• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 148
  • 81
  • 22
  • 13
  • 7
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 334
  • 62
  • 55
  • 55
  • 37
  • 33
  • 32
  • 31
  • 29
  • 28
  • 26
  • 25
  • 23
  • 22
  • 21
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the 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.
131

The Role of Mitogen-activated Protein Kinases in the Regulation of Plant Development

Satterfield, Erica 10 April 2009 (has links)
Mitogen-activated protein kinases are part of an evolutionarily conserved protein phosphorylation cascade which serves essential regulatory functions in eukaryotic organisms. Although the role of MAPKs in the regulation of a plant’s response to environmental stress and plant defense has been well established, very little is known about their role in the regulation of plant developmental processes. In order to examine the role of MAPKs in plant growth and development, a strong mammalian MAPK phosphatase (MKP-1), which is known to inactivate MAPKs in plants, was introduced into tobacco plants. In tobacco plants, MKP-1 overexpression altered plant responses to the phytohormones, ethylene and cytokinin. Tobacco plants expressing MKP-1 flowered earlier and senesced later than wild-type. Additionally, these plants exhibited similar floral morphology as flowers from ethylene-insensitive tobacco plants. These observed phenotypes seem to depend on the protein phosphatase activity, as transgenic lines expressing an inactive form of MKP-1 (MKPCS) did not show the same phenotypes. Furthermore, both tobacco and Arabidopsis MKP-1 transgenic plants exhibited increased shoot regeneration when compared to wild-type plants, suggesting increased cytokinin sensitivity. In an attempt to elucidate the mechanism by which MKP-1 affects plant growth and development, expression of selected genes were analyzed using RT-PCR. MKP-1 transformed tobacco plants exhibited downregulated expression of an ethylene biosynthesis gene (NtACO) and upregulated expression of a pathogenesis-related gene (PR-1b), similar to gene expression studies previously conducted in plants with increased production of cytokinin. The same MKP-1 transgenic plants also exhibited upregulated expression of the flowering time gene, FT. Results from this study indicate that constitutive expression of MKP-1 may interfere with ethylene-related MAPK pathways, which normally serves to restrict plant growth during times of environmental stress. The reduced responses to ethylene resulted in elevated sensitivity to cytokinin, promoting an enhanced shoot regeneration phenotype.
132

Developmental changes of the Olive tree from juvenility to maturity and Genetic basis of vegetative and reproductive traits / Etude du développement de l'olivier de la juvénilité à la maturité et du déterminisme génétique des caractères végétatifs et reproducteurs.

Ben Sadok, Inès 05 July 2013 (has links)
L'un des défis auxquels sont confrontés les producteurs de fruits est de réussir à maintenir d'année en année un équilibre entre croissance végétative et production. La productivité des arbres fruitiers au cours des années est étroitement liée à leur développement. Intégrer les caractères architecturaux dans les programmes de sélection pourrait donc, améliorer la régularité de production et aider à optimiser la gestion des cultures. Dans cette thèse, nous avons étudié le déterminisme génétique des caractères architecturaux chez l'olivier (Olea europaea L. subsp. Europaea), en incluant le développement végétatif et reproducteur. L'olivier a un grand intérêt en raison de l'importance de l'huile d'olive et des olives dans l'alimentation humaine. L'étude a porté sur une descendance issue du croisement entre les variétés 'Olivière' et ‘Arbequina' qui a été cultivée en verger dans deux environnements contrastés. En premier lieu, nous avons étudié le déterminisme génétique de la croissance et ramification des arbres durant la phase juvénile sur un site en considérant trois échelles d'observation: arbre, unité de croissance et entrenœuds. Les interactions entre les facteurs liés à l'ontogénie de l'arbre ainsi que les facteurs génotype et environnement ont été prises en compte. Des modèles génétiques, incluant les effets année de croissance et/ou ordre de ramification, environnement, génotype et leurs interactions respectives, ont été construits en intégrant une fonction de variance et une structure de covariance lorsque cela était nécessaire. Après une étape de sélection de modèle, les facteurs impactant significativement l'architecture de l'arbre ont été identifiés et les valeurs d'héritabilité au sens large ont été estimées. Ces résultats nous ont permis de définir à quel moment au cours de l'ontogenèse de l'olivier et à quelle échelle d'observation, les caractères de croissance et ramification sont déterminés génétiquement. De plus, cette étude a permis d'investiguer la plasticité des caractères architecturaux et leur stabilité entre environnements contrastés. Enfin, les changements associés à l'acquisition des facultés reproductives ont été observés. Quand tous les descendants ont atteint l'âge adulte, j'ai étudié les bases génétiques du développement reproducteur. La stratégie était basée sur (i) une décomposition d'un sous échantillon d'unités de croissance localisées à la périphérie de la couronne de l'arbre en variables quantitatives liées à la fois aux processus de floraison et fructification en relation avec leur croissance et ramification (ii) une évaluation annuelle du rendement des arbres durant quatre années. L'observation d'arbres 'ON' ou ‘OFF' pour une année donnée a révélé des tendances de production régulière vs irrégulière au sein de la descendance. Après avoir développé une nouvelle carte génétique, une recherche QTLs associés aux caractères reproductifs a été réalisée. Des QTLs présentant les effets des deux parents et des co-localisations ont été identifiés. Cette étude a mis en évidence le schéma de développement de l'olivier pendant les phases juvénile et mature mettant en évidence l'existence de gradients ontogéniques se traduisant par des caractères héritables qu'à la périphérie de l'arbre. Une stratégie de phénotypage adaptée aux caractéristiques architecturales de l'olivier a été proposée. Enfin, les descendants montrant une supériorité intéressante par rapport à leurs parents ont été identifiés. Ces génotypes pourraient être valorisés dans les programmes de sélection futurs pour la création de variétés innovantes. / One of the most challenging questions that fruit growers are facing is to maintain trees in a stable balance between production and vegetative growth from year to year. Fruit trees productivity over years is closely linked to their development. Integrating architectural traits in breeding programs could thus, optimise cultivation management and improve bearing regularity. Here, we investigate the genetic determinism of architectural traits in the olive tree (Olea europaea L. subsp. europaea) including vegetative and reproductive behaviour. The olive tree raises high interest because of the importance of olive oil and olives in the human diet. The segregating population under study derived from a cross between ‘Olivière' and ‘Arbequina' cultivars and was grown on two orchards under contrasting environments. First, we investigated the genetic determinism of juvenile growth and branching traits in one site at three different scales: whole tree, growth unit and internodes. Interaction between tree ontogeny, genetic and environmental factors were considered. Genetic models, including the year of growth, environment, genotype effects and their interactions, were built with variance function and covariance structure of residuals when necessary. After a model selection step, morphogenetic factors impacting significantly tree architecture were identified and heritabilities were estimated. These finding allow us to define when during the olive tree ontogeny and at which observation scale, growth and branching traits are under genetic influence. Moreover, progenies plastic response to contrasted environments was highlighted and traits showing significant genotype-by-environment effect were identified. Changes over time associated to the acquisition of reproductive competence were further observed. Once all progenies attempt adulthood, we studied the genetic basis of reproductive behaviour. Our strategy was based on (i) a decomposition of adult growth units at the crown periphery in quantitative variables related to both flowering and fruiting process in relation to their growth and branching (ii) an annual assessment of individual trees yield. The observation of ‘on' or ‘off' olive trees in a given year over four years revealed patterns of regular vs. irregular bearing. After developing a new genetic map, a QTL mapping was carried out on reproductive traits, leading to the identification of QTLs with effects from both parents and co-localizations. This study gives an overview of olive tree development during juvenility and maturity periods showing the existence of ontogenic trends, which result in traits heritable mostly at the tree periphery. A phenotyping strategy adapted to its architectural characteristics is proposed. Finally, progenies showing interesting superiority in comparison to their parents were identified and could constitute interesting sources for innovative materials in future selection programs.
133

Etude des bases (épi) génétiques de l'adaptation dans une expérience de sélection divergente pour la précocité de floraison chez le maïs / (Epi)-genetic basis of adaptation in a divergent selection experiment for flowering time in maize inbred lines

Durand, Eléonore 10 June 2011 (has links)
La variation quantitative résulte de l’action combinée des gènes et de leur environnement. Pour comprendre la relation génotype-phénotype et disséquer l’architecture des caractères complexes, deux approches sont couramment employées. D’une part l’évolution expérimentale qui permet de quantifier le nombre et l’effet des mutations dans la construction d’un phénotype soumis à une pression de sélection, d’autre part la cartographie de QTL (Quantitative Trait Loci) et/ou la génétique d’association qui permettent d’identifier les locus responsables de la variation phénotypique. Au cours de cette thèse, nous avons combiné l’ensemble de ces approches pour (1) évaluer le rôle relatif des nouvelles mutations et de la variabilité résiduelle dans la réponse à la sélection ; (2) identifier les déterminants génétiques sous tendant cette réponse ; (3) disséquer, pour un locus candidat, les mécanismes génétiques de sa contribution à la variation phénotypique. Pour cela, nous disposons d’un matériel génétique résultant d’une expérience de sélection divergente pour la date de floraison menée depuis plus de dix ans. Cette expérience a été conduite en parallèle à partir de deux lots de semences de lignées commerciales de maïs (F252 et MBS847). Pour chaque lignée de départ, deux populations ont été constituées, une population précoce et une population tardive produites en sélectionnant et autofécondant les génotypes les plus précoces/tardifs à chaque génération. Nous avons caractérisé la réponse à la sélection après 7 générations. Cette réponse est rapide, asymétrique entre populations et significative dans 3 des 4 populations. Elle est linéaire avec le temps ce qui indique que des nouvelles mutations contribuent à créer de la variance génétique à chaque génération. Nous avons identifié un locus majeur contribuant à 35% de la variation pour la date de floraison dans la population F252 tardive et pour lequel les deux allèles étaient présents dans le lot de semence initial sous forme d’hétérozygotie résiduelle. Les deux allèles présentent des haplotypes très divergents autant au niveau de leur variation nucléotidique (5.7%) que d’un point de vue structural (16 indels) sur une région proche du gène eIF-4A (Eukaryotic Initiation Translation Factor 4A). L’association de ce locus avec la date de floraison et d’autres caractères corrélés tels que la hauteur et le nombre de feuilles a été confirmée par une caractérisation développementale fine de génotypes précoces et tardifs et également dans un panel d’association comprenant 317 lignées de maïs cultivé. En plus d’un effet pléiotrope, nous avons montré grâce au développement de méthodes statistiques que ce locus présente des interactions épistatique fortes avec d’autres locus en ségrégation puisque son effet dépend largement du fond génétique. Nous avons finalement utilisé des AFLP (Amplified Fragment Length Polymorphisms) sur tous les génotypes issus des 7 premières générations de sélection afin d’identifier d’autres polymorphismes potentiellement impliqués dans la réponse à la sélection. Nos résultats préliminaires montrent une différenciation génétique et épigénétique entre les populations sélectionnées qui semble être préférentiellement due à de l’hétérozygotie résiduelle. / Quantitative variation results from the combined action of multiple genes and their environment. Two approaches are currently employed to gain insights into the link between genotype and phenotype and to dissect the genetic architecture of complex traits. On one hand, experimental evolution allows quantifying the number of mutations and their effect on the evolution of a phenotype subject to artificial selection. On the other hand, QTL (Quantitative Trait Locus) and association mapping are used to identify loci responsible for phenotypic variation. In this work, we have combined all 3 approaches in order to (1) evaluate the role of new mutations and standing genetic variation to the response to selection ; (2) to identify the genetic determinants underlying this response ; (3) to dissect at one candidate locus the genetic mechanisms of its contribution to phenotypic variation. We have used the material produced by a divergent selection experiment for flowering time conducted for over 10 years in the field. This experiment was conducted in parallel from two commercial maize inbred line, F252 and MBS847. From each initial seed lot, two populations, an early population and a late population, were created by selecting and selfing the earliest/latest individuals at each generation. We characterized the response to selection after 7 generations. The response was fast, asymmetric between populations and significant in 3 out of 4 populations. It was linear through time indicating that new mutations have generated new additive genetic variance at each generation. We identified a major locus contributing to 35% of the variation for flowering time in the late F252 population. At this locus, two alleles were present as residual heterozygocity in the initial seed lot. The two alleles exhibited haplotypes extending on a region around the eIF-4A (Eukaryotic Initiation Translation Factor 4A) that diverged drastically both at the nucleotide (5.7%) and structural level. We were able to confirm the association of the candidate locus to flowering time variation and other traits such as height and leaf number, first using an association panel containing 317 maize lines, second through the developmental characterization of early and late genotypes. In addition, to its pleiotropic effect, we have shown by developing a specific statistical framework that this locus exhibit pervasive epistatic interactions with other loci segregating in the population. Hence, its effect largely depended on the genetic background. We have finally applied methyl-sensitive AFLP (Amplified Frgament length Polymorphisms) to screen all genotypes in order to identify the polymorphisms potentially involved in the response to selection during the first 7 generations Our preliminary results indicate both a genetic and epigenetic differentiation between early and late populations. This differentiation seems however to be mainly driven by standing genetic variation.
134

Análise das vias genéticas reguladas pelo microRNA156 e o gene SINGLE FLOWER TRUSS (SFT) em resposta a baixa temperatura no controle do florescimento de tomateiro (Solanum lycopersicum L.) / Analysis of the genetic pathways regulated by microRNA156 and the SINGLE FLOWER TRUSS gene (SFT) in response to low temperature in control of tomato flowering (Solanum lycopersicum L.)

Fava, Raphael Denys 30 November 2018 (has links)
O florescimento é um processo essencial no desenvolvimento vegetal. A mudança de fase vegetativa para reprodutiva em plantas reprograma várias vias genéticas e metabólicas fundamentais para a complementação de seu ciclo de vida. Em Arabidopsis thaliana, modelo mais estudado para o desenvolvimento floral, cinco rotas genéticas são descritas para o controle do florescimento, apresentando redundância de regulação entre essas vias. Dentre essas, a via AGE, regulada pela idade da planta, tem como seu principal efetor o microRNA156 (miR156) e os seus alvos diretos, os fatores de transcrição do tipo SBP/SPL (SQUAMOSA PROMOTER BINDING PROTEIN-like). Em tomateiro (Solanum lycopersicum L.), planta considerada insensível ou pouco responsiva a duas das cinco vias do florescimento (fotoperíodo e vernalização), a via AGE também controla a transição de fase vegetativa para reprodutiva. Plantas de tomateiro superexpressando o miR156 atrasam a transição de fase vegetativa para reprodutiva. Ao contrário, plantas superexpressando o florígeno SINGLE FLOWER TRUSS (SFT) aceleram a mudança de fase vegetativa para reprodutiva. Após curta exposição a baixa temperatura (16°C) o tomateiro também altera o tempo de florescimento, atrasando a transição de fase e prolongando o número de dias até a antese, tanto no cultivar determinado Micro-Tom (MT), quanto no cultivar indeterminado Ailsa Craig. Interessantemente, houve redução de número de folhas nesses cultivares quando expostos a curto período de baixa temperatura (16°C). Entretanto, a diminuição do número de folhas, que está relacionada ao plastochron, pode ter assumido funções específicas em tomateiro que não estão diretamente correlacionadas com o controle do tempo de florescimento em resposta a baixas temperaturas. A baixa oferta do florígeno SFT, em resposta a baixa temperatura, foi necessária para o atraso no tempo de florescimento das plantas, associando sua expressão a via AGE, com regulação da expressão do miR156 e do seu alvo SlSBP15, alterando o acúmulo de seus transcritos no ápice e cotilédones. Em arabidopsis, a redução da expressão de genes SPLs em plantas superexpressando o miR156 resulta em extremo atraso no florescimento e concomitante aumento da produção de folhas em resposta a baixas temperaturas, Em tomateiro, a repressão dos genes SBPs/SPLs em plantas miR156OE também promove atraso no florescimento, mas não afeta a produção de folhas em resposta a baixa temperatura, o que também é observado com o aumento de SFT e plantas p35S::SFT. Além disso, a regulação transcricional, pós-transcricional e possivelmente epigenética de alguns genes da via miR156/SPL/SBP, sugere uma complexa inter-relação entre essa via e a temperatura ambiental em tomateiro. / Flowering is an essential process in plant development. The change from vegetative to reproductive phase in plants reprograms several genetic and metabolic pathways fundamental to the complementation of their life cycle. In Arabidopsis thaliana, the most studied model for floral development, there are five genetic routes described for the control of flowering, which present regulatory redundancy between them. Among these, the AGE pathway, regulated by plant age, has microRNA156 (miR156) as its main effector and the transcription factors SBP/SPL (SQUAMOSA PROMOTER BINDING PROTEIN-like) as its direct targets. In tomato (Solanum lycopersicum L.), plant considered insensitive or not responsive to two of the five flowering pathways (photoperiod and vernalization), the AGE pathway also controls vegetative to reproductive phase transition. Tomato plants overexpressing the miR156 delay the transition from vegetative to reproductive phase. In contrast, plants overexpressing the flowering SINGLE FLOWER TRUSS (SFT) accelerate the vegetative to reproductive phase shift. After short exposure to low temperature (16°C) the tomato also altered the flowering time, delaying the phase transition and extending the number of days until the anthesis, both in the determined Micro-Tom (MT) cultivar and in the indeterminate cultivar Ailsa Craig. Interestingly, there was a reduction in the number of leaves in these cultivars when exposed to a short period of low temperature (16°C). However, the decrease in number of leaves, related to plastochron, may have assumed specific functions in tomatoes that are not directly correlated with the control of flowering time in response to low temperatures. The low supply of the SFT florigen, in response to low temperature, was necessary for the delay in the flowering time of the plants, associating its expression to the AGE path, with regulation of the expression of miR156 and its target SlSBP15, changing the accumulation of its transcripts at the apex and cotyledons. In arabidopsis, the reduction of SPL gene expression in plants overexpressing miR156 results in extreme flowering delay and concomitant increase of leaf production in response to low temperatures. In tomato, repression of SBPs / SPL genes in miR156EE plants also promotes delay in flowering, but does not affect leaf production in response to low temperature, which is also observed with increasing SFT and p35S::SFT plants. In addition, the transcriptional, post-transcriptional and possibly epigenetic regulation of some genes in the miR156 / SPL / SBP pathway suggests a complex interrelationship between this pathway and the environmental temperature in tomato.
135

Iniciação floral e ácido giberélico no florescimento e na produção da lima ácida 'Tahiti' (Citrus latifolia, Tanaka) /

Sanches, Frauzo Ruiz. January 2005 (has links)
Orientador: Izabel Cristina Leite / Banca: Paulo Roberto de Camargo e Castro / Banca: José Orlando de Figueiredo / Banca: Durvalina Maria Mathias dos Santos / Banca: Antonio Baldo Geraldo Martins / Resumo: O objetivo do trabalho foi de observar o efeito de diferentes concentrações do ácido giberélico, de 20, 40 e 80 mg/L, aplicadas em julho, agosto, setembro e outubro; sobre o florescimento e produção da lima ácida 'Tahiti'. Foi determinada a época em que ocorriam os processos de mudança da gema vegetativa para a floral. Foram analisados cortes histológicos de gemas axilares de ramos com quatro a seis meses de idade. Pôde-se observar quando ocorriam as mudanças morfológicas no meristema apical. A análise morfológica das gemas mostrou que no período de junho a novembro foi possível encontrar com maior facilidade gemas com início de formação de sépalas. Este momento marca o começo do processo de diferenciação morfológica do meristema apical e é determinante para as aplicações de GA3. No ano de 2003, as aplicações realizadas nos meses de agosto e setembro foram as mais efetivas em reduzir o número de flores por ramo e de frutos por planta. Neste mesmo ano, os cortes histológicos mostraram que nos referidos meses podiam ser observadas com maior facilidade gemas em início de formação de sépalas. A conclusão geral é que a concentração e a época de aplicação do GA3 influenciaram na produção de flores por ramo e frutos por planta. Quando analisada conjuntamente época e concentração, os melhores resultados estiveram associados com a concentração de 80 mg/L, em agosto e setembro. / Abstract: The present work was developed to evaluate the effect of gibberellic acid on the flowering and production of 'Tahiti' lime. Treatments represent a combinati among different doses (20, 40 and 80 mg/L) and time of application (July, August, September and October). To determine the best time for GA3 spray, this work evaluated the time of the transition from vegetative to floral bud. It was collected 4 and 6 months-old buds with their branches to conduct this experiment. These buds were subjected to anatomic meristem studies, evaluating the morphological changes in the apical meristem. Along the study, the period from July to November was probably the best time to find buds at the initiation process of morphological differentiation (initiation of sepals). In 2003, when GA3 application was performed, the results show that the best periods to reduce the number of flowers formed by branch and the number of fruits were August and September. In that year, the histological cuts from buds showed that in August and September it was easy to find bud with initiation of sepal formation. The conclusion is that there was significant reduction in flowering and fruit production when the concentration increased and when the favorable period to application of GA3 was chosen. The effective reduction was a combination between the concentration and time of application. The best results were obtained with application of 80 mg/L in August and September. / Doutor
136

Caractérisation moléculaire et fonctionnelle des gènes impliqués dans la mise en place et la lecture de la méthylation d'histones chez l'Arabidopsis thaliana / Molecular and functional characterization of genes involved in setting up and reading histone methylation in Arabidopsis thaliana

Zhao, Wei 30 June 2017 (has links)
La méthylation des histones constitue un niveau important de contrôle épigénétique chez les eucaryotes. Mes études portent sur la caractérisation des facteurs potentiellement intervenant dans la mise en place et la lecture de la méthylation pour mieux apprécier son rôle et des mécanismes sous-jacents dans la régulation de la transcription et du développement des plantes chez l’Arabidopsis thaliana. Ainsi, la première partie de mes travaux de thèse a contribué à l’étude d’une protéine à domaine SET (SET DOMAIN GROUP7, SDG7) et à montrer que SDG7 est nécessaire au bon déroulement de l'induction de VIN3 et du processus de vernalisation pour la floraison. Nos résultats suggèrent que SDG7 pourrait méthyler une protéine non-histone encore inconnue dans la régulation de la transcription et le contrôle de la durée de vernalisation. La deuxième partie de ma thèse porte sur l’étude de SDG8 et les H2B-UBIQUITIN-ligases HUB1/HUB2 pour examiner un cross-talk éventuel entre la triméthylation de H3K36 (H3K36me3) et la monoubiquitination d’H2B (H2Bub1). Nous avons montré que H3K36me3 et H2Bub1 sont déposés largement indépendamment, qui diffère d’une dépendance hiérarchique de déposition préalablement observée chez la levure. La dernière partie de ma thèse a permis l’identification des protéines HUA2/HULK2 à domaine PWWP comme lecteurs éventuels de H3K36me3 dans la régulation de la floraison et du développement des plantes. / Histone methylation is one of the keys epigenetic marks evolutionarily conserved in eukaryotes. My study focuses on the characterization of factors potentially involved in the deposition and reading of lysine (K) methylation to appreciate its role and underlying mechanisms in the regulation of transcription and plant development, using Arabidopsis thaliana as a model organism. In the first part of my thesis, I report on our study of SET DOMAIN GROUP7 (SDG7), a protein containing the evolutionarily conserved SET domain, which is generally recognized as a signature of K-methyltransferases. We found that SDG7 plays an important role in the regulation of VIN3 induction associated with cold duration measure during vernalization treatment. Intriguingly, levels of several different histone methylations were found unchanged in the sdg7 mutant plants and the recombinant SDG7 protein failed to show a histone-methyltransferase activity in vitro. We thus conclude that SDG7 might methylate a yet unknown non-histone protein to regulate transcription and proper measurement of the duration of cold exposure in the vernalization process. In the second part, I studied interaction between SDG8 and HISTONE MONOUBIQUITINATION1 (HUB1) and HUB2. My results unravel that H3K36me3 and H2Bub1 are deposited largely independently in Arabidopsis, which is in contrast to the dependent crosstalk of these two different epigenetic marks previously reported in yeast. In the last part of my thesis, I report on the identification of the PWWP-domain proteins HUA2/HULK2 as readers of H3K36me3 and demonstrate that sdg8 and hua2 genetically interacts in the regulation of flowering time.
137

Att konstruera en barndom : Det litterära barnet i Harry Martinsons Nässlorna blomma och Henning Mankells Comedia Infantil

Törnsten, Emma January 2018 (has links)
The aim of this esseay is to analyse the configuration of the literary child in Henning Mankells Comedia Infantil and Harry Martinssons Flowering Nettle. The teoretical outset is interdisciplinary, informed by both literarystudies and childstudies adopting a psycho-social perspective which allows a reading of the childprotagonists inside as well as outside preconditions and how these are constructed in the texts. The narratological concepts of focalization is used to investigate in detail how the narrator and narrative constructs a childperspectiveand conception of childhood. A point of interest is also to examine how the novels relate to the idea of the innocent or/and the competent child.
138

The Systematics and Evolution of Euphorbiaceae Tribe Plukenetieae

Cardinal-McTeague, Warren Martin 01 October 2018 (has links)
The aim of this dissertation is to study the systematics and evolution of Euphorbiaceae vines (tribe Plukenetieae), a diverse pantropical lineage (~365 species and 18 genera) composed of three morphologically distinct subtribes, Dalechampiinae, Plukenetiinae, and Tragiinae. Through the course of my research I largely resolved the evolutionary history of Plukenetieae and made broader contributions to the study of pollen and seed evolution, pantropical biogeography, and plant diversification. In chapter two I developed the first well-sampled molecular phylogeny for Plukenetieae (154 terminals, ~93 species, 2,207 character dataset composed of ITS and psbA-trnH with indel gap-scored data), and determined baseline species group relationships of the tribe. Molecular phylogeny largely agreed with pollen morphology hypotheses and confirmed that the large genus Tragia was para- and/or polyphyletic and should be split into smaller genera. Analysis of pollen morphology revealed a trend towards aperture reduction and loss in Tragiinae, with four origins of weakly defined apertures and up to three origins of inaperturate pollen. In chapter three, I studied the seed size evolution of Plukenetia, a pantropical genus with large edible oil-rich seeds, by developing a near-exhaustive phylogeny (83 terminals, 20 of ~24 species, 5,069 bp dataset of ETS, ITS, KEA1 introns 11 and 17, TEB exon 17, matK, ndhF) and conducting ancestral state estimation and phylogenetic regression. Seed size evolution in Plukenetia was dynamic and associated with competing selective pressures of plant size, fruit type (and inferred dispersal syndrome), and seedling ecology. In chapter four I presented a revised sectional classification of Plukenetia based on phylogeny and morphological evidence, including three new taxa from South America. Chapters three and five included biogeographical investigations on Plukenetia and Plukenetieae. Analyses revealed that pantropical disjunct distributions arose one to three times in each subtribe via periodic long-distance dispersals from the Oligocene to the Pliocene, most often from South America to Africa and then Southeast Asia. Lastly, in chapter five, I developed an improved phylogeny for Plukenetieae (289 terminals, ~109 species, 5,160 bp dataset of ETS, ITS, KEA1 intron 11, TEB exon 17, matK, ndhF) to study the influence of innovative traits (twining growth form, stinging hair defences, and pseudanthial inflorescences) on diversification in the tribe. However, increased diversification was not associated with innovative traits. Instead, diversification was associated with clades that shifted into drier open habitats, aided by habitat expansion following the Late Miocene cooling period.
139

IMPACT OF A HIGH OIL AND PROTEIN ON AGRONOMIC TRAITS AND OVERALL SEED COMPOSITION IN SOYBEAN

AL-Amery, Maythem 01 January 2017 (has links)
New soybean lines have been developed with significantly higher oil, protein + oil and higher meal protein. These soybeans contain a VgD1 gene (highly active acyl-CoA:diacylglycerol acyltransferase, DGAT from Vernonia galamensis (VgDGAT1A) produces much higher oil synthesis and accumulation activity in soybean. Soybean with active DGAT from Vernonia galamensis (VgDGAT1A) has active TAG biosynthesis relative to other DGATs including from soybeans and Arabidopsis. DGATs catalyze the final step of TAG synthesis: DAG (diacylglycerol) + acyl-CoA → TAG + CoASH (Coenzyme A is notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle). A thorough analysis of the major components in VgD1 lines, especially those of nutritional or anti-nutritional value including what else changed (decreased); and what remained at normal levels was conducted. A field study was conducted in Spindletop and Princeton KY, reviled no reduction in yield nor protein, and about 4 % (DW) more oil was obtained in Princeton and 2% (DW) in Spindeltop. No consistent reduction in the other seed composition.VgDGAT1A soybean lines indicated noticeably early maturation compared to the parental line. This is associated with higher expression of the flowering genes FT2 (FLOWERING LOCUS T2) and FT5 (FLOWERING LOCUS T5), for the high oil lines. A single recessive mutation in soybean (MIPS) myo-inositol 1-phosphate synthase, confers a seed phenotype of increase inorganic phosphate (Pi) crossed with high oil lines expressing a DGAT from Vernonia galamensis (VgDGAT1A) (VgD). The oil and protein were maintained compart to VgD. VgD X MIPS (VM), had 21.2, and 22 % oil in 2015, and 23.3 and 24.0 oil in 2016, and protein 46, 49 in 2015, and 37 and 39 % in 2016. Phosphate results suggesting the cross MV is still segregating for MIPS and more selection and planting are needed. Measurement of seed phosphate levels is an established technique for screening for low phytate mutants but to date, it has not been performed non-destructively from single soybean seeds. A protocol was developed greatly reducing the sample size thereby reducing the cost and time and saving a generation in the selection of low phytate mutant seeds based on the high Pi phenotype. Genotyping single seeds are useful in breeding and genetics while maintaining high germination rates. Nondestructive single-seed genomic DNA extraction protocols using 12 mg cotyledon tissue with a modified cetyl trimethyl ammonium bromide (CTAB) technique and a commercial seed DNA extraction kit using 1 mg cotyledon tissue were developed for dry soybean seeds and cross-verified with leaf DNA analysis.
140

The Influence of Chilling and Heat Accumulation on Bloom Timing, Bloom Length and Crop Yield in Almonds (Prunus dulcis (Mill.))

Covert, Melanie M 01 December 2011 (has links)
Almonds are one of the first commercial nut trees to bloom in early spring and thus are susceptible to temperature patterns prior to and during bloom which affect bloom timing, bloom length, pollination and nut set. Data used in this project include yearly dates of 90% bloom from 1996-2006, bloom length in days and final crop yields in pounds per tree for Nonpareil and Mission varieties. Data were collected from the University of California Cooperative Extension reports on the 1993-2006 Regional Almond Variety Trials in Butte, San Joaquin and Kern Counties. Temperature pattern models in the form of Chill Hours (Chill Hour Model), Chill Units (Chill Unit Model), Chill Portions (Chill Portion Model) and Growing Degree Hours (GDH°) (Heat Model) prior to bloom were used to predict the date of 90% bloom for each variety, site and year. Temperature model results were compared to averaged actual dates of 90% bloom by site and variety used to predict bloom timing (Calendar Model). The relationship between bloom length in days and GDH° during bloom and the relationship between bloom length, GDH° during bloom and final crop yields were also evaluated. The average error in predicting the 90% bloom date for both Nonpareil and Mission was smaller using the Calendar Model compared to the four temperature pattern models. The Chill Portion model did not have significantly higher average error in predicting the date of 90% bloom than the Calendar model in Nonpareil. The Chill Unit and Chill Portion models had smaller errors in predicting 90% bloom date than the Chill Hour or GDH° model in Mission. GDH° during bloom was positively correlated with bloom length. GDH° during the first four days of Nonpareil bloom was significantly correlated with crop yields, with each additional GDH° during bloom correlated with a 0.4 lbs./tree increase in crop yield. Further research is needed on specific temperature thresholds and their relationship to physiological changes during almond bloom and pollination. The practice of monitoring chilling and heat accumulation will allow growers to anticipate bloom, prepare to optimize bee activity during bloom, and plan for possible crop yield variations due to adverse weather conditions during bloom in almonds.

Page generated in 0.1041 seconds