A floricultura é uma atividade altamente rentável e exerce um papel importante no agronegócio brasileiro, se destacando cada vez mais em relação ao seu faturamento anual. Dentre as flores mais cultivadas e comercializadas, as gérberas (Gerbera jamesonii) são conhecidas pela grande quantidade de cores de suas inflorescências. O objetivo do presente trabalho foi avaliar o desenvolvimento e a produtividade da cultura da gérbera em ambiente protegido associado a malhas vermelha, azul e preta de sombreamentos e fertirrigadas com cinco soluções nutritivas de fertirrigação, elaboradas a partir da diluição (25%, 50%, 75%) e concentração (125%) da solução proposta por Hoagland e Arnon (1950) (solução padrão, 100%), sobre as características que conferem a qualidade da planta para comercialização em vasos. A malha azul associada à fertirrigação com concentração de 25% dos nutrientes da solução padrão proporcionaram maior massa fresca e seca de capítulos florais, hastes e total das gérberas e, ainda, maior massa seca das folhas. Os tratamentos aplicados não ifluenciaram o número de capítulos e de folhas e a classificação segundo os padrões qualidade. O diâmetro do capítulo floral não foi afetado pelos tratamentos de fertirrigação e sombreamento; entretanto, o diâmetro e a altura das hastes das gérberas foram reduzidos com a apliacação da solução mais concentrada (125%). Oíndice de estresse hídrico (CWSI) da cultura foi mais próximo de 1, nas três malhas coloridas, nos horários próximos ao meio do dia e aos 58 DAT foi verificado maior estresse das plantas sombreadas pelas malhas vermelhas. O índice de clorofila total (índice Falker) aos 59 e 99 DAT foi menor na malha vermelha, o que pode indicar maior eficiência das plantas sob esta malha, uma vez que não houve redução da produtividade das gérberas neste ambiente. Os teores de antocianina foram muito semelhantes nas folhas das gérberas cultivadas sob as malhas coloridas, sendo observada uma maior média do pigmento nas gérberas cultivadas sob a malha azul. / The flower culture is a highly profitable activity and plays a major role in agribusiness, increasingly standing out in terms of annual sales. One of the most cultivated and marketed flowers, gerbera (Gerbera jamesonii), is known for its abundance of colors of its inflorescences. This work aimed to evaluate development and productivity of gerbera culture in protected environment associated to shading meshes of red, blue and black under fertirrigation with five nutritional solutions elaborated from the dilution ( 25%, 50%, 75%) and concentration (125%) of the solution proposed by Hoagland and Arnon (1950) (standard solution, 100%) on the characteristics that confer quality to the plant for marketing in pots. The blue mesh associated with fertigation of 25% of nutrient concentration of the standard solution provided fresh and dry mass of inflorescence, stems and total of gerbera, as well as greater dry mass of leaves. The treatments applied did not influence the number of inflorescences and leaves, as well as the classification of quality standards. The diameter of inflorescences was not affected by fertigation and shading; however, stem diameter of gerbera was reduced with the application of concentrated solution (125%). The crop water stress index (CWSI) was closer to 1, in the three colored meshes, at times near the middle of the day, and at 58 DAT, greater stress was verified in plants shaded by red meshes. The index of total chlorophyll (Falker index) at 59 and 99 DAT was smaller in red fabric, which may indicate greater efficiency of plants under this mesh, since there was no reduction in the productivity of gerbera in this environment. The contents of anthocyanin were very similar in leaves of gerbera grown under colored meshes, being observed a grater average of the pigment in gerbera grown under the blue fabric.

A modulação da forma e tamanho em órgãos vegetais depende do controle temporal e espacial de divisão e expansão celular. Entretanto, pouco se sabe a respeito dos mecanismos moleculares que regulam este processo durante o desenvolvimento floral. O estudo da via de sinalização de SCI1 (Stigma/style Cell Cycle Inhibitor 1) pode contribuir para o entendimento do processo de crescimento das flores. Este gene produz uma proteína, localizada no nucléolo, que está relacionada à inibição da proliferação celular no estigma e no estilete de Nicotiana tabacum, modulando o tamanho destes órgãos florais. Experimentos feitos para a identificação de parceiros de interação de SCI1 identificaram as proteínas 14-3-3A e 14-3-3D de N. tabacum como candidatas à interação. A família 14-3-3 é composta de proteínas altamente conservadas, que formam dímeros em sua conformação nativa e são responsáveis pela modulação da atividade das mais variadas proteínas em resposta a sinais intracelulares. Por isso, estas proteínas estão associadas à regulação de uma série de processos, incluindo o metabolismo, transcrição, ciclo celular, entre outros. Neste contexto, o presente trabalho teve como objetivo estudar as proteínas 14-3-3A e 14-3-3D de N. tabacum e o seu papel durante o desenvolvimento floral. Os resultados aqui obtidos revelaram que a 14-3-3A possui localização citoplasmática e nuclear, enquanto a 14-3-3D se distribui apenas no citoplasma. Também foi evidenciado que estas proteínas são capazes de formar homodímeros e heterodímeros entre si. Os homodímeros de 14-3-3A estão distribuídos no citoplasma e no núcleo, enquanto os homodímeros de 14-3-3D e heterodímeros se encontram apenas no citoplasma. Adicionalmente, a interação in vivo entre a 14-3-3A e SCI1 foi confirmada por BiFC, apresentando localização nuclear, fora do nucléolo. Análises in silico da sequência de aminoácidos de SCI1 identificaram duas regiões putativas de reconhecimento por proteínas 14-3-3s. Estas regiões estão sendo analisadas funcionalmente por meio de ensaios de BiFC com sequências mutadas de SCI1. A análise deste conjunto de resultados, juntamente com outros resultados obtidos em nosso laboratório, sugere que apenas homodímeros de 14-3-3D e heterodímeros formados entre 14-3-3A e 14-3-3D sejam capazes de interagir com SCI1. Adicionalmente, a localização nuclear dessa interação difere daquelas observadas para SCI1 e para as 14-3-3s individualmente, sugerindo que as 14-3-3s migrem para o núcleo para interagir com SCI1. Nossa hipótese é de que as proteínas 14-3-3s possam modular a localização subnuclear de SCI1. Com o objetivo de levantar dados a respeito das possíveis funções desempenhadas pelas proteínas 14-3-3A e 14-3-3D de N. tabacum, foram identificados os grupos de possíveis ortólogos dessas proteínas em A. thaliana, O. sativa, S. lycopersicum, S. tuberosum e N. benthamiana. Esta análise mostrou que os ortólogos às 14-3-3A e D em Arabidopsis estão associados ao ciclo celular, o que sugere que as proteínas de tabaco possam ter conservado essa função. Além disso, também foram produzidas plantas transgênicas silenciadas para cada uma dessas 14-3-3s de maneira independente. A análise dos fenótipos das plantas transgênicas não levou à elaboração de uma hipótese definitiva sobre a função dessas 14-3-3s no desenvolvimento floral. No entanto, algumas plantas transgênicas apresentaram estruturas menores, especialmente as pétalas, sugerindo que estas proteínas podem estar envolvidas no controle do tamanho de órgãos vegetais. / The modulation of size and shape in plant organs depends on temporal and spatial control of cell division and expansion. However, the molecular mechanisms that regulate this process during floral development are poorly understood. The study of SCI1 (Stigma/style Cell Cycle Inhibitor 1) signaling pathway can contribute to the understanding of the flower growing process. This gene produces a protein which is located in the nucleolus and is related to the inhibition of cell proliferation in the Nicotiana tabacum stigma and style, modulating the size of these organs. Experiments performed to identify SCI1 interaction partners have identified the N. tabacum 14-3-3A and 14-3-3D proteins as interaction candidates. The 14-3-3 family is composed of highly conserved proteins, which form dimers in their native conformation and are responsible to modulate the activity of a large variety of proteins in response to intracellular signals. Therefore, these proteins are associated to the regulation of several processes, including metabolism, transcription, and cell cycle, among others. In this context, the present work aimed to study the N. tabacum 14-3-3A and 14-3-3D proteins and their role during flower development. The results here obtained revealed that 14-3-3A is located in the nucleus and the cytosol, while 14-3-3D protein is distributed only in the cytosol. It was also shown that these proteins can form homodimers and heterodimers with each other. Homodimers of 14-3-3A are distributed in nucleus and cytosol, while 14-3-3D homodimers and heterodimers are located only in the cytosol. Furthermore, the in vivo interaction between SCI1 and 14-3-3A was confirmed by BiFC, showing nuclear localization, outside the nucleolus. In silico analyzes of SCI1 amino acid sequence identified two putative regions of recognition by 14-3-3 proteins. These regions are being evaluated by BiFC assays with SCI1 mutated sequences. The analyses of this set of results, together with other results obtained in our laboratory, suggests that only 14-3-3D homodimers and heterodimers between 14-3-3A and 14-3-3D are capable to interact with SCI1. Moreover, the nuclear localization of this interaction differs from the ones observed for SCI1 and for the 14-3-3s individually, which suggests that the 14-3-3s migrate to the nucleus to interact with SCI1. Our hypothesis is that the 14-3-3 proteins can modulate the subnuclear localization of SCI1. To obtain data concerning the possible roles of the N. tabacum 14-3-3A and 14-3-3D proteins, groups of possible orthologous of these proteins in A. thaliana, O. sativa, S. lycopersicum, S. tuberosum and N. benthamiana were identified. This analysis has shown that the orthologs of 14-3-3A and D in Arabidopsis are associated to the cell cycle, suggesting that the tobacco proteins might have conserved this function. Furthermore, transgenic plants silenced for each of the 14-3-3s independently were also produced. Phenotype analyzes of transgenic plants did not lead to a definitive hypothesis about the function of these 14-3-3s during floral development. However, some transgenic plants exhibited smaller structures, specially petals, which suggests that these proteins may be involved in the size control of plant organs.

Orientador: Jorg Kobarg / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-21T03:42:39Z (GMT). No. of bitstreams: 1 Migueleti_DeividLucasdosSantos_M.pdf: 8057948 bytes, checksum: ef239a4533686a90e511e97afd0f97ba (MD5) Previous issue date: 2012 / Resumo: A proteína UNC-76 foi identificada como necessária para a fasciculação e elongação de axônios do verme Caenorhabditis elegans durante o desenvolvimento do sistema nervoso. A homóloga de mamíferos FEZ1 apresenta altos níveis de expressão em tecidos neuronais e camundongos knockout para o gene FEZ1 apresentam desvios de comportamento que remetem a desordens neurológicas. O papel de FEZ1 no desenvolvimento do sistema nervoso parece residir na sua associação com elementos do citoesqueleto e vias de sinalização (e.g., PKC?, E4B, DISC1) que conduzem o crescimento axonal e a polarização celular. Trabalhos do grupo mostram que FEZ1 é uma proteína multifuncional (hub), capaz de interagir com mais de 50 parceiros através de seus domínios coiled-coil. Além disso, a superexpressão de FEZ1 em células HEK293 provoca o aparecimento de núcleos multilobulados, um fenótipo comum em alguns tipos de leucemia. Nesse trabalho foi investigado o papel de FEZ1 nos mecanismos causadores dos núcleos multilobulados e as consequências funcionais de sua superexpressão na viabilidade celular, tentando extrapolar esse modelo para leucemias. Análises in silico de diversas leucemias mostraram que FEZ1 está superexpressa em LMAs e que isso pode se relacionar à ocorrência da fusão 11q23/MLL. A expressão de FEZ1 na linhagem leucêmica THP-1 foi detectada por Western blotting, mas, a expressão em PBMCs de pacientes ainda permanece sem provas empíricas. Para avaliar as consequências funcionais da superexpressão, uma linhagem com expressão estável e indutível foi obtida e utilizada em ensaios de proliferação e resistência a quimioterápicos. Porém, não foram observadas diferenças entre as linhagens expressando a fusão FLAG-FEZ1 e as que expressavam o FLAG tag apenas. Em um ensaio de IP-MS utilizando tais linhagens, foram identificadas proteínas cuja interação com FEZ1 pode ser modulada pela atividade de PKCs. Finalmente, a cotransfecção de FEZ1 inteira com coiled-coils C-terminais diminui a formação de núcleos multilobulados em quase 40%. A transfecção com o mutante FEZ1 nocys contendo 5 cisteínas mutadas não teve o mesmo efeito, mas, novos experimentos são necessários para determinar o potencial de sinergismo que esses dois componentes podem ter sobre a ocorrência desse fenômeno / Abstract: The protein UNC-76 was identified as necessary for fasciculation and elongation of axons of the worm Caenorhabditis elegans during development of the nervous system. The mammalian homologue FEZ1 is mostly expressed in neuronal tissues and FEZ1 knockout mice present behavior abnormalities that resemble neurological disorders. The role of FEZ1 in the development of the nervous system seems to lie in its association with cytoskeletal elements and signaling pathways (e.g., PKC?, E4B, DISC1) regulating axon outgrowth and cell polarization. The studies of our group have shown that FEZ1 is a hub, able to interact with more than 50 partners through its coiled-coil domains. Furthermore, overexpression of FEZ1 in HEK293 cells causes the appearance of flower-like nuclei, a common phenotype to certain types of leukemia. In this work the role of FEZ1 in the mechanisms of flower-like nuclei formation and functional consequences of its overexpression on cell viability were investigated, attempting to extrapolate this model for leukemias. In silico analysis of several leukemias showed that FEZ1 is overexpressed in AML patients and that this may relate to the occurrence of 11q23/MLL genetic fusion. FEZ1 expression in leukemic THP-1 cells was detected by Western blotting, but the expression in PBMCs of leukemic patients still lacks empirical evidence. To assess the functional consequences of overexpression, cell lineage with stable and inducible expression of FEZ1 was obtained and used in proliferative assays. However, it was not observed any differences between lineages expressing FLAG-FEZ1 fusion protein or FLAG tag alone. IP-MS assay using these lineages identified proteins whose interaction with FEZ1 could be modulated by the activity of PKCs. Finally, cotransfection of C-terminal coiled-coils and FEZ1 full-length decreases flower-like nuclei formation to nearly 40%. Transfection with FEZ1nocys mutant containing five substituted cysteines did not play the same, but further experiments are needed to determine the potential synergism these two components may have on this phenomenon / Mestrado / Genetica Animal e Evolução / Mestre em Genética e Biologia Molecular

En dépit de ses succès, le modèle agricole fondé sur un recours massif aux intrants est mis à mal du fait de ses externalités négatives. L’agroécologie propose de substituer aux intrants le pilotage des processus écologiques naturels. La production cidricole est engagée dans cette démarche. Nous avons cherché à évaluer l’apport de deux types d’aménagements agro-écologiques : les haies et les mélanges fleuris. Nous avons caractérisé la faune entomologique présente dans 14 vergers cidricoles du nord-ouest de la France (Bretagne, Normandie) et son évolution au cours de la saison. L’analyse des données collectées a confirmé que les aménagements étaient attractifs pour les ennemis naturels des ravageurs des pommiers.L’étude des dynamiques d’abondance du puceron cendré (Dysaphis plantaginea) au cours de la saison permet de hiérarchiser les contributions des différents ennemis naturels à la régulation de ses populations et de montrer leur complémentarité temporelle. Les syrphes et les coccinelles jouent le rôle principal avec une action plus précoce des premiers. Le rôle favorable au puceron de la présence des fourmis est confirmé. Les mélanges fleuris réduisent les abondances du puceron et accroissent celles de la plupart des groupes d’ennemis naturels. Au contraire, la présence des haies est favorable au ravageur. Un dispositif d’exclusion des fourmis réduit significativement leurs abondances et celles des pucerons et augmente les abondances des syrphes et des coccinelles, confirmant l’effet délétère des fourmis sur les ennemis naturels. Enfin, le prototype d’un indicateur du / In spite of their successes, agricultural systems based on the massive use of inputs are questioned for their negative externalities. Agroecology offers to substitute inputs with natural ecological processes. Apple-cider production is engaged in the development of agroecology. Here, we aimed at assessing the benefits provided by two types of agroecological infrastructures: hedgerows and flower strips. We characterised the entomological fauna encountered in 14 cider-apple orchards in northwestern France (Bretagne, Normandy) and its evolution along the season. Data analysis confirmed agroecological infrastructure attractiveness to apple pest natural enemies. The observation of rosy apple aphid (Dysaphis plantaginea) population dynamics allows hierarchizing the contributions of several natural enemies to pest control and demonstrates their temporal complementaritySyrphids and coccinellids are the most effective with the firsts being the most precocious. The beneficial role to aphids of ant presence is confirmed. Flower strips reduce aphid abundances and increase the abundances of most natural enemy groups. Conversely, hedgerows are favourable to the pest. An ant-excluding device reduces significantly ant and aphid abundances and increases syrphid and coccinellid abundances, confirming the deleterious effect of ants on natural enemies. Finally, a prototype of an indicator of biological control potential against D. plantaginea was designed.

No description available.

L’Idiot de la famille est complément de Questions de Méthode. Sartre demande dans Questions de Méthode un changement de langage. Il s’agira dans cette thèse de déchiffrer l’écriture sartrienne en ses nuances, détails et couleurs. En d’autres mots, il s’agira d’étudier les livres de Sartre pour trouver un sens qui nous parle, là où sa parole se contredit et s’affirme en même temps. Notre tâche de relecture dans L’Idiot de la famille est ainsi d’expliciter l’axe central de la psychanalyse existentielle et d’aller chercher le sens le plus caché de la philosophie de la vie. Dans la mesure où Sartre va montrer que nous devons décider du genre de vie que nous voulons avoir, cette étude vise à éclairer pourquoi Sartre est un penseur nécessaire pour l’homme d’aujourd’hui. Il s’agira ainsi de traiter L’Idiot de la famille comme une œuvre d’apprentissage. Dans ce sens, le sens et la signification de notre recherche ne sont pas fermés et continuent ouverts à des nouvelles relectures. Notre principal objectif est aussi bien d’expliciter quel a été le fil conducteur de Sartre pour écrire L’Idiot de la famille que de vérifier si l’essence de l’écrivain peut être définie par ses écritures. Autrement dit, est-ce que les écritures montrent qui est l’auteur en tant qu’homme, ou bien pouvons-nous plutôt voir son double, celui qui parle à sa place et qui devient parole écrite ? / The Fool of the family is complement to the book of philosophy Questions of Method. Sartre asks in Questions of Method a change of language. It will be in this thesis to decipher Sartre writing in its nuances, details and colors. In other words, it is designed to study books from Sartre in order to find a meaning that makes sense for us, where his words are full of statements and their contrary at the same time. Our task of re-reading in The Fool of the family is to clarify the central axis of the existential psychoanalysis and point the most hidden of the philosophy of life. Insofar as Sartre will show that we must decide on the kind of life we want to have, this study aims to illuminate why Sartre is an indispensable thinker for the man of today. Thus, it will be necessary to treatThe Fool of the family as a work for learning. In this sense, the meaning and significance of our research are not closed and still opened to new readings. Our main objective is to clarify what has been the main theme of Sartreto write The Fool of the family and to check if the essence of the writer can be defined by his writings. In other words, do the writings show us who is the author as a man, or else can we rather see his double, one who speaks at his place and then become written word?

Tshwane is a city that is expanding eastwards. In the process, valuable cultural and ecological landscapes are being neglected. These unique landscapes, which contain critical environmental assets, could be made attractive to the general public and thus should be protected wherever possible. The expansion of the city is inevitable. While cities need to accommodate more people, they should also provide socially and culturally enriching outdoor spaces. This study uses landscape architecture and regenerative theory to suggest ways of making post-industrial sites productive again. The Hazeldean dairy; a site of cultural significance, environmental assets and physical charm, is in danger of becoming a deteriorating and forgotten landscape. The hypothesis argues that that by adapting to current social, economic and sustainable requirements, a new and living landscape can be created. This would prevent Hazeldean from becoming a characterless buffer between surrounding property developments. The design interventions proposed for the Hazeldean farm should enhance its historical and ecological value and attract visitors to the property for many different reasons, throughout the year. Ultimately, Hazeldean should endure as a physical and socially valuable asset within the rapidly expanding city of Tshwane. / Dissertation ML(Prof)--University of Pretoria, 2014 / Architecture / ML(Prof) / Unrestricted

Dans le domaine des plantes, la formation de la fleur a été un pas crucial dans la capacité des végétaux à coloniser une grande diversité de niches écologiques sur notre planète. Les deux espèces Petunia x hybrida et Arabidopsis thaliana représentent deux groupes majeurs des plantes à fleur. Nous avons montré que les gènes à homéodomaine d’une famille appelée WOX (Wuschel homeobOX) sont fortement impliqués dans le développement des organes dotés de polarité (dont les feuilles et des organes de la fleur : sépales, pétales, carpelles). Un double mutant (maw mawb), chez le Pétunia, développe des pétales en forme de filament, avec disparition du tube floral. De plus, nous avons découvert que ces mêmes gènes interagissent au niveau génétique avec d’autres gènes (appelés gènes à boite MADS) dans la formation des ovules, structures à partir desquelles les graines se forment. Nous avons aussi montré que des gènes de la même famille sont impliqués dans la formation d’autres structures chez le Pétunia : les trichomes ou poils aériens de surface. Ces derniers sont impliqués dans plusieurs taches, qui vont de la protection contre les pathogènes à celles contre les stress abiotiques. Grâce à des études de génétique fonctionnelle nous avons pu montrer un recrutement différentiel des gènes WOX ici étudiés, dépendant de l’organe et de l’espèce. Ces travaux de thèse montrent l’importance de cette famille génique pour les études d’evo-devo (Biologie Evolutionniste du Développement). Finalement, une analyse de RNA-Seq (séquençage du transcriptome), dévoile les réseaux génétiques contrôlés par ces gènes WOX. / In the Kingdom of Plants, the emergence of flowers was a crucial step in their ability to colonize a large variety of ecological niches on our planet. The two species Petunia x hybrida and Arabidopsis thaliana represent two major groups of flowering plants. In this work, we have shown that HOMEOBOX genes from the WOX family (Wuschel homeoboxes) are heavily involved in polar organ development (such as leaves and sepals, petals, and carpels at the flower level). The maw mawb double mutant in Petunia displays string-like petals, with consequent disappearance of the floral tube. Moreover, we found that these two genes genetically interact with genes from a different family (the MADS family) in ovule identity (ovules are the structures from which seeds develop). We have also shown that other genes from the WOX family are involved in development of a different kind of structures in Petunia: the trichomes. Trichomes are involved in different tasks, protecting the plant from pathogens or abiotic stress. Thanks to functional genetics studies, we have shown functional genetic recruitment of these WOX genes among different plant organs and among different species. This PhD thesis provides evidence for the importance of the WOX family in Evo-Devo studies. Eventually, we unravelled genetic networks controlled by MAW and MAWB trough RNA-Seq analysis.

This dissertation explored the way in which bumblebees' visual system helps them discover their first flower. Previous studies found bees have unlearned preferences for parts of a flower, such as its colour and shape. The first study pitted two variables against each other: pattern type: sunburst or bull's eye, versus the location of the pattern: shapes appeared peripherally or centrally. We observed free-flying bees in a flight cage using Radio-Frequency Identification (RFID) tracking. The results show two distinct behavioural preferences: Pattern type predicts landing: bees prefer radial over concentric patterns, regardless of whether the radial pattern is on the perimeter or near the centre of the flower. Pattern location predicts exploration: bees were more likely to explore the inside of artificial flowers if the shapes were displayed near the centre of the flower, regardless of whether the pattern was radial or concentric. As part of the second component, we implemented a mathematical model aimed at explaining how bees come to prefer radial patterns, leafy backgrounds and symmetry. The model was based on unsupervised neural networks used to describe cognitive mechanisms. The results captured with the results of multiple behavioural experiments. The model suggests that bees choose computationally "cheaper" stimuli, those that contain less information. The third study tested the computational load hypothesis generated by the artificial neural networks. Visual properties of symmetry, and spatial frequency were tested. Studying free-flying bees in a flight cage using motion-sensitive video recordings, we found that bees preferred 4-axis symmetrical patterns in both low and high frequency displays.

Le déterminisme du sexe est un processus qui aboutit à la séparation physique des structures à l’origine des gamètes mâles et femelles, soit sur des fleurs séparées sur une même plante, pour les espèces monoïques, soit sur des individus séparés, dans le cas des espèces dioïques. Ce mécanisme favorise la fécondation croisée et augment ainsi la variabilité génétique. Il pourrait être influencé par les facteurs endogène (génétique ou hormonal) ou environnementaux. Chez le melon, le déterminisme du sexe est contrôlé par le gène A (andromonoecious) et le gène G (gynoecious). Le gène A code pour 1-aminocyclopropane-1-carboxylique acide synthase (ACS), un enzyme impliqué dans la voie de biosynthèse d’éthylène qui inhibe le développement des étamines dans les fleurs femelles. Le gène G code pour une protéine C2H2 à doigt de zinc appartenant à la famille WIP de facteurs de transcription qui inhibe le développement des capelles dans les fleurs mâles. Chez Arabidopsis thaliana, Il y a six gènes WIP et on en sait très peu sur leur fonction moléculaire. TT1/AtWIP1 est impliqué à l’accumulation de PA dans endothélium de graines. NTT/AtWIP2 est impliqué dans le développement de TRANSMITTING TRACT de carpelle. Dans cette thèse, nous avons essayé de mettre en évidence la fonction moléculaire de gènes WIP. Dans cette étude, nous avons montré que les gènes WIP des espèces différents partiellement restaurent le phénotype de graines jaune de tt1-3 mutants et régulent positivement les gènes tardifs de biosynthèse de flavonoïdes chez Arabidopsis thaliana La complémentation fonctionnelle de mutants tt1-3 par le gène WIP de melon et le gène WIP de la mousse montre que les gènes WIP ont la même fonction globale mais diffèrent à l’échelle spatio-temporelle. Il a été montré que le second motif conservé, à l’extrémité N-terminal, du gène TT1 était essentiel pour qu’il soit fonctionnel. La substitution d’acides aminés de ce motif (N2) par des alanines diminue l’accumulation de proanthocyanidines (PA) dans l’endothélium de la graine. TT1 perturbe également le développement des pétales, des étamines et des carpelles quand il est surexprimé de manière ectopique sous le contrôle des promoteurs d’AP3 et CRC. Il a été exprimé dans les racines secondaires sous le promoteur du gène SOLITARY ROOT (SLR/IAA14) ainsi que dans les stipules sous le promoteur du gène GLABROUS1 (GL1). TT1 inhibe le développement des racines secondaires et la formation des trichomes sur les feuilles. Dans cette étude, nous avons constaté que TT1 agit comme un inhibiteur de la formation d’organes quand il est exprimé de manière ectopique. On cherchera dans cette étude à comprendre les mécanismes mis en jeu lors de l’arrêt du développement de ces organes au cours du déterminisme du sexe et a évoqué de nouvelles pistes pour expliquer ce processus. / Sex determination in plants is a process that results the development of either male or female flower on the same or different individuals. This mechanism enhances the cross pollination and raises the genetic variability. It can be influenced by endogenous (genetic or hormonal) and/or external environmental factors. In melon, gene A arrests the stamen development in the female flowers and gene G arrests the development of carpel in the male flowers hence these two genes control the sex determination mechanism in melon. Gene A encodes 1-aminocyclopropane-1-carboxylic acid synthase (ACS), an enzyme which is involved in the ethylene biosynthesis pathway. Gene G encodes a C2H2 zinc finger proteins that belongs to WIP family of transcription factors. In Arabidopsis thaliana, there are six WIP genes and very little is known about their molecular function. TT1/AtWIP1 is involved in the accumulation of PA in the seed endothelium. NTT/AtWIP2 is involved in the development of transmitting tract in the carpel. In this thesis, we tried to highlight the molecular function of the WIP genes. Here we show that WIP genes from different species partially restore the yellow seed coat color phenotype of tt1-3 mutant and upregulate the late flavonoid biosynthetic genes. The functional complementation of tt1-3 mutants by WIPs from Cucumis melo and Physcomitrella patens indicates that WIP genes have the same global function but differ on the spatio-temporal level. Second conserved motif in the N-terminus of TT1 protein was found to be essential for its proper function as alanine scanning of N2 motif of TT1 decreased the accumulation of PAs in the seed endothelium. TT1 disturbed the development of petals, stamens and carpels in flower when ectopically expressed under AP3 and CRC promoter. TT1 was expressed in the lateral roots under the promoter of SOLITARY ROOT (SLR/IAA14) and in the stipules under the promoter of GLABROUS1 (GL1). TT1 was able to inhibit the development of the lateral roots and leaf trichomes. In this study, we found that TT1 can act as organ inhibitor when ectopically expressed. Our study will help us to understand the organ arrest during sex determination mechanism and will evoke new dimensions for further explanations of this process.