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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Isoprenoid biosynthesis, specificities and homeostasis in plants : genetic approach for the identification of regulators by screening for suppressors of growth defect / Biosynthèse, spécificités et homéostasie d’isoprénoïdes chez les plantes : approche génétique pour l’identification de régulateurs par le criblage de suppresseurs de défauts de croissanceVillette, Claire 11 May 2017 (has links)
Les plantes produisent une grande diversité de produits naturels parmi lesquels les isoprénoïdes prédominent. Ces molécules ont des fonctions essentielles pour la croissance et le développement : hormones végétales, régulateurs de croissance comme les brassinostéroïdes, pigments photosynthétiques, tous agissant sur des processus biologiques majeurs. Ainsi, la germination, la floraison, la tolérance aux stress thermiques et hydriques, ou la production de semences, sont contrôlées par l’action d’isoprénoïdes. Le but de mon projet est d’identifier par une sélection génétique les éléments régulateurs de l’homéostasie des isoprénoïdes. Pour cela, j’ai réalisé le criblage de suppresseurs de défaut de croissance dans deux mutants de biosynthèse d’isoprénoïdes chez Arabidopsis thaliana et un mutant de signalisation de brassinostéroïdes chez Hordeum vulgare. J’ai par ailleurs étudié la voie de biosynthèse de stérols spécifique ayant lieu dans un type cellulaire particulier, le tube pollinique en croissance. / Plants produce a great diversity of natural compounds, among which isoprenoids prevail. These molecules have essential functions for growth and development: plant hormones, growth regulators as brassinosteroids, photosynthetic pigments, acting on major biological processes. Thus, germination, flowering, heat and draught stress tolerance, or seed production are controlled by the action of isoprenoids. The aim of my project is to identify by genetic selection the regulators of isoprenoid homeostasis. For this, I carried out genetic screens for suppressors of growth defects in two isoprenoid biosynthesis deficient Arabidopsis thaliana mutants and a brassinosteroid signaling Hordeum vulgare mutant. The second part of my project was focused on the specific sterol biosynthetic pathway occurring in a specialized cell type, the germinating pollen tube.
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Investigation of Structure-function and Signal Transduction of Plant Cyclic Nucleotide-gated Ion ChannelsChin, Kimberley 07 January 2014 (has links)
Cyclic nucleotide-gated channels (CNGCs) are non-selective cation channels that were first identified in vertebrate photosensory and olfactory neurons. Although the physiological roles and biophysical properties of animal CNGCs have been well studied, much less is known about these channels in plants. The Arabidopsis genome encodes twenty putative CNGC subunits that are postulated to form channel complexes that mediate various physiological processes involving abiotic and biotic stress responses, ion homeostasis and development.
The identification of Arabidopsis autoimmune CNGC mutants, such as defense no death class (dnd1 and dnd2), and the constitutive expressor of pathogenesis related genes 22 (cpr22) implicate AtCNGC2, 4, 11 and 12 in plant immunity. Here, I present a comprehensive study of the molecular mechanisms involved in CNGC-mediated signaling pathways with emphasis on pathogen defense. Previously, a forward genetics approach aimed to identify suppressor mutants of the rare gain-of-function autoimmune mutant, cpr22, identified key residues that are important for CNGC subunit interactions and channel function.
First, I present a structure-function analysis of one of these suppressor mutants (S58) that revealed a key residue in the cyclic nucleotide binding domain involved in the stable regulation of CNGCs. Second, I present a new suppressor screen using AtCNGC2 T-DNA knockout mutants that specifically aimed to identify novel downstream components of CNGC-mediated pathogen defense signaling. In this screen, I successfully isolated and characterized the novel Arabidopsis mutant, repressor of defense no death 1 (rdd1), and expanded this study to demonstrate its involvement in AtCNGC2 and AtCNGC4-mediated signal transduction. Additionally, I demonstrated for the first time, the physical interaction of AtCNGC2 and AtCNGC4 subunits in planta.
The findings presented in this thesis broaden our current knowledge of CNGCs in plants, and provide a new foundation for future elucidation of the structure-function relationships and signal transduction mediated by these channels.
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Investigation of Structure-function and Signal Transduction of Plant Cyclic Nucleotide-gated Ion ChannelsChin, Kimberley 07 January 2014 (has links)
Cyclic nucleotide-gated channels (CNGCs) are non-selective cation channels that were first identified in vertebrate photosensory and olfactory neurons. Although the physiological roles and biophysical properties of animal CNGCs have been well studied, much less is known about these channels in plants. The Arabidopsis genome encodes twenty putative CNGC subunits that are postulated to form channel complexes that mediate various physiological processes involving abiotic and biotic stress responses, ion homeostasis and development.
The identification of Arabidopsis autoimmune CNGC mutants, such as defense no death class (dnd1 and dnd2), and the constitutive expressor of pathogenesis related genes 22 (cpr22) implicate AtCNGC2, 4, 11 and 12 in plant immunity. Here, I present a comprehensive study of the molecular mechanisms involved in CNGC-mediated signaling pathways with emphasis on pathogen defense. Previously, a forward genetics approach aimed to identify suppressor mutants of the rare gain-of-function autoimmune mutant, cpr22, identified key residues that are important for CNGC subunit interactions and channel function.
First, I present a structure-function analysis of one of these suppressor mutants (S58) that revealed a key residue in the cyclic nucleotide binding domain involved in the stable regulation of CNGCs. Second, I present a new suppressor screen using AtCNGC2 T-DNA knockout mutants that specifically aimed to identify novel downstream components of CNGC-mediated pathogen defense signaling. In this screen, I successfully isolated and characterized the novel Arabidopsis mutant, repressor of defense no death 1 (rdd1), and expanded this study to demonstrate its involvement in AtCNGC2 and AtCNGC4-mediated signal transduction. Additionally, I demonstrated for the first time, the physical interaction of AtCNGC2 and AtCNGC4 subunits in planta.
The findings presented in this thesis broaden our current knowledge of CNGCs in plants, and provide a new foundation for future elucidation of the structure-function relationships and signal transduction mediated by these channels.
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