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International audience; Context: Douglas-fir, a fast growing conifer from western North America, recently suffered diebacks following drought in France. We investigated the link between native-source climate and provenance drought resistance in a common garden in France. We compared the adaptive potential of provenances from different parts of the natural area. Methods: We collected branches from a 25-year-old provenance trial replicated in two test sites in southern France. We estimated provenance variation of cavitation resistance traits, survival and circumference. We compared Washington-Oregon provenances to coastal and interior Californian provenances. Results: In the common gardens, the hydraulic traits were significantly variable between provenances, with a strong site x provenance interaction, and significantly related to the climate of the natural area and survival. The relationships were different between variables and test-sites. The two test-sites and their particular climatic selective pressure revealed different geographical adaptive structures in the natural area. Conclusions: Douglas-fir evolutionary adaptation to drought results from natural selection to summer climate and shapes populations for cavitation resistance. In the dryer site only, the Interior California provenances seem more drought resistant. The strong within-provenance variations suggest that there is also a certain withinprovenance adaptation potential to drought at the cost of variable mortality rates.

This is the accepted manuscript of the paper "Breeding progress and preparedness for mass‐scale deployment of perennial lignocellulosic biomass crops switchgrass, miscanthus, willow and poplar", published as final paper in "Global Change Biology Bioenergy Volume 11, Issue 1, 08 February 2019, Pages 118–151 https://doi.org/10.1111/gcbb.12566”. Genetic improvement through breeding is one of the key approaches to increasing biomass supply. This paper documents the breeding progress to date for four perennial biomass crops (PBCs) that have high output–input energy ratios: namelyPanicum virgatum(switchgrass), species of the generaMiscanthus(miscanthus),Salix(willow) andPopulus(poplar). For each crop, we report on the size of germplasm collections, the efforts to date to phenotype and genotype, the diversity available for breeding and on the scale of breeding work as indicated by number of attempted crosses. We also report on the development of faster and more precise breeding using molecular breeding techniques. Poplar is the model tree for genetic studies and is furthest ahead in terms of biological knowledge and genetic resources. Linkage maps, transgenesis and genome editing methods are now being used in commercially focused poplar breeding. These are in development in switchgrass, miscanthus and willow generating large genetic and phenotypic data sets requiring concomitant efforts in informatics to create summaries that can be accessed and used by practical breeders. Cultivars of switchgrass and miscanthus can be seed‐based synthetic populations, semihybrids or clones. Willow and poplar cultivars are commercially deployed as clones. At local and regional level, the most advanced cultivars in each crop are at technology readiness levels which could be scaled to planting rates of thousands of hectares per year in about 5years with existing commercial developers. Investment in further development of better cultivars is subject to current market failure and the long breeding cycles. We conclude that sustained public investment in breeding plays a key role in delivering future mass‐scale deployment of PBCs.

International audience; Somatic embryogenesis techniques have been developed for most coniferous species, but only using very juvenile material. To extend the techniques' scope, better integrated understanding of the key biological, physiological and molecular characteristics of embryogenic state is required. Therefore, embryonal masses (EMs) and non-embryogenic calli (NECs) have been compared during proliferation at multiple levels. EMs and NECs originating from a single somatic embryo (isogenic lines) of each of three unrelated genotypes were used in the analyses, which included comparison of the lines' anatomy by transmission light microscopy, transcriptomes by RNAseq Illumina sequencing, proteomes by free-gel analysis, contents of endogenous phytohormones (indole-3-acetic acid, cytokinins and ABA) by LC-MS analysis, and soluble sugar contents by HPLC. EMs were characterized by upregulation (relative to levels in NECs) of transcripts, proteins, transcription factors and active cytokinins associated with cell differentiation accompanied by histological, carbohydrate content and genetic markers of cell division. In contrast, NECs were characterized by upregulation (relative to levels in EMs) of transcripts, proteins and products associated with responses to stimuli (ABA, degradation forms of cytokinins, phenols), oxidative stress (reactive oxygen species) and carbohydrate storage (starch). Sub-Network Enrichment Analyses that highlighted functions and interactions of transcripts and proteins that significantly differed between EMs and NECs corroborated these findings. The study shows the utility of a novel approach involving integrated multi-scale transcriptomic, proteomic, biochemical, histological and anatomical analyses to obtain insights into molecular events associated with embryogenesis and more specifically to the embryogenic state of cell in Douglas-fir.

article déposé dans un entrepôt de documents d'accès libre (serveur de preprints) en attente de validation par les pairs; Recent literature on the differential role of genes within networks, including the omnigenic model, distinguishes core from peripheral genes in the layout underlying phenotypes. Cores are typically few, each of them highly contributes to phenotypic variation, but because they are so few, they altogether only explain a small part of trait heritability. In contrast, peripherals, each of small influence, are so numerous that they finally lead phenotypic variation. We collected and sequenced RNA from 459 European black poplars and built co-expression networks to define core and peripheral genes as the most and least connected ones. We computed the role of each of these gene sets in the prediction of phenotypes and showed that cores contribute additively to phenotypes, consistent with a downstream position in a biological cascade, while peripherals interact to influence phenotypes, consistent with an upstream position. Quantitative and population genetics analyses further revealed that cores are more expressed than peripherals but they tend to vary less and to be more differentiated between populations suggesting that they are more constrained by natural selection. Our work is the first attempt to integrate core and peripheral terminologies from co-expression networks and omnigenic theory. In the end, we showed, that there seems to be a strong overlap between them, with core genes from co-expression networks likely being a mixture of integrative hubs with a direct effect on phenotype in agreement with the omnigenic theory, and master regulators which control the overall metabolic flow towards the phenotype.

BackgroundPredicting the evolutionary potential of natural tree populations requires the estimation of heritability and genetic correlations among traits on which selection acts, as differences in evolutionary success between species may rely on differences for these genetic parameters. In situ estimates are expected to be more accurate than measures done under controlled conditions which do not reflect the natural environmental variance.AimsThe aim of the current study was to estimate three genetic parameters (i.e. heritability, evolvability and genetic correlations) in a natural mixed oak stand composed of Quercus petraea and Quercus robur about 100 years old, for 58 traits of ecological and functional relevance (growth, reproduction, phenology, physiology, resilience, structure, morphology and defence).MethodsFirst we estimated genetic parameters directly in situ using realized genomic relatedness of adult trees and parentage relationships over two generations to estimate the traits additive variance. Secondly, we benefited from existing ex situ experiments (progeny tests and conservation collection) installed with the same populations, thus allowing comparisons of in situ heritability estimates with more traditional methods.ResultsHeritability and evolvability estimates obtained with different methods varied substantially and showed large confidence intervals, however we found that in situ were less precise than ex situ esti-mates, and assessments over two generations (with deeper relatedness) improved estimates of heritability while large sampling sizes are needed for accurate estimations. At the biological level, heritability values varied moderately across different ecological and functional categories of traits, and genetic correlations among traits were conserved over the two species.ConclusionWe identified limits for using realized genomic relatedness in natural stands to estimate the genetic variance, given the overall low variance of genetic relatedness and the rather low sampling sizes of currently used long term genetic plots in forestry. These limits can be overcome if larger sample sizes are considered, or if the approach is extended over the next generation.

Projet Gentree (H2020); International audience

International audience

Background To explore poorly understood differences between primary and subsequent somatic embryogenic lines of plants, we induced secondary (2ry) and tertiary (3ry) lines from cotyledonary somatic embryos (SEs) of two Douglas-fir genotypes: SD4 and TD17. The 2ry lines exhibited significantly higher embryogenic potential (SE yields) than the 1ry lines initiated from zygotic embryos (SD4, 2155 vs 477; TD17, 240 vs 29 g− 1 f.w.). Moreover, we observed similar differences in yield between 2ry and 3ry lines of SD4 (2400 vs 3921 g− 1 f.w.). To elucidate reasons for differences in embryogenic potential induced by repetitive somatic embryogenesis we then compared 2ry vs 1ry and 2ry vs 3ry lines at histo-cytological (using LC-MS/MS) and proteomic levels. Results Repetitive somatic embryogenesis dramatically improved the proliferating lines’ cellular organization (genotype SD4’s most strongly). Frequencies of singulated, bipolar SEs and compact polyembryogenic centers with elongated suspensors and apparently cleavable embryonal heads increased in 2ry and (even more) 3ry lines. Among 2300–2500 identified proteins, 162 and 228 were classified significantly differentially expressed between 2ry vs 1ry and 3ry vs 2ry lines, respectively, with special emphasis on “Proteolysis” and “Catabolic process” Gene Ontology categories. Strikingly, most of the significant proteins (> 70%) were down-regulated in 2ry relative to 1ry lines, but up-regulated in 3ry relative to 2ry lines, revealing a down-up pattern of expression. GO category enrichment analyses highlighted the opposite adjustments of global protein patterns, particularly for processes involved in chitin catabolism, lignin and L-phenylalanine metabolism, phenylpropanoid biosynthesis, oxidation-reduction, and response to karrikin. Sub-Network Enrichment Analyses highlighted interactions between significant proteins and both plant growth regulators and secondary metabolites after first (especially jasmonic acid, flavonoids) and second (especially salicylic acid, abscisic acid, lignin) embryogenesis cycles. Protein networks established after each induction affected the same “Plant development” and “Defense response” biological processes, but most strongly after the third cycle, which could explain the top embryogenic performance of 3ry lines. Conclusions This first report of cellular and molecular changes after repetitive somatic embryogenesis in conifers shows that each cycle enhanced the structure and singularization of EMs through modulation of growth regulator pathways, thereby improving the lines’ embryogenic status. Electronic supplementary material The online version of this article (10.1186/s12870-018-1337-y) contains supplementary material, which is available to authorized users.

Chapitre 12; International audience; Forest trees are long-lived organisms subject to repeated environmental constraints throughout their long lifetimes. They have developed various mechanisms enabling them to cope with fluctuating environmental conditions during their life span, and to survive to current climate change. Epigenetics has recently emerged as a powerful set of mechanisms regulating various developmental processes, plant growth and responses to environmental variations. Such epigenetic mechanisms, which may remain stable along tree life or across generations, constitute a source of rapid phenotypic variations potentially improving adaptation of the plants in situations in which naturally occurring mutations are very rare. In this review, we summarize recent advances in forest tree epigenomics. We first draw the particularities of trees and the available (epi) genomics resources and strategies. Then, we discuss the potential contributions of epigenetics to cope with global climate change and regulate various developmental processes, such as developmental transitions during the annual cycle, phenotypic plasticity in response to environmental variations and stress memory, as well as local adaptation. Finally, we propose some challenges for forest management and highlighted the need to take epigenetics into account in forest tree breeding strategies.

Backgroud Populus nigra is a major tree species of ecological and economic importance for which several initiatives have been set up to create genomic resources. In order to access the large number of Single Nucleotide Polymorphisms (SNPs) typically needed to carry out a genome scan, the present study aimed at evaluating RNA sequencing as a tool to discover and type SNPs in genes within natural populations of P. nigra. Results We have devised a bioinformatics pipeline to call and type SNPs from RNAseq reads and applied it to P. nigra transcriptomic data. The accuracy of the resulting RNAseq-based SNP calling and typing has been evaluated by (i) comparing their position and alleles to those previously reported in candidate genes, (ii) assessing their genotyping accuracy with respect to a previously available SNP chip and (iii) evaluating their inter-annual repeatability. We found that a combination of several callers yields a good compromise between the number of variants type and the accuracy of genotyping. We further used the resulting genotypic data to carry out basic genetic analyses whose results confirm the quality of the RNAseq-based SNP dataset. Conclusions We demonstrated the potential and accuracy of RNAseq as an efficient way to genotype SNPs in P. nigra. These results open prospects towards the use of this technology for quantitative and population genomics studies. Electronic supplementary material The online version of this article (10.1186/s12864-018-5239-z) contains supplementary material, which is available to authorized users.

Genomic selection - the prediction of breeding values using DNA polymorphisms - is a disruptive method that has widely been adopted by animal and plant breeders to increase productivity. It was recently shown that other sources of molecular variations such as those resulting from transcripts or metabolites could be used to accurately predict complex traits. These endophenotypes have the advantage of capturing the expressed genotypes and consequently the complex regulatory networks that occur in the different layers between the genome and the phenotype. However, obtaining such omics data at very large scales, such as those typically experienced in breeding, remains challenging. As an alternative, we proposed using near-infrared spectroscopy (NIRS) as a high-throughput, low cost and non-destructive tool to indirectly capture endophenotypic variants and compute relationship matrices for predicting complex traits, and coined this new approach ”phenomic selection” (PS). We tested PS on two species of economic interest (Triticum aestivum L. and Populus nigra L.) using NIRS on various tissues (grains, leaves, wood). We showed that one could reach predictions as accurate as with molecular markers, for developmental, tolerance and productivity traits, even in environments radically different from the one in which NIRS were collected. Our work constitutes a proof of concept and provides new perspectives for the breeding community, as PS is theoretically applicable to any organism at low cost and does not require any molecular information.

International audience; Field-grown genetically engineered and wild-type poplars were pyrolyzed in a micro-pyrolysis (Py-GC/MS) setup under fast pyrolysis conditions. Poplars (Populus tremula x P. alba) down-regulated for cirmamoyl-CoA reductase (CCR), which catalyzes the first step of the monolignol-specific branch of the phenylpropanoid biosynthetic pathway, were grown in field trials in France and harvested after a full rotation of 2 years. The effect of small compositional differences, specifically small shifts in lignin composition and their impact on the bio-oil composition, could not be identified using principal component analysis (PCA), necessitating the use of more advanced analysis techniques. The combination of parallel factor analysis 2 (PARAFAC2) and partial least squares discriminant analysis (PLS-DA) for detailed characterization and classification of the pyrolysis data enabled the classification of the poplars with a success rate above 99% using the PARAFAC2 scores. This methodology proved to be extremely valuable to identify subtle information in complex datasets, such as the one used in this study. The obtained PLS-DA models were validated by cross-validation, jackknifing and permutation tests in order to ensure that the model was not overfitting the data. PLS-DA showed that down-regulation of CCR dis-favored the relative amount of both guaiacyl and syringyl lignin-derived compounds. This study shows that lignin engineering can be a promising strategy to alter the lignin composition of the biomass for the production of high value-added phenolic compounds.

International audience; Deciphering climatic factors limiting cambial activity is critical to forecast the potential of trees to respond to ongoing climatic change. We explored multiple xylem traits, including tree-ring width, inter-annual micro-density variation and intra-annual density fluctuations (IADF), to unveil the climatic factors constraining cambial activity of a Mediterranean conifer (Pinus pinaster) along a continental-aridity gradient. Secondary growth responded mainly to water availability, explaining as much as 64.7% of earlywood growth variance for earlywood growth. The continuous and non-overlapping timing of the climatic signals of earlywood and late wood growth reflected a continuous water limitation of secondary growth along the growing season. Drought also had an extraordinary impact on minimum (D-min) and maximum (D-max) density, with maximal explained variances reaching 47.4% and 39.1%, respectively. D-min was negatively associated to water availability during the initiation of earlywood formation, whereas D-max responded positively to water availability during two distinct periods: previous winter and the initiation of latewood formation. IADFs in the latewood were quite common along the gradient, occurred in 21-51% of the rings, and responded to episodes of high rainfall and elevated temperature at different phases of latewood formation. Xylem traits identity outperformed site as a driver of climatic signal, revealing the potential of a multi-proxy approach to unveil multiple facets of the xylogenetic cycle. Cambial plasticity, i.e. the ability to adjust the xylogenesis rate and to arrest and resume cambial activity to exploit favorable climatic windows, was critical for Pinus pinaster to thrive within wide climatic envelopes. Nevertheless, the pervasive effect of water availability on all analyzed traits indicates that forthcoming reduced precipitation and increased evapotranspiration, as predicted by climate change models, will negatively impact P. pinaster secondary growth along its whole environmental range.

The dataset presented here was collected by the GenTree project (EU-Horizon 2020), which aims to improve the use of forest genetic resources across Europe by better understanding how trees adapt to their local environment. This dataset of individual tree-core characteristics including ring-width series and whole-core wood density was collected for seven ecologically and economically important European tree species: silver birch (Betula pendula), European beech (Fagus sylvatica), Norway spruce (Picea abies), European black poplar (Populus nigra), maritime pine (Pinus pinaster), Scots pine (Pinus sylvestris), and sessile oak (Quercus petraea). Tree-ring width measurements were obtained from 3600 trees in 142 populations and whole-core wood density was measured for 3098 trees in 125 populations. This dataset covers most of the geographical and climatic range occupied by the selected species. The potential use of it will be highly valuable for assessing ecological and evolutionary responses to environmental conditions as well as for model development and parameterization, to predict adaptability under climate change scenarios. Measurement(s) growth ring • wood density Technology Type(s) measuring table • calculation Factor Type(s) tree species Sample Characteristic - Organism Betula pendula • Fagus sylvatica • Picea abies • Populus nigra • Pinus pinaster • Pinus sylvestris • Quercus petraea Sample Characteristic - Location Europe Published

National audience; Les forêts de l’hémisphère nord sont plus productives qu’il y a plusieurs décennies. Telle est la tendance observée et quantifiée dans différentes études menées depuis les années 1970 et qui mettent en cause plusieurs facteurs : les modifications des régimes pluviothermiques, les dépôts azotés et l’augmentation de la concentration atmosphérique en dioxyde de carbone. À partir de données de l’inventaire forestier national, les auteurs de cet article se sont penchéssur l’évolution des forêts françaises. Leurs résultats à des échelles plus fines mettent en évidence des variations extrêmes (négative et positive) liées aux espèces et au contexte environnemental local qu’il conviendrait de suivre en « temps réel » compte tenu des grandes incertitudes futures liées au climat.

International audience

To better understand micromorphological and structural changes, histological sections provide additional insight into cellular process and developmental pathways occurring in oat somatic embryogenesis. Environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM) were also used to follow the ultrastructural modifications during this system. Histological observations allowed following the events leading to the development of mature somatic embryos. The scheme includes the following steps: cell reactivation, the first organized cell division in diads, triads, tetrads as well as octant stages, the observation of an extracellular matrix (ECM) as a fibrillar material that bounded the surface of individualized proembryos. The transition from proembryo stage to an early globular somatic embryo was noted, where the embryogenic cortex is surrounded by the protoderm. The late globular stage was marked by bipolarity. The early and late transitional stages, the coleoptilar, mature and germinated stages were also described. The ESEM allowed us to follow some rearrangements, related to the morphology and surfaces involved in somatic embryos development. These events are proembryo formation, transition from proembryo to globular stage, marked by protoderm formation, scutellum and coleoptile development and finally somatic embryos germination. The TEM showed that embryogenic cells were very rich in organelles; mitochondria, rough endoplasmic reticulum, Golgi apparatus and ribosomes. Cells of proembryos, globular and late somatic embryos showed more vacuoles and differentiated organelles. The ECM was also detected by TEM as fibrillar material coating the cell walls. These results on structural and ultrastructural changes provided new insights and findings on oat somatic embryogenesis.

Douglas-fir is a conifer species of major economic importance worldwide, including Western Europe and New Zealand. Herein we describe some characterization and significant refinement of somatic embryogenesis in Douglas-fir, with focus on maturation. The most typical structures observed in the embryonal masses were large polyembryogenic centres (up to 800-1500 μm) with a broad meristem, creating a compact ce ll “package” with suspensor cells. Singulated somatic embryos composed of both a embryonal head (300-400 μm) and long, tightly arranged suspensor were also frequent. Embryo development was enhanced following embryonal mass dispersion on filter paper discs at low density (50-100 mg fresh mass). Moreover, increasing gellan gum concentration in maturation medium (up to 10 g L-1) improved both the quantity and quality of cotyledonary somatic embryos (SEs), which were subsequently able to germinate and develop into plantlets at high frequency. Embryogenic yield was highly variable among the seven embryogenic lines tested (27-1544 SE g-1 fresh mass). Interestingly secondary somatic embryogenesis could be induced from cotyledonary SEs of both low- and highly-productive lines with some useful practical outcomes: secondary lines from low-performance lines (30-39 478 SE g-1) displayed significantly higher embryogenic yield (148-1343 SE g-1). In our best conditions, the total protein content in cotyledonary SEs increased significantly with maturation 41 duration (up to 150 μg mg-1 fresh mass after 7 weeks) but remained below that of mature zygotic embryos (300 μg mg-1). The protein pattern was similar in both somatic and zygotic embryos, with major storage proteins identified as 7S-vicilin- and legumin-like proteins.

Annual radial growth and latewood formation increase during the period 1966–2015 in Larix cajanderi Mayr. and Pinus sylvestris L. along a latitudinal gradient on Siberian permafrost. Warmer temperatures and precipitation at the onset of the growth season favor growth in both species. A vast area of Siberian boreal forest is covered by continuous permafrost, where tree radial growth is strongly limited by low temperatures. Understanding how climate controls Siberian conifer growth is critical in order to predict their response to ongoing climate change. To explore variations in the radial growth and earlywood/latewood formation of Pinus sylvestris L. and Larix cajanderi Mayr. trees along a climate gradient within the continuous permafrost zone in Central Yakutia (Russia), a region experiencing accelerated warming. We evaluated spatiotemporal differences in tree-ring and latewood width among sites by using generalized additive mixed models. Pearson’s correlations were used to analyze the effect of local climate (temperature, precipitation) and drought (SPEI) on the formation of earlywood and latewood. Both conifers showed increased radial growth in recent decades. Radial growth was controlled by temperature and precipitation in both species along the gradient, with earlier precipitation events being critical for the formation of wide rings. Although temperature is considered as the main limiting factor triggering tree growth in the continuous permafrost zone, our results showed that water availability also plays a key role in radial tree growth even in the coldest sites.

International audience; To maximize utilization of our forest resources, detailed knowledge of wood property variation and the impacts this has on end-product performance is required at multiple scales (within and among trees, regionally). As many wood properties are difficult and time-consuming to measure our knowledge regarding their variation is often inadequate as is our understanding of their responses to genetic and silvicultural manipulation. The emergence of many non-destructive evaluation (NDE) methodologies offers the potential to greatly enhance our understanding of the forest resource; however, it is critical to recognize that any technique has its limitations and it is important to select the appropriate technique for a given application. In this review, we will discuss the following technologies for assessing wood properties both in the field: acoustics, Pilodyn, Resistograph and Rigidimeter and the lab: computer tomography (CT) scanning, DiscBot, near infrared (NIR) spectroscopy, radial sample acoustics and SilviScan. We will discuss these techniques, explore their utilization, and list applications that best suit each methodology. As an end goal, NDE technologies will help researchers worldwide characterize wood properties, develop accurate models for prediction, and utilize field equipment that can validate the predictions. The continued advancement of NDE technologies will also allow researchers to better understand the impact on wood properties on product performance.

International audience

International audience

Le GIS Peuplier continue de suivre les populetums deltoïdes vis-à-vis des risques sanitaires et des performances agronomiques dans des conditions pédoclimatiques variées. A terme, ce réseau de dispositifs constituera un jeu de données conséquent afin d’améliorer les recommandations d’utilisation de ces clones (Delgas, Delvignac et Dellinois).L’innovation variétale de clones euraméricains se traduit en 2018 par la sélection finale de trois clones 661200701, 12-GIS-02-11 et 12-GIS-16-10 en vue d’une inscription. Ce matériel végétal a été mis en élevage chez trois pépiniéristes à la fois pour faire connaître le matériel et le diffuser au sein des plantations comparatives auprès des populiculteurs. En parallèle, le GIS poursuit son effort d’installation de populetums avec 6 nouvelles plantations au printemps 2018 mais également de caractérisation des DN vis-à-vis des bio-agresseurs (rouille, puceron lanigère et Marssonina).Les 28 clones GIS de type Dx(DxT) sélectionnés en 2017 ont été évalués de manière complémentaire aux conventions précédentes vis-à-vis de Mlp et Map. Sept clones se sont révélés sensibles à des isolats portant des virulences connues de Mlp. Pour les 20 autres clones, des réactions compatibles ont pu être observées ; ceux-ci ne portent donc pas de résistance qualitative non contournée par Mlp. La sensibilité à Map n’a pas pu être testée comme prévu initialement, de nouveaux tests seront mis en place en 2019. Un seul couple isolat/clone a été testé et aucune réaction compatible n’a été observée.La sélection 2016 P. trichocarpa du GIS, en élevage dans deux pépinières, a été caractérisée notamment par la phénologie et la vigueur juvénile. Les analyses des mesures réalisées à ce stade laissent entrevoir un potentiel non négligeable pour identifier de bons clones de P. trichocarpa. Un nouvel élevage a été initié à Guémené-Penfao. L’objectif est d’installer un nombre suffisant de populetums pour évaluer les clones in situ mais également en vue d’une homologation. Une vigilance particulière sera portée, toutefois, sur la rectitude au vu de la notation de forme réalisée en pépinière.En 2015, 36 combinaisons P. trichocarpa x P. maximowiczii et P. maximowiczi x P. trichocarpa ont été réalisées par des croisements contrôlés. A partir des mesures réalisées dans le PPM de Guémené-Penfao, 423 clones ont été sélectionnés et installés en test juvénile au printemps 2018 à Guémené-Penfao.En parallèle des activités de sélection et d’évaluation, le GIS peuplier explore de nouvelles approches pour caractériser la sensibilité des clones à des bio-agresseurs avec la mise au point d’un protocole d’évaluation en populetum, inspiré du protocole DSF. L’analyse par génotypage des populations de Mlp récoltées sur des clones DN de l’essai T/NT de Charrey-sur-Saône a permis de conclure qu’il n’y avait aucune contre-indication au déploiement des clones DN sélectionnés.La convention GIS Peuplier 2018 s’est également traduite par l’organisation d’une journée d’information auprès de la filière populicole sur les activités du GIS et l’avancement du programme d’amélioration. Cette journée, couronnée de succès, a été riche en échanges et a permis de présenter les trois clones euraméricains sélectionnés début 2018.

International audience; With EcoAF, download a group of concrete farm parcels, place if needed the polygons of main soil types, then play with possible futures! You can choose whatever combinations of lines, straight or broken or in spots, around or inside the field, decide where to plant trees, shrubs and grasses, in hedges or placed points, the species/varieties and the quality of the bundles of plants. The growth will depend on further choices on how you intend to manage the bundle of plants, the plantation, then all the components during their life. A further development will include simplified crop/animal productions, and the possible impact of the growth of trees and shrubs on them. Each simulation will include variability and aleas. 2D and 3D graphic interfaces and visualizations, at once and delayed datasheets let compare the consequences of different choices. The EcoAF module is developed in French and English on CAPSIS (Computer-Aided Projec-tion of Strategies In Silviculture ; http://www.inra.fr/capsis), with the aims to be user-friendly and transparent about the degree of reliability of parameters. Its conception and evolution take into account the need of advisors in agroforestry. We illustrate some consequences of genetic and silvicultural choices: plant an ordinary or improved variety, densify or not the plantation, take great care or not of the young plants while planting etc.

Master

International audience

Master

Several turn-of-the-20th-century diebacks have shown that French Douglas-fir was vulnerable to drought. Whether the Douglas-fir forests can adapt to the new warmer and dryer climate is a key concern in France. We estimated variation of resistance to cavitation traits of a set of Washington, Oregon and Californian provenances in two common garden experiments located in the south of France. We studied the relationships between resistance to cavitation, xylem microdensity and pit anatomy in the trunk and branches. We found that climatic selection pressure in the natural area has shaped local adaptation for resistance to cavitation, microdensity and pit's anatomy. Inland California provenances tend to be significantly more cavitation resistant, with a denser latewood and safer pits than coastal Californian, then Washington and Oregon provenances. However, we also found significant within region variation that could not be explained by the available climatic data. We found different structure-functions relationships, according to the observation level (tree or provenance) and the tree part (trunk or branch). For example, at the individual level, the most cavitation-resistant trees have branches with denser latewood and smaller pit aperture, while at the provenance level, the most cavitation resistant provenances have less dense wood in both trunk and branches, and safer pits. Overall, we conclude that there is a potential for evolutionary adaptation for resistance to drought in Douglas-fir, available at different levels, individual and provenance. However, in a tree improvement context, the complex network of relationships among the resistance to cavitation, the microdensity and the anatomy traits should be carefully monitored in order to avoid possible unfavourable correlative response to selection., Plusieurs dépérissements du début du XXe siècle ont montré que le Douglas français était vulnérable à la sécheresse. La question de savoir si les forêts de Douglas peuvent s'adapter au nouveau climat plus chaud et plus sec est une préoccupation majeure en France. Nous avons estimé la variation de la résistance à la cavitation d'un ensemble de provenances de Washington, de l'Oregon et de Californie dans deux expériences de jardins communs situées dans le sud de la France. Nous avons étudié les relations entre la résistance à la cavitation, la microdensité du xylème et l'anatomie du tronc et des branches. Nous avons constaté que la pression de sélection climatique dans la zone naturelle a façonné l'adaptation locale pour la résistance à la cavitation, la microdensité et l'anatomie des ponctuations du xylème. Les provenances de Californie intérieure tendent à être plus résistantes à la cavitation, avec une plus grande densité de bois d'été et des ponctuation plus sûres que les provenances de Californie côtière, puis de Washington et d'Oregon. Cependant, nous avons également constaté des variations importantes à l'intérieur d'une même région qui ne pouvaient pas être expliquées par les données climatiques disponibles. Nous avons trouvé différentes relations structure-fonctions, selon le niveau d'observation (arbre ou provenance) et la partie de l'arbre (tronc ou branche). Par exemple, au niveau individuel, les arbres les plus résistants à la cavitation ont des branches plus denses avec une ouverture de ponctuation plus petite, tandis qu'au niveau de la provenance, les arbres les plus résistants à la cavitation ont du bois moins dense dans le tronc et les branches, et des ponctuations plus sûrs. Dans l'ensemble, nous concluons qu'il existe un potentiel d'adaptation évolutive pour la résistance à la sécheresse du Douglas, disponible à différents niveaux, individuel et de provenance. Cependant, dans un contexte d'amélioration des arbres, le réseau complexe de relations entre la résistance à la cavitation, la microdensité et les traits anatomiques doit être soigneusement examiné afin d'éviter une éventuelle réponse corrélative défavorable à la sélection.

Partie 3 : Douglas-fir ecology; International audience

Partie 3 : Douglas-fir ecology; International audience

Partie 4 : Management of Douglas-fir and technological properties of its wood; International audience

[Notes_IRSTEA]revue en libre accès ; lien vers le texte intégral donné dans la notice [Departement_IRSTEA]Territoires [ADD1_IRSTEA]Dynamique et fonctionnement des écosystèmes; International audience; The link between phenotypic plasticity and heterosis is a broad fundamental question, with stakes in breeding. We report a case-study evaluating temporal series of wood ring traits of hybrid larch (Larix decidua x L. kaempferi and reciprocal) in relation to soil water availability. Growth rings record the tree plastic responses to past environmental conditions, and we used random regressions to estimate the reaction norms of ring width and wood density with respect to water availability. We investigated the role of phenotypic plasticity on the construction of hybrid larch heterosis and on the expression of its quantitative genetic parameters. The data came from an intra-/interspecific diallel mating design between both parental species. Progenies were grown in two environmentally contrasted sites, in France. Ring width plasticity with respect to water availability was confirmed, as all three taxa produced narrower rings under the lowest water availability. Hybrid larch appeared to be the most plastic taxon as its superiority over its parental species increased with increasing water availability. Despite the low heritabilities of the investigated traits, we found that the expression of a reliable negative correlation between them was conditional to the water availability environment. Finally, by means of a complementary simulation, we demonstrated that random regression can be applied to model the reaction norms of non-repeated records of phenotypic plasticity bound by a family structure. Random regression is a powerful tool for the modeling of reaction norms in various contexts, especially perennial species.

National audience; Trees are able to grow high and to live old thanks to the remarkable properties of their wood. As a matter of a fact, wood delivers three major functions: (1) water conduction from roots to crown, (2) support of the ever-increasing mass of the growing tree and (3) storage of temporary reserves, important for tree growth over the years. In angiosperm trees, different wood cell types are affected to each of these functions. Fibers are involved in tree mechanical support, vessels in water conduction and parenchyma rays in starch and/or lipid storage during the resting period. In addition, these cell types have distinct developmental programs. While fibers and vessels are early-dying cells, parenchyma rays stay alive longer. Therefore wood is a complex patchwork of cells and its structure results from the three-dimensional assembly of the cell walls of dead fibers and vessels, interconnected with still living parenchyma rays. This great complexity stands as an obstacle when studying wood formation and the construction of wood properties. However, this can be circumvented thanks to the development of cell-specific approaches. We developed a non-destructive method based on ATR-FTIR imaging on poplar wood sections. This technology enables to collect IR-absorbance spectra from small areas of cross-sections, which makes possible to differentiate between wood cell-types or even between the different cell wall layers from a single fiber. We first demonstrated that spectra taken from fiber cell walls on cross-sections differed from spectra obtained from wood powder. We also showed that ATR-FTIR imaging is able to discriminate the cell walls of fibers, vessels and rays. These findings are in accordance with other studies [1], but with an improved spatial resolution. ATR-FTIR microspectroscopy is thus a promising tool to finely characterize the cell wall of different wood cell types. This work has been partly supported by the OPeNSPeNU project (funded by the Centre Val de Loire Region)

International audience; This articles reports on an experiment conducted in August 2017 in a group of islands in the Loire river cove- ring some 13 hectares downstream of Orleans involving automated sensing of habitats. We used a drone in combination with a Lidar equipped with photo cameras. One of these cameras was altered to access infra- red. Following various analyses, we compared our predictions with our field data categorised under the SIEL (Loire habitats) typology. The kappa value (0.52) of our map reflects discontinuities in the quality of predic- tion, particularly as between open and semi-open environments. For the latter, our findings show that it is preferable to stay at the upper level of the classification, particularly for bank vegetation. On the other hand, the positive aspect of this feedback is that it shows that sedge meadows, hardwood forests and, to a lesser extent, birch-leaved poplar groves and areas with boxelder maple, are accurately predicted.; Le présent article fait état d’une expérimentation qui s’est déroulée en août 2017 sur un complexe d’îles de Loire d’environ 13 hectares, en aval d’Orléans et dont le sujet portait sur la détection automatique des habi- tats. Nous avons utilisé un drone couplé à un lidar avec des appareils photos dont un était modifié pour accéder aux infrarouges. Après différentes analyses, nous avons comparé nos prédictions à nos données de terrain classées selon la typologie des habitats de Loire (SIEL). Le kappa moyen (0,52) de notre carte reflète des discontinuités de qualité de prédiction notamment entre les milieux ouverts et semi-ouverts. Pour ces derniers, nos résultats montrent qu’il est préférable de rester au niveau supérieur de classification particuliè- rement pour les végétations de grèves. En revanche, le point positif de ce retour d’expérience montre que les cariçaies, les forêts à bois durs ainsi que dans une moindre mesure les peupleraies noires et les zones à Érable américain, sont correctement prédites.

International audience

International audience; AbstractKey messageAdvanced hybridization between first-generation interspecific hybrids is an attractive alternative to breed and mass-produce hybrid seed lots. Nevertheless it faces two major drawbacks, namely hybrid depression and inbreeding depression. Their impact may be highly detrimental on some traits (seed yield) especially for the highest level of consanguinity, but much less on some others (seed quality and early growth) as shown in this study for hybrid larch (Larix x eurolepis).ContextMass-production of 1st-generation larch hybrids (Larix x eurolepis) in interspecific hybridization orchards is problematic. Alternatives are searched such as advanced-generation orchards combining 1st-generation hybrid clones.AimsOur aim was to investigate how important hybrid and inbreeding depressions can be in 2nd-generation hybrids with a special focus on reproductive success (and early growth) and their consequences on the success of advanced-generation hybridization seed orchards.MethodsSecond-generation hybrids were created by control crosses among 18 1st-generation (F1) hybrid clones with 3 different levels of relatedness (OC (outcrossed), HS (half-sib) and FS (full-sib)). Seed yield and quality and growth in nursery were assessed for the 3 groups and compared with related F1 crosses. Hybrid breakdown and inbreeding depression were then estimated.ResultsF1 hybrids are fertile and mating among them is feasible. Nevertheless hybrid depression is observed when passing to 2nd-generation hybrids for crossing success rate (− 20%) and for seed yield (> 50% less filled seed/cone). Hybrid depression is reinforced by inbreeding and more severely with increasing consanguinity levels: negligible for HS, a supplementary drop of over 50% of seed yield is observed for FS. In contrast, seed quality traits as well as first-year growth are little impacted by both hybrid and inbreeding depressions. Nevertheless a great variation in inbreeding depression level exists among mother clones. Overall, total depression overpasses 70% for the FS parent group but is limited to less than 34% for OC parents for a synthetic trait (number of germinated seed/cone) and remains negligible for growth.ConclusionAdvanced hybridization is possible with larch but with a more or less severe impact on reproductive success depending on level of relatedness among the parents. Growth seems much less impacted than reproduction and this is a promising result. The proper choice of 1st-generation parents is unavoidable for success of 2nd-generation seed orchards.

International audience; Multispecies surveys have shown that there is a weak but significant trade-off between xylem efficiency and safety in woody species, with no species maximizing both attributes at the same time. Relationships between xylem structure and function are studied mostly at the interspecific level, with few studies considering the relationships at the intraspecific level, particularly in angiosperms. Studies have shown that relationships between xylem anatomy or wood density and vulnerability to cavitation (which determines xylem safety) observed in multi-species surveys may be different to those observed within a species. This raises the question about the value of multispecies studies to shed light over what is adaptive within a given species, the organization level at which natural and human selection operates. To contribute to this debate, we studied xylem structure and function in four Eucalyptus species, and made focus within one of them, E. globulus, to determine if patterns observed at the interspecific level are also held within a species. Eucalyptus species have a xylem composed by solitary vessels surrounded and connected to imperforate tracheary cells and parenchyma, a particular anatomy poorly known in terms of its function. Correlation analyses revealed that the trends observed between vessel size (mean and distribution) and vulnerability to cavitation are similar at the interspecific and intraspecific levels. Moreover, no trade-off has been observed between xylem efficiency (maximum hydraulic conductivity) and safety (water potential at 12% and 50% of hydraulic conductivity loss), but the opposite trend: individuals with mean larger vessels presented lower vulnerability to cavitation. Cells around vessels (parenchyma, vasicentric tracheids, fibertracheids) could be involved in this phenomenon since they correlate both with maximum hydraulic conductivity (positively) and vulnerability to cavitation (negatively) at the interspecific level. In addition, large xylem vessels presented smaller pits than small xylem vessels. This suggests that pit size is involved in the lack of trade-off between xylem safety and efficiency. Finally, vulnerability to cavitation was correlated with branch and stem wood density of the same tree, but correlations had opposite sign depending on the plant organ. These results provide new insights into the relationships between wood structure and function of angiosperm species.

BackgroundGenomic selection accuracy increases with the use of high SNP (single nucleotide polymorphism) coverage. However, such gains in coverage come at high costs, preventing their operational implementation by breeders. Low density panels imputed to higher densities offer a cheaper alternative. Our study is one of the first to explore the imputation in a tree species: black poplar. About 1000 pure-breed Populus nigra trees corresponding to a subsample of the French breeding population were selected and genotyped with a 12K custom Infinium Bead-Chip. Forty-three of those individuals corresponding mostly to nodal trees in the pedigree were fully sequenced (reference), while the remaining majority (target) was imputed from 8K to 1.4 million SNPs using FImpute. Each SNP and individual was evaluated for imputation errors by leave-one-out cross validation in the training sample of 43 sequenced trees. Some summary statistics such as Hardy Weinberg Equilibrium exact test p-value, quality of sequencing, depth of sequencing per site and per individual, minor allele frequency, marker density ratio or SNP information redundancy were calculated. Principal component and Boruta analyses were used on all these parameters to rank the factors affecting the quality of imputation. Additionally, we characterize the impact of the relatedness between reference population and target population.ResultsDuring the imputation process, we used 7,540 SNPs from the chip to impute 1,438,827 SNPs from sequences along the 19 Chromosomes. At the individual level, imputation accuracy was very high with a proportion of SNPs correctly imputed between 0.84 and 0.99. The variation in accuracies was mostly due to differences in relatedness between individuals. At a SNP level, the imputation quality strongly depended on genotyped SNP density and to a lesser extent on the original minor allele frequency. The imputation did not appear to result in an increase of linkage disequilibrium. The genotype densification not only brought a better distribution of markers all along the genome, but also we did not detect any substantial bias in annotation categories.ConclusionsThis study shows that it is possible to impute low-density marker panels to whole genome sequence with good accuracy under certain conditions that could be common to many breeding populations.

International audience; center dot Key message Spring temperature increase is the main driver of larch tree wood formation onset along a 1000-m elevation gradient in the Southern Alps, while its cessation is more probably controlled by water stress at the lowest elevation and photoperiod at higher ones. center dot Context The survival of perennial plants depends on their adaptation to changing environment and specially temperature, which in trees is notably implemented through wood formation process. center dot Aims Our main objective is to understand how the phenology of wood formation is related to environmental factors and to temperature in particular. center dot Methods We monitored the xylogenesis of 60 larch trees, distributed in four stands along an elevation gradient of 1000 m in the French Southern Alps. center dot Results Cambial activity started around mid-May at the lowest site (1350 m) and around mid-June at the highest one (2300 m), showing a delay of 5.4 days per degrees C. The onset of wall-thickening and mature phenophases followed the same linear trend with a delay of 5.2 and 3 days per degrees C, respectively. Phenophase cessations followed a parabolic trend with trees from the lowest site finishing their growth the first, while those from 1700 m finished the last. Our results show that the onset of xylem formation is mainly driven by spring temperature increase, while its cessation is more related to photoperiod, with water shortage being able to hasten it. center dot Conclusion Future climatic changes will most probably increase growing season length (but not necessarily wood production) and shift upwards the optimal elevation for larch growth in the Southern Alps.

International audience

Genetic engineering is a powerful tool to steer bio-oil composition towards the production of speciality chemicals such as guaiacols, syringols, phenols, and vanillin through well-defined biomass feedstocks. Our previous work demonstrated the effects of lignin biosynthesis gene modification on the pyrolysis vapour compositions obtained from wood derived from greenhouse-grown poplars. In this study, field-grown poplars downregulated in the genes encoding CINNAMYL ALCOHOL DEHYDROGENASE (CAD), CAFFEIC ACID O-METHYLTRANSFERASE (COMT) and CAFFEOYL-CoA O-METHYLTRANSFERASE (CCoAOMT), and their corresponding wild type were pyrolysed in a Py-GC/MS. This work aims at capturing the effects of downregulation of the three enzymes on bio-oil composition using principal component analysis (PCA). 3,5-methoxytoluene, vanillin, coniferyl alcohol, 4-vinyl guaiacol, syringol, syringaldehyde, and guaiacol are the determining factors in the PCA analysis that are the substantially affected by COMT, CAD and CCoAOMT enzyme downregulation. COMT and CAD downregulated transgenic lines proved to be statistically different from the wild type because of a substantial difference in S and G lignin units. The sCAD line lead to a significant drop (nearly 51%) in S-lignin derived compounds, while CCoAOMT downregulation affected the least (7–11%). Further, removal of extractives via pretreatment enhanced the statistical differences among the CAD transgenic lines and its wild type. On the other hand, COMT downregulation caused 2-fold reduction in S-derived compounds compared to G-derived compounds. This study manifests the applicability of PCA analysis in tracking the biological changes in biomass (poplar in this case) and their effects on pyrolysis-oil compositions., Graphical Abstract Unlabelled Image

La compréhension des mécanismes de différenciation cellulaire et de lignification impliqués dans la formation du bois nécessite un accès au transcriptome. Or, avec le développement récent du Single Cell RNA Seq, nous avons la possibilité de nous rapprocher du transcriptome de chaque cellule. L’obtention de cellules de xylème secondaire isolées est une étape sine qua none. Cependant, la paroi végétale se dresse comme une barrière entre nous et le transcriptome. Pour cette raison, il est primordial de développer une méthode de protoplastisation de bois. Parti d’un protocole initial, nous avons ajusté différents paramètres tels que l’âge des enzymes, le temps de digestion, la température du milieu de digestion, l’âge du plant, l’utilisation de laccases et les conditions de centrifugation. L’objectif final du projet étant d’appliquer cette méthode sur des lignées transgéniques, nous avons testé notre protocole sur certaines lignées. Ainsi, nous avons mis au point un protocole fonctionnel de protoplastisation de xylème secondaire qui peut encore être optimiser.

International audience

Au cours de l’année 2017, plusieurs pépiniéristes disposant d’une licence de commercialisation pour les clones P. deltoides du GIS Peuplier (Delvignac, Dellinois et Delgas) ont reçu la visite d’un ou plusieurs membres du GIS Peuplier, ce qui a permis de recueillir leur sentiment et leur ressenti vis-à-vis de ces 3 variétés. Une évaluation de leur comportement en plantation, hors réseau expérimental GIS, a également été conduite sur la base des résultats communiqués par le réseau IDF et par quelques résultats étrangers.Pour les hybrides euraméricains, la sélection de fin d’année 2017 a abouti à un groupe restreint de 9 clones où seront choisis les 3 premiers clones qui seront proposés à l’inscription dans les prochaines années. Les efforts ont porté essentiellement cette année sur l’évaluation de la sensibilité à Xanthomonas populi et au puceron lanigère. L’effort d’installation en populetums à parcelles unitaires de 9 plants s’est également poursuivi avec l’installation de 7 parcelles dans différentes régions populicoles françaises. Parallèlement, l’élevage de plançons pour de futures plantations à parcelles pluri-arbres DxN se poursuit.Les rétrocroisements ont été installés pour la première fois sur le terrain en populetums à PU monarbre, sur deux parcelles expérimentales. Ces essais permettront de vérifier leurs performances agronomiques en plantation, mais aussi de surveiller leur état sanitaire, en particulier leur tolérance à M. larici-populina en conditions naturelles, critère déterminant pour ce type botanique. Des évaluations sur leur comportement face à M. larici-populina et M. allii-populina ont également été conduites au laboratoire.Une deuxième année de suivi de plus de 1000 individus issus de 21 familles interspécifiques entre les espèces P. trichocarpa et P. maximowiczii, à la pépinière de Guémené-Penfao a permis de collecter des informations de croissance et de phénologie du débourrement qui permettront une première sélection en 2018. Un test clonal sera ensuite installé, avec un nombre réduit de clones, pour affiner encore la sélection.Pour les clones de P. trichocarpa, des observations dans la parcelle d’Amance et une première année d’observation en pépinière de Guémené-Penfao ont permis de collecter des informations relatives à la vigueur, la forme, le comportement face à la rouille et l’arrêt de croissance, sur un groupe de 17 clones. Ces informations, complétées par les résultats des populetums, qui restent à installer, permettront de sélectionner quelques génotypes en vue d’une inscription, à échéance de 5 ou 6 ans.Enfin, un travail de transfert méthodologique, concernant Marssonina brunnea, a été conduit entre l’INRA de Nancy et Irstea de Nogent-sur-Vernisson, ce qui permettra de conduire des tests de sensibilité à M. brunnea en conditions contrôlées, à Nogent-sur-Vernisson.

International audience; The current distribution area of the two sympatric oaks Quercus petraea and Q. robur covers most of temperate Western Europe. Depending on their geographic location, populations of these trees are exposed to different climate constraints, to which they are adapted. Comparing the performances of trees from contrasting populations provides the insight into their expected resilience to future climate change required for forest management. In this study, the descendants of 24 Q. petraea and two Q. robur provenances selected from sites throughout Europe were grown for 20 years in three common gardens with contrasting climates. The 2420 sampled trees allowed the assessments of the relationship between radial growth and climate. An analysis of 15-year chronologies of ring widths, with different combinations of climate variables, revealed different response patterns between provenances and between common gardens. As expected, provenances originating from sites with wet summers displayed the strongest responses to summer drought, particularly in the driest common garden. All provenances displayed positive significant relationships between the temperature of the previous winter and radial growth when grown in the common garden experiencing the mildest winter temperatures. Only eastern provenances from continental cold climates also clearly expressed this limitation of growth by cold winter temperatures in the other two common gardens. However, ecological distance, calculated on the basis of differences in climate between the site of origin and the common garden, was not clearly related to the radial growth responses of the provenances. This suggests that the gradient of genetic variability among the selected provenances was not strictly structured according to climate gradients. Based on these results, we provide guidelines for forest managers for the assisted migration of Quercus petraea and Q. robur provenances.

International audience

International audience; In a context of climate change and forest decline, a better understanding of the sources of tree flexibility involved in phenotypic plasticity and adaptation is needed. These last years, the role of epigenetics in the response to environmental variations has been established in several model plants at the genotype level but little is known at the level of natural populations grown in pedoclimatic sites. Here, we focused on three French natural populations of black poplar, a key pioneer tree from watersheds, planted in common garden and subjected to controlled variations of water availability. We estimated common genetic parameters such as narrow-sense heritability (h(2)), phenotypic differentiation index (P-ST), and the overall genetic differentiation index (F-ST) from genome-wide SNPs to evaluate the extent of epigenetic variations. Indeed, global DNA methylation levels from individuals exposed to drought or irrigated in a common garden were used. We found that the three populations were not distinguished by their levels of DNA methylation. However, a moderate drought was associated to a significant decrease in DNA methylation in the populations. Narrow-sense heritability and P-ST estimates of DNA methylation were similar to those found for biomass productivity. Heritability and P-ST were higher when trees were subjected to drought than in control condition. Negative genetic correlations between global DNA methylation and height or biomass were detected in drought condition only. Altogether, our data highlight that global DNA methylation acts as a genetic marker of natural population differentiation under drought stress in a pedoclimatic context.

National audience

Confronted with growing competition, wood industry manufacturers are increasingly looking to optimize their processing processes and to control the quality of their finished products. Similarly, research and development teams in genetics and forest genetic improvement need new powerful tools enabling the evaluation of a large number of samples at a low cost and quickly. In this context, the development of non-destructive tools for measuring wood material performances (in all its forms: massive, de structured or reconstructed) is essential. Since the early 1990s, numerous research studies have explored the usefulness of using Near Infrared Spectroscopy (NIRS) to estimate the properties of wood material.This chapter, divided into two parts, aims to present a state of the art on the use of NIRS methodology in the wood domain. The first part describes technology and principles of its operation as well as its various fields of application for macromolecules, some physical and mechanical properties. The second part takes stock of the latest knowledge gained to date on the use of NIRS in the cooperage sector and takes example of an original industrial process for measuring the quality of oak wood directly on the production line.