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  • 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.
11

Caracterização funcional do gene ScPetC de cana-de-açúcar em plantas de tabaco transgênicas / Functional characterization of ScPetC sugarcane gene in transgenic tobacco plants

Liberato, Carolina Ribeiro, 1984- 26 August 2018 (has links)
Orientador: Marcelo Menossi Teixeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-26T06:15:33Z (GMT). No. of bitstreams: 1 Liberato_CarolinaRibeiro_M.pdf: 4975605 bytes, checksum: 97b439dccaccd215ccfca5504f9c6cb5 (MD5) Previous issue date: 2014 / Resumo: A cana-de-açúcar é uma das plantas cultiváveis de maior importância para o Brasil. Embora atualmente o país seja responsável pela produção de 671 milhões de toneladas (safra 2014/2015), a produtividade da cana no Brasil é afetada por diversos fatores ambientais, dentre os quais se destaca a seca. A produção de novos cultivares com maior tolerância à seca não só contribuiria para aumentar a produtividade como aumentaria a sustentabilidade da cultura. Com o intuito de compreender o funcionamento do gene ScPetC, que codifica uma proteína com similaridade a ISP (Iron Sulfur Protein), este trabalho estudou os efeitos da superexpressão do gene ScPetC na tolerância à seca em plantas transgênicas de tabaco. Nossos estudos mostram que sua superexpressão em tabaco aumenta a sobrevivência das plantas em resposta à suspensão de rega. Ainda, foi observada maior tolerância dessas plantas ao estresse oxidativo, e maior eficiência dos fotossistemas I e II sob condições de estresse por seca / Abstract: Sugarcane is one of the most important cultivated plants in Brazil and the estimated production in the 2014/2015 harvest is 671 million tones. The productivity of sugarcane is affected by various environmental factors, and drought is considered as the major abiotic stress. The production of new cultivars with increased drought tolerance can help to increase productivity and enhance the sustainability in the sugarcane fields. In order to understand the function of ScPetC gene, which encodes a protein with similarity to ISP (Iron Sulfur Protein), this study evaluated the drought tolerance in transgenic tobacco plants overexpressing the ScPetC gene. Our studies showed that overexpression of ScPetC increases the ability of plants to survive to water withheld. Moreover, we provide evidence that plants had increased tolerance to oxidative stress and improved efficiency of photosystems I and II under drought / Mestrado / Genetica Vegetal e Melhoramento / Mestra em Genética e Biologia Molecular
12

O fator de transcrição AtbZIP63 como integrador de sinais energéticos e estresses biótico/abiótico / The transcription factor AtbZIP63 as a integrator of energetic signals and biotic/abiotic stresses

Matiolli, Cleverson Carlos, 1980- 08 March 2012 (has links)
Orientador: Michel Georges Albert Vincentz / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-21T07:49:06Z (GMT). No. of bitstreams: 1 Matiolli_CleversonCarlos_D.pdf: 11712676 bytes, checksum: dd78e2f749da48afd1fc31207bc95b06 (MD5) Previous issue date: 2012 / Resumo: A manutenção do balanço energético em plantas é de crucial importância para a otimização de seu crescimento e desenvolvimento em resposta às condições sempre flutuantes do meio. A energia obtida através da fotossíntese deve ser utilizada parcimoniosamente e dividida entre crescimento, desenvolvimento, armazenamento e respostas a estresses bióticos e abióticos. Entender como a energia é canalizada para cada um destes processos e como os diversos sinais ambientais e metabólicos são integrados é de vital importância para a compreensão dos mecanismos que permitem o sucesso reprodutivo das plantas mesmo frente a condições ambientais adversas. Os fatores reguladores de transcrição desempenham um papel importante como pontos de convergência de vias de sinalização distintas e regulam a expressão dos conjuntos de genes mais adequados para cada combinação de sinais, permitindo uma resposta equilibrada diante de desafios muitas vezes concomitantes. Neste trabalho, mostramos que o fator de transcrição de Arabidopsis thaliana AtbZIP63, o qual pertence a família bZIP e é um mediador das respostas a carência energética induzidas pela quinase KIN10, é reprimido a curto prazo (2h e 4h) pela hexose glicose e o hormônio ácido abscíssico (ABA). A repressão da expressão de AtbZIP63 por 2% de glicose é independente da atividade sensora de glicose da enzima Hexokinase 1 (HXK1) e não envolve mudanças nos níveis endógenos de ABA, um mediador das respostas a glicose. No entanto, o ABA é capaz de modular a amplitude da resposta de AtbZIP63 a glicose. ABA e glicose interagem de maneira sinérgica para repressão da expressão de AtbZIP63 e esta interação envolve mecanismos de regulação pós-transcricionais. Análises em escala genômica de diferenças de perfis transcricionais entre mutantes para AtbZIP63 e seus respectivos genótipos selvagens foram desenvolvidas para identificar os genes alvos de AtbZIP63 e definir a rede de regulação da qual AtbZIP63 participa. A classificação funcional dos 280 e 348 genes desregulados nos mutantes por inserção de T-DNA atbzip63-1 e atbzip63-2, respectivamente, sugere que AtbZIP63 está envolvido na regulação de genes relacionados as respostas à carência energética, síntese e resposta a hormônios, estresses abióticos e bióticos e ciclo circadiano, provavelmente modulando o uso equilibrado de energia em resposta aos desafios ambientais. Baseado na observação de que os mutantes para AtbZIP63 apresentam diversos genes relacionados a respostas contra estresses bióticos, avaliamos a resposta dos mutantes atbzip63-1 e atbzip63-2 a patógenos usando o patossistema Arabidopsis-Pseudomonas O mutante atbzip63-1 é mais resistente a infecção com o fitopatógeno Pseudomonas syringae pv tomato DC3000, mostrando seu envolvimento nas respostas a estresse biótico. O mutante atbzip63-2 apresenta atraso de crescimento quando cultivado em condições limitantes de energia, sugerindo sua participação também no crescimento/desenvolvimento de Arabidopsis nestas condições. A busca de proteínas interatoras de AtbZIP63 utilizando o sistema de duplo híbrido em levedura (Y2H) revelou genes relacionados a degradação de proteínas sugerindo que controle da estabilidade da proteína de AtbZIP63. Em conjunto, os resultados apresentados neste trabalho sugerem que AtbZIP63 é um nó de integração entre diferentes vias de sinalização para modular o crescimento e desenvolvimento de Arabidopsis de acordo com diversos sinais ambientais / Abstract: The maintenance of energy balance in plants is crucial to optimize their growth and development in response to ever changing environment. The energy obtained through photosynthesis must be used sparingly and divided between growth, development, storage, and responses to biotic and abiotic stresses. Understand how energy is channeled to each of these processes and how the environmental and metabolic signals are integrated have a vital importance to understanding the mechanisms by which plants reach the reproductive success even in adverse environmental conditions. Transcription factors play an important role as convergence points of several signaling pathways and regulate the expression of sets of genes most appropriate for each signal combination. We show that the transcription factor AtbZIP63 from Arabidopsis thaliana, which belongs to the bZIP family and mediates partially the response to energy deprivation induced by kinase KIN10, is repressed in short-term treatments (2h and 4h) with glucose and hormone absicisic acid (ABA). The repression of AtbZIP63 by 2% glucose is independent of the glucose sensing activity of the enzyme Hexokinase 1 (HXK1) and does not involve changes in endogenous ABA levels, a mediator of glucose responses. However, ABA modulates the amplitude of AtbZIP63 responses to glucose. ABA and glucose interact synergistically to repress AtbZIP63 mRNA accumulation and that this interaction involves post-transcriptional mechanisms. Genomic scale transcriptional profile comparison between AtbZIP63 mutants and their respective wild-type genotypes have been developed to identify target genes and the regulatory context which AtbZIP63 is involved. The functional classification of 280 and 348 misregulated genes in T-DNA insertion mutants atbzip63-1 and atbzip63-2, respectively, suggests that AtbZIP63 regulates genes involved in responses to energy starvation, synthesis and hormone response, biotic and abiotic stress, and circadian clock, probably by modulating the energy usage in response to environmental challenges. Based on the observation that the AtbZIP63 mutants have several misregulated genes related to responses to biotic stress, we evaluated the response of atbzip63-1 and atbzip63-2 to pathogens using the Arabidopsis-Pseudomonas pathosystem. The atbzip63-1 mutant is more resistant to infection with the pathogen Pseudomonas syringae pv tomato DC3000, showing their involvement in responses to biotic stress. The atbzip63-2 mutant has arrested growth in energy-limiting conditions, also suggesting its participation in the growth / development of Arabidopsis under these conditions. A searching for interacting proteins of AtbZIP63 using Yeast Two-Hybrid (Y2H) system revealed proteins related to protein degradation and suggests stability control of AtbZIP63 protein. Together, the results presented here suggest that AtbZIP63 is an integration node of different signaling pathways and modulates growth and development of Arabidopsis under different environmental conditions / Doutorado / Genetica Vegetal e Melhoramento / Doutor em Genetica e Biologia Molecular
13

Biotecnologia de cana-de-açúcar (Saccharum spp.) para tolerância a estresse hídrico / Biotechnology of sugarcane (Saccharum spp.) for drought stress tolerance

Souza, César Bueno de, 1982- 21 August 2018 (has links)
Orientador: Marcelo Menossi Teixeira, Andrea Akemi Hoshino / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-21T05:45:50Z (GMT). No. of bitstreams: 1 Souza_CesarBuenode_D.pdf: 2755272 bytes, checksum: 945d7a45c10893c9a58603f1e04813ef (MD5) Previous issue date: 2012 / Resumo: O Brasil é o maior produtor mundial de cana-de-açúcar e no cenário atual, em que o aumento na busca por energia renovável é visível, o aumento na produtividade da cana é de extremo interesse para o setor sucroalcooleiro. Estresses abióticos influenciam grandemente a produtividade de espécies como a cana e, sendo assim, estudos relacionados com a tentativa de diminuir esse impacto na produtividade são de grande importância. A seca é o estresse ambiental que mais causa prejuízos ao agronegócio e por esse motivo é muito desejável que se desenvolvam novas variedades de cana-de-açúcar que sejam mais tolerantes a esses estresses e com isso o setor sucroalcooleiro será largamente beneficiado. A transgenia é uma das ferramentas utilizadas na produção de novos cultivares comerciais com características agronômicas interessantes e, para o seu sucesso, a identificação de genes com potencial para melhorar essas características faz-se necessária. Sendo assim, o maior objetivo desse trabalho foi a avaliação do potencial biotecnológico de seis genes de cana-de-açúcar que são modulados por seca. Os genes aqui estudados tiveram seu perfil de resposta a seca anteriormente avaliado por microarranjos de DNA e foram selecionados como candidatos para a produção de um novo cultivar de cana-de-açúcar que seja mais tolerante a estresses abióticos. Esses genes foram analisados em plantas transgênicas de tabaco, cana-de-açúcar e/ou Brachypodium. A superexpressão de dois genes de cana em tabaco conferiu maior tolerância a seca e salinidade das plantas transgênicas quando comparadas às selvagens e a proteção de seus usos na produção de plantas tolerantes a estresses abióticos foi solicitada. Há evidências de que um terceiro gene de cana conferira tolerância ao estresse oxidativo em plantas transgências de cana. Além disso, outros três genes de cana foram inseridos em Brachypodium, mas os eventos gerados ainda não foram avaliados. Com o trabalho desevolvido foi, portanto, possível gerar plantas transgênicas tolerantes a estresses abióticos e com isso é possível concluir que a seleção de genes candidatos para melhorias de características agronômicas de interesse através de microarranjos é algo que deve ser explorado e pode-se concluir, ainda, que alguns dos genes analisados estão envolvidos na resposta a seca e/ou aos estresses ambientais em geral / Abstract: Brasil is the largest producer of sugarcane in the world and the seeking for renewable energy is currently visible what makes the increase of sugarcane productivity highly desirable. Abiotic stresses greatly influence the productivity of species such sugarcane. Therefore, studies related to the reduction of these impacts on productivity are highly important. Drought is the environmental stress that causes more damage to agribusiness and because of it the development of new cultivars with higher tolerance to abiotic stresses is desirable since the sugar and ethanol sector will be largely benefited. Transgenic plants production is one of the tools that have been used in the development of new cultivars with interesting agronomic traits and for its success identifying genes that can improve these characteristics is necessary. Thus, the main objective of this study was evaluating the biotechnological potential of six drought-modulated genes from sugarcane. The genes studied here have their drought response profile previously showed by microarray and were selected as candidates for the production of a new sugarcane cultivar with higher tolerance to abiotic stresses. These genes were analyzed in transgenic tobacco, sugarcane and/or Brachypodium plants. The overexpression of two sugarcane genes in tobacco conferred higher drought and salinity tolerance in tobacco plants compared to wild-type and the protection of their uses in the production of plants with higher tolerance to abiotic stress was requested. There are evidences that a third sugarcane gene confers tolerance to oxidative stress in transgenic sugarcane. Furthermore, three other genes were inserted in Brachypodium but these transgenic events were not yet analyzed. With this work was possible to produce transgenic plants that are tolerant to abiotic stresses what let us to conclude that the selection of candidate genes to improve agronomic traits by microarrays is useful and that some of the analyzed genes are involved into drought and/or abiotic stresses in general responses / Doutorado / Genetica Vegetal e Melhoramento / Mestre em Genética e Biologia Molecular
14

Modelling amenity landscape plant water use in South Africa

Hoy, Leslie Higham 12 1900 (has links)
South Africa is classified as a semi-arid environment with limited natural water sources. Amenity landscapes provide broad ranging benefits for society. Amenity landscapes account for between 31% - 50% of water supplied for domestic and urban use. To reduce water use and water conservation in amenity landscapes, strategies, regulations and interventions are required. Every landscape is a unique complex system with a large number of variables that differ from each other. The variability can be summarized into management/design, irrigation, climatological, edaphic and plant related aspects. Several amenity landscape water use models have been developed around the world and two in South Africa. This study developed a comprehensive South African hydrozone based plant database and an Amenity Landscape Water Use Model South Africa (ALWUMSA). This will improve hydrozoning of amaneity landscapes and ultimately also improve water conserbvation for these sites. It allows users/owners to determine water use requirements through an extensive data gathering, from aspects such as design, management, microclimate, environmental, edaphic, irrigation and plant related factors. Comparisons of results from ALWUMSA to three test sites, selected existing models and a range of scenarios produced results demonstrating that ALWUMSA consistently projected lower water requirements. The model also allows for site aspects to be changed thus encouraging end users to implement specific water saving intiatives with the amenity landscape to reduce water use. These savings will be translated into both water-use savings as well as financial savings for users of the amenity landscape water use model. / Environmental Sciences / Ph. D. (Environmental Science)
15

Interactions spatiales et auto-organisation des végétations semi-arides / Spatial interaction and self-organisation in semi-arid vegetations

Barbier, Nicolas Serge 06 March 2006 (has links)
Les recherches récapitulées dans cette thèse de doctorat ont porté sur les causes de l’organisation spatiale des végétations périodiques. Ces structures paysagères aux motifs réguliers, tachetés, tigrés ou labyrinthiques, d’échelle décamétrique à hectométrique, couvrant des étendues considérables sur au moins trois continents, constituent un cas d’école dans l’étude des processus endogènes présidant à l’hétérogénéité du couvert végétal. Ces structures prennent place sur un substrat homogène, mis à part la rétroaction du couvert lui-même, et sont marquées par des écotones abrupts et la persistance d’une proportion considérable de sol nu. Plusieurs modèles ont mis en avant l’existence possible d’un phénomène d’auto-organisation du couvert, qui verrait une structure d’ensemble émerger des interactions locales entre individus. Ces modèles se basent sur le jeu simultané de la consommation de la ressource (compétition) et de l’amélioration de l’un ou l’autre des éléments du bilan de la même ressource par le couvert (facilitation). La condition à l’existence d’une structure d’ensemble spatialement périodique et stable réside dans une différence entre la portée de la compétition (plus grande) et celle de la facilitation. L’apparition de ces structures est modulée par le taux de croissance biologique, qui est le reflet des contraintes extérieures telles que l’aridité, le pâturage ou la coupe de bois. Le modus operandi des interactions spatiales supposées entre individus reste largement à préciser.<p>Nos recherches ont été menées au sud-ouest de la République du Niger, à l’intérieur et dans les environs du parc Régional du W. Trois axes ont été explorés :(i) Une étude de la dépendance spatiale entre la structure de la végétation (biovolumes cartographiés) et les paramètres du milieu abiotique (relief, sol), sur base d’analyses spectrales et cross-spectrales par transformée de Fourier (1D et 2D). (ii) Une étude diachronique (1956, 1975 et 1996) à large échelle (3000 km²) de l’influence de l’aridité et des pressions d’origine anthropique sur l’auto-organisation des végétations périodiques, basée sur la caractérisation de la structure spatiale des paysages sur photos aériennes via la transformée de Fourier en 2D. (iii) Trois études portant sur les interactions spatiales entre individus :En premier lieu, via l’excavation des systèmes racinaires (air pulsé) ;Ensuite, par un suivi spatio-temporel du bilan hydrique du sol (blocs de gypse) ;Enfin, via le marquage de la ressource par du deutérium. <p>Nous avons ainsi pu établir que les végétations périodiques constituent bien un mode d’auto-organisation pouvant survenir sur substrat homogène et modulé par les contraintes climatiques et anthropiques. Un ajustement rapide entre l’organisation des végétations périodiques et le climat a pu être montrée en zone protégée. La superficie et l’organisation des végétations périodiques y ont tour à tour progressé et régressé en fonction d’épisodes secs ou humides. Par contre, en dehors de l’aire protégée, la possibilité d’une restauration du couvert semble fortement liée au taux d’exploitation des ressources végétales. Ces résultats ont d’importantes implications quant à la compréhension des interactions entre climat et écosystèmes et à l’évaluation de leurs capacités de charge. La caractérisation de la structure spatiale des végétations arides, notamment par la transformée de Fourier d’images HR, devrait être généralisée comme outil de monitoring de l’état de ces écosystèmes. Nos études portant sur les modes d’interactions spatiales ont permis de confirmer l’existence d’une facilitation à courte portée du couvert végétal sur la ressource. Cependant, cette facilitation ne semble pas s’exercer sur le terme du bilan hydrique traditionnellement avancé, à savoir l’infiltration, mais plutôt sur le taux d’évaporation (deux fois moindre à l’ombre des canopées). Ce mécanisme exclut l’existence de transferts diffusifs souterrains entre sols nu et fourrés. Des transferts inverses semblent d’ailleurs montrés par le marquage isotopique. L’étude du bilan hydrique et la cartographie du micro-relief, ainsi que la profondeur fortement réduite de la zone d’exploitation racinaire, jettent de sérieux doutes quant au rôle communément admis des transferts d’eau par ruissellement/diffusion de surface en tant que processus clé dans la compétition à distance entre les plantes. L’alternative réside dans l’existence d’une compétition racinaire de portée supérieure aux canopées. Cette hypothèse trouve une confirmation tant par les rhizosphères excavées, superficielles et étendues, que dans le marquage isotopique, montrant des contaminations d’arbustes situés à plus de 15 m de la zone d’apport. De même, l’étude du bilan hydrique met en évidence les influences simultanées et contradictoires (facilitation/compétition) des ligneux sur l’évapotranspiration.<p>/<p><p>This PhD thesis gathers results of a research dealing with the causes of the spatial organisation of periodic vegetations. These landscape structures, featuring regular spotted, labyrinthine or banded patterns of decametric to hectometric scale, and extending over considerable areas on at least three continents, constitute a perfect study case to approach endogenous processes leading to vegetation heterogeneities. These patterns occur over homogeneous substratum, except for vegetation’s own feedbacks, and are marked by sharp ecotones and the persistence of a considerable amount of bare soil. A number of models suggested a possible case of self-organized patterning, in which the general structure would emerge from local interactions between individuals. Those models rest on the interplay of competitive and facilitative effects, relating to soil water consumption and to soil water budget enhancement by vegetation. A general necessary condition for pattern formation to occur is that negative interactions (competition) have a larger range than positive interactions (facilitation). Moreover, all models agree with the idea that patterning occurs when vegetation growth decreases, for instance as a result of reduced water availability, domestic grazing or wood cutting, therefore viewing patterns as a self-organised response to environmental constraints. However the modus operandi of the spatial interactions between individual plants remains largely to be specified.<p>We carried out a field research in South-West Niger, within and around the W Regional Park. Three research lines were explored: (i) The study of the spatial dependency between the vegetation pattern (mapped biovolumes) and the factors of the abiotic environment (soil, relief), on the basis of spectral and cross-spectral analyses with Fourier transform (1D and 2D). (ii) A broad scale diachronic study (1956, 1975, 1996) of the influence of aridity and human induced pressures on the vegetation self-patterning, based on the characterisation of patterns on high resolution remote sensing data via 2D Fourier transform. (iii) Three different approaches of the spatial interactions between individuals: via root systems excavation with pulsed air; via the monitoring in space and time of the soil water budget (gypsum blocks method); and via water resource labelling with deuterated water.<p>We could establish that periodic vegetations are indeed the result of a self-organisation process, occurring in homogeneous substratum conditions and modulated by climate and human constraints. A rapid adjustment between vegetation patterning and climate could be observed in protected zones. The area and patterning of the periodic vegetations successively progressed and regressed, following drier or wetter climate conditions. On the other hand, outside protected areas, the restoration ability of vegetation appeared to depend on the degree of vegetation resource exploitation. These results have important implications regarding the study of vegetation-climate interactions and the evaluation of ecosystems’ carrying capacities. Spatial pattern characterisation in arid vegetations using Fourier transform of HR remote sensing data should be generalised for the monitoring of those ecosystems. Our studies dealing with spatial interaction mechanisms confirmed the existence of a short range facilitation of the cover on water resource. However, this facilitation does not seem to act through the commonly accepted infiltration component, but rather on the evaporative rate (twice less within thickets). This mechanism excludes underground diffusive transfers between bare ground and vegetation. Inverse transfers were even shown by deuterium labelling. Water budget study and micro-elevation mapping, along with consistent soil shallowness, together cast serious doubts on the traditional mechanism of run-off/diffusion of surface water as a key process of the long range competition between plants. An alternative explanation lies in long range root competition. This hypothesis find support as well in the excavated root systems, shallow and wide, as in isotopic labelling, showing contaminations of shrubs located up to 15 m of the irrigated area. Water budget study also evidenced simultaneous contradictory effects (facilitation/competition) of shrubs on evapotranspiration.<p> / Doctorat en sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished
16

Flore et végétation de la Presqu'île de Madicaque, Aquin, sud d'Haïti

Hilaire, Jean 25 April 2008 (has links)
La Presqu’île de Madicaque, située sur la côte sud ouest de la République d’Haïti est couverte d’une végétation sèche, fragmentée à cause des activités d’extraction de bois et de fabrication de charbon. Cette Presqu’île est formée de trois formations calcaires s’élevant jusqu’à 286 mètres d’altitude et séparées par deux bandes d’alluvions marines. Des relevés phytosociologiques et des transects ont permis d’identifier la flore et les groupements végétaux de la Presqu’île. La flore vasculaire est composée de 296 espèces, 214 genres et 80 familles. La microphyllie, le nanisme et le spinescence sont parmi les principales caractéristiques de cette flore. Les familles les plus importantes sont Poaceae, Boraginaceae, Rubiaceae, Verbenaceae, Euphorbiaceae, Celastraceae, Cactaceae et les Légumineuses. Les espèces endémiques d’Hispaniola représentent 19% de cette flore dont la composition est différente dépendant du substrat (sable et calcaire). Sur le sable, la flore est moins épineuse et principalement de distribution pantropicale. La flore calcaire est épineuse, plutôt antillaise et possède presque toutes les espèces endémiques d’Hispaniola trouvées sur la Presqu’île. Un total de 13 groupements végétaux a été identifié dont 3 sont des recrus forestiers issus de l’exploitation de la végétation. Les 10 groupements naturels sont disposés selon une zonation qui part du cordon littoral vers la partie nord de la Presqu’île limitée par un étang salé. Les formations végétales naturelles sur le sable sont communes à toutes les Antilles à l’exception de la forêt basse caractérisée par Collubrina arborescens et Randia parvifolia occupant la majeure partie de la végétation sableuse. Les autres formations sont :la Mangrove (Laguncularia racemosa et Rhizophora mangle), les salines (Salicornia bigelovii et Batis maritima), la plage (Canavalia maritima et Ipomoea pes-caprae) et les zones inondables, sorte de mangrove atypique caractérisée par Conocarpus erectus et Cyperus globulosus. Sur le calcaire, les 4 formations naturelles identifiées sont plus spécifiques et peuvent être considérées comme des associations originales. Ce sont :1) l’association à Echites umbellata et Caesapinia sphaerosperma formant la broussaille épineuse et microphylle du cordon littoral calcaire. 2) L’association à Cissus carnifolia et Aristolochia leptosticta formant le matorral microphylle sempervirente épineux de la côte au vent. 3) L’association à Pilosocereus polygonus et Capparais ferruginea, qui est la forêt épineuse microphylle semi-caducifoliée sub-côtière occupant l’intérieur et les parties élevées des collines calcaires. 4) l’association à Ocotea coriacea et Coccoloba diversifolia qui est une forêt semi-humide occupant les parties sous-le-vent des collines calcaires. Trois facteurs majeurs influencent la végétation de la Presqu’île. Ce sont le substrat qui détermine la composition floristique, l’activité humaine et les embruns, dont l’impact est fonction de la topographie et de la distance à la mer, qui induisent la disposition des groupements. <p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
17

Characterization of a cold-responsive dehydrin promoter

Osadczuk, Elizabeth A. 27 August 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Dehydrins are type II LEA proteins induced in many plants during drought, low temperature, and high salinity to confer stress tolerance. AtERD14 is an Arabidopsis thaliana dehydrin that functions in part of the cold stress pathway. AtERD14 has chaperone-like capabilities that allow it to bind and protect various proteins from dehydration stresses. In order to determine the necessary components for cold induction of AtERD14, AtERD14prom::GFP/GUS and AtERD14prom::AtERD14 in AtERD14 KO constructs were created and stably transformed into A. thaliana. Analysis of the constructs showed the AtERD14 promoter alone was insufficient to respond to cold, and it was necessary to attach the AtERD14 coding region to the promoter to induce a cold response in ERD14. On the other hand, the RD29aprom::GFP/GUS promoter did respond to cold stress, indicating that RD29a does not require its coding region to support an increased amount of reporter activity after cold stress. The protoplast transformation system, while capable of transient expression of introduced constructs in protoplasts, was difficult for use for cold-inducible expression.

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