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Kurmann, Marie Helena. "Pollen wall ultrastructure and development in selected gymnosperms /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487322984316368.
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Hall, N. A. "A taxonomic revision of some Mesozoic Ginkgoales, Czekanowskiales and related gymnosperms." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383336.
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Rendon, Paula Andrea Sucerquia. "Gimnospermas eocretáceas da Formação Crato, bacia do Araripe, Nordeste do Brasil." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/44/44139/tde-22082007-105023/.
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A Formação Crato, localizada na bacia do Araripe, Nordeste do Brasil, contém um dos registros fossíferos vegetais mais importantes do Cretáceo Inferior. Estes fósseis apresentam excelente estado de preservação, no geral, com pouca fragmentação, órgãos em conexão e estruturas epidérmicas e anatômicas delicadamente substituídas por óxidos de ferro. Como acontecia globalmente, as gimnospermas eram o grupo vegetal dominante na paleoflora eocretácea da Formação Crato, ocorrendo na forma de Bennettitales, Coniferales e Gnetales. As Bennettitales foram um componente aparentemente raro, estando representado pelas espécies Otozamites sp. e Zamites sp. Dentre as Coniferales, encontram-se as famílias Araucariaceae e Cheirolepidiaceae, as Araucariaceae registradas nas espécies Araucarites vulcanoi Duarte e Araucarites kunzmanni sp. nov.; as Cheirolepidiaceae, o grupo mais diverso, estão representadas pelas espécies Brachyphyllum obesum Heer, Brachyphyllum ponsi sp. nov., Brachyphyllum araripense sp. nov., Tomaxellia aff. T. biforme Archangelsky, Toxamellia aff. T. degiustoi e Pseudofrenelopsis sp. As Gnetales ocorrem na forma das espécies Limaephyton cratense gen. et sp. nov., Limaephyton duartei gen. et sp. nov. e Limaephytophyllum mohrium gen. et sp. nov. Características morfológicas, epidérmicas e anatômicas presentes nos macrofitofósseis da Formação Crato, evidenciam adaptações a um ambiente de baixa umidade. Esta flora se desenvolveu dentro da Região Equatorial, numa área intracontinental sob condições climáticas áridas e semi-áridas.Crato Formation, located in the Araripe Basin, Northeastern Brazil, bears one of the most important Lower Cretaceous fóssil plant Record. The fossils have an excellent preservation, usually low fragmentated, with attached organs and epidermic and anatomic features delicatedly replaced by iron oxides. As it happens worldwide, gymnosperms were the dominant group in the Lower Cretaceous Crato Formation paleoflora, existing as Bennettitales, Coniferales e Gnetales. Bennettitales were an apparently scarce component, represented by the species Otozamites sp. and Zamites sp. Between the Coniferales, are the families Araucariaceae and Cheirolepidiaceae, the Araucariaceae recorded by the species Araucarites vulcanoi Duarte and Araucarites kunzmanni sp. nov.; Cheirolepidiaceae, the most diverse group, is registered by species Brachyphyllum obesum Heer, Brachyphyllum ponsi sp. nov., Brachyphyllum araripense sp. nov., Tomaxellia aff. T. biforme Archangelsky, Toxamellia aff. T. degiustoi e Pseudofrenelopsis sp. As Gnetales are documented by the species Limaephyton duartei gen. et sp. nov. and Limaephytophyllum mohrium gen. et sp. nov. Morphologic, epidermic and anatomic features founded in the plant fossils from Crato Formation, evidence low moisture environment adaptations. That flora was developed in the Equatorial Region, in an intracontinental area with arid to semi-arid climatic conditions.
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Yagi, Eiki. "The distribution of the Au SINE family in angiosperms and gymnosperms and its evolutionary history." Kyoto University, 2012. http://hdl.handle.net/2433/157684.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第16893号
農博第1909号
新制||農||996(附属図書館)
学位論文||H24||N4654(農学部図書室)
29568
京都大学大学院農学研究科応用生物科学専攻
(主査)准教授 河原 太八, 教授 遠藤 隆, 教授 奥野 哲郎
学位規則第4条第1項該当
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Fanton, Jean Carlo Mari 1983. "Novas Gimnospermas e possivel Angiosperma da Paleoflora Crato, Eocretaceo da Bacia do Araripe, Nordeste do Brasil." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287326.
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Orientadores: Fresia Soledad Ricardi-Branco, Mary Elizabeth Cerruti Bernardes-de-OliveiraDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias
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Resumo: Fitofósseis inéditos excelentemente preservados na forma de impressões/ são descritos e revelam novas espermatófitas da Paleoflora Crato, proveniente dos calcários laminados do Membro Crato, Fonnação Santana, Cretáceo Inferior, Aptiano da Bacia do Araripe, Ceará, Nordeste do Brasil. Importantes lacunas taxonômicas da paleoflora deverão ser preenchidas a partir de três novos táxons, com designações já sugeridas e que futuramente serão erigidos através de publicações: Cratopteris fertilis, uma gimnosperma basal (pteridospenna mesozóica), afim da família Caytoniaceae, ordem Caytoniales, preservada como um galho portador de folhagem composta com padrão reticulado típico e de ramificações férteis (cupuladas e sinangiadas) organicamente conectadas, fato inusitado na literatura do grupo; Araripephedra papiliofoliata, uma gimnosperma derivada, afim da família Ephedraceae, ordem Gnetales, preservada na forma de caules articulados, ramificações caulinares opostas estéreis de folhas amplas, opostas e férteis com estróbilos solitários pedunculados, abundantes raízes, além de excepcionais detalhes anatômicos externos e internos preservados. As partes vegetativas e reprodutivas compõem uma planta completa, fato inédito na literatura do grupo. Alguns desses caracteres revelam profundas semelhanças com o atual gênero Ephedra L., confirmando as afinidades efedráceas da nova espécie; Iara ipaguassu (Incertae sedis), possível gnetaleana ou ainda uma monocotiledônea alismataleana, preservada como um eixo articulado e lenhoso, com sucessivos verticilos de ramificações tubulares a cilíndricas, áfilas, delgadas e flexíveis. Tais espennatófitas distribuíam-se em habitats distintos ao redor do sistema lacustre do Membro Crato: Cratopteris fertilis foi um arbustó/ arvoreta que habitava áreas não inundáveis, compondo estratos intennediários do dossel de florestas dominadas por gimnospennas; Araripephedra papiliofoliata foi um sub-arbusto de porte muito reduzido, rasteiro, caracteristicamente xerófilo, desenvolvendo-se em moitas devido à propagação vegetativa, fortemente ancorado ao substrato poroso de áreas -secas expostas à radiação solar e vivendo sob tufos de outras gimnospennas xerófitas; Iara ipaguassu, de design sugestivamente hidrodinâmico e muito similar às atuais ervas aquáticas alismataleanas, foi possivelmente uma hidrófila que vivia submersa em ambientes aquáticos do amplo sistema lacustre, influenciados por deltas/ estuários que garantiam condições fisico-químicasnão adversas até o período de estiagem. Caracteres morfológicos e anatômicos (por exemplo, os tipicamente xeromórficos) e as implicaçõestafonômicas e paleoecológicas apartadas a partir da análise dos espécimes permitiram sugerir a grande variedade de paleohabitats existentes ao redor do paleoambiente deposicional e corroborar assim condições climáticas predominantementequentes, de altas taxas de evaporação, porém marc~damentesazonais, com ciclos úmidos a secos.
Abstract: Unknown phytofossils well-preserved as impressions-replacements are described and reveal new spermatophytes from the Early Cretaceous Crato Palaeotlora, which is preserved in the Crato Member laminated limestones, Santana Formation, Aptian, Araripe Basin, Ceará State in the northeastern of Brazil. Three new taxa are proposed: Cratopteris fertilis, Araripephedra papiliofoliata and laTa ipaguassu. These taxonomic novelties will be submitted to publication in specific joumals. Cratopteris fertilis is a basal gymnosperm (mesozoic seed fern) related to the Caytoniaceae family, Caytoniales order, preserved as a twig bearing of compound foliage with typical reticulate venation and fertile branches (bearing cupules and synangia), organically connected, that is reported for the first time in the group literature. Araripephedra papiliofoliata is a derived gymnosperm, related to the Ephedraceae family, Gnetales order, preserved as articulated stems with sterile and fertile opposite branches. The sterile ones bear large opposite leaves, and the fertile, with non-compound pedunculate strobili. The roots are dense. Furthermore, exceptional anatomic details (external and internal) are exhibited. All these parts are attached, in a whole plant. This fact is totally new in the literature. Some of these features reveal deep similarities with extant genus Ephedra L. supporting the fossil ephedracean affinity. lara ipaguassu (Incertae sedis), a possible gnetalean or an alismatalean monocot, is preserved as a wood articulated axis with successive whorls of tubular to cylindrical, flexible, thin, leatless branches. Such plants possibly inhabited distinct habitats around Crato lacustrine system. Cratopterisfertilis was probably a shrub or a small tree which inhabited non-flooded areas compounding the intermediate strata in the canopy gymnosperm forests. Araripephedra papiliofoliata was a sub-shrub, with caulinar branches erect or prostrate, typically xerophyllous, and that grew like bush formations due to the vegetative propagation. This underbrush was strongly sticked to the porous substrate in dry areas exposed to sun light, and living under the xeromorphic gymnosperms tufts. lara ipaguassu of hydrodynamic design and very similar to the extant alisma!alean aquatic herbs, might have been a hydrophyll which lived submerged in aquatic environrnents of wide lacustrine system with delta! estuarine intluence. Morphological and anatomical characters from studied specimens and their taphonomic and palaeoecological implications aIlowed to suggest a diversity of palaeohabitats around the depositional palaeoenvironment, and confirmed mostly warm climatic conditions with high evaporation rates, although pronounced seasonal with cyc1es from moisture to dry ones.
Mestrado
Geologia e Recursos Naturais
Mestre em Geociências
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Fagundes, Paula Braga. "Um lugar ao sol : a influência do fator histórico sobre o nicho de luz e respostas ecofisiológicas de plantas com semente da floresta ombrófila mista." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/90470.
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Em ambientes florestais, a luz é o recurso que com mais frequência limita o crescimento, a sobrevivência e a reprodução em plantas. Assim, a variação na disponibilidade de luz no sub-bosque influencia a composição local de espécies lenhosas, que se segregam em diferentes nichos de luz de acordo com suas preferências e tolerâncias, conferidas através de suas adaptações e plasticidade fenotípica. Os atributos das espécies atuais, além de serem adaptados ao ambiente onde vivem, são um legado de seus ancestrais, motivo pelo qual espécies mais próximas filogeneticamente, com frequência compartilham atributos semelhantes e, por consequência, ocupam nichos similares, padrão conhecido como conservação filogenética. Estudos recentes mostram que atributos funcionais relacionados à captação de luz teriam se diversificado através de diferentes grupos filogenéticos, conferindo a estes capacidades distintas para a conquista de novos ambientes de luz. Nosso trabalho teve como objetivo detectar a presença de padrões filogenéticos na distribuição e nas respostas ecofisiológicas de oito espécies lenhosas co-ocorrentes e de seus respectivos clados em um sub-bosque florestal, a partir da comparação do nicho de luz e do desempenho de plantas juvenis em resposta ao gradiente luminoso existente. Assim nossas hipóteses são de que 1) as espécies filogeneticamente próximas tem maior semelhança em estratégias adaptativas do que espécies filogeneticamente distantes; 2) a amplitude de nicho e 3) a plasticidade de atributos em resposta à luz aumentam em clados mais derivados. Os resultados apresentados aqui mostraram uma maior similaridade entre as espécies mais relacionadas do que entre aquelas que são filogeneticamente distantes, sugerindo conservação filogenética do nicho. Quanto à amplitude de nicho, também há uma influência filogenética, porém, contrário ao esperado, os clados mais antigos apresentaram um nicho mais amplo. Para a plasticidade dos atributos os resultados aqui apresentados mostram que não há padrões filogenéticos na plasticidade das respostas de espécies e clados estudados, sugerindo o efeito de outros fatores sobre a plasticidade das plantas, como efeitos ontogenéticos ou estresse ambiental.In forest environments, light is the resource that most often limits the growth, survival and reproduction in plants. Thus, the variation in light availability, regarded as one of the most important resources for woody plants in the understory, results in differences in species composition, which segregate in different light niches according to their preferences and tolerances, conferred by their adaptations and phenotypic plasticity. Extant plant traits are not only adapted to the present environment, they are also a legacy from their ancestors and, for that reason, phylogenetically related species often share similar attributes and consequently occupy similar niches, pattern known as phylogenetic conservatism. Recent studies show that functional traits related to the capture of this resource have diversified across different phylogenetic groups, giving them distinct abilities to occupy new light environments. The present study aimed to detect the presence of phylogenetic patterns in species distribution along a light gradient and in ecophysiological responses of eight co-occurring woody species and their respective clades in a forest understory. This was accomplished by comparing the light niche of juvenile plants in response to the existing light gradient, as well as their physiological plasticity in response to understory light variations. We hypothesized that (1) phylogenetic related species have greater similarity of adaptive strategies, and consequently of their niche, than more distantly related ones; and that (2) the niche breadth is wider and (3) traits plasticity is greater in more recent than in more basal clades. The results presented here showed that there is a greater niche similarity between closely related species than between those that are phylogenetically distant, suggesting niche conservatism. Regarding to niche amplitude, there is also a phylogenetic influence but, contrary to our expectations, the older clades showed a greater niche breadth. For plasticity of selected plant traits, results showed no phylogenetic pattern for the studied species and clades, suggesting that other factors act on the phenotypic plasticity of plants, such as ontogenetic effects and/or environmental stress.
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Sheth, Mili. "Discovery and characterization of KNOX proteins lacking a homeodomain, produced by alternative splicing of KNAT1-like genes in gymnosperms and angiosperms." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31639.
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Bonet, Amandine. "Réponses de plusieurs espèces de mélèzes et du sapin de Douglas aux éléments traces : Étude de mécanismes de tolérance et des capacités d'accumulation." Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0018/document.
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Face à la toxicité des éléments traces métalliques (ET) dans l’environnement, les plantes ont développé différentes stratégies aujourd’hui exploitées en phytoremédiation. Les arbres paraissent plus efficaces que les herbacées pour la phytoextraction de par leur importante biomasse et leur système racinaire plus profond. Ces travaux ont donc été menés sur des espèces ligneuses largement répandues dans la région Limousin, plus particulièrement des conifères: le Douglas, le mélèze hybride et ses deux parents, le mélèze d’Europe et le mélèze du Japon. Plusieurs modèles de culture ont été utilisés pour permettre, par des approches complémentaires, une meilleure appréhension des réponses de ces conifères aux ET : des plantules cultivées in vitro et des germinations ou des arbres âgés de 2 ans cultivés sous serre. Les conifères ont été exposés soit à un seul ET, le Cadmium (Cd), soit à plusieurs ET (As, Pb, Sb) présents dans des sols collectés sur deux anciens sites miniers. Les résultats ont montré que, parmi les espèces étudiées, le Douglas présentait le taux d’accumulation le plus élevé en Cd. Cependant, la quantité stockée dans la biomasse aérienne est restée faible par rapport à d’autres espèces d’arbres déjà utilisées en phytoextraction. Par ailleurs, la caractérisation chimique des pectines de la paroi a mis en évidence des modifications quantitatives et qualitatives suggérant un processus d’exclusion du Cd. Au niveau intracellulaire, les résultats ont montré que les polyamines et les oligopeptides riches en thiols ne semblaient pas impliqués dans la compartimentation du Cd. En revanche, une accumulation de proline a été observée en réponse au Cd et à d’autres ET, suggérant une implication de la proline comme molécule antioxydante et / ou chélatrice d’ET. L’ensemble des résultats a mis en évidence la nécessité d’optimiser la croissance des conifères et la phytodisponibilité des ET du sol avant de pouvoir proposer ces conifères, et notamment le Douglas, pour la phytoextraction d’ETGiven the toxicity of trace elements (TE) in the environment, plants developed varions strategies used currently for phytoremediation. Trees appear more efficient than herbaceous species for phytoextraction as they have a larger biomass and a deeper root system. The work was thus performed on woody species widespread in Limousin region, particularly conifers: Douglas fir, hybrid larch and its two parents, European larch and Japanese larch. Several culture models were used to allow, through complementary approaches, a better understanding of the response of these conifers to TE: in vitro grown plantlets and seedlings or 2-year-old trees grown in greenhouse. Conifers were exposed to a single TE, cadmium (Cd), or to several TE (As, Pb, Sb) present in soils collected from two former mining sites. Among investigated species, results showed that Douglas exhibited the highest rate of Cd accumulation. However, the amount stored in aboveground biomass remained low compared to other tree species already used in phytoextraction. Furthermore, the chemical characterization of cell wall pectins highlighted quantitative and qualitative modifications suggesting a Cd exclusion process. At the intracellular level, results showed that polyamines and thiol-rich oligopeptides did not appear to be involved in Cd compartmentation. However, a proline accumulation was observed in response to Cd and other TE, suggesting an involvement of proline as antioxidant molecule and / or TE scavenger. Overall, results highlighted the need to optimize conifer growth and soil TE phytoavailability before to propose these conifers, particularly Douglas, for the phytoextraction of TE
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Nohra, Youssef A. "Résines végétales actuelles et fossiles : origine, caractérisation chimique et évolution." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S165.
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Les travaux de cette thèse portent sur la caractérisation chimique des ambres provenant de plusieurs gisements d’âges et d’origines géographiques variés, dont certains sont inédits. Des protocoles identiques à tous les échantillons et combinant les analyses spectroscopiques (IR et RMN 13C) et chromatographiques (THM-CPG-SM) ont été appliqués, permettant d’identifier l’origine botanique des ambres et fournissant des indices pour la reconstitution des paléoenvironnements terrestres. La caractérisation chimique des gisements d’ambre du Jurassique supérieur (Kimméridgien) jusqu’au Crétacé supérieur (Santonien) du Liban, de Jordanie, du Congo, d’Equateur et de France, permet de proposer des biomarqueurs pour les résines de Cheirolepidiaceae, une famille exclusivement mésozoïque de Conifères. Une évolution des sources botaniques des résines produites durant le Mésozoïque et le Cénozoïque est alors discutée. Une production dominée par les familles de Conifères Araucariaceae et Cheirolepidiaceae est remarquée au Jurassique supérieur et Crétacé inférieur. La production au Crétacé supérieur est plutôt dominée par des Cupressaceae. Au Cénozoïque, les origines botaniques des ambres sont plus variées, et des familles d’Angiospermes sont à l’origine de nombreux gisements, dont l’ambre du Pérou produit par une Fabaceae. La production par des Conifères reste toutefois importante au Tertiaire, à l’exemple des ambres de Nouvelle-Zélande qui ont pour origine les Araucariaceae. Les données obtenues ont permis une ré-évaluation de la classification des ambres par Py-GC-MS. Ainsi, une nouvelle molécule dont la structure est inconnue encore, a été identifiée dans les chromatogrammes d’ambres de classe Ib et Ic, ajoutant un caractère discriminant entre ces deux sous-classes. Enfin, la relation âge / maturation des résines fossiles est discutée, qui dépend avant tout des conditions d’enfouissement des résines. Une large base de données moléculaires est ainsi établie pour un grand nombre de gisements d’âges et d’origines botaniques variés, qui permettra une comparaison globale dans les travaux futursThis work focuses on the chemical characterisation of amber from different outcrops from different localities, and varied ages. Some of these outcrops had never been studied. All the amber samples were analysed with the same analytical techniques. The combination of the data obtained from spectroscopic (IR and 13C NMR) and chromatographic (THM-GC-MS) analysis allows the identification of the botanical origin of the amber and provide some information, for the reconstruction of the palaeoenvironment. Biomarkers for the cheirolepidiaceous resins were proposed based on the chemical characterisation of different amber outcrops dating from the Upper Jurassic (Kimmeridgian) to the Upper Cretaceous (Santonian) from Lebanon, Jordan, Congo, Ecuador and France. The Cheirolepidiaceae familt was exclusively present in the Mesozoic era. Hence, the evolution of the botanical origins of the produced resins during the Mesozoic and Cenozoic eras was discussed. It seems that Araucariaceae and Cheirolepidiaceae were the dominant resin producing trees during the Upper Jurassic and the Lower Cretaceous. While, cupressaceous resiniferous plants were dominant during the Upper Cretaceous. Howerver, resins dating from the Cenozoic era, were produced by a wider variety of plants, as resiniferous families of Angiosperm intensively participated in the resin production, i.e. the Peruvian amber produced by Fabaceae. Conifer resins traces were also detected in the Tertiary, such as the amber from the Araucariaceae found in New Zealand. The obtained data allowed a re-evaluation of the classification of ambers by Py-GC-MS, leading to the discovery of a novel molecule. This molecule of an unknown structure brings a new discrimination factor between the classes Ib and Ic. Finally, the age / maturity relationship is showed to be dependent on the burial and the conservation conditions of the resins. A broad molecular database is established based a large group of amber outcrops from different ages, and having diverse botanical origins. This database could be used as a comparative platform for further work in the future
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Everett, Richard Gobin. "A biosystematic survey of Sierra Lodgepole pine (Pinus contorta var. murrayana [Critchfield]) populations in the transverse and peninsular ranges of Southern California." CSUSB ScholarWorks, 1997. https://scholarworks.lib.csusb.edu/etd-project/30.
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Helmersson, Andreas. "Programmed cell death and genetic stability in conifer embryogenesis /." Uppsala : Dept. of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/2007127.pdf.
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CONCEIÇÃO, Domingas Maria da. "Prospecção, mapeamento e caracterização de depósitos fitofossilíferos da porção nordeste da bacia sedimentar do Paraíba (formação pedra de fogo, permiano)." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/17794.
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CAPEs
Os afloramentos fitofossilíferos da margem nordeste da Bacia Sedimentar do Parnaíba, em estratos do Permiano (Cisuraliano) da Formação Pedra de Fogo, ainda estão pouco estudados. Este trabalho visou o reconhecimento e análise de alguns dos afloramentos da margem supracitada, tendo se concentrado no estudo de áreas nos municípios de Altos, no Piauí, e de Duque Bacelar e Coelho Neto, no Maranhão. Em Altos, detectou-se em um único afloramento, uma associação autóctone?/parautóctone, dominada por grandes lenhos gimnospérmicos (com até 1,80 m de diâmetro). A área de Duque Bacelar e Coelho Neto apresentou mais de cinco afloramentos contendo associações formadas, especialmente, por lenhos gimnospérmicos de grande porte (de até 1,15 m de diâmetro), alguns em posição de vida, e, secundariamente, por caules de pteridófitas horizontalizados, e.g. Psaronius sp. (com até 5 m de comprimento). Análises espectroscópicas em amostras de fósseis do Maranhão apresentaram um elevado nível de sílica e a permanência residual de carbono amorfo, evidenciando nestes troncos um processo de permineralização por sílica. Foram confeccionadas lâminas petrográficas de troncos fósseis com o intuito de verificar o grau de preservação de tecidos e determinar o seu potencial para futuras análises taxonômicas. Finalmente, foi possível corroborar que as associações encontram-se inseridas em rochas lacustres da base da Formação Pedra de Fogo (Membro Sílex Basal), próximas ao contato com a infrajacente Formação Piauí (Carbonífero, Pensilvaniano). Esta observação contrasta com estudos anteriores, realizados na margem sudoeste da bacia, que referem o posicionamento dos fitofósseis na parte superior da Formação Pedra de Fogo (Membro Trisidela) ou, ainda, na sobrejacente Formação Motuca.
Petrified plant-bearing outcrops of lower Permian (Cisuralian) strata of the Pedra de Fogo Formation located in the northeastern margin of the Parnaíba Sedimentary Basin, are still poorly studied, and dominated mostly by gymnosperm trunks and, rarely, pteridophyte stems (Psaronius sp.). This work aimed prospection and analysis of some of the outcrops in the aforementioned margin of the basin, being focused on two new areas in the municipalities of Altos, Piauí state, and Duque Bacelar-Coelho Neto, Maranhão state. In Altos, an autochthonous?/parautochthonous assemblage dominated by huge gymnosperm trunks (reaching 1,8 m in diameter) was recorded in a single outcrop. The Duque Bacelar-Coelho Neto area evinced more than five exposures formed mostly by large gymnosperm trunks, some of them in life position (reaching 1,15 in diameter) and, less often, by pteridophyte stems in horizontal position, e.g. Psaronius sp. (reaching 5 m long). Invertebrate traces and stromatolites are exposed here too. Spectroscopic analyses in fossil samples from Maranhão showed a high concentration of silica and the residual presence of amorphous carbon, evincing a process of silica-permineralization. Petrographic thin-sections of fossil trunks were produced in order to verify the degree of tissue preservation and determinate its potential for future taxonomic analyses. Finally, it was possible to assess that these assemblages are placed within lacustrine rocks at the base of the Pedra de Fogo Formation (Sílex Basal Member), close to the contact with the underlying Piauí Formation (Carboniferous, Pennsylvanian). This observation contrasts with former studies made at the southwestern margin of the basin that refer the placement of fossil-plant horizons of the Pedra de Fogo Formation to the uppermost Trisidela Member or even to the overlying Motuca Formation.
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Yao, Xuanli. "Gymnosperm reproductive organs from the Triassic of Antarctica /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487858417982483.
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Serres-Giardi, Laurana. "Diversité et évolution des paysages nucléotidiques des plantes." Thesis, Montpellier, SupAgro, 2012. http://www.theses.fr/2012NSAM0045/document.
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Le paysage nucléotidique – la manière dont la composition nucléotidique varie le long du génome – est une caractéristique marquante de l'organisation des génomes et varie fortement entre espèces. Plusieurs hypothèses émergent des nombreux débats autour des mécanismes évolutifs à l'origine de ces hétérogénéités du taux de GC, parmi lesquelles la conversion génique biaisée vers G et C (BGC) et la sélection sur l'usage du code (SUC). La BGC est un processus neutre associé à la recombinaison qui favorise les allèles en G ou C au détriment des allèles en A ou T. La SUC est une force de sélection qui favorise les codons dits « préférés », ceux dont la traduction serait la plus efficace. Contrairement à ceux des vertébrés, les paysages nucléotidiques des plantes sont peu connus. La plupart des études ont été consacrées au génome d'Arabidopsis thaliana, pauvre en GC et homogène, et à celui du riz, riche en GC et hétérogène. Le contraste entre ces deux génomes a souvent été généralisé comme une dichotomie entre dicotylédones et monocotylédones, mais cette vision est clairement phylogénétiquement biaisée.Les objectifs de ce travail de thèse sont de caractériser les paysages nucléotidiques des angiospermes à une large échelle phylogénétique et de mieux comprendre quels sont les mécanismes évolutifs jouant sur l'évolution de ces paysages nucléotidiques. Comment varient les paysages nucléotidiques le long de la phylogénie des angiospermes ? SUC et BGC façonnent-elles ces paysages nucléotidiques ? Les différents taxons sont-ils affectés avec la même intensité ?Pour répondre à ces questions, j'ai utilisé une approche de génomique comparative basée sur l'analyse de données EST chez plus de 230 espèces d'angiospermes et de gymnospermes. L'exploration des paysages nucléotidiques de ce large éventail de plantes a montré que les patrons d'hétérogénéité des paysages nucléotidiques suivent un continuum le long de la phylogénie, avec des groupes particulièrement riches et hétérogènes en GC, les graminées par exemple. Mes résultats suggèrent que les paysages nucléotidiques des plantes pourraient avoir été façonnés par la BGC et, dans une moindre mesure, par la SUC. Des épisodes indépendants d'enrichissement et d'appauvrissement en GC ont vraisemblablement eu lieu au cours de l'évolution des plantes, et pourraient être expliqués par des variations d'intensité de ces mécanismes. En utilisant une prédiction du degré d'expression des EST, j'ai également mis en évidence une diversité dans les codons préférés entre espèces. Les préférences d'usage des codons se sont révélées plus labiles au cours de l'évolution pour les codons des acides aminés au code quatre et six fois dégénéré. J'ai pu lier l'évolution des préférences d'usage des codons à l'évolution de la composition nucléotidique des génomes. Mes résultats suggèrent que la composition en base des génomes, affectée en partie par la BGC, orienterait la coévolution entre préférence d'usage du code et ARNtThe nucleotide landscape – the way base composition varies along a genome – is a striking feature of genome organization and is highly variable between species. The evolutionary causes of such heterogeneity in GC content have been much debated. Biased gene conversion towards G and C (BGC) and selection on codon usage (SCU) are thought to be main forces. BGC is a neutral process associated with recombination favouring G and C alleles over A and T ones. SCU is a selection process favouring the so-called “preferred” codons, i.e., those whose translation is the most efficient. Contrary to vertebrates, plant nucleotide landscapes are still poorly known. Most studies focused on the GC-poor and homogeneous Arabidopsis thaliana genome and on the GC-rich and heterogeneous rice genome. The contrast between these two genomes was often generalized as a dicot/monocot dichotomy but this vision is clearly phylogenetically biased.The objectives of this study are to characterize angiosperm nucleotide landscapes on a wide phylogenetic scale and to better understand the evolutionary mechanisms acting upon the evolution of nucleotide landscapes. To what extent do nucleotide landscapes vary across angiosperm phylogeny? Are nucleotide landscapes shaped by BGC and SCU? Are taxa affected with the same intensity?To tackle these issues, I used a comparative genomic approach relying on EST data analysis on over 230 angiosperm and gymnosperm species. Through the nucleotide landscape survey for such a wide range of species I found a continuum of GC-heterogeneity patterns across phylogeny, some taxa such as Poaceae being strikingly GC-rich and heterogeneous. My results suggest that nucleotide landscapes could have been shaped by BGC and, to a lesser extent, by SCU. GC-content enrichment and impoverishment are likely to have occurred several times independently during plant evolution and could be explained by intensity variations of BGC and SCU. Using a proxy for EST expression level, I also characterized the diversity of preferred codons between species. Codon usage preferences were shown to be evolutionarily more unstable for four- and six-fold degenerate codon families. Finally, I could link the evolution of codon usage preferences to the evolution of genome base composition. My results suggest that genome base composition, partially shaped by BGC, seems to drive the coevolution between codon usage preferences and tRNAs
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Meyer-Berthaud, Brigitte. "Contribution à l'étude des gymnospermes du carbonifère inférieur d'Europe." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37607979t.
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Van, der Merwe Martha Magdalena. "Genetic variation of a widely distributed gymnosperm - Juniperus communis." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621173.
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Mimoun-Labé, Sylvie. "Etude de la cuticule des feuilles de quelques angiospermes et gymnospermes." Aix-Marseille 3, 1997. http://www.theses.fr/1997AIX30102.
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L'epiderme des plantes herbacees et des jeunes plantes ligneuses est recouvert de strates lipophiles appelees "cuticule" ; ce qui forme un revetement protecteur, souple, impermeable a l'eau tout en permettant des echanges gazeux. Cette cuticule de structure complexe est constituee d'un polyester, la cutine, et de cires. Ce travail a consiste a identifier les divers composants de la cutine et des cires de surface et a etudier leur repartition a des fins chimiotaxonomiques a partir des feuilles de douze plantes regionales, sept gymnospermes et cinq angiospermes. Suivant des methodologies specifiques, nous avons isole et caracterise d'une part le polymere de cutine et ses monomeres et d'autre part les cires de surface hydrolysees et efficacement separees en fraction acide et neutre sur resine echangeuse d'ions. Du fait de la structure homologue des constituants, la cpg et la cg-sm sont des methodes de choix pour leur dosage et leur identification apres derivation. La cutine est principalement constituee d'-hydroxy acides en c16 et en c18 eventuellement oxygenes dans la chaine. Les acides 9(10), 16-dihydroxy palmitiques y sont les plus abondants. Cependant, la cutine du fustet est une exception : l'acide 9-hydroxy palmitique, pour la premiere fois mis en evidence dans une cutine de feuille, y est majoritaire. Trois -hydroxy-acides homologues (c12, c14 et c16) sont preponderants dans les cires des pins et du genevrier, l'acide ricinoleique l'est dans l'ephedra, des acides lineaires a longue chaine plutot saturee le sont dans les autres especes. Des hydrocarbures, des alcools a tres longue chaine constituent l'insaponifiale des cires. La presence de nonacosan-10-ol, d',-diols et de m,10-nonacosanediols est notable dans les pins et le genevrier. Les angiospermes se distinguent par la presence d'alcools triterpeniques pentacycliques.
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Fink, Daniel [Verfasser]. "Phloembeladung und Zuckertransport in ausgewählten Gymnospermen / Daniel Fink." Wuppertal : Universitätsbibliothek Wuppertal, 2019. http://d-nb.info/1196220921/34.
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Becker, Annette. "Charakterisierung phylogenetisch informativer MADS-Box-Gene aus der Gymnosperme Gnetum gnemon L." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962815179.
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CALVIA, GIACOMO. "Distribution, floristic and ecological characterization of Sardinian Gymnospermae communities." Doctoral thesis, Università degli Studi di Cagliari, 2021. http://hdl.handle.net/11584/315905.
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A complete analysis of the distribution, ecology and floristic composition of the natural pine woods of Sardinia, belonging to Pinus halepensis Mill., P. pinaster Ait. subsp. pinaster and P. pinea L., was for the first time produced in Sardinia by means of aerial photographs, literature, Local Ecological Knowledge (LEK) and phytosociological surveys carried out within the areas where the three pine species are considered native or putative native. The phytosociological work allowed the description of two new associations for P. halepensis woods, located in the south-western coastal area, as well as the confirmation of a previously described one on the island of San Pietro, which is currently in a more mature stage than its original description. A new association related to P. pinaster subsp. pinaster woods was described in north-eastern Sardinia, with two new sub-associations. Finally, a new association for P. pinea woods on coastal dunes of the south-western Sardinia.
The diachronic study of pine woods’ decrease and subsequent recovery represents an important step in the analysis of how human impact and land use change can influence the vegetation dynamics of pioneer species with restricted distribution ranges in insular contexts. In this respect, the help of local people and toponymy was crucial for trying a reconstruction of the loss happened in recent times. The method here applied can be an example for further research on rare and declining species.
We improved the knowledge of the distribution, ecology and threats of Taxus baccata L. populations in Sardinia as well, by analysing climatic factors, to define yew’s ecological niche and the species potential distribution in the island. In this study, we found 234 different localities were T. baccata grows or was known in recent times, then confirming how the potential distribution is similar to the real one. On the other hand, we highlighted that in many localities the presence of the species is today related to isolated to scattered old individuals.
Many factors are driving this species to become more and more rare in the Mediterranean environments. We selected 40 sites, a part of which are characterised by the presence of T. baccata old-growth woods, then compared these woods with others where human impact and mean dimensions of the samples identify them as younger formations. This comparison was useful to understand which of the structural features are significantly differentiating old-growth stands with yew from younger ones, and can therefore have a methodological value. The places where the species still thrives today are subject to a long pressure by overgrazing and are often the remnants of wider populations reduced by practices such as wildfires, cuttings, and subsequent reforestations. This work increases the knowledge in relation to the health of the species and its distribution in Sardinia. Moreover, it represents a crucial point for its conservation since it shows how future conservation measures seem to be necessary to preserve the most endangered populations. In managed forests, silvicultural systems should be able to maintain, restore or develop structural attributes useful to a reprise of yews free of competition of alien naturalised taxa. Moreover, the application of protection protocols can represent an effective tool for the characterisation of the old growth stands with yews, in order to plan better management and conservation measures.
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Osborn, Jeffrey Mark. "Comparative ultrastructure of fossil gymnosperm pollen and implications regarding the origin of angiosperms /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487757723994964.
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Eldfjell, Yrin. "Identifying Mitochondrial Genomes in Draft Whole-Genome Shotgun Assemblies of Six Gymnosperm Species." Thesis, Stockholms universitet, Matematiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-175410.
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Sequencing efforts for gymnosperm genomes typically focus on nuclear and chloroplast DNA, with only three complete mitochondrial genomes published as of 2017. The availability of additional mitochondrial genomes would aid biological and evolutionary understanding of gymnosperms. Identifying mtDNA from existing whole genome sequencing (WGS) data (i.e. contigs) negates the need for additional experimental work but previous classification methods show limitations in sensitivity or accuracy, particularly in difficult cases. In this thesis I present a classification pipeline based on (1) kmer probability scoring and (2) SVM classification applied to the available contigs. Using this pipeline the mitochondrial genomes of six gymnosperm species were obtained: Abies sibirica, Gnetum gnemon, Juniperus communis, Picea abies, Pinus sylvestris and Taxus baccata. Cross-validation experiments showed a satisfying and forsome species excellent degree of accuracy.Vid sekvensering av gymnospermers arvsmassa har fokus oftast lagts på kärn- och kloroplast-DNA. Bara tre fullständiga mitokondriegenom har publicerats hittills (2017). Fler mitokondriegenom skulle kunna leda till nya kunskaper om gymnospermers biologi och evolution. Då mitokondriernas arvsmassa identifieras från tillgängliga sekvenser för hela organismen (så kallade “contiger”) behövs inget ytterligare laboratoriearbete, men detta förfarande har visat sig leda till bristfällig känslighet och korrekthet, särskilt i svåra fall. I denna avhandling presenterar jag en metod baserad på (1) kmer-sannolikheter och (2) SVM-klassificering applicerad på de tillgängliga contigerna. Med denna metod togs arvsmassan för mitokondrien hos sex gymnospermer fram: Abies sibirica, Gnetum gnemon, Juniperus communis, Picea abies, Pinus sylvestris och Taxus baccata. Korsvalideringsexperiment visade en tillfredställande och för vissa arter utmärkt precision.
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Schmidt, Marion. "Phytochrome in Gymnospermen Genfamilien, Evolution und Expression in Pinus sylvestris L. /." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=960650113.
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Prévost, Alain. "Contribution à l'étude cytophysiologique de la symbiose ectomycorhizienne chez les végétaux ligneux (gymnospermes et angiospermes)." Nancy 1, 1992. http://www.theses.fr/1992NAN10239.
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Les ectomycorhizes de gymnospermes et d'angiospermes, synthétiques ou naturelles montrent des structures identiques dans leurs grandes lignes. Elles sont constituées d'un manteau et d'un réseau de hartig, des composes tanifères sont observes dans le manteau. Les ectomycorhizes lisses du hêtre (lactaricus/fagus sylvatica) ont un rôle protecteur plus marqué que leur rôle nutritionnel, contrairement aux ectomycorhizes à mycelium frangeant. La comparaison des ectomycorhizes à lactarius blennius et à l. Subdulcis révèle que les structures de leurs manteaux et de leurs réseaux de hartig sont différentes. Dans l'ectomycorhize a l. Subdulcis, un champignon ascomycète parasite (leucoscypha leucotricha) envahit de nombreuses cellules corticales. Une étude des deux précédentes associations (lactaires/hêtre) a été réalisée sur une année de végétation. Elle montre que les échanges entre les partenaires sont ralentis pendant une grande partie de l'année, alors que les rapports symbiotiques vrais sont concentres sur une brève période automnale
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Finet, Cédric. "Rôle des familles géniques YABBY et ARF dans la mise en place du carpelle au cours de l'évolution." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2008. http://tel.archives-ouvertes.fr/tel-00340441.
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L'apparition de la fleur a nécessité trois événements majeurs: (i) le regroupement des organes reproducteurs mâles et femelles sur un même axe, (ii) l'internalisation des ovules au sein d'un organe: le carpelle, (iii) la mise en place de pièces stériles en périphérie des organes reproducteurs. Ce travail de thèse consiste en l'identification d'événements moléculaires à l'origine du carpelle. Les gènes ARF3 et ARF4 jouent un rôle clé dans le développement du carpelle chez l'espèce modèle Arabidopsis thaliana. La reconstruction de l'histoire évolutive de ces gènes a permis de montrer qu'ils résultaient d'une duplication dans le lignage menant aux angiospermes. Leurs structures indiquent qu'ils ont évolué par perte de certains domaines protéiques, ceci de manière indépendante dans les lignages ARF3 ou ARF4. Ces changements dans la partie codante constituent un mode d'évolution généralisable à l'ensemble des embryophytes. La famille génique YABBY intervient dans l'établissement de la polarité adadiale-abaxiale des organes latéraux. En particulier, les gènes CRC et INO constituent respectivement deux marqueurs moléculaires du carpelle et de l'ovule. L'étude préliminaire de cette famille semble indiquer l'absence du gène CRC chez les gymnospermes, suggérant que l'apparition de CRC aurait été un pré-requis pour l'origine évolutive du carpelle.
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Karlgren, Anna, Niclas Gyllenstrand, Thomas Källman, and Ulf Lagercrantz. "Conserved function of core clock proteins in the gymnosperm Norway spruce (Picea abies L. Karst)." Uppsala universitet, Växtekologi och evolution, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-192151.
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From studies of the circadian clock in the plant model species Arabidopsis (Arabidopsis thaliana), a number of important properties and components have emerged. These include the genes CIRCADIAN CLOCK ASSOCIATED 1 (CCA1), GIGANTEA (GI), ZEITLUPE (ZTL) and TIMING OF CAB EXPRESSION 1 (TOC1 also known as PSEUDO-RESPONSE REGULATOR 1 (PRR1)) that via gene expression feedback loops participate in the circadian clock. Here, we present results from ectopic expression of four Norway spruce (Picea abies) putative homologs (PaCCA1, PaGI, PaZTL and PaPRR1) in Arabidopsis, their flowering time, circadian period length, red light response phenotypes and their effect on endogenous clock genes were assessed. For PaCCA1-ox and PaZTL-ox the results were consistent with Arabidopsis lines overexpressing the corresponding Arabidopsis genes. For PaGI consistent results were obtained when expressed in the gi2 mutant, while PaGI and PaPRR1 expressed in wild type did not display the expected phenotypes. These results suggest that protein function of PaCCA1, PaGI and PaZTL are at least partlyconserved compared to Arabidopsis homologs, however further studies are needed to reveal the protein function of PaPRR1. Our data suggest that components of thethree-loop network typical of the circadian clock in angiosperms were present beforethe split of gymnosperms and angiosperms.
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Baki, Alexander. "A comparative biogeochemical study of extant, and fossil gymnosperm wood from Axel Heiberg Island, Canada." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484811.
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An analysis of the main lignin, polysaccharide and hemicellulose components of modern and fossil Metasequoia and Larix woods was conducted through the application of Py-GC/MS, tetramethylammonium .hydroxide (TMAH) thermochemolysis, 13C NMR, Py-MS and TG-DSC in order to discern the main similarities and differences between modern and fossil woods, an~ to discover the main reasons for their preservation, the main processes involved in the initial stages of fossilisation, and the palaeoenvironment associated with their depositional sites in Axel Heiberg Island, Canada. Four modern Larix species woods were compared to each other, and then to the only extant Metasequoia species wood to discover the exact similarities and .any differences between them. This was done because the exact species of fossil Larix and Metasequoia are unknown. No differences were found and it is assumed that as no differences exist between modern species, no differences exist between fossil species. The Py-GC/MS total ion chromatogram of the modern woods showed carbohydrate and guaiacyl lignin-derived compounds indicative of gymnosperm wood. A decrease in carbohydrates relative to the modern woods was discovered in the fossil woods and a relative increase in methoxyphenols and tannins. Similarities to the effects of degradation through fungal invasion were noted in the analysis of the fossil woods with a relatively decreased polysaccharide compared to their modern counterpart, with the possibility of fungal degradation during early diagenesis. The TMAH thermochemolysis total ion chromatograms showed an increase of threo/erythro 1-(3,4-dimethoxyphenyl)-1,2,3-trimethoxypropane (G14/G15 - long chain) over 3,4-dimethoxybenzaldehyde/3,4-dimethoxybenzoic acid methyl ester (G4/G6 - short chain) guaiacyl structures from modern to fossil. Similarities to the effects of degradation through fungal invasion were again noted in the analysis of the fossil woods where long chain guaiacyl structures dominate over the short chain guaiacyl structures, reinforcing the possibility of fungal input during early diagenesis. 13C NMR analysis highlighted an increase in side chain degradation from the guaiacyl units thus forming condensed guaiacyl structures, and a decrease in carbohydrate content from the fossil woods relative to the modern woods. Possible tannin input was detected contributing to wood preservation. TG-DSC and Py-MS analysis showed carbohydrate content decreased from modern relative to fossil sample and condensed lignin structures increased. Polysaccharides were shown to be more in abundance within the Metasequoia than Larix sample indicating less degradation had occurred. The fossil woods although degraded, had maintained their basic carbohydrate/lignin structure and were comparable to modern woods degraded through fungal invasion. In addition the nature of the degradation was found to resemble that caused by white rot fungi. The general state of degradation was less severe in the Metasequoia than the Larix. The Metasequoia wood had probably been deposited after that of the Larix and in different environmental conditions, being slightly anoxic, with less fungal input. The presence of tannins together with the subsequent extreme cold of Axel Heiberg Island probably contributed to the woods preservation over time.
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Winter, Kai-Uwe. "Charakterisierung von Orthologen floraler homöotischer B-Funktionsgene der Gymnospermen Gnetum gnemon L." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961482168.
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Gomez, Bernard. "Paléoenvironnements de la marge occidentale de la Téthys au crétacé inférieur : apports taxonomiques et taphonomiques de gisements espagnols." Lyon 1, 2000. http://www.theses.fr/2000LYO10099.
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Une étude taxonomique et taphonomique est consacrée aux Gymnospermes de trois localités du Crétacé inférieur du nord-est de l'Espagne : Montsec (calcaires lithographiques, Berriasien-Barrémien, Pyrénées), Un̂a (Fm La Huérguina, Barrémien supérieur, Chaîne Ibérique Sud-occidentale) et Rubielos de Mora (Fm Escucha, Albien inférieur-moyen, Chaîne Ibérique Orientale). Dix espèces ont été décrites dont neuf sont nouvelles. Pour le Montsec une révision taxonomique est proposée. Uña renferme une association paucispécifique (Frenelopsis ugnaensis sp. Nov. , Classostrobus ugnaensis sp. Nov. Et Glenrosa falcatum sp. Nov. ) contrastant avec la diversité de Las Hoyas, un équivalent latéral de faciès. Rubielos de Mora présente une grande variété végétale : Frenelopsis turolensis sp. Nov. , Classostrobus turolensis sp. Nov. , Turolia escuchaensis gen. Nov. Et sp. Nov. , Nehvizdya penalveri sp. Nov. , Pseudotorellia hispanica sp. Nov. Et Mirovia gothanii sp. Nov. D'après les analyses sédimentologiques et taphonomiques, ces taphoflores appartenaient à des habitats variant de zones côtières saumâtres à des plaines deltai͏̈ques intracontinentales dulçaquicoles. Les restes allochtones de Frenelopsis rubiesensis poussaient à une distance relativement courte des bords de l'étang côtier oligohalin de La Pedrera (El Montsec). Les Cheirolépidiacées allochtones des dépôts deltai͏̈ques et de la plaine d'inondation de Uña provenaient principalement de la plaine deltai͏̈que supérieure du lac de Uña-Las Hoyas. Les végétaux fossiles de Rubielos de Mora furent majoritairement issus de la plaine deltai͏̈que inférieure et s'accumulèrent dans des marais côtiers saumâtres. Les multiples adaptations de ces végétaux étaient associées à des stress écologiques. Leur xénomorphisme s'accorde avec un contexte climatique comprenant une saison chaude aride ou semi-aride. Cependant, les contraintes édaphiques ont également dû entrer en jeu par fluctuation de la nappe phréatique (Uña) ou de la salinité (Rubielos de Mora).
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Sperlich, Dominik. "Mediterranean forests in a changing environment - Impacts of drought and temperature stress on tree physiology." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/327595.
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The Mediterranean Basin is a climate-change hotspot of the world. Predicted reductions in annual precipitation, increases in mean temperature, and increases in the variability and occurrence of extreme droughts and heat waves are likely to affect species abundance and distribution. The existence of sympatric plants with different morphological and phenological strategies raises the question how they will respond to novel climate conditions. There is a strong need to improve the mechanistic understanding of key foliar ecophysiological parameters in response to abiotic stressors on a small scale if we are to predict the carbon budget of plant ecosystems in larger scales.
We first reviewed contrasting growth responses to temperature of angio- and gymnosperms in the Iberian Peninsula. Secondly, we studied the seasonal acclimation of different foliar ecophysiological traits in two leaf positions of four Mediterranean tree species in extensive field experiments. We aimed to shed light on the mechanistic understanding of the foliar respiratory and photosynthetic responses to abiotic stress such as drought and temperature.
We found contrasting demographic responses in Mediterranean conifer and angiosperm trees. Widespread forest successional advance of angiosperms and negative growth responses of gymnosperms to temperature are currently occurring in the Iberian Peninsula. Trait-based differences in these two groups contribute to explain their different responses to temperature and their different role during successional processes.
The acclimation behaviour of photosynthetic and morphological traits to seasonal variable growth conditions was strongly pronounced in all tree species. Photosynthetic machineries were resilient to moderate drought, whereas severe drought induced acclimation of morphological traits, photosynthetic downregulation and leaf abscission. The lack of replenishment of soil-water reserves during the early growing season critically enforced the summer drought.
We also observed a notable seasonal acclimation of the thermal optima and of the curvature of temperature responses of photosynthetic assimilation. The photosynthetic system was better acclimated to lower temperatures in winter and to heat stress in the drier and hotter year.
Mild winter temperatures provided a period of growth and recovery that resulted in biochemical recovery, new shoot growth, and moderate transpiration across all evergreen species. High radiation and sudden low temperatures had a combinatory negative effect on the photosynthetic apparatus leading to photoinhibitory stress -especially in sunlit leaves.
Species-specific acclimation partly offset these overall trends in responses to drought and temperature stress. Quercus ilex L. and to a lesser extent Q. pubescens Wild. showed the highest plasticity in photosynthetic traits whereas Pinus halepensis Mill. was most tolerant across the seasons with the most stable temperature response pattern. Arbutus. unedo L. was the most vulnerable to drought and photoinhibitory stress in winter. A. unedo and Q. pubescens had a less sclerophyllic leaf habit and invested the least in acclimation of the morphological structure being most vulnerable to drought-induced leaf abscission. Shaded leaves showed generally a lower photosynthetic potential, but cushioned negative impacts under stress periods. A long-term rainfall-exclusion experiment in a Q. ilex forest increased the foliar carbon-use efficiency and the plasticity of foliar respiratory and photosynthetic traits, but did not affect the biochemical photosynthetic potential. A favourable growth period was thus exploited more efficiently. Overall, our results indicate that Mediterranean climax-species exhibit a strong acclimatory capacity to warmer and drier conditions, but can be sensitive to extreme drought and extreme temperature stress. The performance of the plants during winter might give important insights in the dynamics of Mediterranean forest communities under novel environmental conditions. Leaf position is an indispensable factor when estimating the canopy carbon balance. Angiosperms and gymnosperms had fundamental different photosynthetic strategies of stress-avoidance versus stress-tolerance, respectively.El cambio climático aumentará la sequía en la Cuenca Mediterránea y posiblemente afectará a la abundancia y la distribución de especies. Revisamos las respuestas contrastadas del crecimiento a la temperatura de angio- y gimnospermas en la Península Ibérica. Estudiamos la variación de los efectos del estrés térmico y por sequía en rasgos morfológicos, fotosintéticos y de la respiración foliar según la especie y la posición en el dosel. Además, evaluamos el efecto de una sequía crónica sobre la respiración foliar y la fotosíntesis de Quercus ilex L. La maquinaria fotosintética se mostró resiliente frente a la sequía moderada, mientras que la sequía extrema, agravada por las bajas reservas de agua en el suelo, indujo la aclimatación de la morfología foliar, la inhibición de la bioquímica fotosintética y la abscisión foliar. El sistema fotosintético se aclimató mejor a las temperaturas bajas que al estrés por calor. Las temperaturas suaves en invierno derivaron en la recuperación bioquímica, un nuevo crecimiento de los brotes y una transpiración moderada. La elevada radiación y el frío repentino mostraron un efecto combinado negativo, causando estrés fotoinhibitorio. El estrés térmico y por sequía fue más pronunciado en hojas de sol y aminorado en hojas de sombra. Q.ilex y, en menor grado, Q. pubescens Wild. mostraron la plasticidad más elevada de los rasgos fotosintéticos, mientras que Pinus halepensis Mill. fue más tolerante, mostrando la respuesta más estable a la temperatura. Arbutus unedo L. fue la especie más vulnerable a la sequía y al estrés fotoinhibitorio. En respuesta a la sequía crónica, Q. ilex incrementó la eficiencia en el uso del carbono y la plasticidad de los atributos fotosintéticos y de respiración foliar, pero no afectó al potencial fotosintético. En resumen, las especies climácicas mediterráneas se aclimatan frente a condiciones más cálidas y secas, pero pueden ser sensibles ante sequías extremas. El funcionamiento durante el invierno es vital para entender la dinámica de los bosques mediterráneos. La posición de las hojas en la copa es indispensable para estimar el balance de carbono del dosel. Angiospermas y gimnospermas presentan estrategias fotosintéticas contrastadas, de evitación y tolerancia del estrés, respectivamente.
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Reynolds, Elizabeth A. "Studies on the evolution of the ethylene forming enzyme : 1-aminocyclopropane-1-carboxylate (ACC) oxidase." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343225.
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Suren, Haktan. "Sequence capture as a tool to understand the genomic basis for adaptation in angiosperm and gymnosperm trees." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/86383.
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Forest trees represent a unique group of organisms combined with ecological and economic importance. Owing to their random mating system and widespread geographical distribution, they harbor abundance genetic variation both within and among populations. Despite their importance, research in forest trees has been underrepresented majorly due to their large and complex genome and scarce funding. However, recent climate change and other associated problems such as insect outbreaks, diseases and stress related damages have urged scientists to focus more on trees. Furthermore, the advent in high-throughput sequencing technologies have allowed trees to be sequenced and used as reference genome, which provided deeper understanding between genotype and environment. Whole genome sequencing is still not possible for organisms having large genomes including most tree species, and it is still not feasible economically for population genomic studies which require sequencing hundreds of samples. To get around this problem, genomic reduction is required. Sequence capture has been one of the genomic reduction techniques enabled studying the subset of the DNA of interest. In this paper, our primary goal is to outline challenges, provide guidance about the utility of sequence capture in trees, and to leverage such data in genome-wide association analyses to find the genetic variants that underlie complex, adaptive traits in spruce and pine, as well as poplar. Results of this research will facilitate bridging the genomic information gap between trees and other organisms. Moreover, it will provide better understanding how genetic variation governs phenotype in trees, which will facilitate both marker assisted selection for improved traits as well as provide guidance to determine forest management strategies for reforestation to mitigate the effects of climate change.Ph. D.
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Lopez-Gallego, Cristina. "Effects of habitat degradation on the evolutionary dynamics of populations in a rainforest cycad (Gymnospermae)." ScholarWorks@UNO, 2007. http://scholarworks.uno.edu/td/555.
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In addition to habitat loss and fragmentation, habitat degradation can have important consequences for biodiversity and population persistence, including effects on ecological and genetic processes beyond decreased demographic viability and the loss of genetic variation. Particularly interesting is the potential for evolutionary changes and adaptation to degraded habitats, that can affect population viability even in the short-term. Here, I explore how environmental changes after habitat degradation affect the evolutionary dynamics of populations of the rainforest cycad Zamia fairchildiana, specifically how habitat degradation affects gene dispersal, inbreeding, directional selection, and genotype-by-environment interactions, and the potential for genetic differentiation between populations. Colonies of Z. fairchildiana showed little genetic differentiation in neutral molecular markers across study sites, thus can be considered as subpopulations. Subpopulations in the disturbed habitat are experiencing different environmental conditions when compared to subpopulation in their native habitat. Disturbed-habitat subpopulations showed a faster life-history. This faster life history is associated with a weaker spatial genetic structure and higher levels of inbreeding in the disturbed-habitat subpopulations. In addition, higher light availability in the disturbed habitat seems to be a major agent of selection on traits like leaf production that have the potential to respond to selection in these subpopulations. Different traits were under selection in the native-habitat subpopulations, suggesting the potential for genetic differentiation between native and disturbed-habitat subpopulations. Genotype by environment interactions in seed germination and seedling survival, in response to light and water availability, further suggested that subpopulations can adaptively diverge between habitats, but the relative role of genetic and environmental factors, particularly maternal effects, on the magnitude and rate of genetic differentiation between subpopulations remains to be evaluated. These results suggest that habitat degradation can have important consequences for the evolutionary dynamics of populations of this cycad, not necessarily typical of habitat loss and fragmentation. This study identified factors and processes important for population persistence in degraded habitats, but population responses to habitat degradation are complex. Thus further studies and long-term experiments are required for better understanding the effects of habitat degradation on population viability.
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Nair, Hema. "A study of intra-ring checking and xylogenesis in Pinus radiata D.Don." Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1325.
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Pinus radiata is the dominant species of the plantations forests in New Zealand. The forest industry in New Zealand is heavily dependant on it. However, Pinus radiata can develop wood quality flaw called 'intra-ring checking'. The checks or splits appear in wood during kiln drying and usually affect the earlywood region of the wood. It lowers value of appearance grade timber leading to huge economic loses for the forest industry. This thesis presents a study that was undertaken as a part of ongoing collaborative work that is being carried out to understand wood quality issues in Pinus radiata, with a vision of improving its wood quality. This study was a part of that effort and was conducted with an aim to gain an insight into intra-ring checking, and the process of xylogenesis in Pinus radiata. The investigations for this study were carried out in two steps. The first step was to understand intra-ring checking. The location of intra-ring checking was determined by observing the checks using various microscopy techniques. Scanning electron microscopy confirmed that checking was as an intercell failure that usually occurs at the cm1/S1 boundary. A comparative study was also conducted to see if the checked wood had some inherent properties that made it more susceptible to checking. It was found that checking could be influenced by tracheid geometry and cell wall thickness. If the wood had large tracheids with thin walls, it was more likely to develop checks during drying. Lignin distribution in the cell wall layers was also seen to play an important role in checking. Lower lignin levels and disruption in the pattern of lignification of the cell wall layers increased the tendency of the wood to develop checks. Similarly, it the tracheids have larger pits then their tendency to check increases. Structural features that disrupt the uniformity of the interlocking pattern of the tracheid such as rays and resin canals could also play a role in checking. Checked wood tends to have more surface area occupied by ray tissue. However, resin canals do not seem to be directly involved in checking, though their arrangement could indicate disturbances during xylogenesis. The second step was to understand the process of xylogenesis in Pinus radiata especially with respect to the influence of auxin and boron on it. Nutrient and organ culture methods were manipulated and successfully used to study xylogenesis. An exhaustive comparative study was carried out to observe and measure selected wood properties. Microscopy and image analysis revealed that auxin and boron changes in the medium led to the alterations in the cell division, expansion and lignification. However, the analysis of the measurements and the observations displayed complex 'between-tree' and 'within-culture variations'. Clear trends did not emerge from the analysis hence, a confident conclusion on the association between auxin, boron and lignification could not be drawn from this organ culture study. The study has added to the knowledge about checking and wood properties associated with it. A new tool of organ culture had been established that can hlep future research on the process of xylogenesis in Pinus radiata.
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Seridi-Benkaddour, Ratiba. "Etudes ultrastructurales et biochimique de la sécrétion de la goutte micropylaire par le nucelle au moment de la pollinisation chez quatre gymnospermes." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376185586.
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Baumann, Alexander [Verfasser], Birgit [Akademischer Betreuer] Classen, and Thomas [Gutachter] Kunze. "Isolierung und Charakterisierung von Arabinogalactan-Proteinen aus Gymnospermen und Interaktionsstudien mit humanen Galektinen / Alexander Baumann ; Gutachter: Thomas Kunze ; Betreuer: Birgit Classen." Kiel : Universitätsbibliothek Kiel, 2020. http://d-nb.info/1221129805/34.
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Johns, Jason W. "Araucaria in the Urban Landscape: A Novel Leaning Pattern and Evidence of Cultivated Hybridization." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1784.
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Our understanding of the natural world is constantly evolving and strengthening as more observations are made and experiments are performed. For example, we understand that tree stems grow toward the light (positive phototropism; Darwin 1880, Loehle 1986, Christie et al. 2013) and against gravity (negative gravitropism; Knight 1806, Hashiguchi et al. 2013). We also know that plants respond to mechanical stimulus and perturbation (thigmotropism; Braam 2005). Genes and their resulting proteins have been described to uncover some of the mechanisms for these environmental responses, but relatively speaking, we have just scratched the surface (Wyatt et al. 2013). While the discovery of the molecular mechanisms responsible for these behaviors is certainly dependent on the ever-improving lab technology available, every molecular discovery is dependent on a macroscopic observation.
In this manuscript I present the two novel macroscopic observations I made on members of Araucaria in the urban forest. The first describes a hemisphere-dependent lean in A. columnaris, and the second provides genetic and morphological evidence that hybrids exist between A. columnaris and A. heterophylla.
Araucaria columnaris (J.R. Forst.) Hooker, or the Cook Pine is a conifer with a narrow native range that has been cultivated worldwide and grows unlike any other tree known. The initial observation we made was that trees in California and Hawaii lean south, and trees in California lean to a greater extent than trees in Hawaii. Measuring 250 trees in 16 regions worldwide, however, produced statistically significant evidence for a hemisphere dependent directional leaning pattern. Trees in the northern hemisphere lean south, and trees in the southern hemisphere lean north. Additionally, the lean becomes more pronounced at greater distances from the equator.
We also gathered morphological and genetic evidence in the California urban forest that A. columnaris and A. heterophylla (Salisb.) Franco are hybridizing. Many individuals have intermediate characteristics of both species, which originally led me to believe that hybrids exist in cultivation. After analyzing several individuals with microsatellite genetic markers, I have enough evidence to conclude that hybrids between A. columnaris and A. heterophylla exist. This is an important observation mainly for municipalities and arborists interested in properly identifying trees in the urban forest. Knowing the proper identity of trees is imperative to informing decisions about their protection or removal.
As we continue to ask questions about the inner workings of nature we will continue to gain a better appreciation for what we still do not know. The evidence provided in this manuscript better informs our future questions about a leaning pattern in A. columnaris and about the history of the cultivation of Araucaria.
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Kögler, Anja [Verfasser], Stefan [Gutachter] Wanke, and Michael [Gutachter] Göttfert. "Diversity and Evolution of Short Interspersed Nuclear Elements (SINEs) in Angiosperm and Gymnosperm Species and their Application as molecular Markers for Genotyping / Anja Kögler ; Gutachter: Stefan Wanke, Michael Göttfert." Dresden : Technische Universität Dresden, 2020. http://d-nb.info/1227201877/34.
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Seridi-Benkaddour, Ratiba. "Etude ultrastructurale et biochimique de la secretion de la goutte micropylaire par le nucelle au moment de la pollinisation chez quatre gymnospermes : thuya orientalis, cupressacees, cephalotaxus drupacea, cephalotaxacees, taxus baccata, taxacees." Paris 7, 1988. http://www.theses.fr/1988PA077152.
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Droin-Josserand, Albane. "Etude expérimentale des mouvements de l'eau dans l'aubier de pin sylvestre dans le domaine hygroscopique : modélisation et simulation." Saint-Etienne, 1988. http://www.theses.fr/1988STET4009.
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Une étude expérimentale des transferts d'humidité dans l'aubier de pin sylvestre dans le domaine hygroscopique a été effectuée. L'étude de l'influence de plusieurs paramètres sur les transferts (direction de diffusion, teneur en eau du bois, température, dimensions de l'échantillon) a permis d'obtenir les données nécessaires à l'élaboration d'un modèle mathématique. Ce modèle permet de simuler les cinétiques de transfert d'humidité dans le bois (aubier de pin mais aussi d'autres espèces), à humidité relative constante ou variant au cours du temps. Le modèle étant tridimensionnel, on peut connaitre les teneurs en eau à chaque instant et en chaque point de l'échantillon. Ces renseignements sont nécessaires pour prévoir une éventuelle biodégradation par les champignons
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Efransjah, M. "Contribution à l'étude de la préservation du bois : Amélioration de l'imprégnabilité de l'épicéa (picéa SP.) par un pré-traitement bactérien et caractérisation du comportement du bois par l'utilisation des ultrasons." Nancy 1, 1988. http://www.theses.fr/1988NAN10032.
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On a sélectionné trois souches appartenant aux germes bacillus et pseudomonas, produisant les enzymes susceptibles de détruire les composés pecto-cellulosiques du torus des ponctuations. On a évalué l'augmentation de la perméabilité par la mesure de la rétention du PCP, de CUSO::(4) et de CCA, on a vérifié l'activité des procaryotes par meb. On a constaté une action positive des germes aussi bien en condition stérile qu'en condition semi-industrielle. L'application d'une technique ultrasonore a montré l'absence de modification significative des propriétés mécaniques selon l'axe longitudinal. On a observé cependant une réduction de 30% du module de rigidité selon les axes radial et tangentiel
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Ibnusantosa, Gatot. "Contribution à l'étude de l'imprégnation de plaquettes de bois par des solutions aqueuses de soude." Grenoble INPG, 1988. http://www.theses.fr/1988INPG0063.
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On a mesure les gonflements directionnels et la masse volumique de plaquettes de hetre, peuplier et epicea de diverses epaisseurs, saturees par des solutions de soude. Les gonflements observes sont compris entre deux valeurs limites et sont d'autant plus importants que les plaquettes sont moins epaisses. Seul le gonflement tangentiel est affecte par la presence de soude en solution. Les masses volumiques mesurees indiquent qu'il n'y a pas additivite des volumes de la matiere vegetale et de la solution impregnante et que la masse volumique est d'autant plus faible que le gonflement volumique est plus important
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Buratti, Lionel. "Etude des acides diterpeniques des aiguilles du pin sylvestre, pinus silvestris l. : incidences sur le comportement alimentaire des larves de diprion pini l. (hymenoptere : diprionidae)." Orléans, 1988. http://www.theses.fr/1988ORLE2019.
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Lelu, Marie-Anne. "Embryogenese somatique chez picea abies l. Karst. A partir de cotyledons de jeunes plantes." Paris 6, 1987. http://www.theses.fr/1987PA066485.
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Les travaux relatant l'embryogenese somatique chez les gymnospermes sont encore recents et n'ont ete realises qu'a partir de materiel tres juvenile. C'est ce genre d'explant que nous avons utilise comme temoin pour caracteriser et visualiser l'embryogenese somatique. Nous avons par la suite obtenu ce phenomene a partir de cotyledons de jeunes plantes agees de 3 a 7 jours apres germination, places directement en conditions de callogenese. Cependant, le taux de cals embryogenes est ameliore quand les cotyledons subissent un traitement caulogene d'une semaine prealablement; dans nos meilleures conditions experimentales 22,7% de cotyledons forment des cals embryogenes. Ceux-ci, places sur un milieu de multiplication, doivent etre subdivises et repiques tous les 10 a 12 jours afin de favoriser leur proliferation
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Pilate, Gilles. "Etude du role des phytohormones dans le developpement vegetatif et floral chez pseudotsuge menziesii (mirb. ) franco, par des methodes immunoenzymatiques." Paris 6, 1987. http://www.theses.fr/1987PA066580.
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Fouret, Yolande. "Etude in vitro du rajeunissement prealable a la micropropagation chez le sequoia sempervirens (endl. ) : recherche de marqueurs morphologiques, physiologiques et biochimiques." Paris 6, 1987. http://www.theses.fr/1987PA066379.
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En utilisant la technique de culture in vitro, nous nous sommes attaches a etudier les modalites du rajeunissement par des subcultures reiterees d'explants miniaturises chez deuxx clones de sequoia sempervirens issus d'arbres ages de 50 et 500 ans. Le choix du traitement doit etre d'autant plus drastique que le clone est issu d'arbres ages. Parmi les nombreux criteres etudies, nous en avons determine plusieurs permettant de suivre l'evolution du rajeunissement du materiel : la hauteur des tiges, le nombre de feuilles, l'enracinnement ( pourcentage et delai) et la reactivation des meristemes caulinaires isoles
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Kaushal, Parvinder. "Analyse écophysiologique des effets de stress liés aux transplantations des arbres forestiers." Nancy 1, 1987. http://www.theses.fr/1987NAN10299.
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Influence d'un stress hydrique sur l'établissement et la croissance des semis transplantés (effets sur la photosynthèse et la transpiration). Aide à la règlementation racinaire et à la reprise des plants par habillage des racines et apport d'une fertilisation azotée. Évolution des réserves carbonées : sucres solubles et amidon. Enrichissement atmosphérique en CO::(2) pour augmenter la production de biomasse et réduire le temps d'élevage en pépinière
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Arquilliere, Sylvie. "Morphologie, croissance, reproduction végétative de l'épicéa (Picea abies(L. )Karsten. ) dans une zone de combat subalpine : massif du Taillefer, Alpes dauphinoises." Grenoble 1, 1986. http://www.theses.fr/1986GRE10080.
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On examine les caracteristiques ecologiques essentielles de la zone de combat de l'epicea, a sa limite superieure subalpine afin de mieux connaitre la dynamique du peuplement etudie. Etude des interactions etroites entre parametres microstationnels, facteurs climatiques et comportement des arbres (morphologie, croissance, reproduction vegetative). Une analyse dendroclimatologique, realisee a posteriori, permet de completer et de confirmer les precedents resultats
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Grieu, Philippe. "Écophysiologie du douglas : Contribution à l'étude de l'influence des déficits hydriques sur les échanges gazeux, la croissance et l'accumulation de métabolites organiques." Nancy 1, 1986. http://www.theses.fr/1986NAN10354.
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Analyse en milieu naturel des potentialités intraspécifique de viabilité et de croissance de plants forestiers adultes à travers leur aptitude à une régulation des pertes d'eau. Étude en milieu contrôlé des potentialités photosynthétiques et des flux transpiratoires en fonction des principaux paramètres climatiques. Une approche plus moléculaire de cette étude a consisté à préciser les éventuelles accumulations de certains composés organiques dans les tissus végétaux lors de contraintes hydriques édaphiques
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Bon, Marie-Claude. "Aspects biochimiques du clonage de sequoias geants (sequoiadendron giganteum buchholz) jeunes et ages." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF21076.
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L'efficacite de la micropropagation du sequoia geant demeure conditionnee par l'etat de juvenilite des explants, sous la dependance de l'age physiologique. La synthese des analyses proteiques en tenant compte de l'influence des parametres physiologiques et genotypiques permet de proposer une proteine membranaire de 16000 daltons (j16) comme marqueur du degre de juvenilite ou par corollaire de maturite, renseignant notamment sur les potentialites organogenes de reactivite des explants en vue du clonage conforme