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The first and the second generation of improved maritime pine (Pinus pinaster) have produced gains of up to 30% in stem volume, a reduction of final harvesting age by 10 years and a considerable improvement of stem straightness. The third generation will include wood quality traits for different end-uses, including pulp and fibre properties. To facilitate this goal, near infrared spectroscopy (NIRS) was used to estimate chemical composition with regard to lignin, cellulose, hemicelluloses, and extractive content, and lignin quality with regard to 4-hydroxy-phenylpropane/guaiacylpropane ratio. A total of 960 samples were investigated which were collected from a large number of trees (belonging to 80 families obtained by crossing 18 mothers and 20 fathers; there are 12 trees per family). Good calibration data was obtained between NIRS and wet chemistry methods (R2 values higher than 0.9 and good precision of prediction). To complete the NIRS work, kraft cookings in small scale, fibre morphology and microdensitometry investigations were also conducted. Genetic calculations indicated that for a 1% rate of selection on mothers and fathers, genetically induced changes are possible with lignin content (−3.8%), cellulose content (+1.3%), pulp yield (+1.8%), fibre length in pulps (+0.17 mm) and wood density (+50 kg m−3).

International audience; The function of the ectomycorrhizal mutualism depends on the ability of the fungal symbionts to take up nutrients (particularly nitrogen) available in inorganic and/or organic form in the soil and to translocate them (or their metabolites) to the symbiotic roots. A better understanding of the molecular mechanisms underlying nutrient exchanges between fungus and plant at the symbiotic interface is necessary to fully understand the function of the mycorrhizal symbioses. The present review reports the characterization of several genes putatively involved in nitrogen uptake and transfer in the Hebeloma cylindrosporum–Pinus pinaster ectomycorrhizal association. Study of this model system will further clarify the symbiotic nutrient exchange which plays a major role in plant nutrition as well as in resistance of plants against pathogens, heavy metals, drought stress, etc. Ultimately, ecological balance is maintained and/or improved with the help of symbiotic associations, and therefore, warrant further understanding.

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Foram analisadas características de crescimento e de forma num ensaio de proveniências de pinheiro bravo aos 8 anos, na Mata Nacional do Escaroupim, recorrendo a análises em componentes principais para representar graficamente o comportamento das proveniências no conjunto das características, e à elaboração de um índice primário para a selecção multicaracterística. São analisadas as relações entre as proveniências, regiões de proveniência e altitude. As proveniências de altitude apresentam melhores características de forma mas crescimento menor, observando-se o melhor comportamento geral em material com origem em pomares de semente e em Monção. São efectuadas simulações com diferentes números de observações, pretendendo ajustar o número de observações a efectuar em futuras avaliações. Growth and form characteristics were analysed in a provenance trial at age 8, in Mata Nacional do Escaroupim. Principal component analysis was used to obtain a graphic representation of the performance of provenances congregating characteristics. A primary selection index was developed aiming at multicharacteristic selection. Relationships between provenances, provenance regions and altitude were also analysed. Highland provenances show better form but reduced growth, whereas material originating from seed orchards and Monção reveal the best general performance. Simulations with different numbers of observations were made, in order to adjust the number of observations that should be made in future evaluations. Des caractères de vigueur et de forme ont été analysés dans un essai de provenances de pin maritime à 8 ans à la Mata Nacional do Escaroupim, utilisant des analyses à components principaux pour représenter graphiquement le comportement des provenances dans l'ensemble des caractéristiques, et un indice de sélection primaire pour la sélection multicaractéristique. Les relations entre les caractéristiques, régions de provenance et altitude sont analysées. Les provenances d'altitude présentent de meilleures caractéristiques de forme mais vigueur inférieure et le meilleur comportement général appartient au matériel originaire des vergers à semences et de Monção. Des simulations avec un nombre différent d'observations ont été effectuées, envisageant d'ajuster le nombre d'observations à effectuer lors de futures évaluations.

Among abiotic stresses, water deficit is probably the most severe limiting factor of plantgrowth and development. In South-Western France climatologists predict a significantincrease of temperature combined with lower rainfall during the growing period for the nextcentury. Such modifications will place forest trees in the presence of new and suddenenvironmental constraints. It is therefore essential to know if these organisms will be able toface such climatic changes. In other words, if plantation of improved varieties will maintainthe present level of productivity with lower water availability as well as sustain severedrought episodes. The capacity of these organisms to adapt to such perturbations will dependon both their phenotypic plasticity and their genetic diversity. In the frame of this thesis, westudied molecular plasticity of maritime pine seedlings grown in hydroponics and exposed toosmotic stress using polyethylene glycol as osmoticum. A factorial design crossing twoecotypes (France & Morocco) by different levels of stress (short & long term) was used tostudy the transcriptomic and proteomic responses of the root system. Our investigationsfocused on accumulation of 7,000 transcripts and 1,200 proteins. Statistical analysis revealeddifferentially expressed genes according to ecotype and condition effects. More interestingwas genes whose molecular plasticity was genetically controlled, revealing ecotype dependentstrategy to response to the imposed stresses. The adaptive significance of these genes could beconfirmed by analysing their patterns of nucleotidic diversity with the main objective ofdetecting molecular signature of natural selection., L'alimentation en eau constitue le principal facteur limitant la croissance, voire la survie desplantes. Les modèles climatiques prévoient pour les 50 à 100 années à venir une baisse desprécipitations et des températures estivales accrues dans la moitié sud de la France. La duréede vie d'une forêt de pin maritime, de sa plantation jusqu'à la coupe d'exploitation estjustement de 50 ans. Il est donc important de savoir si ces organismes pourront faire face à cesbrusques changements climatiques ; en d'autres termes si les variétés améliorées plantéesaujourd'hui pourront maintenir le niveau actuel de productivité dans un milieu plus pauvre eneau, et tolérer des épisodes de sécheresse intense. La capacité de ces organismes à faire face àces perturbations brutales dépendra à la fois de leur plasticité phénotypique et de leur diversitégénétique. Dans le cadre de cette thèse, nous avons étudié la plasticité moléculaire du systèmeracinaire de jeunes plants de pin maritime élevés en milieu hydroponique et soumis à un stressosmotique par ajout de polyéthylène glycol. Un plan factoriel croisant deux écotypes (Franceet Maroc) par cinq niveaux de stress a permis d'analyser les réponses du transcriptome et duprotéome à court et long terme. Nos investigations ont porté sur l'accumulation des transcritsde 7000 gènes et de 1200 protéines. L'analyse statistique des données a permis d'identifierdes gènes dont la plasticité moléculaire est génétiquement contrôlée, révélant des stratégies deréponse différentes de chaque écotype. La valeur adaptative de ces gènes pourra alors êtreconfirmée par l'interprétation des patrons de diversité nucléotidique de ces gènes candidats.

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Stands of maritime pine (Pinus pinaster Ait.) cover about one million hectares of land in south-western France and produce 19% of all French timber, thanks to the intensive management methods employed. Evaluations of carbon fixation and storage in this forest are facilitated by its general homogeneity with respect to soil, climate and tree genetics. However, initial assessments were based on basic values for expansion factors and carbon concentration in the biomass, and more accurate results could be obtained. The aim of the present study was to estimate the carbon concentration in the 13 main compartments of mature P. pinaster shoots and roots, describing sources of variation within these compartments and quantifying precisely the corresponding carbon contents. The biomass distribution per compartment in the shoots and roots of 12 trees with a range of social status is given. It was obtained by joint architecture and dry weight measurements. The root systems were uprooted with a mechanical shovel and measured by 3D digitizing. Biomass allometric prediction equations per compartment according to girth at breast height were developed. The carbon concentration was analysed in 300 samples from four trees, taking into account their architecture. The carbon concentration varied largely between compartments and showed a quadratic relationship with relative height in the four stem compartments and in branches and buds. It showed a negative exponential relation with root diameter. The carbon concentration of needles was not related to their age or their relative height in the crown. Carbon concentration variations were in accordance with the tissue chemical composition found in literature. The biochemical concentration of softwoods organs is extensively reviewed in the paper. The weighted mean carbon concentration reached 53.6% in the shoots and 51.7% in the roots. This resulted to 53.2% at tree level. The carbon content in the pine stand was 74 t C per hectare. Between and within compartment variations in carbon concentration should be considered in carbon content evaluations and in structural–functional models. The underestimation of carbon storage in mature P. pinaster stands and sawnwood products reaches 6% when the usual 50% conversion factor is used.

International audience; In order to improve the estimation of carbon stored in the French forest biomass from National Forest Inventory data, we developed six species-specific equations for estimating the total aboveground volume of trees, including merchantable volume, branches and twigs. Equations use circumference at breast height and total height as independent variables. They were built from even-aged forests of the Landes massif, the northern half and the eastern mountain regions of France. The sample was selected within archives of volume measurements taken in growth and yield permanent plots between 1920 and 1955. It is made up of 4619 trees belonging to seven important species: 1222 Sessile Oak, 1293 Common Beech, 347 Douglas Fir, 309 Norway Spruce, 389 Scots Pine, 297 Maritime Pine and 762 Silver Fir. These trees were felled and measured in 26 different forests (62 stands). Tree form factor was analysed, rather than volume, to remove heteroscedasticity, and height was substituted by a hardiness coefficient to remove diameter–height correlation. The analysis identified species-specific modes of variation of tree form with respect to developmental stage and tree hardiness. Maritime and Scots Pine did not differ statistically, despite large differences between ecological and silvicultural situations of both species. This suggests the possibility to use identical volume equations for species belonging to the same genus. Regional variations of tree form were explored by a cross-validation technique. Prediction biases did not exhibit a clear geographic structure. A 5% overestimation for hardwoods in southern sites is possible, and would deserve further testing. The hypothesis that recent growth changes may have slightly altered tree form is also discussed. Finally, a national-scale application provided Biomass Expansion Factors consistent with former studies and suggested that these volume equations behave well in extrapolation to coppices, uneven-aged or mixed stands.

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Diplôme : DES

International audience; Somatic embryogenesis (SE) in conifers is at the base of nearly all biotechnology products that potentially might be developed including transgenic trees. SE is a powerful tool for clonal propagation that has opened avenues for deployment of superior clonally replicated planting stock in forest plantations. Although the SE process can be managed for high efficiency there are still several problems that require better understanding of underlying causes. One phenomenon, which occurs after the long-term culture of embryogenic tissue, particularly of pines, is the loss of ability to produce mature somatic embryos and consequently plants. Such unproductive cultures must be replaced, which is both expensive and undesirable. In an attempt to get an insight into the differences between young, primary lines of embryonal mass of maritime pine that produced somatic embryos and the same lines of significantly increased age that stopped producing somatic embryos, we analyzed in both types of material the levels of endogenous hormones and their metabolites, polyamines, global DNA methylation and DNA methylation patterns. DNA methylation plays an important role in regulation of gene expression and may cause epigenetic change leading to suppressed embryogenic potential. To determine if the DNA methylation could be altered, we exposed the cultures to different concentrations of hypomethylating agents such as 5-aza-2'- deoxycytidine, 5-aza-cytidine and zebularine and tested the embryogenic potential of a line after the treatment. For comparison, we induced secondary SE from a few mature somatic embryos of the same lines and carried out the same as above analyzes. Secondary SE has been implicated in restoring/enhancing the embryogenic potential of a given line and therefore theoretically the tissue was expected to be biologically similar to the primary young line. Our results indicated that embryogenic cultures of different ages varied with respect to the polyamines levels and DNA methylation pattern but not with respect to the hormone concentration. Treatment of the cultures with the hypomethylating agents resulted in different methylation patterns and somatic embryo production ability.

Diplôme : Master

Wildland fires are driven by vegetation which is a medium that can be very heterogeneous at several scales. These heterogeneities from shoot to stand levels are likely to affect fire behavior. In the context of theoretical fire modelling, we investigated the effects of departure from randomness in radiative transfer. A methodology derived from approach in other turbid media for solar radiation was adapted to our problem. From several Mediterranean fuel type calculations, conditions on vegetation parameters that provide heterogeneity effects were exhibited. Fuel description was done from field measurements and plant architecture modelling. Results show that both a strong spatial variation in fuel distribution and vegetation dense enough were required to provide heterogeneity effects. The combined effect of fuel surface area, cover fraction and heterogeneity size was studied. Radiative transfer in heterogeneous maritime pines and dense shrub stands is shown to be very significantly affected by heterogeneity. On the contrary, lower effects are expected from Aleppo pine and light shrub fuel distributions. Further work will determine the appropriate resolution scale for vegetation description of each species and a way to take into account heterogeneity when no detailed information is available on fuel distribution. © 2006 Published by Elsevier B.V.

Diplôme : Master

During 2002–2004, three laboratories in Canada and France collaborated to improve initiation of somatic embryogenesis (SE) in jack pine (Pinus banksiana Lamb.), eastern white pine (P. strobus L.), maritime pine (P. pinaster Ait.), and Scots pine (P.␣sylvestris L.), giving particular attention to the effects of (1) N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) versus various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and benzyladenine (BA), (2) differences in basal nutrient media, i.e., macro- and microelements, and (3) gelling agent concentration. The work was carried out separately at␣each laboratory, but the details of media compositions were shared and tested on their respective species. Results indicate that the developmental stage of the zygotic embryo (ZE) and genotype effects had a large influence on SE initiation, and that genetic effects were consistent over time. Different species responded differently to PGR types and concentration, basal nutrient media, trace elements, and their combinations. Currently, our best initiation rates based on a selected group of genotypes, optimal development stage of ZE, and medium are 3.9% for jack pine, 54.6% for eastern white pine, 76.2% for maritime pine, and 19.7% for Scots pine.

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International audience; The effects of climate changes on carbon and water fluxes are quantified using a physiologically multi-layer, process-based model containing a carbon allocation model and coupled with a soil model (CASTANEA). The model is first evaluated on four EUROFLUX sites using eddy covariance data, which provide estimates of carbon and water fluxes at the ecosystem scale. It correctly reproduces the diurnal fluxes and the seasonal pattern. Thereafter simulations were conducted on six French forest ecosystems representative of three climatic areas (oceanic, continental and Mediterranean areas) dominated by deciduous species (Fagus sylvatica, Quercus robur), coniferous species (Pinus pinaster, Pinus sylvestris) or sclerophyllous evergreen species (Quercus ilex). The model is driven by the results of a meteorological model (ARPEGE) following the B2 scenario of IPCC. From 1960 to 2100, the average temperature increases by 3.1 °C (30%) and the rainfall during summer decreases by 68 mm (−27%). For all the sites, between the two periods, the simulations predict on average a gross primary production (GPP) increase of 513 g(C) m−2 (+38%). This increase is relatively steep until 2020, followed by a slowing down of the GPP rise due to an increase of the effect of water stress. Contrary to GPP, the ecosystem respiration (Reco) raises at a constant rate (350 g(C) m−2 i.e. 31% from 1960 to 2100). The dynamics of the net ecosystem productivity (GPP minus Reco) is the consequence of the effect on both GPP and Reco and differs per site. The ecosystems always remain carbon sinks however the sink strength globally decreases for coniferous (−8%), increases for sclerophyllous evergreen (+34%) and strongly increases for deciduous forest (+67%) that largely benefits by the lengthening of the foliated period. The separately quantified effects of the main variables (temperature, length of foliated season, CO2 fertilization, drought effect), show that the magnitude of these effects depends on the species and the climatic zone.

International audience; In the context of biosolids utilisation in forestry, effects of sludge application on mushroom metal concentration were studied in six sites of maritime pine forests in the South-West of France. Municipal sludge were applied at a rate of 6 T dry matter per hectare. Edible mushrooms were collected two years after sludge application. As, Cd, Cu, Hg, Pb, Se and Zn concentrations were determined. Results showed a high variability for trace element concentrations in mushrooms collected from control areas. No significant correlation was found between soil parameters (pH and trace elements concentrations) and mushroom trace element concentrations. Even if the concentration of trace metals increased in the soils, sludge application did not affect As, Cu, Se and Zn concentrations in carpophores but slightly increased Cd, Pb and Hg concentrations on some sites. This effect is dependent on sludge type and sites

International audience; Phase change refers to the transition between juvenile and adult vegetative phases. The study of trees throughout their entire life span requires retrospective analyses and validates the use of a chronosequence by sequencing observations at different and successive stages. The main axis growth pattern of 62 maritime pines (Pinus pinaster) selected in a chronosequence of three stands consisting of 8-, 22-, and 48-yr-old trees was analyzed retrospectively. Comparison of measured features (length, number of axillary products, reproductive organs) at common ages from the three stands supported the validity of using these data to form a continuous chronosequence. Endogenous trends in tree development are revealed free from variability due to annual growth conditions. Two main phases of development corresponding respectively to the juvenile vegetative and adult reproductive stages were identified, and the transition between both occurred in 9-yr-old trees. The relevance of these two phases and more generally the notion of phase changes are discussed in light of observed trends in the values of studied growth and branching parameters that may either show gradual variations (such as length of annual shoot) or a distinctive expression in one or the other phase (such as presence of female cones).

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Among abiotic stresses, water deficit is probably the most severe limiting factor of plant growth and development. In South-Western France climatologists predict a significant increase of temperature combined with lower rainfall during the growing period for the next century. Such modifications will place forest trees in the presence of new and sudden environmental constraints. It is therefore essential to know if these organisms will be able to face such climatic changes. In other words, if plantation of improved varieties will maintain the present level of productivity with lower water availability as well as sustain severe drought episodes. The capacity of these organisms to adapt to such perturbations will depend on both their phenotypic plasticity and their genetic diversity. In the frame of this thesis, we studied molecular plasticity of maritime pine seedlings grown in hydroponics and exposed to osmotic stress using polyethylene glycol as osmoticum. A factorial design crossing two ecotypes (France & Morocco) by different levels of stress (short & long term) was used to study the transcriptomic and proteomic responses of the root system. Our investigations focused on accumulation of 7,000 transcripts and 1,200 proteins. Statistical analysis revealed differentially expressed genes according to ecotype and condition effects. More interesting was genes whose molecular plasticity was genetically controlled, revealing ecotype dependent strategy to response to the imposed stresses. The adaptive significance of these genes could be confirmed by analysing their patterns of nucleotidic diversity with the main objective of detecting molecular signature of natural selection., L'alimentation en eau constitue le principal facteur limitant la croissance, voire la survie des plantes. Les modèles climatiques prévoient pour les 50 à 100 années à venir une baisse des précipitations et des températures estivales accrues dans la moitié sud de la France. La durée de vie d'une forêt de pin maritime, de sa plantation jusqu'à la coupe d'exploitation est justement de 50 ans. Il est donc important de savoir si ces organismes pourront faire face à ces brusques changements climatiques ; en d'autres termes si les variétés améliorées plantées aujourd'hui pourront maintenir le niveau actuel de productivité dans un milieu plus pauvre en eau, et tolérer des épisodes de sécheresse intense. La capacité de ces organismes à faire face à ces perturbations brutales dépendra à la fois de leur plasticité phénotypique et de leur diversité génétique. Dans le cadre de cette thèse, nous avons étudié la plasticité moléculaire du système racinaire de jeunes plants de pin maritime élevés en milieu hydroponique et soumis à un stress osmotique par ajout de polyéthylène glycol. Un plan factoriel croisant deux écotypes (France et Maroc) par cinq niveaux de stress a permis d'analyser les réponses du transcriptome et du protéome à court et long terme. Nos investigations ont porté sur l'accumulation des transcrits de 7000 gènes et de 1200 protéines. L'analyse statistique des données a permis d'identifier des gènes dont la plasticité moléculaire est génétiquement contrôlée, révélant des stratégies de réponse différentes de chaque écotype. La valeur adaptative de ces gènes pourra alors être confirmée par l'interprétation des patrons de diversité nucléotidique de ces gènes candidats.

International audience; Species-rich plant communities may be more resistant to invasive herbivores because of reduced host-plant accessibility and increased natural enemy diversity and abundance. We tested these hypotheses in Corsica, a Mediterranean island recently invaded by the maritime pine bast scale, Matsucoccus feytaudi Duc., which causes widespread tree mortality in Pinus pinaster Ait. The endemic Matsucoccus pini Green infests Corsican pine, Pinus nigra laricio Poiret, where it is controlled by the native predatory bug, Elatophilus nigricornis Zetterstedt. As revealed by kairomone trapping, E. nigricornis was most abundant in pure Corsican pine in areas not yet colonized by M. feytaudi, and in pure maritime pine its density decreased with the distance from the nearest Corsican pine forest. The abundance of M. feytaudi was compared in five pairs of Pure maritime pine and mixed maritime and Corsican pine stands. It was consistently higher in pure than in mixed maritime pine stands, whereas E. nigricornis showed the opposite pattern, and relative differences were correlated with the proportion of Corsican pine in the Mixture. The predation by E. nigricornis was manipulated in pure maritime pine stands using synthetic attractants of the predator. Matsucoccus feytaudi density was significantly reduced in maritime pines baited with kairomone dispensers

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International audience; In southwest France, much of the forested land on sandy spodosols has been converted to continuous maize cropping in the last few decades. To evaluate the impacts of this change on soil organic matter properties, we compared total organic C and neutral and amino sugars content in whole soil and particle size separates of two forested, and five related sites that had been either clear-cut for 12 and 18 mo, or cultivated to maize for 4-22yr. Soil carbohydrates accounted for 4-7% of the total organic C across all sites. Soil organic C contents of clear-cut and cultivated sites were only 57-79% of the average value measured in forested sites. Accordingly, carbohydrate content of clear-cut and cultivated sites were only 35-66% of the value in forested sites. Ordering the sites in a chronosequence indicated that both total organic C and carbohydrate contents decreased with an increase in time elapsed since clear-cutting and maize cultivation. The only exception was a partial recovery of carbohydrate content in the site that had been under continuous maize for 22 yr. The day+silt fraction (0-50 mu m) was enriched in carbohydrates, mainly of microbial origin, whereas the sand size fractions (50-200 and 200-2000 pm) contained fewer carbohydrates which were mainly of plant origin. Monosaccharide analysis of particle size separates revealed significant differences in carbohydrate composition between sites. Relative to forested sites, the coarse and fine sand fractions in clear-cut and cultivated sites were depleted in carbohydrates and were relatively enriched in plant-derived carbohydrates. Carbohydrate content of the day+silt fraction drastically decreased upon clear-cutting. Amino sugar content was consistently lower in clear-cut and cultivated sites than in forested sites, indicating that microbial populations were negatively affected by clear-cutting and cultivation. The fungal population appeared more sensitive than bacteria to these land-use changes as indicated by a greater decline in glucosamine than in muramic acid contents. (c) 2006 Elsevier Ltd. All rights reserved.

International audience; A series of tests were carried out to design pheromone-based monitoring of the pine processionary moth (PPM), Thaumetopoea pityocampa. In a dose–response field test the number of male captures increased significantly with the dosage of pityolure to a plateau around 10 mg. The activity of pheromone dispensers persisted for at least 11 weeks, enough to cover the entire flight period of T. pityocampa. In a comparison of several saturating and non-saturating trap designs, plate sticky traps always showed the highest trapping efficiency. Captures were significantly higher in regularly cleaned traps than in traps without cleaning, and at tree canopy height; however, the latter were positively correlated with captures from traps positioned at breast height. The relationship between the number of PPM males captured in pheromone traps and the density of winter nests was investigated in 14 stands of the maritime pine (Pinus maritima) using 10 traps baited with low doses of pityolure. Mean trap captures calculated from 3 traps schemes to 10 traps were significantly correlated with nest density, indicating that four plate sticky traps baited with 0.2 mg of pityolure would provide a cost-effective tool for monitoring population densities of PPM per hectare. The reliability of this design was tested in 33 pine stands of different age and tree species across a range of geographic regions (France, Italy, Portugal), both in the core and expansion areas of the pest. The results were remarkably consistent, showing significant and positive correlations between mean male captures per day and total number of winter nests per hectare irrespective of the regions. The correlations with the level of infestation in the following generation was also positive for all regions although less significant. Our findings suggest that pheromone-baited traps provide a suitable tool for monitoring of T.pityocampa populations

International audience

We present a systematic list of 91 carabid beetles species caught between 1998 and 2004 in forest plantations and semi-natural neighbouring habitats of 11 municipalities in Landes and Gironde districts. Sampled habitats are different stages of maritime pine plantations from clearcuts to mature stands, and heathlands, grassy firebreaks, deciduous woodlands, riverine forests and wet meadows near the Bassin d’Arcachon. Ground-dwelling carabids were caught with pitfall traps and bark-dwelling carabids with self-adhesive tapes fixed around trunks. Some species are uncommon or interesting from a biogeographic point of view, such as Calosoma sycophanta, Notiophilus germinyi, Odontonyx rotundatus, Batenus livens, Percosia equestris, Ophonus rotundatus, Harpalus smaragdinus, H. neglectus, Masoreus wetterhalli or Pseudomasoreus canigoulensis, Nous présentons une liste systématique commentée de 91 espèces de carabiques piégées de 1998 à 2004 dans 11 communes des Landes et de la Gironde, en forêt de plantation et dans les habitats semi-naturels adjacents. Les habitats échantillonnés sont les différents stades du cycle sylvicole du pin maritime, de la coupe rase à la pinède âgée, ainsi que des landes, des pare-feux, des bois de feuillus, des ripisylves et des prairies humides autour du Bassin d’Arcachon. Les carabiques épigés ont été capturés au piège à fosse et les espèces corticoles avec des bandes collantes fixées sur le tronc des arbres. Parmi les espèces capturées, plusieurs sont peu communes ou intéressantes sur le plan biogéographique comme Calosoma sycophanta, Notiophilus germinyi, Odontonyx rotundatus, Batenus livens, Percosia equestris, Ophonus rotundatus, Harpalus smaragdinus, H. neglectus, Masoreus wetterhalli ou Pseudomasoreus canigoulensis

International audience; A three-generation outbred pedigree of 186 individuals was used to identify the genomic regions involved in the variability of chemical and physical wood properties of Pinus pinaster. A total of 54 quantitative trait loci (QTLs) was detected, with an average of 2.4 QTLs per trait. Clusters of wood properties QTLs were found at several points in the genome, suggesting the existence of pleiotropic effects of a limited number of genes. The colocalizations observed in this study are in accordance with the genetic correlations previously reported in the literature. In addition, in an attempt to identify the genes underlying the QTLs, nine wood quality candidate genes involved in cell wall structure were localized on the genetic map. Only one of them, Korrigan, a gene encoding for a β 1-4 endo-glucanase known in Arabidopis thaliana to be involved in polysaccharide biosynthesis, co-localized with a wood quality QTL cluster involved in hemicellulose content and fibre characteristics. This finding is in accordance with results previously reported for this gene regarding its expression variability (transcriptome and proteome levels) and patterns of molecular evolution. The pertinence of this result will be tested in more rigorous designs in order to identify early selection predictors for wood quality.

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In this study, several improvements and simplifications of SE protocols in Pinus pinaster (Ait.), a species of economic importance in the regions of Western Europe, are described. These improvements pertained to all stages of SE including high initiation frequencies in eight control pollinated seed families, relatively high somatic embryo maturation yield when cells were coated with particles of activated charcoal and a rapid production of plants directly in a shade house. The SE initiation frequency from isolated zygotic embryos was high (up to 100%) and plants were produced from 11 embryogenic lines representing all crosses. Based on these results, the estimated number of somatic embryos required to produce 1,000 plants varied from slightly more than the required number of plants to more than double this number depending on the line. Such an estimate is critical in developing plant production strategy when a number of embryogenic lines are considered for production of clonal plants.

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International audience; Nucleotide diversity in eight genes related to wood formation was investigated in two pine species, Pinus pinaster and P. radiata. The nucleotide diversity patterns observed and their properties were compared between the two species according to the specific characteristics of the samples analysed. A lower diversity was observed in P. radiata compared with P. pinaster. In particular, for two genes (Pp1, a glycin-rich protein homolog and CesA3, a cellulose synthase) the magnitude of the reduction of diversity potentially indicates the action of nonneutral factors. For both, particular patterns of nucleotide diversity were observed in P. pinaster (high genetic differentiation for Pp1 and close to zero differentiation associated with positive Tajima's D-value for CesA3). In addition, KORRIGAN, a gene involved in cellulose-hemicellulose assembly, demonstrated a negative Tajima's D-value in P. radiata accompanied by a high genetic differentiation in P. pinaster. The consistency of the results obtained at the nucleotide level, together with the physiological roles of the genes analysed, indicate their potential susceptibility to artificial and/or natural selection

The Mediterranean basin is characterised by a traditional depletion of forest by man and the human impact has modified species’ genetic diversity. Maritime pine (Pinus pinaster Aiton) occurs naturally in fragmented populations in the western part of the Mediterranean basin. This distribution has been reshaped during the last two centuries by heavy afforestation, particularly in southwest France and in the Iberian Peninsula, and by invasive behaviour in disturbed areas. This presentation summarizes and discusses results of studies in which molecular markers were used to undercover the genetic diversity of this species, which further traced the human impact on its genetic structure, exemplary demonstrated for Portugal. The genetic parameters estimated from chloroplast microsatellites (cpSSR) data revealed that the level of genetic diversity in Pinus pinaster is very high. A clear and significant differentiation among groups of populations of different geographic origin (Portugal, France, Italy, Spain and Morocco) was observed. Conversely, the degree of population divergence within country is generally very low and close to zero, indicating a homogeneous distribution of the variation within groups. The presence of significant differentiation among groups of populations of different geographic areas seems to reflect the existence of different glacial refugia during the Quaternary, for this species. In France the observed haplotypic pattern suggest a genetic ‘melting pot’ of haplotypic diversity, derived from the mixture of material due to the artificial transfer from different regions. Using mitochondrial DNA, a maternally inherited marker, only three-mitochondrial haplotypes were found, which provided a clear picture of nonoverlapping areas colonized from different refugia, with no single population having a mixed composition. The phylogenetic analysis made with allozyme markers showed a high geographical structure in the Iberian Peninsula. The northwestern populations form a cluster and the southeastern populations another. Highest levels of diversity in the eastern and the southern populations and an important reduction of gene diversity in the northwestern range of the species in the Peninsula were observed. Nevertheless, a putative refugium in Portugal was not excluded, because P. pinaster could have survived during the last glaciation in sheltered areas at low altitude close to the Atlantic Ocean, also supported by pollen and charcoal fossil discoveries. The distribution of the genetic variation of P. pinaster in Portugal, as revealed by cpSSR, indicated that there are low levels of differentiation among populations and that the diversity is found mainly within populations. No discernible geographic pattern was found. Evidences of strong anthropogenic influence associated with extensive gene flow could explain these findings, A bacia do Mediterrâneo é caracterizada pelo tradicional desaparecimento da floresta devido à acção do Homem e o impacto humano tem tido influência na alteração da diversidade genética. O pinheiro bravo ocorre em populações fragmentadas na região oeste da bacia do Mediterrâneo e a sua área de distribuição tem sido alterada nos últimos séculos devido a intensa florestação, em particular no SW de França e no Noroeste da Península Ibérica e, também, devido ao comportamento invasivo desta espécie em áreas perturbadas do ponto de vista ecológico. Nesta apresentação pretendemos sintetizar e discutir o resultado de estudos que utilizaram técnicas moleculares para revelar a diversidade do pinheiro bravo e, também, o impacto humano na sua estrutura genética; que é demonstrado paradigmaticamente em Portugal. Os parâmetros genéticos estimados com base em microsatélites do cloroplasto (cpSSR) revelaram que a diversidade genética é muito elevada ao nível da distribuição da espécie. Observou-se uma clara e significativa diferenciação entre grupos de populações de diferente origem geográfica (Portugal, França, Itália, Espanha e Marrocos). Pelo contrário, o grau de divergência dentro dos países é geralmente muito baixo ou próximo de zero, o que indica uma variação homogénea dentro dos grupos. A presença de diferenciação entre grupos de populações de diferentes áreas reflecte a existência de diferentes refúgios durante o Quaternário. Em França, o padrão haplotípico sugere uma mistura de material proveniente de diferentes origens. Só foram encontrados 3 mitótipos, usando marcadores mitocondriais, marcador de herança maternal, o que proporciona uma imagem clara de áreas colonizadas a partir dos diferentes refúgios; nem uma só população possui uma composição mista. Uma análise filogenética feita com base em isoenzimas mostrou que a estrutura geográfica do pinheiro bravo na Península Ibérica (PI) é muito elevada. As populações de Noroeste formam um grupo e as de Sudeste outro. Observou-se níveis elevados de diversidade nas populações de Este e Sul e uma redução importante da variabilidade em populações da região Noroeste da PI. No entanto, pode ter existido em Portugal um refúgio, pois o pinheiro bravo pode ter sobrevivido durante a última glaciação em zonas abrigadas e de baixa altitude junto ao Oceano Atlântico, o que parece também ser evidente devido a descobertas de pólen e carvão fóssil. A distribuição da variação genética do pinheiro bravo em Portugal, observada através de cpSSR indica que a diferenciação entre populações é baixa e que a diversidade existe principalmente dentro das populações. Não se observa nenhum padrão geográfico, mas as evidências existentes de uma forte influência antrópica antropogénica associada a um fluxo genético extensivo poderiam explicar esse resultado

National audience

Root morphology influences strongly plant/soil interactions. However, the complexity of root architecture is a major barrier when analysing many phenomena, e.g. anchorage, water or nutrient uptake. Therefore, we have developed a new approach for the representation and modelling of root architecture based on branching density. A general root branching density in a space of finite dimension was used and enabled us to consider various morphological properties. A root system model was then constructed which minimizes the difference between measured and simulated root systems, expressed with functions which map root density in the soil. The model was tested in 2D using data from Maritime pine Pinus pinaster Ait. structural roots as input. We showed that simulated and real root systems had similar root distributions in terms of radial distance, depth, branching angle and branching order. These results indicate that general density functions are not only a powerful basis for constructing models of architecture, but can also be used to represent such structures when considering root/soil interaction. These models are particularly useful in that they provide a local morphological characterization which is aggregated in a given unit of soil volume.

Cet ouvrage existe également en espagnol "Mejoramiento genético del Pino marítimo en Aquitania" et en anglais "Genetic breeding of the maritime pine in Aquitaine"; National audience

Diplôme : Master Recherche

International audience; Two methods of sampling stemwood nutrients have been compared on 10 Pinus pinaster (Ait.) trees: the increment borer method (non-destructive but producing samples which are not weighed according to the tissues’ proportion) and the disc method (destructive but producing weighed samples). The samples were divided into sapwood and heartwood, and nutrient concentrations were determined for major nutrients (N, P, K, Ca, Mg). Compared with the disc sampling method, the increment borer sampling method significantly underestimated N, P and K concentration in sapwood, whereas it overestimated Ca and Mg concentration in heartwood. The mean error ranged from - 13 per cent (N and P in sapwood) to +14 per cent (Ca in heartwood). These results were in agreement with previous studies which showed horizontal variations in the nutrient concentration of stemwood.

Ce chapitre existe également en espagnol : Hacia una 4ta generación de huertos dans l'ouvrage : Mejoramiento genético del Pino marítimo en Aquitania; International audience; To prepare the fourth generation of seed orchards, a major genitor evaluation programme has been undertaken, characterised by the size and quality of the test network: 120 hectares of progeny trials installed in 8 successive sets to evaluate 1300 genitors. The selection of these genotors between 2005 and 2010 will allow the development of new orchards which will become productive in about 2020