Adhesion between the plasma membrane and the cell wall and the existence of the continuum of these two compartments is needed for signal transmission, e.g. under pathogen attack, during cell expansion and cell wall growth, or in response to environmental conditions. This adhesion is, in addition to the turgor, provided by physical connection of both compartments. One of the best-known examples of physical connection is found in the root system, in the Caspary strip region, where it is required to maintain apoplastic barriers of the root system, even under adverse conditions and consequent plasmolysis. There is little information about the physical interconnection and the participating macromolecules but there are candidates, which could participate in this interaction. The diploma thesis deals with arabinogalactan (AGP) proteins with fasciclin-like domain (namely FLA9 and FLA2). These proteins may play a role in the adhesion of plasma membrane and cell wall and may be involved in the growth regulation and development of the root system. Both genes are are relatively strongly expressed in the roots, especially in the elongation zone and in the cortex, including the endodermis (according to chip data). Also, to a smaller extent, the thesis deals with integrin-like At14A protein. The most interesting...

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A adubação equilibrada com nitrogênio, potássio e boro pode alterar a nutrição, produção e valor nutritivo das gramíneas forrageiras. Mediante as aplicações de combinações de doses de nitrogênio, potássio e boro objetivou-se avaliar os efeitos: a) nos aspectos morfológicos, na produção de massa seca e no estado nutricional da parte aérea; b) nas características morfológicas, produtivas e nutricionais das raízes e, c) nos componentes de parede celular e fracionamento de proteínas do capim-tanzânia. O experimento foi conduzido em casa de vegetação no período de janeiro a maio de 2010, utilizando quartzo moído como substrato. Cinco doses de nitrogênio (2, 10, 18, 26 e 34 mmol L-1) foram combinadas com cinco doses de potássio (0,2; 3,1; 6,0; 8,9 e 11,8 mmol L-1), que foram combinadas com cinco doses de boro (0; 45,45; 90,90; 136,35 e 181,80 mol L-1) em fatorial 53 fracionado, perfazendo 23 combinações de nitrogênio, potássio e boro, com quatro repetições. Realizaram-se três cortes das plantas de capim-tanzânia, nos seguintes períodos: 32 dias após o transplantio, 39 dias após o primeiro corte e 45 dias após o segundo corte. As doses de boro não interferiram nos aspectos produtivos e morfológicos da parte aérea e das raízes nem na composição de parede celular e frações proteicas. O boro somente influenciou a concentração de nitrogênio, potássio e boro da parte aérea. A interação doses de nitrogênio x doses de potássio foi significativa para as variáveis número de perfilhos, número de folhas, área foliar, valor SPAD e produção de massa seca da parte aérea. Com o pouco crescimento da planta ocorreu acumulação de nitrogênio, potássio e boro e diluição desses nutrientes nas folhas diagnósticas com a maior produção das plantas. A produção de massa seca das raízes, comprimento total e superfície total aumentaram com as combinações de doses de nitrogênio e potássio. As concentrações de nitrogênio, potássio e boro nas raízes foram influenciadas pela combinação das doses de nitrogênio com potássio. As concentrações de nitrato e amônio foram influenciadas positivamente pela combinação das doses de nitrogênio e potássio, tendo ocorrido maior concentração de amônio do que nitrato nas raízes. Com o aumento das doses de nitrogênio e potássio o comprimento específico e a superfície específica das raízes diminuíram. Os teores de FDN, FDA aumentaram e a relação FE+LM/CB diminuiu com as doses de potássio no segundo e terceiro cortes. O teor de PB no segundo corte aumentou com as doses de nitrogênio e diminuiu com as doses de potássio. As frações proteicas B1+B2 aumentaram e a fração B3 diminuiu no segundo e terceiro cortes com o aumento das doses de nitrogênio. A fração C para o terceiro corte diminuiu com as doses de nitrogênio. A combinação das doses de nitrogênio e potássio aumentou os teores da fração A para o terceiro corte. O suprimento de nitrogênio e potássio proporcionou aumento nos aspectos produtivos, morfológicos e nutricionais da parte aérea e das raízes, além de ter melhorado o valor nutritivo do capim-tanzânia. / The balanced fertilization with nitrogen, potassium and boron may change plant nutrition, yield and nutritive value of forage grass. Through the supply of combinations of nitrogen, potassium and boron it was aimed to evaluate the following effects on Tanzania guineagrass: a) plant morphology, dry matter production and nutritional status in the shoots; b) morphological, productive and nutritional aspects in the roots and c) cell wall components and protein fractions in the shoots. The experiment was conducted in a greenhouse from January to May 2010, using ground quartz as substrate. Five rates of nitrogen (2, 10, 18, 26 and 34 mmol L-1) were combined with five rates of potassium (0.2, 3.1, 6.0, 8.9 and 11.8 mmol L-1) and five rates of boron (0, 45.45, 90.90, 136.35 and 181.8 mol L-1) in 53 fractionated factorial design, which had 23 combinations of nitrogen, potassium and boron, with four replications. Three harvests of Tanzania guineagrass were made: 32 days after transplanting, 39 days after the first harvest and 45 days after the second harvest. Boron rates did not interfere with production and morphological aspects of shoots and roots and in cell wall composition and protein fractions. Boron only influenced the concentration of nitrogen, potassium and boron in the shoots. The interaction nitrogen rates x potassium rates was significant for the number of tillers, number of leaves, leaf area, SPAD value and shoots dry matter production. When plants had short growth, nitrogen, potassium and boron accumulated in plant tissues and those nutrients were diluted in plants with great growth. The dry mass of roots, total root length, total root area increased with the combination of nitrogen and potassium rates. The concentration of nitrogen, potassium and boron were influenced by the combinations of nitrogen and potassium rates. The concentrations of nitrate and ammonium were positively influenced by the combinations of nitrogen and potassium rates, and higher concentrations of ammonium than nitrate were found in root tissues. Root specific length and specific surface area decreased as rates of nitrogen and potassium increased. The NDF and ADF increased and EF+MB/SS ratio decreased with the potassium rates in the second and third harvests. The CP content of the second harvest increased with the nitrogen and decreased with potassium rates. Fractions B1+B2 increased and fraction B3 decreased for the second and third harvests with increasing nitrogen rates. The fraction C for the third harvest decreased with nitrogen rates. The combination of nitrogen and potassium increased the content of fraction A in the third harvest. Nitrogen and potassium supply provided to increase the productive changes, morphological and nutritional aspects in shoots and roots well as it improved the nutritive value of Tanzania guineagrass.

Made available in DSpace on 2017-07-25T19:29:44Z (GMT). No. of bitstreams: 1 Itacir Feldhaus.pdf: 550488 bytes, checksum: 13f0af90b9e23ee384c7dd7fe7d06acb (MD5) Previous issue date: 2006-03-17 / The effects of surface liming and nitrogen application on soil chemical attributes, on the dry matter production of black oats and on the root growth, mineral nutrition and grain yield of corn, under a no-till system, were evaluated in a field trial carried out on a loamy Typic Hapludox, in Ponta Grossa, State of Paraná, Brazil. A randomized complete block, split-plot design was employed, with three replications. The plots received four treatments of lime: no lime, 4, 8 and 12 t ha-1 of dolomitic lime applied on the surface before the sowing of the oats. In the subplots were employed four treatments of nitrogen: without nitrogen, 60, 120 and 180 kg ha-1 of nitrogen spread out manually at tillering of oat plants. After 110 days of the application, liming provided soil acidity correction to a depth of 20 cm, with effects of larger magnitude in the uppermost soil layer (0-5 cm). After 330 days of the application, liming raised pH and reduced the potential acidity (H+Al) to a depth of 20 cm, reduced Al3+ to a depth of 40 cm and raised bases saturation to a depth of 60 cm. The treatments of N promoted acidification of the uppermost soil layers and raised the levels of N-Mineral in the uppermost soil layers 60 days after the application, and in the subsoil 280 after the application. The levels of Ca2+ in the uppermost layers were reduced with N application, but there was no correlation between NO3 - leaching and the amelioration in the subsoil chemical attributes with liming. The dry matter production of oats was not affected by the treatments of liming and N. The root growth of the corn cultivated in succession was also not affected by the treatments. Liming increased the Ca and S levels in the leaves and in the grains of corn, respectively, and reduced the leaf Mn content. The treatments of N fertilization increased the content of N in the grains and of Mn in the leaves and in the grains of corn. Liming had no effect in the dry matter production, grain yield and content of oil and protein of corn. The N treatments had no effect in the dry matter production, but raised the grain yield and the content of oil and protein of corn. / Os efeitos da calagem superficial e da adubação nitrogenada nas alterações químicas do solo, na produção de massa seca de aveia preta e no crescimento radicular, nutrição mineral e rendimento de grãos da cultura do milho, em sistema plantio direto, foram avaliados em um experimento realizado em Latossolo Vermelho Distrófico textura média, em Ponta Grossa (PR). O delineamento experimental empregado foi o de blocos ao acaso em parcelas subdivididas, com três repetições. As parcelas receberam quatro tratamentos de calagem: sem calcário, 4, 8 e 12 t ha-1 de calcário dolomítico na superfície antes da semeadura da aveia. Nas subparcelas foram empregados quatro tratamentos de adubação nitrogenada: sem N, 60, 120 e 180 kg ha-1 de N aplicados a lanço no perfilhamento da aveia. Aos 110 dias após a aplicação, a calagem proporcionou correção da acidez do solo até a profundidade de 20 cm, apresentando efeito de maior magnitude na camada superficial do solo (0-5 cm). Aos 330 dias após a aplicação, a calagem elevou o pH e reduziu a acidez potencial até a profundidade de 20 cm, reduziu o Al3+ até a profundidade de 40 cm e elevou a saturação por bases até a profundidade de 60 cm. As doses de N promoveram acidificação das camadas superficiais do solo e elevaram os teores de N-Mineral nas camadas superficiais aos 60 dias após a aplicação, e nas do subsolo, aos 280 dias após a aplicação. Houve redução dos teores de Ca2+ nas camadas superficiais com a adubação nitrogenada, mas não houve correlação entre a lixiviação de NO3 - e as melhorias nos atributos químicos do subsolo pela calagem. A produção de massa seca de aveia não foi influenciada pelos tratamentos de calagem e de N. Também não houve efeito dos tratamentos sobre o crescimento radicular do milho cultivado em sucessão à aveia. A calagem aumentou a concentração de Mg e de S nas folhas e nos grãos de milho, respectivamente, e reduziu a concentração foliar de Mn. Os tratamentos de adubação nitrogenada aumentaram a concentração de N nos grãos e de Mn nas folhas e nos grãos de milho. A calagem não influenciou a produção de massa seca, o rendimento de grãos e a concentração de óleo e de proteína de milho. Os tratamentos de N não afetaram a produção de massa seca, mas aumentaram o rendimento de grãos e o teor de óleo e de proteína de milho

A adubação equilibrada com nitrogênio, potássio e boro pode alterar a nutrição, produção e valor nutritivo das gramíneas forrageiras. Mediante as aplicações de combinações de doses de nitrogênio, potássio e boro objetivou-se avaliar os efeitos: a) nos aspectos morfológicos, na produção de massa seca e no estado nutricional da parte aérea; b) nas características morfológicas, produtivas e nutricionais das raízes e, c) nos componentes de parede celular e fracionamento de proteínas do capim-tanzânia. O experimento foi conduzido em casa de vegetação no período de janeiro a maio de 2010, utilizando quartzo moído como substrato. Cinco doses de nitrogênio (2, 10, 18, 26 e 34 mmol L-1) foram combinadas com cinco doses de potássio (0,2; 3,1; 6,0; 8,9 e 11,8 mmol L-1), que foram combinadas com cinco doses de boro (0; 45,45; 90,90; 136,35 e 181,80 mol L-1) em fatorial 53 fracionado, perfazendo 23 combinações de nitrogênio, potássio e boro, com quatro repetições. Realizaram-se três cortes das plantas de capim-tanzânia, nos seguintes períodos: 32 dias após o transplantio, 39 dias após o primeiro corte e 45 dias após o segundo corte. As doses de boro não interferiram nos aspectos produtivos e morfológicos da parte aérea e das raízes nem na composição de parede celular e frações proteicas. O boro somente influenciou a concentração de nitrogênio, potássio e boro da parte aérea. A interação doses de nitrogênio x doses de potássio foi significativa para as variáveis número de perfilhos, número de folhas, área foliar, valor SPAD e produção de massa seca da parte aérea. Com o pouco crescimento da planta ocorreu acumulação de nitrogênio, potássio e boro e diluição desses nutrientes nas folhas diagnósticas com a maior produção das plantas. A produção de massa seca das raízes, comprimento total e superfície total aumentaram com as combinações de doses de nitrogênio e potássio. As concentrações de nitrogênio, potássio e boro nas raízes foram influenciadas pela combinação das doses de nitrogênio com potássio. As concentrações de nitrato e amônio foram influenciadas positivamente pela combinação das doses de nitrogênio e potássio, tendo ocorrido maior concentração de amônio do que nitrato nas raízes. Com o aumento das doses de nitrogênio e potássio o comprimento específico e a superfície específica das raízes diminuíram. Os teores de FDN, FDA aumentaram e a relação FE+LM/CB diminuiu com as doses de potássio no segundo e terceiro cortes. O teor de PB no segundo corte aumentou com as doses de nitrogênio e diminuiu com as doses de potássio. As frações proteicas B1+B2 aumentaram e a fração B3 diminuiu no segundo e terceiro cortes com o aumento das doses de nitrogênio. A fração C para o terceiro corte diminuiu com as doses de nitrogênio. A combinação das doses de nitrogênio e potássio aumentou os teores da fração A para o terceiro corte. O suprimento de nitrogênio e potássio proporcionou aumento nos aspectos produtivos, morfológicos e nutricionais da parte aérea e das raízes, além de ter melhorado o valor nutritivo do capim-tanzânia. / The balanced fertilization with nitrogen, potassium and boron may change plant nutrition, yield and nutritive value of forage grass. Through the supply of combinations of nitrogen, potassium and boron it was aimed to evaluate the following effects on Tanzania guineagrass: a) plant morphology, dry matter production and nutritional status in the shoots; b) morphological, productive and nutritional aspects in the roots and c) cell wall components and protein fractions in the shoots. The experiment was conducted in a greenhouse from January to May 2010, using ground quartz as substrate. Five rates of nitrogen (2, 10, 18, 26 and 34 mmol L-1) were combined with five rates of potassium (0.2, 3.1, 6.0, 8.9 and 11.8 mmol L-1) and five rates of boron (0, 45.45, 90.90, 136.35 and 181.8 mol L-1) in 53 fractionated factorial design, which had 23 combinations of nitrogen, potassium and boron, with four replications. Three harvests of Tanzania guineagrass were made: 32 days after transplanting, 39 days after the first harvest and 45 days after the second harvest. Boron rates did not interfere with production and morphological aspects of shoots and roots and in cell wall composition and protein fractions. Boron only influenced the concentration of nitrogen, potassium and boron in the shoots. The interaction nitrogen rates x potassium rates was significant for the number of tillers, number of leaves, leaf area, SPAD value and shoots dry matter production. When plants had short growth, nitrogen, potassium and boron accumulated in plant tissues and those nutrients were diluted in plants with great growth. The dry mass of roots, total root length, total root area increased with the combination of nitrogen and potassium rates. The concentration of nitrogen, potassium and boron were influenced by the combinations of nitrogen and potassium rates. The concentrations of nitrate and ammonium were positively influenced by the combinations of nitrogen and potassium rates, and higher concentrations of ammonium than nitrate were found in root tissues. Root specific length and specific surface area decreased as rates of nitrogen and potassium increased. The NDF and ADF increased and EF+MB/SS ratio decreased with the potassium rates in the second and third harvests. The CP content of the second harvest increased with the nitrogen and decreased with potassium rates. Fractions B1+B2 increased and fraction B3 decreased for the second and third harvests with increasing nitrogen rates. The fraction C for the third harvest decreased with nitrogen rates. The combination of nitrogen and potassium increased the content of fraction A in the third harvest. Nitrogen and potassium supply provided to increase the productive changes, morphological and nutritional aspects in shoots and roots well as it improved the nutritive value of Tanzania guineagrass.

Les tempêtes hivernales causent des pertes en bois qui s’élèvent à 50% du volume des dégâts dans les forêts européennes. Les phénomènes de déracinement des arbres (chablis) sont les plus fréquents or ils sont encore mal compris. Cette thèse vise à mieux comprendre le processus de déracinement de l’arbre et à identifier les traits structuraux et matériels (racines, sol) ayant un effet du premier ordre sur l’ancrage racinaire dans le cas du Pinus pinaster. Un modèle d’éléments finis a été développé et permis de simuler et suivre la chronologie des ruptures successives au cours du déracinement. Un seuil de rupture globale de l’ancrage est ainsi défini comme une résultante de l’architecture et de la résistance des matériaux en jeu (racines, sol). Cela devrait permettre à terme d’améliorer les modèles de risque au vent qui actuellement n’incluent pas de relation mécaniste pour le chablis. Dans la même logique, nous nous sommes appuyés sur les données expérimentales pour construire une architecture simplifiée du système racinaire du P. pinaster. L’importance des différentes composantes sur le mécanisme d’ancrage a été étudiée et le rôle essentiel joué par le pivot et les racines traçantes montré. Ce résultat confirme de nombreuses études expérimentales et théoriques et pour la première fois permet de quantifier ces effets. Le nombre de paramètres pertinents pourra ainsi être réduit pour exprimer l’ancrage. Cela ouvre des perspectives intéressantes pour simplifier l’utilisation du modèle pour l’appliquer à d’autres espèces, d’autres conditions de sol et différentes pratiques sylvicoles. / Winter storms cause 50% of wood damage by volume to European forests. Tree uprooting isthe most frequent phenomenon during storms ; however the mechanism is not well understood.This thesis aims to better understand the tree uprooting process and to identify both rootstructural features and material properties which have first-order effects on tree anchoragestrength for the case ofPinus pinaster. A Finite Element Model has been developed and allowedsimulating and tracking the sequential root breakage during the course of tree overturning. Anoverall tree anchorage strength is thus defined as the resultant of contribution of root systemarchitecture and material strength (roots, soil). This would allow improving the risk modelswhich currently don’t include any mechanistic relationships to describe tree uprooting. In thesame spirit, we have relied on root architectural data to build a simplified root system patternwith features ofP. pinaster. Importance of different root components has been studied andthe essential role of the taproot and shallow roots demonstrated. This result has confirmednumerous experimental and theoretical studies and for the first time quantified these impacts.Therefore the number of relevant parameters can be reduced to express overall root anchorage.This opens new prospects to simplify the model in order to apply to other species under othersoil conditions and considering different silvicultural practices

Pour d'évidentes raisons agronomiques et environnementales, être en mesure de concevoir et mettre en place des systèmes de culture dans lesquels les plantes accèdent aux ressources de manière optimale revêt une importance cruciale pour tous les intervenants impliqués dans la production agricole. Les techniques d'intensification telles que la mise en place de cultures d'inter-rang et l'agro-foresterie visent à accroître la productivité globale des terres tout en assurant la durabilité des agro-écosystèmes, via une optimisation de l'utilisation des ressources environnementales (lumière, eau et nutriments) par les plantes et une préservation des cycles géochimiques. En théorie, les moyens d'atteindre ces objectifs sont nombreux mais en pratique, les interactions souterraines sont complexes et difficiles à mesurer, de sorte que les progrès réalisés dans la conception d'agro-écosystèmes améliorés et durables demeurent modestes. Dans ce contexte, l'objectif de ce travail a été d'évaluer, au travers de mesures racinaires detaillées en rhizotron et au champ, les effets des cultures d'inter-rang sur la croissance des jeunes hévéas. La dynamique des interactions souterraines a été étudiée, tant au niveau de la racine individuelle qu'à celui du système racinaire entier, sur la base, notamment, de descriptions numériques détaillées. Une telle approche a permis de proposer, en outre, une voie novatrice pour l'analyse de la dynamique racinaire à l'echelle du systeme racinaire entier, à savoir l'analyse des trajectoires de croissance. Dans le cas de l'association maïs-hévéa, les expérimentations en rhizotron ont permis de mettre en evidence que les interactions souterraines entre ces deux plantes peuvent induire des modifications de la croissance de leurs racines, à la fois à l'échelle de la racine individuelle et à celle du système racinaire entier. Toutefois, une telle coordination des dynamiques racinaires des plantes associées n'a pas pu être confirmée dans le cas des traitements manioc-hévéa et arachide– hévéa. Les expérimentations au terrain ont fourni, de manière assez prévisible, une image complexe des interactions souterraines entre hévéa et cultures d’inter-rang. Toutefois, un premier résultat obtenu par le biais de la mise en place de 'pièges à racines' dans un traitement niébé-hévéa, a été de montrer que ces deux plantes n'avaient pas un comportement compétitif marqué l'une vis-à-vis de l'autre. Il est également apparu que les hévéas paraissent ‘investir’ dans des racines ‘coûteuses’, car de faible longueur spécifique, probablement pour assurer une certaine durabilité de ces organes, tandis que les cultures d’inter-rang favorisent l'allocation des assimilâts vers des racines de longueur spécifique élevée, de construction moins ‘coûteuses’, probablement en réponse a un impératif de croissance plus rapide (suggéré par les taux d’élongation racinaire mesurés au cours des expérimentations en rhizotron). Enfin, excepté le cas du manioc, l’introduction de cultures d’inter-rang telles que le maïs et l'arachide n'a pas eu d'impact significatif sur le développement des jeunes hévéas, comme en attestent l'évolution de leur circonférence, hauteur et développement foliaire. Ce résultat de terrain est compatible avec les résultats des expérimentations en rhizotron qui n'ont démontré aucun effet inhibiteur des cultures d’inter-rang sur le développement de la partie aérienne des hévéas. Bien que les travaux présentés dans ce rapport, ne permettent pas, à eux seuls de conclure de manière définitive sur la façon dont les espèces cultivées en association peuvent se compléter mutuellement sur le plan fonctionnel, ils apportent des éléments de réponse préliminaires à cette question complexe ainsi que des méthodes permettant de les obtenir. Au total, ce travail représente donc une contribution à la conception des agro-écosystèmes durables qui deviennent de plus en plus indispensables dans le contexte d'une demande mondiale croissante en produits alimentaires et matières premières. En outre, certains des résultats obtenus dans le cadre de cette thèse ouvrent des perspectives pour des recherches plus approfondies, avec une finalité agronomique appliquée / For obvious agronomic and environmental reasons, being able to design and implement agro-ecosystems in which crops have optimal access to resources is of pivotal importance to all stakeholders involved in agricultural production. Intensification techniques such as agro-forestry or the introduction of inter-crops aim to increase land productivity while conserving geochemical cycles, to ensure the sustainability of agro-ecosystems through an optimized use of environmental resources (light, water and nutrients). In theory, there are many ways of achieving such a goal, but in practice, below-ground interactions between plants are complex and difficult to measure, so that progress with the development of sustainable agro-ecosystems has been slow and remains modest. In this context, the objective of this work was to assess the effects of inter-crops on the growth of young rubber trees, based on a detailed analysis of below-ground interactions between the associated plants. The dynamics of below-ground interactions has been studied in rhizoboxes, at both the scale of individual roots and that of the whole root system, using detailed numerical descriptions of root architecture. Such an approach resulted in the design of an innovative method for the analysis of the entire root system dynamics, namely, the analysis of growth trajectories. In the case of the maize-rubber tree association, the experiments in rhizoboxes showed that the below-ground interactions between these two plants can induce changes in root growth, at both the individual root and the whole root system levels. However, such a coordination of rooting patterns could not be confirmed in the case of the cassava-rubber tree and groundnut-rubber tree associations. Not unexpectedly, field experiments provided a rather complex picture of the underground interactions between rubber trees and inter-crops. However, initial results obtained using 'root traps' in a cowpea-rubber tree treatment indicated that these two plants were unlikely to have a marked underground competitive behavior relative to each other. Results of field experiments also indicated that, in general, rubber trees seem to 'invest' in 'expensive roots' of low specific root length, presumably to confer some degree of durability to these organs, while inter-crops favoured the allocation of assimilates to 'cheaper' roots, i.e. roots of much higher specific length, probably in response to a 'fast growth imperative' (an hypothesis supported by the root elongation rate values measured during the rhizobox experiments). Finally, to the possible exception of cassava, inter-crops were found to have no significant impact on the development of young rubber trees, as evidenced by measured changes in tree circumference, height and leaf development. This result is consistent with results from the rhizobox experiments which also showed no inhibitory effect of inter-crops on the above-ground development of rubber trees. Although the work presented in this report does not allow, in itself, to conclude firmly on the issue of the functional complementarity between plants grown in association in inter-cropping systems, they provide preliminary answers to this complex issue together with methods to obtain such answers. Overall, this work therefore represents a contribution to the design of sustainable agro-ecosystems which are becoming increasingly needed in the context of a growing global demand for food and raw materials. In addition, some of the results generated by this work open up prospects for future research for the development of sustainable agro-ecosystems

Le but de cette thèse est d’étudier les structures obtenues à partir des groupes de réflexion finis. Ce travail consiste en quatre articles publiés, un article soumis et un article en préparation dont les résultats partiels constituent un chapitre de cette thèse. Dans le premier article, nous présentons une réduction des orbites des groupes de Coxeter finis vers leurs sous-groupes. Nous utilisons des matrices de projection, c’est-à-dire, des applications qui transforment les racines simples d’un groupe de réflexion en les racines simples du sous-groupe associé. Les résultats présentés dans ce papier se concentrent sur les groupes finis de réflexion non crystallographiques. De plus, nous utilisons les polytopes engendrés par le groupe non crystallographique H3 pour illustrer les lois de ramification (branching rules), c’est-à-dire une réduction des orbites des groupes finis de Coxeter. Dans le deuxième article, nous étudions les polytopes avec 60 sommets engendrés par le groupe non crystallographique H3. Nous utilisons la méthode de décoration des diagrammes de Coxeter–Dynkin pour décrire leurs structures en détails et décomposer les sommets en somme des orbits de symétries de dimension inférieure. Le troisième article compare deux notations utilisées pour décrire le polyèdre engendré par le groupe de réflexion. Il s’agit du symbole de Schläfli et de la notation des points dominants. Nous y présentons les avantages de chaque méthode, expliquons les deux approches et nous les illustrons par des exemples. Dans le quatrième article, nous nous concentrons sur le graphène, c’est-à-dire un pavement d’hexagones sur le plan, qui possède de remarquables propriétés quand les sommets sont modélisés par des atomes de carbone. Dans ce travail, nous présentons différentes méthodes pour obtenir du graphène à partir de réseaux (lattices) et des orbites de dimension 3 des groupes finis de réflexion. De plus, une technique de coloriage des hexagones au moyen d’un nombre fini de couleurs est donnée avec une méthode systématique pour raffiner le graphène. Dans le cinquième article, nous utilisons des v fonctions spéciales et les transformations de Fourier pour traiter les données échantillonnées sur un réseau de carrés du groupe de Lie SU(2)×SU(2), relié au groupe de symétrie A1×A1. / The goal of this thesis is to study structures obtained from finite reflection groups. The work is contained in four published papers, one submitted article and a research paper currently in preparation, with partial results presented as a chapter of this thesis. In the first article, we present a reduction of the orbits of finite Coxeter groups to their subgroups. We use projection matrices, that is, mappings that transform the simple roots of a reflection group to the simple roots of the appropriate subgroup. The results presented in this paper focus on non-crystallographic finite reflection groups. Moreover, we use polytopes generated by the non-crystallographic group H3 to illustrate the obtained branching rules, i.e., reductions of orbits of the finite Coxeter groups. In the second article, we study polytopes with 60 vertices, generated by the non-crystallographic group H3. We use a method of decoration of the Coxeter–Dynkin diagram to describe their structure in detail, and decompose their vertices into sums of orbits of lower-dimensional symmetries. The third article compares two notations used to describe polyhedra generated by reflection groups, namely the Schläfli symbol, and the dominant point notation. Here, we present the advantages of each method, we explain the two approaches, and we illustrate them through examples. In the fourth article, we focus on graphene, i.e., a hexagonal tiling of the plane that possesses remarkable properties when the vertices are modelled with carbon atoms. In this work, we present different methods to obtain graphene from lattices and three-dimensional orbits of finite reflection groups. Moreover, a technique to colour the hexagons by a finite number of colours is provided, along with a systematic method to refine the graphene. In the fifth article, we use special functions and Fourier transforms to process data sampled on a square lattice of the Lie group SU(2) × SU(2), related to the A1 × A1 symmetry group.

Die arbuskuläre Mykorrhiza (AM) ist eine mutualistische Symbiose, die die Phosphataufnahme und Pathogenresistenz von Pflanzen verbessern kann. In der vorliegenden Doktorarbeit wurde die Rolle der Protonen-pumpenden ATPase MtHA1 für die AM Symbiose in Medicago truncatula untersucht. In MtHA1 Mutanten konnten AM Pilze nur noch verkürzte Arbuskel ohne typische Verzweigungen ausbilden. Dies zeigte sich auch in Expressionsmustern von Genen, die für Proteine in verschiedenen Bereichen der periarbuskulären Membran kodieren. Außerdem waren AM Pilzbesiedelung, die verbesserte Nährstoffaufnahme und die Wachstumsförderung in MtHA1 mutierten Pflanzen reduziert. Die Mykorrhiza-induzierte Resistenz (MIR) wurde näher in M. truncatula Pflanzen untersucht, die von Aphanomyces euteiches infiziert waren, dem Erreger einer Wurzelfäule in Leguminosen. In einem geteilten Wurzelsystem, das eine hohe Expression von Verteidigungsgenen aufwies, unterdrückte ein AM Pilz diese Expression und erhöhte in Folge die Empfindlichkeit für das Pathogen. In Wurzeln von Topfkulturen dagegen konnte eine typische MIR beobachtet werden, die wahrscheinlich auf erhöhter Aktivität der Jasmonat/Ethylen-regulierten Verteidigungsantwort beruht, verursacht durch eine Unterdrückung der Salizylsäuresynthese. Im Ergebnis zeigt diese Arbeit die bedeutende Rolle des Gens MtHA1 für die Bildung und Funktion der arbuskelhaltigen Zellen. Die Mutation des Gens führt zur verminderten Arbuskelverzweigung, reduzierter Phosphataufnahme und Wachstumsförderung in der Mykorrhiza und schließlich zu einer geringeren Gesamtbesiedelung durch den AM Pilz. Genexpressionsanalysen weisen darauf hin, dass unterschiedliche Mechanismen den lokalen und systemischen Wechselwirkungen zwischen AM Pilzen und Pathogenen in der Wurzel zu Grunde liegen. Verschieden physiologische Zustände von geteilten Wurzelsystemen und Wurzeln in Topfkulturen erschweren allerdings einen direkten Vergleich der beiden experimentellen Ansätze. / Arbuscular mycorrhiza (AM) is a wide spread mutualistic symbiosis, which can improve phosphate acquisition and pathogen resistance of plants. In the current Ph.D. thesis the role of a proton pumping ATPase (MtHA1) for the AM symbiosis in Medicago truncatula was investigated. In MtHA1 mutant plants, different AM fungi only developed truncated arbuscules without forming typical hyphal branches, and this phenotype was mirrored by expression patterns of genes for proteins located in different areas of the periarbuscular membrane. AM fungal colonization, improved phosphate uptake and plant growth promotion were reduced in MtHA1 mutant plants. Mycorrhiza-induced resistance (MIR) and the nodule symbiosis were, however, not affected. MIR was further analyzed in the M. truncatula infected with Aphanomyces euteiches which causes a root-rot disease in legumes. In a split root system showing high levels of defense-gene expression, colonization of an AM fungus reduced this expression and in consequence increased susceptibility of the roots for the pathogen. In roots of pot cultures, however, a typical MIR was observed and could be based on the higher activity of jasmonate/ethylene-regulated defense responses due to suppression of salicylic acid biosynthesis. In conclusion, this work shows that the gene MtHA1 encoding a proton pumping-ATPase plays a critical role in the formation and function of arbuscule-containing cells. Expression of the mutated gene results in reduced formation of arbuscule branches. This in turn negatively influences mycorrhizal phosphate uptake, plant growth promotion and overall mycorrhizal colonization of the roots. Gene expression analyses indicate that different mechanisms underlay local and systemic interactions between the mycorrhizal fungus and the root pathogen. The different physiological stages of pot culture and split root system make a comparison of the two experimental approaches, however, difficult.

Analyse de la diversité inter et intra-spécifique des paramètres de l’architecture des systèmes racinaires chez les Solanacées. Les racines des plantes jouent un rôle important pour garantir productivité et résistance à de nombreux stress. Dans le nouveau contexte agricole, l’importance de ce système racinaire et de sonarchitecture sont remises au premier plan. Notre étude porte sur la dynamique de l’architecture racinaire des solanacées, qui contient un ensemble d’espèces horticoles importantes pour l’alimentation. Notre travail porte sur 32 génotypes, parmi 3 groupes d’espèces: aubergines, piments et tomates.Dans cette étude, nous proposons tout d’abord une analyse de la diversité inter et intraspécifique de l’architecture racinaire à travers l’évaluation d’un ensemble de traits qui sont aussi les paramètres d’un modèle dynamique de simulation (ArchiSimple : Pagès et al, 2012). Cette première évaluation a été faite en pots, en utilisant un milieu très favorable à la croissance des plantes et à l’enracinement. Nous montrons que les traits racinaires choisis présentent en effet des variations d’origine génétique, généralement plus fortes entre espèces qu’au sein des espèces. Nous avons également observé des corrélations entre certains traits qui révèlent des compromis ou des coordinations dans les processus de développement.Pour aller plus loin dans la signification des traits racinaires choisis et leur stabilité vis‐à‐vis des conditions environnementales, nous avons également évalué ces traits en conditions de culture hydroponique. C’est un milieu reconnu comme radicalement différent, intéressant pour les possibilités de visualisation des racines qu’il offre. Un dispositif avec des rhizotrons hydroponiques a été construit spécifiquement pour cette expérimentation. Nous avons confirmé, dans ces nouvelles conditions, les différences d’origine génétique entre les différents génotypes utilisés. De plus, nous avons comparé de manière systématique les valeurs de traits mesurés avec celles de la précédente expérimentation. Certains traits se révèlent stables ou très corrélés (e.g. diamètres, distances interramification)alors que d’autres présentent des différences beaucoup plus fortes (e.g. vitesses de croissance, vitesses d’émergence des racines adventives).Une troisième expérimentation, utilisant différentes combinaisons de greffage entre génotypes, nous a permis d’approfondir la question du contrôle des traits par des interactions au sein de la plante: soit à courte distance au sein du système racinaire, soit à plus longue distance parle système aérien. Deux traits importants ont été étudiés (le diamètre apical et la densité de ramification) en utilisant des combinaisons de génotypes ayant des valeurs contrastées par rapport à ces traits. Il en ressort des réponses très différentes, avec un effet marqué du greffon sur les111RésuméBui H.H. (2015), Diversité inter- et intra-spécifique des paramètres racinaires chez les Solanacées diamètres, révélant qu’une partie au moins du contrôle de ce trait est effectuée par le système aérien, et un effet faible ou inexistant du greffon sur la densité de ramification, révélant un contrôle local de ce trait, par des interactions à courte distance entre les racines. Cette expérimentation par greffage a montré un potentiel très intéressant pour mettre en lumière divers mécanismes de contrôle des traits au sein de la plante entière.Cette étude mérite d’être prolongée par des analyses plus systématiques des déterminismes de variation des traits de l’architecture racinaire, et par des simulations par modèle qui permettront de synthétiser les conséquences des variations de traits sur les performances globales des systèmes racinaires pour la prospection du sol. / Analysis of the inter and intra specific diversity of the parameters of the root system architecture in the Solanaceae.Plant roots play an important role to ensure the productivity and the resistance to manystresses. In new agricultural context, the importance of root system and its architecture are placed tothe forefront. Our study focuses on the root architecture dynamics of Solanaceae, which contains aseries of important horticultural species for the alimentation. Our work was based on 32 genotypesbelonging to three groups of species: aubergines, capsicums, and tomatoes.In this study, we propose firstly an analysis of inter‐ and intra ‐ specific diversity of rootarchitecture through evaluating a set of traits which are also the parameters of a dynamic simulationmodel (ArchiSimple: Pagès et al, 2012). The experiment in pots with a very favorable condition forplant growth and rooting was conducted for the first evaluation. It showed that the selected roottraits present an effect of genetic ‐ originated variations and this effect is usually stronger amongspecies than within species. We also found correlations between certain traits, which revealcompromises or coordinations in the developmental processes.In order to go deeper into the signification of selected root traits and their stability toenvironmental conditions, we also evaluated these traits in hydroponic culture. This environment isradically different, and interesting for its possibilities to visualize the roots. An experimental setupwith hydroponic rhizotrons was specially built for this experiment. In the new conditions, the genetic‐ originated differences between different genotypes used also were found. In addition, wecompared systematically the traits values with those of the previous experiment. Certain traits arestable or highly correlated (e.g., apical diameter, inter‐branch distance), while others are muchdifferent (e.g., root growth rate, emission rate of adventitious roots).In a third experiment, we used different grafting combinations between genotypes todeepen the question of the control of root traits by interactions within plant: either short distancecontrol within root system or long distance control by aerial system. Two important root traits (apicaldiameter and branching density) have been studied by grafting between genotypes which havecontrasting values on these traits. The different responses appear: a significant effect of scion ondiameters, which indicate that at least of this trait is controlled by shoot system, and a weak effect orno effect of scion on branching density, revealing the local control of this trait, by short distanceinteractions between the roots. This experiment showed a great potential of grafting to highlightvarious control mechanisms of root traits within whole plant.AbstractBui H.H. (2015), Diversité inter- et intra-spécifique des paramètres racinaires chez les Solanacées 113This study deserve to be extended by more systematic analysis of determinisms of variationsof root architecture traits, and by using simulation model which allow to integrate the consequencesof traits variations on global performances of root system for prospecting of soil.