International audience
Context: Woodcutting is a very old technology but scientific research is scarce on the subject. In the last 50 years much work on basic mechanisms as well as industrial processes has been done in France. Aims: The specific nature of wood introduces strong differences between wood and metal cutting processes. The paper focuses on French teams' contributions. Results: The basic aspects of the tool–material interaction for different basic modes in woodcutting are highlighted. In primary conversion such as sawing, veneer cutting or green wood chipping, huge progress comes from automation and the possibility of linking the process to log and product quality through new sensors. In secondary processing much has been done on the links between the cutting process, surface qualification and the properties of these surfaces for further processing, such as gluing or coating. Tool wear depends on the cutting process, timber quality, and species. Trade-offs are required in tool technology and coating technologies may improve tool life. Conclusion: A large amount of knowledge and innovation has come from 50 years of worldwide research effort, with France being particularly active in this period. The transfer of skills from metals cutting industry was often a key, but much is needed to move closer to both metal cutting sector and woodcutting skills among craftsmen.
ISSN: 1286-4560

hal-01135156
https://hal.archives-ouvertes.fr/hal-01135156
https://hal.archives-ouvertes.fr/hal-01135156/document
https://hal.archives-ouvertes.fr/hal-01135156/file/Wood_machining_focus_French_research_Thibaut_al_2015.pdf
DOI : 10.1007/s13595-015-0460-2

Éditeur(s) : HAL CCSD
Résumé : Couche G ou couche tertiaire : quel nom pour la couche interne des fibres du bois de tension ?. 11es Journées du Réseau Français des Parois
11es Journées du Réseau Français des Parois
Orléans, France

hal-01603178
https://hal.archives-ouvertes.fr/hal-01603178
PRODINRA : 398652

Éditeur(s) : HAL CCSD CRC Press
Résumé : Among the ecosystem services provided by forests, wood provisioning takes a central position. Wood and derived products have played a critical role in the evolution of human kind and demand for raw material is increasing in a foreseeable future. Wood is used for energy production, construction and a wide variety of products for which different properties are required. Anatomical, chemical and physical properties of wood are determined through a complex process called xylogenesis controlled by internal and external signals and occurring during the life of the tree. In this chapter we describe i/how wood is formed and ii/the different factors controlling this developmental process with emphasis on the molecular machinery involved, iii/the functions of wood and iv/the biotechnology approaches developed to improve wood biomass production and properties genetically.
Tree Biotechnology

ISBN : 9781466597143
hal-01204210
https://hal.archives-ouvertes.fr/hal-01204210
PRODINRA : 257126

Éditeur(s) : HAL CCSD Wiley/Blackwell
Résumé : Whole genome sequencing is helping generate robust phylogenetic hypotheses for a range of taxonomic groups that were previously recalcitrant to classical molecular phylogenetic approaches. As a case study, we performed a shallow shotgun sequencing of eight species in the tropical tree family Chrysobalanaceae to retrieve large fragments of high-copy number DNA regions and test the potential of these regions for phylogeny reconstruction. We were able to assemble the nuclear ribosomal cluster (nrDNA), the complete plastid genome (ptDNA) and a large fraction of the mitochondrial genome (mtDNA) with approximately 1000x, 450x and 120x sequencing depth respectively. The phylogenetic tree obtained with ptDNA resolved five of the seven internal nodes. In contrast, the tree obtained with mtDNA and nrDNA data were largely unresolved. This study demonstrates that genome skimming is a cost-effective approach and shows potential in plant molecular systematics within Chrysobalanaceae and other under-studied groups.
ISSN: 1755-098X

hal-01204217
https://hal.archives-ouvertes.fr/hal-01204217
DOI : 10.1111/1755-0998.12246
PRODINRA : 283530

Éditeur(s) : HAL CCSD
Résumé : International audience
A key element of the biomechanical design of trees is their ability to generate largemechanical stresses in wood at the stem periphery. This function is necessary for the tree tocontrol the orientation of its axes, and therefore to grow in height, maintain its branches at anoptimal angle or achieve adaptive reorientations (Fournier et al., 2013). This “maturationstress” appears in wood fibres during their cellular maturation when their secondary cell wallis thickening. In hardwoods, the stress asymmetry is generated by the formation of specificfibres with a very high tensile growth stress on the upper side of the inclined axis. Theresulting tension wood has microstructural features highly different from the normal wood.Tension wood in almost all temperate species has a specific gelatinous cell wall layer, calledG-layer, that is not lignified and highly mesoporous (Chang et al., 2015). It has been shownrecently, at the macroscopic scale, that cellulose tension appears during maturation and issynchronous with the development of this specific layer (Clair et al., 2011). Tropical species,like simarouba, are able to generate lignified tension wood fibres. The mechanisms of stressgeneration in tension wood fibres are not yet well known. The aim of our study is tounderstand these mechanisms and to know the spatial and temporal kinetics of the differentcell wall layers stiffening during maturation, in parallel with tensile stress generation.Contact-Resonance Atomic Force Microscopy, CR-AFM, was used here to address thisquestion on embedded samples (Arnould and Arinero, 2015) using dual resonance frequencytracking (DRFT, Rodriguez et al., 2007). Change in the contact modulus between, and within,each layer of the cell wall has been measured on several radial lines of developing fibres atdifferent steps. In order to understand the obtained results, and to estimate the sensitivity ofthe AFM indentation-like technique to the different cell wall components stiffness, an elasticanisotropic indentation model was used (Vlassak et al., 2003; Jäger et al., 2011). Finally,these mechanical measurements have been compared to topochemical data obtained on thesame fibres.
8th Plant Biomechanics International Conference
Nagoya, Japan

hal-01436113
https://hal.archives-ouvertes.fr/hal-01436113