Дисертації з теми "Adaptation aux plantes"
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Dutartre, Leslie. "Co-évolution plantes-insectes : adaptation des lépidoptères aux Poaceae." Nice, 2011. http://www.theses.fr/2011NICE4047.
To study the principle of plant-insect co-evolution, we studied the interaction between a Poaceae, Zea mays, and the insect Spodoptera frugiperda. The Poaceae developed the DIMBOA-biosynthetic pathway, compound with bactericide, fungicide and insecticide effects. Noctuid moths like S. Frugiperda, a maize pest, had to coevolve when the pathway expanded. We studied the origin of the DIMBOA-biosynthetic pathway in Poaceae by a bioinformatic approach and demonstrated that the origin of the pathway was the rearrangement of two new duplicated genes, Bx1 and Bx2, at the tip of a chromosome of a poaceous ancestor. Bx2 was further duplicated, leading to the 4 P450s of the pathway which further evolved by functional divergence and/or positive selection processes, explaining their actual high substrate specificity. We also characterized maize lines for which the pathway was blocked in the Bx1 and Bx3 genes by metabolomic and transcriptomic approaches and demonstrated that they could be used to simulate disappeared evolutionary ancestral steps. We then compared the influence of the ingestion of wild type or Bx1 and Bx3 mutant plants on S. Frugiperda larvae by a toxicological study and a transcriptomic approach. Finally, we studied the toxicological impact of different pathway intermediates on insect larvae. Our results demonstrate that, during coevolution, the polyphagous insect S. Frugiperda has optimized its response to the entire pathway and is no longer adapted to ancestral steps of the pathway and DIMBOA precursors. This observation allows us to envisage the manipulation of a maize constitutive defense as a way to fight against one of its main pest
Tamisier, Lucie. "Adaptation des populations virales aux résistances variétales et exploitation des ressources génétiques des plantes pour contrôler cette adaptation." Thesis, Avignon, 2017. http://www.theses.fr/2017AVIG0696/document.
Plants carrying major resistance genes have been widely used to fight against diseases. However, the pathogensability to overcome the resistance after a few years of usage requires the search for efficient and durable resistances.The objectives of this thesis were (i) to identify plant genomic regions limiting pathogen evolution by inducinggenetic drift effects and (ii) to study the impact of the evolutionary forces imposed by the plant on the pathogenability to adapt to resistance, the goal being to further use these forces to limit pathogen evolution. The pepper(Capsicum annuum) – PVY (Potato virus Y) pathosystem has been mainly used to conduct these researches.Regarding the first objective, quantitative trait loci (QTL) were mapped on a biparental pepper population andthrough genome-wide association on a pepper core-collection. These approaches have allowed the detection ofgenomic regions on chromosomes 6, 7 and 12 controlling viral effective population size during the inoculationstep. Some of these QTLs were common to PVY and CMV (Cucumber mosaic virus) while other were virusspecific.Moreover, the QTL detected on chromosome 6 colocalizes with a previously identified QTL controllingPVY accumulation and interacting with a QTL affecting the breakdown frequency of a major resistance gene.Regarding the second objective, a correlation analysis between the evolutionary forces imposed by the plant andan experimental estimation of the durability of a major resistance gene has been done. Experimental evolution ofPVY populations on plants contrasted for the levels of genetic drift, selection and virus accumulation they imposedhas also been performed. Both studies demonstrated that a plant inducing a strong genetic drift combined to areduction in virus accumulation limits virus evolution and could even lead to the extinction of the virus population.These results open new perspectives to deploy plant genetic factors directly controlling pathogen evolutionarypotential and could help to preserve the durability of major resistance genes
Thouvenot, Lise. "Stratégies de réponse de l'espèce invasive Ludwigia grandiflora aux contraintes environnementales." Rennes 1, 2012. http://www.theses.fr/2012REN1S141.
The success of invasive species depends on the characteristics of exotic species (their biological traits) and the characteristics of their introduced habitats (biotic and abiotic characteristics). The success of these species will depend on their response strategies to environmental constraints. In this thesis, we focus on the the Large Water Primrose plant species, Ludwigia grandiflora subsp. Hexapetala,. This amphiphyte species is considered as the most invasive aquatic plant in France. The present thesis aims to improve our knowledge on the adaptive strategies of Ludwigia grandiflora to environmental constraints in order to better understand and explain its invasive success. The responses of this species to abiotic parameters and biotic interaction were investigated using a functional traits approach. To achieve these goals, we conducted microcosm and mesocosm experiments. We demonstrated that L. Grandiflora possesses a large adaptive capacity to respond to fluctuations of abiotic factors (e. G. Variation of water depth, light intensity, salinization of ecosystems). Furthermore, our results showed that L. Grandiflora had a high growth rate, compensated herbivore damages and was able to produce a dense canopy in response to competition. However, the response strategy of L. Grandiflora to biotic pressure (competition and predation) depended on its own density, on the density and the status (native vs exotic) of neighboring species and on its environment (terrestrial vs aquatic). The response strategies of L. Grandiflora face to abiotic parameters and biotic pressure could explain its invasive success
Jiménez-Ambriz, Georgina. "Hétérogénéité environnementale et polymorphisme chez Thlaspi caerulescens (Brassicaceae) : étude conjointe de la diversité génétique neutre et sélectionnée chez une espèce tolérante aux métaux lourds." Montpellier 2, 2006. http://www.theses.fr/2006MON20089.
Amezian, Dries. "Utilisation du modèle cellulaire de la légionnaire d'automne, Spodoptera frugiperda, les cellules Sf9 pour étudier le rôle de facteurs de transcription sur l'expression des gènes de détoxification en réponse aux xénobiotiques." Thesis, Université Côte d'Azur, 2022. http://theses.univ-cotedazur.fr/2022COAZ6000.
The fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) is a polyphagous pest feeding on numerous host-plants including important crops such as maize, rice and sorghum. It is one of the world’s most destructive pests which only recently invaded the eastern hemisphere incl. Asia. It provides exceptional economic damage in many crops across continents each year. Controlling this insect pest largely relies on the application of insecticides resulting in the development of resistance to many classes of synthetic insecticides. FAW has developed sophisticated adaptive mechanisms to eliminate xenobiotics (plant secondary metabolites and insecticides), among them, upregulation and duplication of genes expressing detoxification enzymes. They are often expressed at low basal level and induced when the insect is exposed to xenobiotics. While the role of these enzymes is well characterized in several pest insects, the transcription factors controlling their expression remain largely unexplored. The aim of my thesis was to determine the role of Cap'n'collar isoform C (CncC) and musculoaponeurotic fibrosarcoma (Maf) in S. frugiperda adaptation to xenobiotics employing an Sf9 cell model.I used the cell model of S. frugiperda, the Sf9 cells and showed that CncC, Maf and several detoxification enzymes are induced after exposure to indole 3-carbinol (I3C), a glucosinolate found in Brassicaceae such as cabbage and broccoli, and methoprene (Mtp), a juvenile hormone (JH) mimic insecticide. I showed that transient overexpression of CncC and Maf in Sf9 cells was followed by overexpression of several detoxification genes. In order to characterize the role of these transcription factors in response to xenobiotics two types of stably transformed cell lines were established. The first cell lines overexpress CncC, Maf or both genes while the second were mutated for CncC (Knock-Out, KO) using the CRISPR/Cas9 technique. I performed cell viability assays (MTT) and used molecular probes in High Content Screening (HCS) to test whether the modification of the CncC:Maf pathway affected the ability of Sf9 cells to cope with toxic stress. The OE cell lines were more tolerant to I3C and Mtp than the control (wildtype Sf9 cell line), whereas the KO cell lines were more sensitive to these xenobiotics. The activities of some detoxification enzymes, carboxylesterases (CEs) and glutathione S-transferases (GSTs) toward model substrates were also increased in OE cell lines, whereas they were decreased in KO cell lines. Recent studies have suggested that activation of the CncC:Maf pathway is mediated by the production of reactive oxygen species (ROS) upon toxic stress. I therefore measured ROS production in Sf9 cells treated with I3C and Mtp. Both xenobiotics triggered in-cell ROS pulses although at limited levels in OE lines, unlike to KO lines for which ROS levels were more prominent. The use of an antioxidant suppressed the ROS pulses and restored tolerance of KO cells to I3C and Mtp. Finally, I compared the differentially expressed genes in the OE and KO cell lines in a transcriptomic analysis using RNA-seq. This allowed me to identify genes potentially controlled by CncC and Maf, most of them being detoxification genes with a role in insecticide resistance and metabolism of plant compounds as demonstrated in several studies. In conclusion, I present here new data in designed model Sf9 cell lines suggesting that the CncC:Maf signaling pathway plays a central role in FAW adaptation to toxic environmental compounds and insecticides. This knowledge helps to better understand pathways in detoxification gene expression and can be helpful to design next- generation insect control measures by interfering with these pathways and detoxification gene expression
Bavay, Cécile. "Adaptation des méthodologies d’évaluation sensorielle aux produits agroalimentaires à forte variabilité." Angers, 2013. https://tel.archives-ouvertes.fr/tel-00846841.
The sensory characteristics are evaluated by descriptive methods of sensory evaluation, such as the conventional profile. The sensory results from profiling present a large variability, due to differences between assessors on the one hand, and within-batch variability, that is differences between units of a sample, on the other hand. To date, differences between assessors are taken into account and sensory methodologies have been adapted for that. Nevertheless, within-batch variability has not been tackled, despite the challenge it represents. With the apple as a model, this PhD work addresses the issue of within-batch variability from two points of view: the measuring of variability and the reduction of variability, with the aim of improving the reliability of the sensory measure. First, the capacity of the panel to discriminate between apples from different cultivars and between apples, identified as different by an instrumental measure, within each cultivar has been observed. Second, in order to take within-batch variability into account, the standard models for analysis of variance used in sensory evaluation has been adapted by adding a fruit factor nested within the cultivar factor. This adaptation requires the sharing of each piece of fruit by several assessors. The application of this model has demonstrated the importance of within-batch variability and the consequence of model choice to obtain more relevant results. In addition, the determined model for analysis of variance has been adapted to distinguish between assessors' disagreement and scaling differences. Finally, a reduction of variability has been obtained through the sharing of fruits and after the homogenization by instrumental measurement, the latter depending on the cultivar and on the chosen measure. The results of the present work provide methodological keys to obtain reliable sensory results in the frame of the evaluation of products subject to biological variation
Thomann, Michel. "Evolution des stratégies de reproduction des plantes à fleurs face aux changements globaux et au déclin des pollinisateurs." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20230.
Global change alters life conditions of numerous populations. Beyond ecological consequences, global change can also modify selection regimes in populations. While the recent pollinator decline may specifically affect the reproductive success of flowering plants, its evolutionary consequences have not been studied yet. This thesis deals with the possibility of adaptation of plant reproductive strategies under global change and more specifically under pollinator decline. This question was addressed in two steps. First, the analysis of the extensive literature on plant mating systems, and, to a lesser extent, the construction of a model for the evolution of attractive floral traits, allowed us to clarify evolutionary scenarios at short-time scales. Second, we conducted an original empirical approach, consisting in the direct comparison of ancestral and descendant populations by re-growing old and recent seeds under identical conditions. This approach allowed us to test whether genetic evolution of reproductive traits occurred in the context of pollinator decline for three annual plant species. Data from the literature indicates that pollinator decline likely increases pollen limitation and thus selection on floral traits. Moreover, the substantial genetic variation within populations suggests that rapid evolution is possible. Increased autonomous selfing or increased pollinator attraction are two possible routes of plant adaptation to pollinator decline emerging from the analysis of the literature and from our theoretical study. Our empirical work brings out two types of evolutionary trends. Firstly, earlier flowering phenology was found in all three studied species. This result shows that genetic evolution, not only phenotypic plasticity; certainly contribute to the spring phenological advancements reported for numerous species. Secondly, unlike phenological traits, floral traits evolved in opposite directions depending on the species. Showy floral traits evolved in a species while joint evolution of autonomous selfing with a reduction of floral attractiveness seemed to evolve in another species. This study shows that plant reproductive traits can evolve in a few decades. Whether or not rapid evolution of plant reproductive traits can act as an evolutionary rescue for threatened populations is a research question that arises from these results
Labarrere, Bastien. "Comment les plantes répondent et s'adaptent aux changements climatiques : étude aux marges froides (subantarctique)." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B002/document.
The adaptive potential of a species can be defined as its capacity to cope with environmental change. Adaptive potential increases with phenotypic variation, from the intra-individual to the inter-population level, but factors controlling and explaining this variation still remain poorly understood.We studied four plant species from Iles Kerguelen in the sub-Antarctic region which is currently facing one of the strongest climate changes worldwide. Plant species from Iles Kerguelen are known to show high phenotypic integration (i.e. strong correlation among traits), a phenomenon that has been suggested to constrain trait variation. For these species we studied what constrains phenotypic variation, considering the external environment, the internal phenotypic integration and the associated performance costs. We found that intra-individual variation, i.e. plasticity, may be constrained by complex environmental change and the performance costs it triggers. In contrast, plasticity may be favored by high degree of phenotypic integration (Chapter 3). We found that inter-individual variation within populations may not be constrained by environmental factors, but may be favored by high phenotypic integration (Chapter 1). We found inter-population variation within regions may be constrained by restricted environmental variation (Chapter 1). Finally, we studied secondary metabolites (amines and flavonols) that connect environmental variation to phenotypic variation. We found that compositions and functions of these metabolites vary among regions, probably reflecting evolutionary differentiation among regions (Chapter 2). Patterns of variation betweenregions suggest that within species metabolites may be functionally redundant or versatile, for which to our knowledge our results are the first hint. Overall, we suggest that climate change in Kerguelen will impact plant species performance, and that the persistence of suitable wet habitats will be determinant in species capacities to cope with such changes. Furthermore, this project identified so far underestimated factors which may favor the adaptive potential of species. Particularly, we emphasize that the adaptive potential of species may increase due to (i) phenotypic integration, (contrary to common suggestion) and (ii) metabolite redundancy or versatility (only poorly studied so far). Moreover, we evidenced, partly for the first time, multiple costs and limits of plasticity and suggest that plasticity does not guarantee plant success in the new environment
Letort, Veronique. "Adaptation du modèle de croissance GreenLab aux plantes à architecture complexe et analyse multi-échelle des relations source-puits pour l'identification paramétrique." Phd thesis, Ecole Centrale Paris, 2008. http://tel.archives-ouvertes.fr/tel-00365172.
Nous avons tout d'abord identifié les conditions sous lesquelles, dans la formulation actuelle du modèle, la production photosynthétique et l'allocation de biomasse dans la plante sont indépendantes de son architecture. Nous avons établi qu'en revanche cette interaction est forte pour certains processus comme la croissance radiale. Deux types de démarches ont été abordées pour répondre au problème soulevé: (1) le développement de modèles simplifiés, avec différents niveaux d'agrégation des variables et (2) l'ajustement du modèle complet sur des cibles simplifiées. Nous avons envisagé trois niveaux de simplification du modèle selon des critères basés sur les applications visées, la faisabilité du protocole expérimental associé et le type de données classiquement collectées pour les modèles forestiers. Pour chacun de ces trois niveaux, nous avons mené une étude théorique pour relier les paramètres du modèle complet à ceux des différents modèles simplifiés de manière à avoir conservation de certaines variables-clés du modèle (notamment le rapport de la production de biomasse sur la demande de la plante). Sur cette base, nous proposons des équations simplifiées régissant le comportement de la plante à l'aide de variables agrégées.
En pratique, nous avons cependant souvent accès à certaines informations sur l'architecture de la plante, même si elles ne sont pas du niveau de détail des données issues de la simulation : ces informations peuvent provenir d'échantillonnages ou bien d'analyses botaniques préliminaires. En conséquence, nous avons étudié les méthodes permettant l'ajustement non seulement des paramètres fonctionnels de la plante mais également des paramètres contrôlant son développement topologique. Différentes méthodes sont proposées selon la version du modèle (déterministe, stochastique ou déterministe avec rétro-action de l'état trophique de la plante sur son développement) et selon la nature des données disponibles. Les applications de la thèse concernent principalement les arbres mais se sont également diversifiées à plusieurs types de plantes branchées.
Brunet, Philippe. "Etude physiologique comparée de l'adaptation au froid chez de jeunes plants de Lycopersicon esculentum Mill. Et Lycopersicon hirsutum Humb. & Bonpl." Montpellier 2, 1990. http://www.theses.fr/1990MON20257.
Tournier, Pierre-Henri. "Absorption de l'eau et des nutriments par les racines des plantes : modélisation, analyse et simulation." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066030/document.
In the context of the development of sustainable agriculture aiming at preserving natural resources and ecosystems, it is necessary to improve our understanding of underground processes and interactions between soil and plant roots.In this thesis, we use mathematical and numerical tools to develop explicit mechanistic models of soil water and solute movement accounting for root water and nutrient uptake and governed by nonlinear partial differential equations. An emphasis is put on resolving the geometry of the root system as well as small scale processes occurring in the rhizosphere, which play a major role in plant root uptake.The first study is dedicated to the mathematical analysis of a model of phosphorus (P) uptake by plant roots. The evolution of the concentration of P in the soil solution is governed by a convection-diffusion equation with a nonlinear boundary condition at the root surface, which is included as a boundary of the soil domain. A shape optimization problem is formulated that aims at finding root shapes maximizing P uptake.The second part of this thesis shows how we can take advantage of the recent advances of scientific computing in the field of unstructured mesh adaptation and parallel computing to develop numerical models of soil water and solute movement with root water and nutrient uptake at the plant scale while taking into account local processes at the single root scale
Walker, Anne-sophie. "Diversité et adaptation aux fongicides des populations de Botrytis cinerea, agent de la pourriture grise." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112067/document.
Natural selection is the most powerful force driving population adaptation to their environment, favoring the variants with the best fitness. Fungi generally exhibit biological traits (diversity of reproduction modes, large population sizes, and intense dispersion) that favor their adaptation to changing environments. Therefore, disentangling the mechanisms that explain their evolution under natural and anthropic constraints constitute a major challenge for plant protection, especially in the actual context of agriculture sustainability. In this thesis, we described Botrytis cinerea population structure and diversity, using neutral and selected markers and a hierarchical sampling, and proposed mechanisms that may explain these observations. We then analyzed the adaptive answer of this species towards fungicide applications. First, we showed that grey mold populations were caused by a complex of two cryptic species, living sympatrically on the same hosts. Second, B. cinerea populations are divided into five demes, according to the cropping system (directional selection), the host-plant (ecological adaptation), and to a lesser extent, by geography. On grapevine, we identified a specific populations exhibiting temporal isolation, as an evidence of extreme exploration of the viticultural conditions. Moreover, fungicide applications select resistance towards all unisite modes of action, with few exceptions, but at varying proportions according to vineyards and fungicide use. More specifically, resistance to succinate dehydrogenase inhibitors (SDHIs) is caused by at least seven mutations altering the target genes of these fungicides, and determines a large variety of phenotypes in the field. At last, we showed that fungicides did not shape population structure but that they could decrease allele richness in treated areas and lead to migration-selection equilibrium, detectable in some situation and for loci under contemporary selective pressures as clines. Modeling the evolution of resistance during winter allowed estimating fitness cost of four loci involved in contemporary fungicide resistance, such as multidrug resistance. As a conclusion, this thesis helped to understand how B. cinerea populations evolve and to detect and quantify selective mechanisms at work in natura. This information will be useful to deign sustainable and locally-adapted anti-resistance strategies
Vidal, Céline. "Etude taxonomique, phylogénétique et génétique des bactéries symbiotes des légumineuses métallicoles adaptées aux sites contaminés par le zinc et le cadmium." Montpellier 2, 2008. http://www.theses.fr/2008MON20232.
Anthyllis vulneraria is a legume present on heavy-metal-enriched spoil heaps of zinc and able to fix nitrogen. It facilitates installation of other vegetal species, allowing fast and lasting post-mining restoration of these sites. Nitrogen-fixing bacteria able to associate with a metallicolous A. Vulneraria ecotype belong to a new species, Mesorhizobium metallidurans. This bacterium is systematically found in all mining samples where metallicolous Anthyllis ecotype is present. To investigate on the origin of this bacterium, a comparative analysis (genetic and phenotypic) of Mesorhizobium associated with metallicolous Anthyllis was performed on contaminated and non contaminated soils. Metallicolous bacteria differ of non metallicolous genetically, taxonomically and in their capacities to tolerate metals. So, M. Metallidurans seems particularly adapted to high level of Zn and Cd. Study of rhizobia associated with several other metallicolous legumes revealed high genetic diversity. It seems that symbiotic bacteria associated with different metallicolous legumes are the result of local adaptations linked to horizontal transfers. Thus, a soil saprophytic bacterium highly adapted to contaminated and able to acquire nodulation genes under selection pressure of plant host would be at the origin of M. Metallidurans
Lalaouna, David. "Role d' ARN non codants régulateurs dans l' adaptation de Pseudomonas brassicacearum à la rhizosphère et aux fluctuations de l' environnement." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4006.
The plant-beneficial bacterium Pseudomonas brassicacearum forms phenotypic variants in vitro as well as in planta during root colonisation under natural conditions. Transcriptome analysis of typical phenotypic variants using microarrays containing coding as well as non-coding DNA fragments showed differential expression of several genes relevant to secondary metabolism and of the small non-coding RNA (ncRNA) genes rsmX, rsmY and rsmZ, which was characterized by down-regulation. Naturally occurring mutations in the GacS/GacA two-component system accounted for phenotypic switching. The importance of these ncRNAs in the survival of the bacteria to changing environments is denoted by the duplication of rsmX gene, which we called rsmX-2 and whose function has been validated. Our data suggest an exclusive activation of rsmX-1 and rsmX-2 genes by GacA and the involvement of additional regulators in the case of rsmY and rsmZ. Given the functional redundancy of these ncRNAs, we investigated their expression level and stability in different culture conditions and showed differences for the four ncRNAs. In response to nutrient depletion, the four ncRNAs expression is strongly activated and reaches its maximum when the ppGpp is detected in bacterial cells, suggesting a link between the Gac/Rsm system and the "stringent" response. Determining the level of each Rsm ncRNA, which is defined by a balance between synthesis and degradation of each transcript, shows the maintenance of a very important pool of RsmZ compared to other ncRNAs
Pham, Hoang-Nam. "Impact des métabolites secondaires de plantes sur des bactéries pathogènes de la rhizosphère : existe-t-il un lien entre la résistance sur métaux et la modulation de résistance aux antibiotiques ?" Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30153/document.
The objective of this thesis is to evaluate the modification of plant secondary metabolism production contaminated with metallic trace elements (MTE) and its consequences on the associated rhizospheric bacterial communities including bacteria presenting MultiDrug Resistant (MDR) phenotypes. We have focused on two contexts of metals exposure: the phytoremediation of mining sites in Vietnam and the reconversion of agricultural soils contaminated by the atmospheric re-deposition of metallurgical activities in France. Our results highlighted that contamination by different types of metals (mainly Cu and Pb) has led to an alteration in the production of secondary metabolites in the roots, stems and leaves of the hyper-accumulating Pteris vittata and for roots, a similar trend in the metabolic changes could be observed in another type of pollution context (Zn and Pb more particularly). Similarly, the metabolic profiles of the underground parts (roots and rhizomes) of Miscanthus x giganteus were modified by the concentrations of Pb, Cd and Zn in agricultural soils. For the two plants examined chlorogenic acid derivatives have been found in increased proportions in the roots despite soil type and pollution context were highly contrasted. However, catechic tannin derivatives are specifically found in higher proportions in the roots of P. vittata under metal pressure. These polyphenols are known for their ability to scavenge free radicals and their antioxidant properties and thus could be involved in the adaptation of these plants to metallic stress by helping to limit the oxidative stress generated by MTE. At the level of the aerial parts, we studied only the change for P. vittata and evidenced higher proportions of flavonoid derivatives for contaminated plants. Our metagenomic results allow us to conclude also on the effect of MTE on the diversity and the specific richness of the bacterial communities of the studied soils: a high contamination of Cu (10 times the allowed limit) decreased dramatically bacterial richness and diversity, while for more moderate MTE levels including Cu Pb and Zn, the diversity of rhizosphere bacterial communities was more explained by plant or season effect rather than an effect of MTE. This effect on P.vittata rhizosphere bacterial composition is reflected by an enrichment in genera known as opportunistic human pathogens, including Ralstonia, Acinetobacter, Burkholderia and Mycobacterium. In addition, Cupriavidus, known as a highly resistant genus, is the only P. vittata specifically associated genus found in increased proportions at both mining sites compared to non-contaminated rhizosphere soils. This genus could then be involved in the adaptation process of this plant with metal stress. As for the rhizospheric communities of Miscanthus x giganteus, the selection of Stenotrophomonas and Pseudomonas in agricultural soils contaminated with MTE was observed. As a part of this thesis, we have also developed a rapid method for testing the impact of plant metabolites on pathogenic strains of clinical and environmental origin and their efflux pump inhibition (EPI) activity of RND family. Our data thus showed interesting and notable EPI activities comparable to that of the efflux pump inhibitor PAßN for tested compounds issued from Fallopia x bohemica roots or for their derivatives
Mohamad, Roba. "Adaptation des bactéries symbiotiques de légumineuses métallicoles : effets des métaux lourds et de la plante hôte sur la composition des populations de rhizobia symbiotiques d’Anthyllis vulneraria et de Lotus corniculatus." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT153/document.
Two legumes (Anthyllis vulneraria and Lotus corniculatus) adapted to heavy metals form an interesting material for phytostabilisation strategy in mining sites. As biological nitrogen fixators, these legumes associated with compatible symbiotic bacteria provide an efficient establishment of a sustainable cover vegetation limiting metal dispersion in the environment. Our objectives were to study the effects of heavy metals and the host plant on symbiotic populations naturally associated with these legumes by analyzing (i) symbiotic populations associated with A. vulneraria on 8 contaminated and uncontaminated sites (ii) rhizobial populations associated with L. corniculatus that were compared with those of Anthyllis. The distribution of mesorhizobial strains isolated from A. vulneraria root-nodules from several contaminated and uncontaminated sites depends on high levels of heavy metals in soils by selecting highly resistant strains and impacting the taxonomic composition. Strains belonging to M. metallidurans were only found in highly contaminated sites. Two new potential metal-tolerant species were detected in two distinct mines. One of them was closely related to M. ciceri and M. loti and its members had the feature of not -possessing the cadA gene, a gene involved in metal-tolerance among M. metallidurans strains. By contrast, uncontaminated sites revealed a different taxonomic diversity with new species sensitive to heavy metals. Four of these new species were defined. A. vulneraria and L. corniculatus share the same taxonomic diversity in the contaminated sites tested. By contrast, symbiotic properties of the strains vary depending on the host plant used for trapping. Strains belong either to symbiovar (sv.) anthyllidis or to sv. loti according to geographic origins and independently of heavy metal levels in soils. A. vulneraria associated with strains of sv. anthyllidis or sv. loti. In contrast, L. corniculatus only associated with strains of sv. loti. In contaminated or uncontaminated soils, A. vulneraria was preferentially nodulated by sv. anthyllidis. In conclusion, A. vulneraria and L. corniculatus established symbiotic relationships with the same taxonomic groups of Mesorhizobium but associated with different symbiovars. The finding of taxonomic groups strongly depends on geographical sites, suggesting special adaptations to environmental conditions. Use of local biological resources is the strategy we recommend for revegetation of old mines
Nardin, Maxime. "Ajustement biologique du mélèze aux variations environnementales le long d’un gradient altitudinal : approche microdensitométrique de la réponse au climat." Thesis, Orléans, 2013. http://www.theses.fr/2013ORLE2071/document.
The strong climatic variation, in particular the temperature variation, which is associated with the altitudinal distribution of certain stands of forest trees, can induce different divergent selection pressure favoring altitude-dependent phenotype expression. The aim of the present thesis is to determine if local adaptation exists and can be identified in an European larch stand (Larix decidua Mill.) distributed along an altitudinal gradient located in the French Alps near Briançon. four plots of about 200 larches were delimited at 2300 m, 2000 m, 1700 m and 1350 m along this altitudinal gradient. A significant phenotypic variability was observed between these altitudinal levels for most characters studied: circumference, tree height, percentage of sapwood and for all the annual-ring microdensity variables except one (ring width). A population genetics analysis using microsatellite markers showed a small effect of genetic drift on the genetic diversity but an intensive gene flow between the altitudinal levels studied. The inter-altitudinal genetic differentiation was estimated using an in-situ approach based on phenotypic data only (PST) and compared with the differentiation observed by means of microsatellite markers (FST). This analysis indicates that the assumption of local adaptation with altitude can be reasonably proposed for the characters of height, circumference, percentage of sapwood and earlywood density. On the contrary, the local adaptation does not appear to be an acceptable assumption concerning characters such as ring width, ring surface area, latewood width and latewood density
Caiserman, Arnaud. "Adapter les stratégies agricoles aux évolutions socio-économiques et climatiques en milieu méditerranéen : comparaison de l'usage de l'eau et des choix de plantes des agriculteurs dans la plaine de la Békaa (Liban) et de Marvdasht (Iran)." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSE3009.
According to Köppen’s climate map, the semi-arid Mediterranean climate covers several countries in this region, including Lebanon and Iran. In order to regionalize the understanding of the water challenge of this region, two agricultural plains with similar characteristics were selected as study areas: the Bekaa plain in Lebanon and the Marvdahst plain in Iran. The Marvdasht plain is slightly drier and through climate change, the Bekaa plain will look like the present climate conditions of Marvdasht before 2100. It is therefore necessary to grasp the agricultural practices in the Marvdasht plain in order to imagine how Bekaa agriculture will look like in the future. Farmers must adapt their strategies to the local climate that is characterized by strong uncertainties (interannual variability of rainfall or frequent droughts) but also to economic uncertainties (prices’ variability). Despite (geo)political differences, some farmers in the Bekaa and Marvdasht have chosen strong water demanding crops, compared to the local renewable water resources. However, these crops are profitable on the market. In total, the water balances for the years under consideration are negative: in Marvdasht, farmers pumped 0,25 km3 of groundwater to meet the total irrigation needs, but the groundwater recharge was only 0,09 km3 in that year. In the Bekaa, this balance is also negative, but to a lesser extent: 0,15 km3 were pumped for a recharge of 0,1 km3. In both cases, irrigation needs are therefore higher than renewable water. They have therefore promoted market adaptation rather than sustainable resource management. Thus, the reasons for crop choices were closely analysed through field surveys and certain remote sensing methods to generate crop maps. The net irrigation requirements of crops are also estimated through remote sensing. Indeed, water needs determine whether or not farmers promote climate change adaptation strategies with relevant crop choices. This regional imbalance at the expense of resources stems from the productivism in the early 1950s. This paradigm is rooted on farm’s profitability and a more ambitious political objective, food self-sufficiency, especially in Iran. This causes an overexploitation of groundwater for irrigation and thus a lowering of groundwater by several tens of meters since the 1980s. Some alternatives consist of growing plants with high added value and modest water requirements: saffron, canola, quinoa and cannabis (in Lebanon). We have highlighted these alternative crops since their cultivation on large areas could save millions of water cubic meters each year. Still not widely cultivated, these plants need incentive markets to attract the interest of agricultural stakeholders. This operational part thus analyses the reasons for this lukewarm success in order to find incentive markets. Such local markets would strengthen a more sustainable agricultural policy than restrictive measures on water management that farmers always manage to circumvent
Hadjou, Belaid Asma. "Démographie et réponses adaptatives des populations végétales aux changements environnementaux." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTG034/document.
Mediterranean region is a biodiversity hot-spot with a high endemism rate and is classified among the areas most sensitive to climate change. Deep understanding of demography and evolution following these changes is a necessity for species conservation. During this thesis, two rare Mediterranean plant species have been studied, Centaurea corymbosa and Brassica insularis, using recent mathematical models to analyse long term demographic datasets (22 and 18 years). In the first part of this thesis, matrix projection models have been used to analyse spatio-temporal variation in population growth rate in C. corymbosa. Major climatic parameters that impact population growth rate and survival, flowering and fecundity have been identified. A population viability analysis has been performed under various climatic scenarios. In a second part, an analysis of the population ability of C. corymbosa to response to these climatic changes has been performed using integral projection models. Temporal variation of life-history traits showed that the realized flowering strategy varied with climatic conditions following the same direction than the optimal flowering strategy. It can thus be concluded that the studied populations can adapt to climatic changes. Finally, capture-recapture models have been applied on the Brassica insularis dataset to analyse the effect of plant detectability on demographic parameter estimations. Survival probabilities obtained with the classical approach are lower than the ones estimated using the CR models. However, the parameters estimated using both methods are highly correlated, except for one population where individual identification is problematic. Results of this thesis are linked to some considerations in conservation biology of plants, particularly in link to their ability to respond to climatic changes
Kassout, Jalal. "Réponse de traits fonctionnels foliaires et anatomiques chez l'olivier sauvage (Olea europaea L.) dans un environnement hétérogène et changeant : le modèle du Maroc soumis aux changements globaux." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTG061.
In the current context of global changes, is mainly important to study adaptive plant strategies in response to environmental changes. Olive (Olea europaea L.), emblematic Mediterranean species, seems vulnerable to the effect of anthropogenic and climatic changes under its distribution area. The Moroccan range of wild (spontaneous) populations of this species extends along a latitudinal gradient integrated into an aridity gradient. Sampling along this gradient made it possible to study 27 populations (19 populations of sylvestris variety of the europaea subspecies, and 8 population of the endemic subspecies Olea maroccana). This thesis explores, (i) Intraspecific variability of leaf and wood anatomical traits along aridity gradient at different organization levels (interpopulation, intrapopulation and intraindividual level) (ii) the functional strategies deployed by the two wild olive subspecies interpreted as adaptive responses (iii) the relationship of these strategies with the plant communities differentiation and ecology where the studied populations were sampled. The obtained results confirm the climatic aspect of the gradient underlying this work, because they show that the main ecological factors explaining the diversity of wild olive plant communities are of climatic nature. Our results show that functional leaf traits variation of oleaster (O. e. subsp. e. var sylvestris) expresses the ability of the species to use available resources to respond to changing climatic conditions, particularly aridity. Moreover, analysis of the leaf traits intraspecific variability of the two wild olive subspecies highlights the existence of a trade-off between resources acquisition and conservation according to climate and plant community type. For wood anatomical traits, our results show a pattern of variations in response to biogeographic, climatic and vegetation gradients allowing the wild olive to maintain its sap conduction performance and consequently adapt to changes in ecological stressful conditions, in particular to aridity and aridification. The differentiation of wild olive populations along the latitudinal gradient by functional leaf and wood traits corresponds also to a differentiation of plant communities, which these populations are part of. Finally, this study has greatly expands our understanding of adaptive strategies of olive tree (Olea europaea L.) in Morocco in response to a latitudinal gradient of aridity
Saltre, Frédérik. "Modélisation de la dispersion à grande échelle : évolution de laire de répartition passée et future du hêtre commun (Fagus sylvatica) en réponse aux changements climatiques." Thesis, Montpellier 2, 2010. http://www.theses.fr/2011MON20106/document.
Current climate change is so fast that some temperate tree species, like Fagus sylvatica, could not adapt nor migrate fast enough to tract their climatic niche. Most models simulating the potential distribution of vegetation as a function of climate consider unlimited or "null" dispersal, which doesn't allow assessing the importance of dispersal compared to climate in the dynamics of the vegetation. In this thesis, we integrate into a process-based species distribution model (Phenofit), a phenomenological model of dispersal (Gibbs-based model) in order to disentangle the effects of climate and dispersal in the response of Fagus sylvatica to climate change in Europe, (i) during the postglacial recolonization from 12000 years BP to present, (ii) during the 21st century. Our results show strong impact of dispersal associated with a strong effect of glacial refugees location on the beech postglacial recolonization, compared to the effect of climat e since 12000 years. Nevertheless, beech dispersal abilities are not sufficient to allow the colonization of newly suitable areas in northern Europe by 2100. This low colonization rate in Northern Europe in addition to a high extinction rate in Southern Europe due to increasing drought lead to a drastic reduction of beech distribution by the end of the 21st century
Flores-Mejia, Sandra. "Les effets de la température et des changements climatiques sur la performance relative d'un réseau trophique : plante-herbivore-parasitoïde." Doctoral thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27306.
Each trophic level of a food-web reacts differently to changes in temperature, because some species are more sensitive than others. Because of the interdependence between the different trophic levels, even the smallest change in temperature could trigger cascading effects throughout the food-web. This may cause a partial or total collapse of the system. As part of my project, I was interested in the effects of temperature and climate change over the relative performance of a tri-trophic food web system (plant-herbivore-parasitoid). The general objectives were to determine: a) which trophic level is more sensitive to an increase in temperature? and b) What are the effects of climate change on a food-web as a whole? In order to determine the effects of temperature on the whole food-web, I developed three parameters to measure the relative performance, by using biomass as common currency between the three trophic levels. The developed parameters are: net generational productivity (NGP), the bi-trophic food-web ratio (φh/p), and the tri-trophic food web ratio (φ3t). In general, my results suggest that the thermal window of the relative performance of each trophic level has a wider span at the base of the food-web (e.g. the plant) and it is reduced by about 4 °C for each subsequent trophic level. Also, the (φh/p) values obtained, suggest that the aphids have the highest performance at low temperatures, but they are incapable of reproducing beyond 28°C, which gives the plant a competitive advantage. Nonetheless, this advantage cannot be maintained for long, due to the negative effects of temperature on the biology of the plant. The φ3t values suggest that the performance of the food-web is influenced by trophic cascades in a « top-down » fashion; but both the inter- and intra-specific variation of the host plant plays a major role in the productivity of the system. The results of the experiments about climate change suggest that: in all three tested climate change scenarios, the parasitoid has the largest relative performance of the system in spite of having the smallest thermal window. This suggests a greater thermal plasticity than previously thought. Nonetheless, in the absence of parasitoids, the herbivore dominates the system. Although there was a 4 °C difference between the three climate change scenarios that were tested, the the performance of the tri-trophic food-web was not significantly affected. In comparison, under two 2050 climate change scenarios, the long-term exposure to high temperatures has a negative effect on the accumulation of biomass for the three components of the food web, both individually and collectively. This is the first study to evaluate empirically and exhaustively the effects of temperature over a great range of plant-herbivore-parasitoid interactions, in order to determine the relative performance of the system in a holistic way.
Castede, Sophie. "Génétique moléculaire de la floraison chez le cerisier doux : étude et compréhension du déterminisme génétique et moléculaire de la floraison chez le cerisier (Prunus avium) en vue de son adaptation aux futures conditions climatiques." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0312/document.
In fruit species, the flowering is a major event which strongly influences fructification. This process tiny controlled by many genetic and environmental factors is still little known. In sweet cherry (Prunus avium), flowers open out only after having satisfied chill and heat requirements. The effects of climate change on the flowering are already notable and could induce important economic losses. Identification of genetic and molecular determinants involved in the flowering will allow the improvement of varietal selection programs to obtain trees adapted to future climate conditions. Objective of this thesis is to increase the knowledge of these determinants and identify genes involved in flowering in sweet cherry. By studying two intraspecific progenies ‘Regina’ × ‘Lapins’ and ‘Regina’ × ‘Garnet’, detection of many quantitative trait loci (QTL) on all linkage groups (LG) has enabled us to confirm the strong involvement of chill requirements in the flowering as well as the complexity of these traits. QTL with major effect was localized on the LG4. In regions covered by all the QTLs controlling flowering date, a hundred candidate genes (CG) for this trait was identified. A subset of these GC was then studied for their expression during development of buds by quantitative PCR (qPCR). In the long term, this work will serve as a basis for the identification and selection of genes that allow obtaining genotypes adapted to future climate conditions
Villemereuil, Pierre de. "Méthodes pour l’étude de l’adaptation locale et application au contexte de l’adaptation aux conditions d’altitude chez la plante alpine Arabis alpina." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAS003/document.
Local adaptation is a micro-evolutionary phenomenon, which arises when populations of the same species are exposed to contrasted environmental conditions.If this environment exert some natural selection pressure, if an adaptive potential exists among the populations and if the gene flow is sufficiently mild, populations are expected to tend toward a local adaptive optimum.In this thesis, I study the methodological means of the study of local adaptation on the one hand, and I investigate this phenomenon along an elevation gradient in the alpine plant Arabis alpina on the other hand.In the first, methodological part, I show that the genome scan methods to detect selection using genetic markers might suffer strong false positive rates when confronted to complex but realistic datasets.I then introduce a statistical method to detect markers under selection, which, contrary to existing methods, make use of both the concept of genetic differentiation (or Fst) and environmental information.This method has been developed in order to reduce its global false positive rate.Finally, I present some perspectives regarding the relationships between the relatively old ``common garden'' experiment and the new developments in molecular biology and statistics.In the second, empirical part, I introduce an analysis of the demographic characteristics of A. alpina in six natural populations. Besides providing interesting biological information on this species (low life expectancy, strongly contrasted reproduction and survival...), these analyses show that growth increase and survival decrease with the decrease of average temperature (hence with altitude).Since these analyses do not allow us to rule out hypotheses such as drift and phenotypic plasticity, I show the results of a common garden experiment which enable us to smooth phenotypic plasticity and, when combined with molecular data, enable us to rule out the hypothesis of drift.The results show the existence of an adaptive phenotypic syndrome, in which plants are smaller, are more compact, grow slower and reproduce less in cold temperature environments.Using the molecular data, I draw a list of 40 locus which might be involved in this adaptive process.In the end, I discuss these empirical findings as a whole to place them in a more general context of alpine ecology. I sum up the main methodological challenges when studying local adaptation and offer some methodological perspectives
Valade, Romain. "Potentiel évolutif et adaptation des populations de l'agent du mildiou de la laitue, Bremia lactucae, face aux pressions de sélection de la plante hôte, Lactuca sativa." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00769939.
Poulicard, Nils. "Emergence et adaptation du Rice yellow mottle virus : relations entre histoire évolutive, contournement de résistance et interactions hôte/pathogène." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20121.
The Rice yellow mottle virus (RYMV) is an emerging virus currently considered as the major constraint to rice production in Africa. Some varieties of African and Asian cultivated rice (Oryza glaberrima and O. sativa, respectively), have recently been identified as highly resistant to RYMV. This resistance phenotype is caused by a recessive gene RYMV1 encoding the translation initiation factor eIF(iso)4G1 of rice.The objectives of this thesis are (i) to investigate the durability of the high resistance of rice against RYMV before broadly deployment in fields, (ii) to characterize the mechanisms of emergence of resistance-breaking (RB) genotypes and (iii) to identify molecular signatures that influence these processes of adaptation. The resistance-breaking of two resistance alleles, identified in both cultivated rice species, is mainly associated with the emergence of mutations in the viral protein VPg that restore in resistant hosts the interaction with the factor eIF(iso)4G1. A site of VPg under diversifying selection directly affects the ability to overcome the high resistance depending on the host species. This site, near the RB mutations, is involved in the adaptation of the RYMV to O. glaberrima species during its evolutionary history. The approach used during this work combines experimental evolution and functional analyses. The results of this integrative study will participate in the development of effective and sustainable control strategies toward the Rice yellow mottle virus in Africa
Pozzi, Adrien C. "Rôles adaptatifs et contraintes de la sporulation chez les microorganismes associés aux plantes : cas de la sporulation in planta dans la symbiose actinorhizienne Frankia (Frankiaceae)–Alnus (Betulaceae)." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10359/document.
Frankia sp. is a telluric actinobacteria able to establish a root symbiosis with actinorhizal plant such as Alnus sp. Only some Frankia strains are able to sporulate in-planta, as spores can be present in (Sp+) or absent from (Sp–) the vegetal cells of the root nodule. It is to our knowledge a unique case of endophytic sporulation. However, the description and the ecological interpretation of this original life-history trait (LHT) were scarce. Our contribution to the study of the in-planta sporulation of Alnus-infective Frankia sp. combines theoretical, descriptive and experimental approaches to precise (i) the relative effect of the bacterial strain, the host-plant species and the pedoclimatic conditions on this LHT, (ii) the effect of the of the environmental variability on the distribution, diversity and selection of the trait, and (iii) the associated costs and benefits for the two symbiotic partners. We demonstrated for the first time that the in-planta sporulation is a LHT (i) specific to some Frankia lineages, (ii) major to understand their evolutionary history and (iii) significantly correlated to particular genetic features. We also shown that the occurrence of the trait varies according to the environment We also proposed a model of the evolution of the trait taking its fitness into account. We bring all the previous considerations and results to discuss the inplanta sporulation trait within a continuum of symbiotic strategies and more generally to discuss the evolutionary ecology of plant-microbe symbioses
Dubois, Catherine. "Comment la végétation des milieux humides du lac Saint-Pierre a-t-elle changé au cours des 15 dernières années?" Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/34428.
Rocle, Nicolas. "L’adaptation des littoraux au changement climatique : une gouvernance performative par expérimentations et stratégies d’action publique." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0896/document.
Sea level rise accelerated by climate change is of major concern at international scale since the 1990’s. From now on, climate change adaptation is institutionalized from global to local scales. I analyze policy making processes related to climate change adaptation in French coastal areas. Two qualitative case studies are at the heart of the thesis: Aquitaine coastline and Martinique Island (French West Indies). They are contrasted in their history, their coastal planning policy and their social dynamics, though they share common processes of attractiveness and vulnerability to submersion and coastal erosion. I analyze discourses, actors and policy instruments in the legitimization of anticipation and preparation as guiding principles to cope with coastal risks and threats. The theoretical framework builds on political sociology of science and policy, as well as insights from pragmatic sociology. Direct observation of local, regional and national consultation and steering committees, semi-structured interviews and documentation analysis are the key methodological approaches. A questionnaire survey has been conducted in the coastal town of Lacanau, on Aquitaine coastline, in order to analyze the way in which residents and users experiment coastal retreat. The main line of argumentation advanced in this thesis is that coastal adaptation to climate change proceeds with performative governance, by which policy devices and narratives are geared towards building adaptation policies upon their interpretive effects. I demonstrate how climate adaptation mainstreaming and planning (adaptation and coastal risks prevention plans…) is combined with experimentalist forms to govern new adaptation options (like planned retreat) and with a new public risk management in which political and institutional risks are as important to prevent as socio-ecological vulnerabilities. The concept of “public action strategy” is built to better capture these forms of managerial policy instruments used for framing, rationalizing and performing a governance of preparedness and adaptation, by means of expert knowledge, collaborative procedures and concertation to render local actors accountable for their own security. State steering practices and decentralization policies are key processes shaping coastal adaptation and risk regulation. This new public risk management strengthens expert configurations for defining and operationalizing coastal risks policy strategies