Um die anderen Arten von Veröffentlichungen zu diesem Thema anzuzeigen, folgen Sie diesem Link: Plants.
Dissertationen zum Thema „Plants“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-50 Dissertationen für die Forschung zum Thema "Plants" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Dissertationen für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
1
Lucas, W. J. „Plant physiology : transport processes in plants /“. Title page, preface and contents only, 1989. http://web4.library.adelaide.edu.au/theses/09SD/09sdl933.pdf.
Der volle Inhalt der QuelleAnnotation:
Thesis (D. Sc.)--Faculty of Science, University of Adelaide, 1990.Published works [representing] original research conducted during the various phases of [his] academic development--Pref. Includes bibliographical references.
2
Davison, Elisabeth, John Begeman, Jimmy Tipton und Tom DeGomez. „Plant Selection and Selecting Your Plants“. College of Agriculture, University of Arizona (Tucson, AZ), 2015. http://hdl.handle.net/10150/560978.
Der volle Inhalt der QuelleAnnotation:
Revised; Originally Published: 20008 pp.
Whether you are beginning a new landscape or renovating an existing one, planning ahead can prevent many problems. The majority of maintenance requirements and plant problems result from either selecting the wrong kind of plant for a location or planting an inferior specimen of the selected plant type. In other words, there are two decisions to be made: ▪ What species, or kind, of tree are you going to buy — an oak, pine, mesquite, or acacia? ▪ Assuming you decide on an oak, which one in the row of oaks at the nursery are you going to buy? The first decision is called Plant Selection and the second is Selecting Plants. Our goal is to install the right plant in the right place. This publication will cover the factors involved in making good decisions to achieve this goal.
3
Davison, Elizabeth. „Plant Selection and Selecting Your Plants“. College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2000. http://hdl.handle.net/10150/144757.
Der volle Inhalt der QuelleAnnotation:
8 pp.The majority of maintenance requirements and plant problems result from either selecting the wrong kind of plant for a location or from planting an inferior specimen of the selected plant type. The first decision is called Plant Selection and the second one is Selecting Plants. This publication covers the factors involved in making good decisions to install the right plant in the right place.
4
Kering, Maru K. Blevins Dale G. „Manganese nutrition and photosynthesis in NAD-malic enzyme C-4 plants“. Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/7201.
Der volle Inhalt der QuelleAnnotation:
Title from PDF of title page (University of Missouri--Columbia, viewed on February 24, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Dale Blevins. Vita. Includes bibliographical references.
5
Olsen, Mary W. „Diseases of Urban Plants in Arizona“. College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/144807.
Der volle Inhalt der QuelleAnnotation:
26 pp.Geographically, Arizona can be divided roughly into four areas, southwest, central, southeast, and northern. These regions correspond with four climatic zones, allowing a large and diverse number of plants to be grown for landscaping purposes. But, interestingly, in this desert environment many of the parasitic diseases in landscape plants are caused by a limited number of plant pathogens. This publication discusses some of those diseases that are sufficiently important to the urban plants in all areas Arizona.
6
Stone, Bethany. „The effects of boron deficiency and aluminum toxicity on plant magnesium /“. free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3036861.
Der volle Inhalt der Quelle
7
Koehler, Samantha 1975. „Relações filogeneticas e diversificação no complexo 'Maxillaria Madida' (Maxillariinae:Orchidaceae)“. [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315354.
Der volle Inhalt der QuelleAnnotation:
Orientador: Maria do Carmo Estanislau do AmaralTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-10T06:25:59Z (GMT). No. of bitstreams: 1 Koehler_Samantha_D.pdf: 6443365 bytes, checksum: 6a01c884fb24c1fbf015cf1b2ab4e212 (MD5) Previous issue date: 2007
Resumo: Não informado
Abstract: Not informed.
Doutorado
Biologia Vegetal
Mestre em Biologia Vegetal
8
Blum, Dale. „The role of red and blue light in leaf and cotyledon expansion /“. Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/5267.
Der volle Inhalt der Quelle
9
au, A. Mccomb@murdoch edu, und Arthur James McComb. „Plants and the environment“. Murdoch University, 2006. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20070828.135211.
Der volle Inhalt der Quelle
10
Singer, Rosana Farias. „Estudos ontogeneticos de flor e fruto em especies de Bignoniaceae com enfase na taxonomia“. [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315177.
Der volle Inhalt der QuelleAnnotation:
Orientador: João SemirTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-10T10:17:49Z (GMT). No. of bitstreams: 1 Singer_RosanaFarias_D.pdf: 19199909 bytes, checksum: a0d90fabd78d18997e2177dedff1b801 (MD5) Previous issue date: 2007
Resumo: O presente trabalho teve como objetivo estudar ontogenética e morfologicamente a flor e o fruto em representantes de Bignoniaceae no intuito de verificar se ocorrem padrões no desenvolvimento do ovário bem como o modo de formação do septo e placentas e a forma de compressão do fruto nesta família. Foram realizados estudos ontogenéticos com abordagens anatômicas e de Microscopia Eletrônica de Varredura em gemas florais, botões florais, flores e frutos de representantes selecionados de acordo com atributos morfológicos de interesse taxonômico como o tipo de fruto (indeiscente/deiscente), deiscência deste em relação à coluna seminífera (paralela/perpendicular), tipo de coluna seminífera e em Jacaranda, um representante de cada seção. As espécies estudadas foram: Cybistax antisyphilitica (Mart.) Mart., Jacaranda mimosifolia D. Don (seção Jacaranda) e Jacaranda simplicifolia K. Schum. ex Bureau & K. Schum. (seção Dilobos), Digomphia laurifolia Benth. (Tecomeae), Arrabidaea brachypoda Bureau (Bignonieae) e Parmentiera cereifera Seem. (Crescentieae). Efetuou-se o estudo morfológico das espécies de Jacaranda e de Digomphia nativas do Brasil, com intuito de obter caracteres diagnósticos com enfoque em Jacaranda que apresenta espécies muito parecidas, de difícil posicionamento taxonômico. Verificou-se que o surgimento dos primórdios de filomas florais ocorre centripetamente, de forma sincrônica ou assincrônica. Os dois carpelos são ascidiados e originam-se na região central do domo, podendo esta se tornar côncava antes da iniciação dos carpelos. O septo pode estar presente desde os estádios iniciais do desenvolvimento ou surgir posteriormente. Através do estudo anatômico, verificou-se que em todas as espécies analisadas os primeiros feixes vasculares a se formarem no ovário são os dorsais, seguidos dos ventrais. Ocorrem quatro placentas, nas quais os óvulos se desenvolvem da região central próxima ao tecido transmissor para as regiões periféricas do septo, de forma basípeta ou acrópeta, variando em número de fileiras e óvulos conforme as espécies. Os óvulos são unitegumentados e anátropos. O estaminódio, mesmo que vestigial, desenvolve-se mais rapidamente que as anteras nos estádios ontogenéticos iniciais. No desenvolvimento do fruto, as maiores modificações ocorrem na região mediana do pericarpo jovem, junto aos feixes vasculares laterais, onde surgem novos feixes e fibras orientadas em vários sentidos. Registrou-se a presença de um replo em A. brachypoda, constituído por um feixe vascular lateral no pericarpo, rico em fibras e adjacências da coluna seminífera. Em Jacaranda, pode-se fazer as seguintes inferências: a Seção Dilobos apresenta plantas com hábito arbustivo ou arbóreo, com as folhas são bipinadas na maioria das árvores e pinadas nos arbustos, exceto em J. simplicifolia, que é um arbusto com folhas simples. Na Seção Jacaranda, a maioria das espécies é arbórea, com folhas bipinadas e as inflorescências são mais complexas. As espécies arbóreas de Jacaranda com folhas bipinadas e anteras monotecas possuem os frutos lenhosos, enquanto que os frutos sublenhosos a cartáceos estão dentre as espécies arbustivas e xilopodíferas deste gênero. Digomphia compartilha com Jacaranda caracteres morfológicos como a forma de compressão do fruto, deiscência perpendicular ao septo e estaminódio alongado com tricomas glandulares. A disposição dos feixes vasculares no ovário e no fruto é característica destes dois gêneros diferindo dos demais gêneros de Bignoniaceae aqui estudados
Abstract: This contribution involves the study on both, morphological and ontogenetic grounds of flower and fruit early development within representative species of Bignoniaceae. Emphasis is given to possible patterns of ovary, placentae, and septum development, as well as on fruit shape and compression. Anatomical and SEM studies were performed on floral primordia, floral buds, flowers and fruits of morphologically and taxonomically representative species. Morphological features of taxonomic relevance (type of fruits and dehiscence; type of seminal axis, etc). The studied species were Cybistax antisyphilitica (Mart.) Mart., Jacaranda mimosifolia D. Don (section Jacaranda), J. simplicifolia K. Schum. ex Bureau & K. Schum. (section Dilobos), Digomphia laurifolia Benth. (Tecomeae), Arrabidaea brachypoda Bureau (Bignonieae) and Parmentiera cereifera Seem. (Crescentieae). Complementary morphological studies were performed on native Brazilian species of Jacaranda and Digomphia. These studies were mainly focused on Jacaranda, a genus with remarkable taxonomic problems and were aimed to assemble sets of diagnostic characters for species of difficult identification. The arising of floral primordia is centripetal, the development of the primordia being synchronic or asynchronic. The two ascidiate carpels arise at the dome¿s center. This dome¿s central region may turn concave prior to carpel initiation. The septum may or may not be present at earliest developmental stages. At the ovary, the dorsal vascular bundles develop first, followed by the ventral ones. There are four placentae and the ovules develop from the central region next to the transmitting tissue, toward septum¿s peripheral region; in a basipetal to acropetal way. The number of ovules and series varies according to the species. The ovules are unitegmic and anatropous. The staminode, even in species where it is vestigial, develops faster than functional anthers during the earlier developmental stages. During fruit development, most significant modifications involve the median region of the young pericarp; where a number of variously arranged vascular bundles and fibers appear near the vascular bundles. The tissue originating the line of fruit dehiscence appears soon after the ovules are fertilized. A replum was recorded in A. brachypoda. This replum consists of a fiber-rich central vascular bundle, part of the pericarp and part of the seminal axis. Considering Jacaranda, the following inferences can be done: In its current delimitation, section Dilobos includes shrubs or trees. Most trees display bipinnate leaves. Conversely, shrubs show pinnate leaves. Remarkably, one species within this section (J. simplicifolia) is a shrub with simple leaves. Within the section Jacaranda, most species are trees with bipinnate leaves. The inflorescences are more complex in this section. Arboreal, monotecic species with bipinnate leaves display lignified fruits. Conversely, coriaceous fruits are restricted to the shrubby or xylopodiferous species. Digomphia shares a number of morphological features with Jacaranda, such as fruit shape, compression type and dehiscence, presence of an elongate staminodium covered with glandular trichomes and a characteristic arrangement of ovary and fruit vascular bundles. This latter feature is quite different in the other studied Bignoniaceae genera
Doutorado
Doutor em Biologia Vegetal
11
Tront, Jacqueline Marie. „Plant Activity and Organic Contaminant Processing by Aquatic Plants“. Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5234.
Der volle Inhalt der QuelleAnnotation:
This research explored fate of organic contaminants in aquatic plant systems through (i) experimental development of relationships to describe sorption, uptake and enzymatic processing of contaminants by plants and inhibition of aquatic plants by contaminants and (ii) incorporation of experimental relationships into a conceptual model which describes contaminant fate in aquatic plant systems. This study focused on interactions of aquatic plants L. minor and M. aquaticum with halogenated phenols. 2,4,5-trichlorophenol (2,4,5-TCP) and 2,4-dichlorophenol (2,4-DCP) are precursors for the highly toxic and heavily applied herbicides 2,4,5-T and 2,4-D and were examined in detail. Chlorophenols are generally resistant to microbial degradation, a property which may limit microbial remediation options as effective alternatives for clean up of contaminated sites.
Relationships for fundamental interactions between plants and contaminants that dictate uptake, enzymatic processing and sequestration of contaminants by aquatic plants were established. An assay which quantified production of oxygen by plants was developed to quantify plant metabolic activity and inhibition. Uptake of chlorinated phenols depended on plant activity and aqueous phase concentration of contaminant in the protonated form. Therefore, plant activity, contaminant pKa and media pH were established as critical parameters controlling rate of contaminant uptake. A conceptual model was developed which incorporated plant activity and inhibition into a mathematical description of uptake of organic contaminants by aquatic plants. The conceptual model was parameterized using experimental data delineating effect of plant activity, inhibition and speciation on contaminant uptake and the model was verified using independently gathered data. Experimentation with radio-labeled chlorinated phenols established that contaminants were sequestered internal to plants by plant enzymatic processing. 19F NMR was established as a technique to quantify transformation and conjugation products internal to plants and contaminant assimilation by plants and demonstrated that multiple metabolites containing the parent compound were present and quantifiable internal to plants. Finally, fate of plant-sequestered contaminants in an anaerobic bioassay was examined using Desulfitobacterium sp. strain Viet1.
The results of this study address the role of aquatic plants in sequestration of contaminants in surface waters that indicate the potential and limitations of use of aquatic plants in natural and engineered treatment systems.
12
Hall, Anthony James William. „The characterisation of Arabidopsis plants expressing lower plant phytochromes“. Thesis, University of Leicester, 1999. http://hdl.handle.net/2381/29794.
Der volle Inhalt der QuelleAnnotation:
Two phytochrome-like gene fragments have been isolated using a degenerate PCR strategy from the fern Pteridium aquilinum (bracken). Both share a high degree of similarity with each other and to previously isolated phytochromes. In an attempt to isolate larger phytochrome gene fragments and full length phytochrome genes a cDNA library was constructed from light-grown young bracken fronds. The library was screened with one of the bracken phytochrome fragments. The low level of abundance of phytochrome message, however, hindered the isolation of phytochrome genes from the cDNA library. The high degree of sequence homology between lower and high plant phytochromes has led to speculation on whether or not lower plant phytochromes can be functional in higher plants. This speculation can be addressed by expressing the lower plant phytochromes transgenically in higher plants and assaying for biological function. Arabidopsis thaliana ecotype Landsberg erecta has been transformed using an Agrobacterium mediated root explant transformation system with a phytochrome-like gene isolated from the fern Anemia phyllitidis. The phytochrome gene, PHY3 was placed under the control of a double 35S cauliflower mosaic virus (CaMV) promoter. A second construct has also been used to transform Arabidopsis containing the NH2-terminal half of Anemia PHY3 gene fused to the C-terminal half of oat PHYA. This construct was also attached to a CaMV promoter. Expression of these two constructs causes a reduction in sensitivity of the seedlings to continuous FR. This decreased sensitivity results in a long hypocotyl phenotype under FR, a reduction in anthocyanin production in FR and an inability of FR to block greening. The transgenic lines, however, showed a WT response to VLF light. It is apparent that the expression of the Anemia PHY3 gene is, in some way, interfering with the normal transduction of the phyA signalling pathway. The interference is restricted to the FR HIR.
13
Hervé, Maxime. „Écologie chimique de l'interaction colza - méligèthe : vers de nouvelles stratégies de contrôle des insectes ravageurs ?“ Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S070/document.
Der volle Inhalt der QuelleAnnotation:
Les plantes possèdent de multiples systèmes de défense contre les insectes phytophages. Dans un contexte agronomique, manipuler ces défenses au moyen de la sélection pourrait contribuer à réduire les dommages causés par les insectes ravageurs en augmentant la résistance naturelle des plantes. Cette stratégie se heurte cependant à des contraintes très fortes lorsqu'il s'agit de l'appliquer aux insectes. Après avoir détaillé ces contraintes, nous proposons une démarche alternative aux méthodes classiques. Celle-ci vise à identifier des traits-clés de la plante qui modulent son interaction avec le ravageur. Si de tels traits sont identifiés et validés expérimentalement, ils permettront ensuite de conduire la sélection sans nécessiter d'insecte. Nous avons testé cette démarche dans un système composé du colza (Brassica napus) et du méligèthe Meligethes aeneus, un ravageur majeur de cette culture. Le méligèthe est un coléoptère pollinivore dont les adultes sont généralistes mais ne pondent que sur certaines brassicacées. Les dégâts agronomiques sont causés par ces adultes qui, avant que la floraison ne démarre, détruisent les boutons floraux pour atteindre le pollen qu'ils contiennent. Quatre étapes cruciales de l'interaction ont été étudiées : l'attraction à distance, l'alimentation des adultes, la production et la ponte des œufs, et le développement larvaire. Six génotypes de colza ont été comparés dans une série d'expérimentations au laboratoire. La mise en relation des résultats de préférence/performance de l'insecte avec des profilages métaboliques larges de tissus floraux a permis d'identifier des traits-clés candidats. Les conclusions principales de ce travail sont (i) que la composition biochimique du périanthe est déterminante dans la stimulation de l'alimentation des adultes, et que cette stimulation pourrait être largement sous l'influence d'un petit nombre de composés dont le saccharose ; (ii) que cette stimulation détermine de façon majeure, par un effet domino, la production d'œufs en contraignant l'ovogenèse ; (iii) que la qualité nutritionnelle du pollen impacte à la fois les larves et les adultes, et que cette qualité pourrait être déterminée en bonne partie par la concentration en amidon et en certains glucosinolates (des métabolites secondaires typiques de quelques familles végétales dont les brassicacées). La combinaison des différents résultats obtenus permet également de proposer des hypothèses plus générales, parmi lesquelles le fait que le contexte agronomique dans lequel l'interaction a lieu ait largement influencé, voire perturbé, l'interaction qui liait le méligèthe et les brassicacées sauvages avant que les cultures de colza ne se généralisent. Cette thèse a montré qu'une nouvelle voie était peut-être envisageable pour contribuer à protéger les cultures de façon durable contre les insectes ravageurs, en particulier pour les systèmes agronomiques où les dégâts sont causés à un stade temporairement sensible de la culturePlants display multiple defense systems against phytophagous insects. Manipulating these defenses by means of selection could contribute to decrease damages caused by insect pests, by increasing natural resistance of crops. This strategy faces great constraints when applied to insects. We first detail these constraints and then propose an alternative approach to classical methods. It consists in identifying key plant traits that determine the intensity of the interaction between the plant and the pest. If such traits are identified, selection could be conducted on the basis if these sole traits, without needing any insect. We tested this approach in a system composed of oilseed rape (Brassica napus) and the pollen beetle (Meligethes aeneus), a major pest of this culture. This coleopteran generalist pollen feeder lays eggs only on certain brassicaceous plants. Agronomical damage arise before plant flowering and are caused by adults, which destroy flower buds to get the pollen they contain. Four crucial steps of the interaction were studied: attraction, adult feeding, egg production and oviposition, and larval development. Six oilseed rape genotypes were compared in a series of experiments conducted in the laboratory. By linking insect preference/performance to large metabolic profiling of bud tissues, we identified candidate key traits. Main conclusions of this work are (i) that biochemical composition of the perianth, especially a few compounds among which sucrose, is determinant for feeding intensity; (ii) that feeding stimulation has an important impact on egg production by constraining oogenesis; (iii) that pollen nutritional quality, probably mostly determined by starch and some glucosinolates, interacts with both pollen beetle larvae and adults. Combination of several results also allows drawing more general hypotheses about the oilseed rape - pollen beetle interaction. One of these is that the agronomical context in which the interaction takes place may have largely influenced, or even disturbed, the interaction that linked this insect and wild brassicaceous plants before oilseed rape cultivation. This thesis showed that a new way might be possible to protect cultures against insect pests. It could be both efficient and sustainable, especially in systems where agronomical damage is caused at a temporary vulnerable plant stage
14
Tarrant, Valerie M., und valerie tarrant@deakin edu au. „Melbourne's indigenous plants movement: The return of the natives“. Deakin University. School of History, Heritage and Society, 2005. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20061207.113857.
Der volle Inhalt der QuelleAnnotation:
This thesis examines Greater Melbournes indigenous plants movement from the 1930s to the early twenty first century. It demonstrates the important scientific and educational role of the public intellectual, Professor John Turner, and of the Melbourne University Botany School which he led for thirty five years. The case study of the movement within the City of Sandringham and its successor the City of Bayside reveals how the inhabitants of an urbanised are responded to threats to the indigenous trees and wildflowers of their neighbourhood, stimulating botanists to assist them and using political means in order to achieve their conservation objectives. The thesis draws upon a range of local archives, conservation literature and private papers.
15
Reichard, Sarah H. „Assessing the potential of invasiveness in woody plants introduced to North America /“. Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/5534.
Der volle Inhalt der Quelle
16
Naku, Mandilakhe. „Functional role of ammonium and nitrate in regulating transpiration for mass-flow acquisition of nutrients in Phaseolus vulgaris L“. Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2679.
Der volle Inhalt der QuelleAnnotation:
Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2017Transpiration serves in leaf cooling, maintaining turgor pressure, promoting xylem transport of nutrient solutes from roots to shoots and delivering mobile soil nutrients to root surfaces. Soil availability of nitrogen can modulate transpiration rates, consequently powering nutrient delivery to the root surfaces (‗mass-flow'). Although such knowledge on N-regulation of transpiration is available, it remains unknown, however, whether it is NO3- or NH4+ that regulates transpiration. Given that both nitrogen forms co-occur in soils, it is not known how they interact at varying ratios in modulating stomatal behaviour. To test the functional role of NO3- and NH4+ in regulating water fluxes for mass-flow nutrient acquisition, P. vulgaris L. plants were grown with NO3- or NH4+ placed at one of four distances behind a nylon mesh, which prevented direct root access to nitrogen, whilst control plants intercepted the nitrogen source (Chapter 3). Day- and night-time stomatal conductance and transpiration, measured using Infra-Red Gas Analyser (IRGA) declined in NO3- fed plants with the increased distance behind a nylon mesh, with maximum water fluxes at the closest distance (ca. 0 mm), demonstrating a regulatory role of NO3- on stomata closure. An opposite trend was displayed by NH4+ -fed plants, which indicated the incapacity of NH4+ to down-regulate water fluxes and ammoniacal syndrome at high concentrations. To test how different [NO3-] and [NH4+] regulate day- and night-time stomatal conductance and transpiration (Chapter 4), P. vulgaris was fed with six concentrations (0, 0.25, 0.5, 1, 2, 4 and 8 mM) of each nitrogen form. A biphasic trend emerged, as postulated in previous studies (Wilkinson et al., 2007; Matimati et al., 2013), characterized by an increase in stomatal conductance and transpiration as [NO3-] increased, attaining a maximum before declining with higher [NO3-]. Plants displayed 2-fold higher photosynthetic rates, 2.2-fold higher stomatal conductance and 2.3-fold higher transpiration rates at 4 mM than at 0.25 mM of [NO3-]. The lowest [NO3-] up-regulated night-time stomatal conductance and transpiration, indicating that NO3- -fed plants opened their stomata at night-time, but reduced night-time water loss at higher [NO3-]. NH4+-fed plants had the incapacity to regulate day- and night-time water fluxes, but rather displayed wilting and stress known as ‗ammoniacal syndrome'. Thus, under NO3- deprived soil conditions P. vulgaris may be opportunistic in their water uptake, transpiring more when water is available in order to draw nutrients through ‗mass-flow'. This thesis explored and confirmed the functional role of NO3- in regulating day- and night-time water fluxes as a mechanism for increasing ‗mass-flow' acquisition of N and possibly other nutrients, signalling a down-regulation of day-time and night-time water fluxes when [NO3-] is replete (Chapter 3 & 4). Where both NO3- and NH4+ are present in soils, it is the [NO3-] and not [NH4+] that regulated stomatal conductance and transpiration. Since organic nitrogen forms such as amino acids also occur in soils, there is a need for further work on their role in stomatal behaviour. Using amino acids laced with 15N isotopes as a nitrogen source can allow their acquisition and role on stomatal behaviour to be discovered. Current trends in research are focussed around developing real-time in-situ sensing of soil nitrogen status to promote enhanced nitrogen and water use efficiency in agricultural systems. This thesis provides the vital literature on stomatal regulation by [NO3-].
17
Jin, Xin. „Isoprenoid and flavonoid biosynthesis and regulation in higher plants“. Doctoral thesis, Universitat de Lleida, 2019. http://hdl.handle.net/10803/667579.
Der volle Inhalt der QuelleAnnotation:
Aquesta tesi es centra principalment en l'anàlisi funcional i la caracterització dels gens que codifiquen per a alguns metabòlits secundaris i en l’estudi de la seva regulació en les plantes. Els objectius generals varen ser (a) entendre millor la regulació transcripcional del gen de la biosíntesi dels carotenoids, la β-carotè hidroxilasa 2 (BCH2) en el blat de moro i (b) l'anàlisi funcional de les dues isopentenil difosfat isomerasas (OsIPPI) d'arròs i determinar la seva localització subcel·lular. Simultàniament, es va estudiar com la llum afecta la via metabòlica i a la producció de pelargonidina en l'arròs; es van identificar també els gens essencials de la seva biosíntesi en Gentiana lutea L. var. aurantiaca.
Les plantes de blat de moro i arròs es varen transformar amb els gens dels factors de transcripció ZmMYB i ZmPBF. Es va analitzar l’expressió gènica transitòria i es va realitzar transformació estable. Els resultats obtinguts indiquen que tant ZmPBF com ZmGAMYB poden transactivar l'expressió de ZmBCH2 a l’endosperm del blat de moro, i ZmPBF i ZmGAMYB transactiven independentment el promotor de ZmBCH2 en arròs. Els dos paràlegs de IPPI (OsIPPI1 i OsIPPI2) aïllats prèviament en arròs varen tenir un patró d'expressió diferent; l'ARNm de OsIPPI1 va ser més abundant que l'ARNm de OsIPPI2 en tots els teixits. Es va usar la microscòpia de fluorescència confocal i microscòpia inmunoelectrónica per determinar la localització de les dues proteïnes. Aquestes es localitzen en el reticle endoplasmàtic (RE), així com en els peroxisomes i les mitocòndries, mentre que només es va detectar OsIPPI2 en els plastidis. La detecció d'ambdues isoformes en el RE indica que DMAPP es pot sintetitzar de novo en aquest compartiment. Diferents tècniques com UPLC, GC-MS i qRT-PCR també es varen utilitzar per perfilar els metabòlits primaris i secundaris i l'expressió gènica relacionada en plàntules d'arròs des-etioladas. Els resultats varen revelar que el metabolisme primari i secundari i els gens corresponents estan regulats per la llum, especialment en la biosíntesi d'isoprenoides en fulles d'arròs. Onze derivats de pelargonidina es varen identificar en els pètals de G. lutea i es varen perfilar els gens de la seva via de biosíntesi, revelant que DFR, ANS i 3GT afecten principalment a l'acumulació dels glucòsids de pelargonidina. Tots aquests resultats suggereixen la idea que la biosíntesi dels carotenoids en plantes superiors és regulada a diferents nivells.Esta tesis se centra principalmente en el análisis funcional y en la caracterización de los genes que codifican para algunos metabolitos secundarios y en el estudio de su regulación en las plantas. Los objetivos generales fueron (a) profundizar en el conocimiento de la regulación transcripcional del gen de la biosíntesis de los carotenoides, la β-caroteno hidroxilasa 2 (BCH2) en el maíz, y (b) analizar la función de las dos isopentenil difosfato isomerasas (OsIPPI) de arroz, determinando además su localización subcelular. Simultáneamente, se estudió cómo la luz afecta a la vía metabólica y a la producción de pelargonidina en el arroz; se identificaron también los genes esenciales de su biosíntesis en Gentiana lutea L. var. aurantiaca. Las plantas de maíz y arroz se transformaron con los genes de los factores de transcripción ZmMYB y ZmPBF. Se analizó la expresión génica transitoria y se realizó transformación estable. Los resultados obtenidos indicaron que tanto ZmPBF como ZmGAMYB pueden transactivar la expresión de ZmBCH2 en endospermo de maíz, y ZmPBF y ZmGAMYB transactivar independientemente el promotor de ZmBCH2 en arroz. Los dos parálogos de IPPI (OsIPPI1 y OsIPPI2) aislados previamente en arroz tuvieron un patrón de expresión diferente; el ARNm de OsIPPI1 fue más abundante que el ARNm de OsIPPI2 en todos los tejidos. Se usó la microscopía de fluorescencia confocal y microscopía inmunoelectrónica para determinar la localización de ambas proteínas. Estas se localizan en el retículo endoplásmico (RE), así como en los peroxisomas y las mitocondrias, mientras que solo se detectó OsIPPI2 en los plastidios. La detección de ambas isoformas en el RE indica que DMAPP se puede sintetizar de novo en este compartimiento. Diferentes técnicas como UPLC, GC-MS y qRT-PCR también se utilizaron para perfilar los metabolitos primarios y secundarios y la expresión génica en plántulas de arroz des-etioladas. Los resultados revelaron que los genes involucrados en la en el metabolismo primario y secundario están regulados por la luz, especialmente en la biosíntesis de isoprenoides en hojas de arroz. Once derivados de pelargonidina se identificaron en los pétalos de G. lutea y se perfilaron los genes de la vía de biosíntesis, revelando que DFR, ANS y 3GT afectan principalmente a la acumulación de los glucósidos de pelargonidina. Todos estos resultados contribuyen al conocimiento, a diferentes niveles, de la regulación de las rutas biosinteticas de los carotenoides en plantas superiores.
This thesis mainly focuses on functional analysis and characterization of a number of secondary metabolite biosynthetic genes and the regulation of the corresponding secondary metabolite biosynthetic pathway in plants. The overall aims were to elucidate the transcriptional regulation of β-carotene hydroxylase 2 gene (BCH2) in maize, the functional analysis of rice isopentenyl diphosphate isomerases (OsIPPI), and determine their subcellular localization. Simultaneously, the influence of light on the metabolic pathway in rice was studied and the pelargonidin quantification and essential pelargonidin biosynthesis genes in Gentiana lutea L. var. aurantiaca were identified. Maize and rice plants were transformed with transcription factor genes ZmMYB and ZmPBF, via transient gene expression and stable transformation respectively. The results indicated that both ZmPBF and ZmGAMYB can transactivate ZmBCH2 expression in maize endosperm and ZmPBF and ZmGAMYB independently transactivate the ZmBCH2 promoter in rice. The two IPPI paralogs (OsIPPI1 and OsIPPI2) isolated previously in rice had a different expression pattern; OsIPPI1 mRNA was more abundant than OsIPPI2 mRNA in all tissues. Confocal fluorescence microscopy and immuno-electron microscopy were used to determine the localization of both proteins. These localized to the endoplasmic reticulum (ER) as well as peroxisomes and mitochondria, whereas only OsIPPI2 was detected in plastids. The detection of both isoforms in the ER indicates that DMAPP can be synthesized de novo in this compartment. UPLC, GC-MS and qRT-PCR were used to profile the primary and secondary metabolites and gene expression in de-etioleted rice seedlings. The results revealed both primary and secondary metabolism and the corresponding genes are regulated by light, especially isoprenoids biosynthesis in rice leaves. Eleven pelargonidin derivatives were identified in the petals of G. lutea and the biosynthetic pathway genes were profiled, revealing DFR, ANS and 3GT mainly affect the accumulation of pelargonidin glucosides. Collectively my results provide novel insights of the regulation of carotenoid and flavonoid biosynthesis in higher plants at different levels.
18
Wied, Anna. „Conspecific nurse effects and the evolution of monocarpy in plants /“. free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9841363.
Der volle Inhalt der Quelle
19
Nolan, Justin M. „Ethnobotany in Missouri's Little Dixie : knowledge variation in a regional culture /“. free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9974669.
Der volle Inhalt der Quelle
20
Ribeiro, Jose Eduardo Lahoz da Silva. „Estudos sobre a filogenia, taxonomia e evolução de caracteres reprodutivos em Moraceae Gaudich“. [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315027.
Der volle Inhalt der QuelleAnnotation:
Orientador: George John ShepherdTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-10T11:39:18Z (GMT). No. of bitstreams: 1 Ribeiro_JoseEduardoLahozdaSilva_D.pdf: 15364889 bytes, checksum: aff367f6d443eb922d7c26df60d67b5c (MD5) Previous issue date: 2007
Resumo: A família Moraceae é extremamente bem representada em número de indivíduos e espécies em florestas neotropicais de baixa altitude. Entretanto, a maior parte das informações disponíveis sobre o grupo, até o presente, refere-se apenas as espécies de Ficus. São raros os trabalhos sobre a evolução dos caracteres presentes nas diferentes inflorescências que ocorrem na família, que, em alguns casos, estão entre as mais complexas dentro das Angiospermae, e as informações sobre o relacionamento filogenético infrafamiliar, assim como as delimitações de suas tribos, precisam ser enriquecidas com mais dados para serem melhor compreendidas. Neste contexto, foi desenvolvido o presente trabalho, que teve como objetivos o estudo da filogenia de Moraceae, especialmente, as neotropicais, a partir de dados moleculares do segmento trnL-F do cloroplasto e de 50 caracteres morfológicos; o levantamento e análise da evolução de caracteres relacionados às inflorescências do grupo, e a caracterização morfológica das tribos da família. Além da árvore filogenética gerada a partir das análises realizadas para desenvolvimento do presente trabalho, cladogramas disponíveis na literatura, gerados a partir de informações moleculares de outros segmentos gênicos, também foram utilizados para avaliação da delimitação das tribos de Moraceae e estudo da evolução dos caracteres analisados. Os resultados das análises realizadas permitiram a proposição de uma nova tribo, Maclureae; uma nova delimitação para as tribos Dorstenieae e Moreae, correntemente aceitas; a elaboração de uma chave de identificação; a caracterização morfológica de todas as tribos apresentadas, e inferências sobre a evolução de alguns caracteres reprodutivos. Além disso, o sistema reprodutivo das 278 espécies neotropicais foi inferido a partir da observação em campo de 40 espécies, entre essas 28 espécies arbóreas, indicando que monoicia é o sistema reprodutivos mais comum no grupo, seguido de dioicia e androdioicia. As inflorescências de Antiarideae (Castilleae) bem como estruturas associadas a elas receberam novas interpretações após estudos morfológicos
Abstract: The Moraceae family is extremely well represented in individual and species number, in lowland neotropical forests. However, the most expressive part of the available information about this group, up to now, refers to Ficus species. There are few studies focusing on character evolution of the different types of inflorescences in this family, which are, in some cases, among the most complexes in the Angiospermae; and information on within-family phylogenetic relationship, as well as its tribes¿s delimitation, must be enhanced with more data, in order to be better understood. The present work was developed bearing in mind this context and aiming i) the study of the Moraceae phylogeny, especially the neotropical species, using molecular data from the chloroplast trnL-F region and from 50 morphological data; ii) the cataloging and evolutionary analysis of characters related to inflorescences of this group, and iii) the morphological characterization of the tribes. In addition to the phylogenetic tree generated from analysis carried out for the development of the present work; cladograms available in the literature, based on information of different DNA segments, were also used to evaluate the delimitation of Moraceae tribes and to study the evolution of the analyzed characters. The results of the performed analysis allowed the proposition of a new tribe, Maclureae; a new delimitation of Dorstenieae and Moreae, currently accepted; the elaboration of an identification key; the morphological characterization of all depicted tribes, and inferences about the evolution of some reproductive characters. Additionally, the reproductive system of the 278 neotropical species was inferred from field observation of 40 species, 28 of which were tree species, indicating that monoecy is the most common reproductive system in the group, followed by dioecy and androdioecy. After morphological studies, Antirideae (Castilleae) inflorescences, as well as related structures, have received new interpretation
Doutorado
Doutor em Biologia Vegetal
21
Ronchi, Helena Souza [UNESP]. „Potencial alimentício e medicinal das espécies nativas da Área de Proteção Ambiental - APA Corumbataí, Botucatu e Tejupá – perímetro Botucatu“. Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150326.
Der volle Inhalt der QuelleAnnotation:
Submitted by Helena Souza Ronchi null (hsronchi@gmail.com) on 2017-04-18T18:43:50Z
No. of bitstreams: 1
Helena Ronchi_Mestrado.pdf: 4630046 bytes, checksum: 4e3e8e4ff5df0e6404d7667cdbf167b9 (MD5)Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-04-18T20:01:31Z (GMT) No. of bitstreams: 1 ronchi_hs_me_bot.pdf: 4630046 bytes, checksum: 4e3e8e4ff5df0e6404d7667cdbf167b9 (MD5)
Made available in DSpace on 2017-04-18T20:01:31Z (GMT). No. of bitstreams: 1 ronchi_hs_me_bot.pdf: 4630046 bytes, checksum: 4e3e8e4ff5df0e6404d7667cdbf167b9 (MD5) Previous issue date: 2017-02-22
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Esse trabalho tem como objetivo identificar o potencial das florestas nativas da Área de Proteção Ambiental – APA Corumbataí, Botucatu e Tejupá – perímetro Botucatu de fornecer recursos florestais para os usos medicinal e alimentício. A identificação das espécies nativas com usos medicinais e alimentícios ocorreu em duas fases. A primeira consiste em uma revisão de trabalhos científicos onde registram o uso (medicinal e alimentício) das espécies nativas encontradas na APA. E a segunda trata-se de um levantamento uso (medicinal e alimentício) das espécies nativas a partir do conhecimento dos proprietários rurais inseridos na APA. Para aquelas identificadas com esses usos foi calculado o valor potencial de exploração sustentável (VPES) para indicar se as espécies com tais usos podem ser exploradas sustentavelmente. O VPES foi avaliado para aquelas espécies que apresentaram freqüência de citação nas entrevistas maior ou igual a 40% e, também, para aquelas nativas na área da APA e que apresentam interesse em políticas públicas (Relação de espécies de interesse do SUS e a Lista de espécies nativas da sociobiodiversidade com valor alimentício). Na primeira fase, foram identificadas, na região da APA, 735 espécies nativas (de diferentes hábitos de crescimento), onde 219 espécies (30%) possuem o uso medicinal e 110 (15%) com o uso alimentício. No levantamento das espécies a partir do conhecimento dos proprietários rurais, foram identificadas 49 espécies, de 19 famílias diferentes, onde 65% dessas plantas possuem o uso como fonte de alimento, 28,6% como fonte de medicamento e 6% das plantas possuem os dois usos. Para ambas as fases, a família mais representativa, enquanto uso medicinal, foi a Fabaceae. Já para o uso alimentício, a mais representativa foi a Myrtaceae. E em relação ao VPES, 8 espécies atingiram o valor para serem exploradas sustentavelmente, porém muitas espécies que também poderiam ser exploradas não são por falta de pesquisas tanto sobre a sua produtividade quanto manejo.
This work aims to identify the potential of the native forests of the Environmental Protection Area - APA Corumbataí, Botucatu and Tejupá - Botucatu perimeter of natural resource management for medicinal and food uses.The identification of native species with medicinal and food uses occurred in two phases. The first one consists in a literature review of scientific studies where the use (medicinal and food) of the native species found in the APA is reported. The second phase is a survey of the use (medicinal and food) of the native species from the knowledge of the rural owners inserted in the APA. The potential value of sustainable exploitation (VPES) will be calculated to indicate whether species with such uses can be sustainably exploited.The VPES was evaluated for those Species that presented frequency of citation in interviews greater than or equal to 40% and also for those native to the area of the APA and that stand out in public policies (List of species of interest of the SUS and List of species Native of sociobiodiversity with food value). In the first part, 735 native species (different growth habits) were identified, where 219 species (30%) had medicinal use and 110 (15%) with alimentary uses. In the surveying of the species from the knowledge of the rural owners, 49 species were identified, from 19 different families, where 65% of these plants have their use as food source, 28.6% as a source of medicine, and 6% of the plants have both uses. For both phases, the most representative family, as medicinal use, was Fabaceae. On the other hand, within the alimentary use, the most representative was Myrtaceae. Regarding the VPES, 8 valuable exploitation species to be exploited in a sustainable way, however many species that are also exploited are not for lack of research on their production.
22
Aona, Lidyanne Yuriko Saleme. „Revisão taxonomica e analise cladistica do genero Dichorisandra J.C. Mikan (Commelinaceae)“. [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/330318.
Der volle Inhalt der QuelleAnnotation:
Orientador: Maria do Carmo Estanislau do AmaralTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-10T18:13:00Z (GMT). No. of bitstreams: 1 Aona_LidyanneYurikoSaleme_D.pdf: 61203004 bytes, checksum: a647955fc5bcfd2da8ffaf424a76fedb (MD5) Previous issue date: 2008
Resumo: Dichorisandra é o maior gênero da subtribo Dichorisandrinae, essencialmente neotropical e caracterizado pelas anteras de deiscência poricida ou rimosa e funcionalmente poricida e sementes ariladas. São ervas perenes, eretas ou escandentes, às vezes com folhas em rosetas próximas ao solo, ocupando, principalmente, o interior de matas. A última revisão de Dichorisandra tem mais de 110 anos e o objetivo principal do presente trabalho foi elaborar a revisão taxonômica do gênero, avaliando novas coletas e espécies que foram descritas desde então. O estudo taxonômico foi realizado a partir de material depositado em herbários nacionais e internacionais e provenientes de coletas principalmente dos Estados de Minas Gerais, Rio de Janeiro, Espírito Santo e Bahia. Os 63 binômios até então publicados foram reduzidos a 30 espécies. São propostas 24 sinonimizações novas e uma nova combinação. Também estão sendo propostas 24 espécies provenientes do Brasil (a maioria delas da Bahia), Panamá, Equador, Peru e Guiana Francesa. Além da revisão taxonômica, foi realizada a análise cladística do gênero Dichorisandra a partir de caracteres morfológicos e macromoleculares (trnL-F, rsp 16 e rpl 16) visando investigar as relações de parentesco entre as espécies e reavaliar o potencial de caracteres morfológicos na identificação de espécies. As matrizes foram analisadas sob o critério de parcimônia. Os clados não são fortemente sustentados na análise de 'bootstrap¿ e a extrema variação de caracteres morfológicos encontrada dentro do gênero demonstra a dificuldade na definição de grupos monofiléticos
Abstract: The neotropical genus Dichorisandra is the largest within the subtribe Dichorisandrinae, being characterized by its poricidal anthers (sometimes opening by slits but functionally poricidal) and its arillated seeds. The plants are perennial, herbaceous, sometimes with a leaf rosette close to the ground, and live mostly within forests. The last revision of the genus dates from over 110 years ago, and the present work aims to present an up-to-date revision for the genus, evaluating a large volume of new records, including the taxa described after fhe first revision was published. The taxonomic studies were based on material held in national and international herbaria and field work focussing the particularly species rich Brazilian states of Minas Gerais, Rio de Janeiro, Espírito Santo and Bahia. The 63 published names were reduced to 30 accepted species, and 24 synonymies and a new combination are proposed. Twenty four new species from Brasil (mostly from Bahia), Panama, Ecuador, Peru and French Guiana were discovered. Apart from the taxonomic revision, a cladistic analysis of the genus was performed with basis on morphologic and macromolecular characters (trnL-F intergenic spacer, rsp 16 and rpl 16 introns) aiming to investigate the species relationships and the re-evaluation of the morphological characters used to determine the species. The matrixes obtained were analyzed under the criterium of parcimony. The clades within the genus are not strongly supported in the 'bootstrap¿ analysis, as the extreme morphological variation found amongst and within species has made it very difficult to define monophyletic groups
Doutorado
Doutor em Biologia Vegetal
23
Scobie, Andrew Rutherford. „Understanding the causes of reproductive failure in two rare Scottish plants, Linnaea borealis L. and Spiranthes romanzoffiana Cham. and the implications for future conservation management“. Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Restricted: no access until Dec. 21, 2011, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=59437.
Der volle Inhalt der Quelle
24
Palisaar, Jaan. „The floodplain meadows of Soomaa National Park, Estonia vegetation - dispersal - regeneration /“. Connect to this title online, 2006. http://www.opus-bayern.de/uni-regensburg/volltexte/2006/705/.
Der volle Inhalt der Quelle
25
Ingarfield, Patricia Jean. „Effect of water stress and arbuscular mycorrhiza on the plant growth and antioxidant potential of Pelargonium reniforme Curtis and Pelargonium sidoides DC“. Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2794.
Der volle Inhalt der QuelleAnnotation:
Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2018.Pelargoniums have been studied extensively for their medicinal properties. P. reniforme and P. sidoides in particular are proven to possess antimicrobial, antifungal and antibiotic abilities due to their high antioxidant potential from compounds isolated from their tuberous roots. These plants have now been added to the medicine trade market and this is now causing concern for conservationists and they are generally harvested from the wild populations. This study evaluated the effect of water stress alone and in conjunction with arbuscular mycorrhiza on two species of Pelargoniums grown in a soilless medium. The experiment consisted of five different watering regimes which were applied to one hundred plants of each species without inoculation with arbuscular mycorrhiza and to one hundred plants of each species in conjunction with inoculation with AM. All the plants in the experiment were fed with a half-strength, standard Hoagland nutrient solution at varying rates viz. once daily to pot capacity, every three days to pot capacity, every six days to pot capacity, every twelve days to pot capacity and every twenty-four days to pot capacity. The objectives of the study were to measure the nutrient uptake, SPAD-502 levels (chlorophyll production) and metabolite (phenolics) formation of both species, grown under various rates of irrigation and water stress, as well with or without the addition of arbuscular mycorrhiza at planting out. Each treatment consisted of 10 replicates. SPAD-502 levels were measured weekly using a hand held SPAD-502 meter. Determination of nutrient uptake of macronutrients N, K, P, Ca, Mg and Na and micronutrients Cu, Zn, Mn, Al and B were measured from dry plant material at the end of the experiment by Bemlab, 16 Van Der Berg Crescent, Gants Centre, Strand. Plant growth in terms of wet and dry shoot and root weight were measured after harvest. Determination of concentrations of secondary metabolites (phenolic compounds) were assayed and measured spectrophotometrically at the end of the experiment. The highest significant reading of wet shoot weight for P. reniforme was taken in treatments 1 and 2 with and without mycorrhiza i.e. WF1, WF1M, WF2 and WF2M, with the highest mean found in WF1 with no mycorrhiza. This indicates that under high irrigation AM plays no part in plant growth, possibly due to leaching. More research is necessary in this regard. With regard to wet root weight, this was found to be not significant in any of the treatments, other than the longest roots being found in WF4. Measurements for dry root weight showed that WF1,2,3 and 5 were the most significant at P≤ 0.001 significance, with the highest weight found at treatment being WF3 and WF3M. The highest mean of shoot length of the plants was measured in treatment WF2 at moderate watering, but no statistical difference was found with water application and mycorrhiza addition. Nutrient uptake was increased in P. sidoides in all the different watering levels in the experiment except in the uptake of Mg. AM inoculation showed an increase in the uptake of Ca, while absorption of N occurred at higher water availability. K uptake was enhanced by the addition of AM in high water availability and K utilisation decreased as water stress increased. Medium to low watering resulted in higher leaf content in P. sidoides while the interaction between water availability and AM inoculation increased chlorophyll production towards the end of the experiment.
26
Valmorbida, Janice [UNESP]. „Propagação da espécie Trichilia catigua A. Juss (Catiguá)“. Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/103248.
Der volle Inhalt der QuelleAnnotation:
Made available in DSpace on 2014-06-11T19:32:26Z (GMT). No. of bitstreams: 0
Previous issue date: 2007-05-21Bitstream added on 2014-06-13T20:43:33Z : No. of bitstreams: 1
valmorbida_j_dr_botfca.pdf: 653023 bytes, checksum: 354f212c2d30f294ce34c4e7b5512709 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Pertencente à família Meliaceae, a espécie Trichilia catigua A. Juss é conhecida popularmente como catigua, cataguá, argelim-rosa e mangalto-catingam. Sua casca apresenta propriedades adstringente, inseticida, purgativa, tônica, bactericida, antiinflamatória e antidepressiva. Com o objetivo de propagar a espécie T. catigua foram desenvolvidos experimentos testando o enraizamento de estacas e a micropropagação com explantes de matrizes e sementes. Os experimentos de enraizamento de estacas foram realizados na primavera 2004, verão 2004/2005, outono, inverno e primavera 2005 e primavera 2006. Em todos os experimentos, estacas com aproximadamente 15 cm de comprimento foram coletadas de árvores adultas e preparadas da parte apical e mediana dos ramos. A seguir, foram submetidas aos reguladores vegetais IBA (ácido indolbutírico), NAA (ácido naftalenoacético) e IAA (ácido 3-indolacético), variando as dosagens. Para a avaliação dos experimentos determinou-se a percentagem de estacas enraizadas, não enraizadas e mortas e quando enraizadas, seu comprimento e diâmetro. No experimento primavera de 2004 foram testadas as concentrações de 1000 e 2000 mg L-1 dos reguladores vegetais IBA, NAA e IAA. As avaliações aos 90 dias após sua instalação revelaram maiores percentagens de enraizamento e iguais a 33,33, 25,00, 22,91 e 23,43 % para estacas submetidas a IBA 1000, 2000 mg L-1 e NAA 1000 e 2000 mg L-1, respectivamente. No verão 2004/2005, outono, inverno e primavera 2005 os experimentos foram conduzidos com as concentrações dos reguladores IBA, NAA e IAA iguais a 1000, 2000 e 3000 mg L-1 e as avaliações foram realizadas após 120 dias. Não houve enraizamento no outono e inverno. A análise conjunta dos resultados obtidos na primavera e no verão mostrou percentagem de enraizamento superior na primavera. A maior percentagem de enraizamento, igual a 19,17%...
The Trichilia catigua A. Juss from the Meliaceae family is popularly known as catigua, cataguá, argelim-rose and mangalto-catingam. Its bark has astringent, insecticide, purgativa, tonic, bactericide, anti-inflammatory and antidepressant properties. With the aim of propagate T. catigua, experiments of rooting with stem cuttings and of micropropagation with explants of trees and seeds were carried out. In all the rooting experiments the stem cuttings with approximately 15 cm of length were collected from adult trees and prepared from the apical and intermediate parts. The cuttings were immersed in the vegetable regulators IBA (Indole-3- butyric acid), ANA (Naphthalene acetic acid) and IAA (Indole-3 acetic acid). The rooted stem cutting and not rooted stem cutting percentage and, when rooted, the length and diameter of roots, were evaluated. In the experiment spring 2004 the concentrations of 1000 and 2000 mg L-1 of IBA, ANA and IAA were tested, with evaluations 90 days after installation. The highest rooting percentage were 33,33, 25,00, 22,91 and 23,43% for IBA 1000, 2000 mg L-1 and ANA 1000 and 2000 mg L-1, respectively. In the summer of 2004/2005, autumn, winter and spring of 2005 IBA, ANA and AIA, with concentration of 1000, 2000 and 3000 mg L-1, were tested. The evaluation was carried out at 120 days. No rooting was observed in autumn and winter. The analysis of data from summer and spring showed higher rooting percentage in spring. The highest rooting percentage was obtained with IBA 3000 mg L-1 (19,17%). In the spring 2006 IBA (1000, 2000, 3000, 4000 and 5000 mg L-1) and ANA (1000, 2000, 3000 mg L-1) were tested. The highest rooting percentage (41,67%) was obtained with IBA 5000 mg L-1. In the in vitro cultivation, explantes obtained from trees were submitted to asepsis treatments with HgCl2, CaOCl2 and NaOCl and inoculated in Murashige & Skoog culture medium (MS) with 25%... (Complete abstract click electronic access below)
27
Von, Richter Lotte Victoria. „Native plants of Eastern Australia as bedding plants“. Thesis, The University of Sydney, 1996. https://hdl.handle.net/2123/27551.
Der volle Inhalt der QuelleAnnotation:
Bedding plants are used extensively in many landscaping situations. The
majority of bedding plants marketed commercially are exotic species with only limited
propagation material of Australian species available. The objectives of this work was
to assess Australian short—lived perennial species as bedding plants with particular
reference to their ease of propagation from seed.
An extensive survey of Eastern states Australian native annual and short lived
perennial species has identified the following species as showing potential as bedding
plants.
28
Puzey, Joshua Robert. „Plant MicroRNA Evolution and Mechanisms of Shape Change in Plants“. Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10143.
Der volle Inhalt der QuelleAnnotation:
Plant microRNAs have been shown to have important roles in regulating diverse processes ranging from reproductive development to stress response. In the first two chapters, I focus on miRNA diversity in Aquilegia studying both anciently evolved broadly conserved and rapidly evolving species specific miRNAs. In chapter one, I utilize Aquilegia's critical phylogenetic position between the well developed models Arabidopsis thaliana and Oryza sativa to study the evolution of ancient miRNAs across the angiosperms. In chapter two, I utilize smallRNA high-throughput sequencing to annotate Aquilegia specific miRNAs and, in the process, uncover the novel regulation of a floral homeotic gene by an Aquilegia-specific miRNA. In chapter three, I look at the tissue specific development of miRNA regulation in the bioenergetically relevant model organism Populus trichocarpa. High-throughput smallRNA sequencing from four diverse tissue sets including leaves, xylem, mechanically treated xylem, and pooled vegetative and reproductive tissues were analyzed, revealing a total of 155 previously unannotated miRNAs, most of which are P. trichocarpa specific. Expanding on my work with the petal identity pathway, I turned a broader analysis of Aquilegia petal spurs. Petal spurs are the distinguishing characteristic of Aquilegia and are argued to be a key innovation in the adaptive radiation of the genus. In the fourth chapter, I explore the cellular basis of extreme spur length diversity in the genus and find that a single parameter, cell shape, can explain this morphological range. Next, I seek to describe the cellular patterns that give rise to a spur primoridia from an initially flat laminar petal and find that spur initiation is characterized by concentrated, prolonged, and oriented cell divisions. Inspired by this quantitative analysis of growth, chapter five looks at the mechanisms of shape change in cucumber tendrils. I find that anisotropic contraction of a multi-layered gelatinous fiber ribbon explains coiling in cucumbers. Surprisingly, we discover that tendrils display twistless-overwinding when pulled and exhibit an unforeseen force-extension response as a result. These results provide the design basis for twistless springs with tunable mechanical responses and serve as a clear example of how the biological systems can inspire applied mechanical designs.
29
Zhou, Dafeng. „Farnesyltransferase: Gene Expression in Plants and Role in Plant Development“. Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30483.
Der volle Inhalt der QuelleAnnotation:
Protein farnesyltransferase (FTase, E. C. 2.5.1.21) post-translationally modifies regulatory proteins involved in controlling cell growth, division, and differentiation. Recently, a cDNA clone (PsFTb) encoding a pea (Pisum sativum) FTase b subunit was isolated. Initial studies led to the hypothesis that FTase plays a role in the regulation of plant cell division.
To gain insight into FTase function in plants, a detailed study of the expression pattern of FTase genes was carried out. A cDNA (NgFTb) encoding the b subunit of tobacco FTase was cloned from a Nicotiana glutinosa cDNA library to initiate studies in tobacco. In tobacco BY-2 suspension culture, levels of NgFTb mRNA and FTase activity transiently increased at the early log phase of cell growth and rapidly declined before cells entered stationary phase. These data, along with inhibitor studies in the BY-2 system, support our hypothesis. To understand the expression and regulation of pea FTase subunit genes, 5'-upstream sequences of both pea FTase subunit genes (PsFTb and PsFTa) were cloned from a pea genomic library. The 5'-upstream sequence (~2 kb) of PsFTa was fused to GUS (b-glucuronidase) and GFP (green fluorescent protein) reporter genes and introduced into tobacco plants. This 2 kb upstream region appears insufficient to provide PsFTa promoter function. On the other hand, 3.2 kb of PsFTb 5'-upstream sequence expressed as a PsFTb:GUS construct is fully functional in transgenic tobacco plants. GUS expression was most prominent in actively growing cells supporting FTase involvement in plant cell cycle control. GUS activity was also found in mature and imbibed embryos but not premature embryos, consistent with the role of FTase in abscisic acid (ABA) signaling. An unexpected pattern of GUS activity, not correlated with dividing cells or ABA signaling, was also observed in the transgenic plants. GUS activity was detected in vascular bundles adjacent to actively-growing tissues and in regions that connect two organs, e.g., junctions between stems and leaf petioles, cotyledons and hypocotyls, roots and hypocotyls. Auxin promotes PsFTb expression while light and sucrose inhibit expression. These spatial and temporal expression patterns strongly suggest that FTase has a broader role associated with regulation of nutrient transportation or allocation in plants.Ph. D.
30
Fedkenheuer, Michael Gerald. „Understanding Plant Pathosystems in Wild Relatives of Cultivated Crop Plants“. Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/81976.
Der volle Inhalt der QuelleAnnotation:
As the global population rises, the demand for food increases which underscores a
need for improvement in food security. Disease pressures are a major concern
surrounding sustainable agriculture. Static crop populations, containing little to no
genetic diversity, are vulnerable to diverse pathogen populations. Wild relatives of crop
plants are a reservoir for new disease resistance traits that can be introgressed into
cultivated crops. The identification of novel disease resistance is of paramount
importance because pathogen co-evolution is not only defeating current resistance genes
(R genes) but chemical controls as well. Phytophthora sojae (P. sojae), the causal agent
of Phytophthora root and stem rot disease, reduces soybean harvests worldwide. We
developed an approach to screen for new R genes that recognize core effectors from P.
sojae. We expect R genes identified by these screens to be durable because P. sojae
requires core effectors for virulence. We utilized effector-based screening to probe
Glycine soja germplasm with core RXLR effectors from P. sojae to search for novel R
genes. We developed segregating populations from crosses of P. sojae resistant G. soja
germplasm with susceptible G. max cultivar Williams to determine inheritance of
potential R genes in germplasm that responded to core effectors. We are using marker
assisted breeding to map disease resistance traits in recombinant inbred (RI) lines. To
better understand pathosystems, we examined host resistance and susceptibility using
bioinformatics. We analyzed the interaction between Arabidopsis thaliana ecotype Col-0
and Hyaloperonospora arabidopsidis isolate Emwa1 using a publicly available RNA
time-course experiment. We describe a new algorithm to sort genes into time-point
specific clusters using activation and repression parameters. Gene ontology annotations
were used to identify defense genes with unique expression profiles, and A. thaliana null
mutants for these genes were significantly more susceptible to Emwa1 than wild-type.
We plan to use these tools to rapidly identify and guide introgression of durable disease
resistance into crop species.Ph. D.
31
Alamino, Douglas Alvarez. „Características agronômicas de fisalis (Physalis pubescens L.) produzida por diferentes métodos e substratos e aspectos anatômicos e fitoquímicos“. Universidade Tecnológica Federal do Paraná, 2011. http://repositorio.utfpr.edu.br/jspui/handle/1/234.
Der volle Inhalt der QuelleAnnotation:
CNPQPhysalis pubescens L., ou camapu, é uma planta herbácea, cujos frutos são comestíveis e folhas, caules e raízes utilizados na medicina tradicional, contra diversas enfermidades. Como os estudos referentes a esta espécie são escassos o presente trabalho teve como objetivos: 1) avaliar os aspectos agronômicos de plantas cultivadas por diferentes métodos e substratos, 2) descrever anatomicamente as principais estruturas da plantas e 3) detectar a presença de compostos de interesse do metabolismo secundário. Para tanto, no primeiro ensaio foram avaliadas plantas produzidas a partir de sementes e estacas herbáceas. Como substratos foram utilizados: (SA) Solo + areia; (SV) Solo + vermiculita; (SP) Solo + Plantmax; (SAV); Solo + areia + vermiculita e (S) Solo. Foram avaliados os comprimentos da parte aérea e da maior raiz; área foliar; massas fresca e seca das folhas, caules e raízes; e volume radicular. O delineamento experimental utilizado foi inteiramente casualizado, em um esquema fatorial de 2x5, com 10 repetições por tratamento. No segundo ensaio, folhas, caules e flores foram submetidos a cortes paradérmicos e transversais, fixados em FAA 70%, armazenados em etanol a 70% e posteriormente, analisados por microscopia ótica e eletrônica de varredura. No terceiro ensaio, folhas oriundas de plantas cultivadas em vasos mantidos em casa de vegetação foram secas, moídas e extraídas com hexano. O resíduo seco hexânico foi aplicado em coluna cromatográfica, tendo como solventes de partição diclorometano, acetato de etila, metanol e água destilada. As frações foram submetidas à cromatografia em camada delgada (TLC) e ressonância magnética de prótons (RMN 1H). O extrato bruto foi submetido à cromatografia a gás acoplada à espectrometria de massas (CG/EM). Para o primeiro ensaio observou-se interação significativa entre os fatores substrato e método de propagação somente para massa fresca e seca dos caules, com destaque para o método estaquia e os substratos S, SA, SP. Para as demais variáveis não foram constatadas diferenças significativas. Em relação aos aspectos anatômicos constatou-se que P. pubescens apresenta lâmina foliar hipoestomática, mesófilo com a presença de drusas; idioblastos de areia cristalina dispersos aleatoriamente pelo pecíolo, e tricomas glandulares e eglandulares ao longo de toda a lâmina foliar, caule, pecíolo e pétalas. O estudo fitoquímico por CG/EM revelou a possível presença do alcalóide epistefamiersina (86% de probabilidade); também foram observados as presenças de cumarinas, fisalinas, óleo essencial, saponinas, triterpenóides e taninos por TLC, além de triterpenos e compostos aromáticos de baixa intensidade por RMN 1H. Diante destes resultados, conclui-se que P. pubescens possui características anatômicas que auxiliam a diferenciá-la das demais espécies do gênero, e que a mesma sintetiza uma grande variedade de metabólitos secundários, com a estaquia sendo o melhor método de propagação, independente do tipo de substrato.
Physalis pubescens L., or Winter Cherry, is a herbaceous plant, whose fruits are edible and the leaves, stems and roots used in traditional medicine against various diseases. As the studies for this species are scarce this study aimed to 1) assess the agronomic features of crops grown by different methods and substrates, 2) describe the main anatomical structures of plants and 3) the presence of compounds of interest secondary metabolism. For this, the first trials were evaluated plants grown from seed and cuttings. The substrates were used: (SA) Soil + sand; (SV) Soil + vermiculite, (SP) Soil + Plantmax; (SAV) Soil + sand + vermiculite and (S) Soil. We evaluated the length of shoot and main root, leaf area, fresh and dry weight of leaves, stems and roots and root volume. The experimental design was completely randomized in a factorial scheme 2x5, with 10 replicates per treatment. In the second trial leaves, stems and flowers were sectioned transverse paradermic and fixed in FAA 70%, stored in 70% ethanol and subsequently analyzed by optical microscopy and scanning electron microscopy. In the third essay leaves from plants grown in pots in a greenhouse, were dried and extracted with hexane. The hexanic dry residue was applied to the extraction chromatographic column, and as solvents for the partition dichloromethane, ethyl acetate, methanol and distilled water. The fractions were subjected to thin layer chromatography (TLC) and proton magnetic resonance (NMR 1H). The crude extract was subjected to gas chromatography-mass spectrometry (GC / MS). For the first test there was significant interaction between the factors substrate and method of propagation only for fresh and dry weight of stems, especially the cutting method and the substrate S, SA, SP. For the other variables were not significantly different. Regarding the anatomy it was found that P. pubescens leaf presents hypostomatic mesophyll with the presence of drusen, crystalline sand idioblasts scattered randomly around the petiole, and glandular and eglandular throughout the leaf, stem, petiole and flower petals. Phytochemical study by GC / MS revealed the possible presence of alkali epistephamiersine (86% probability) were also observed the presence of coumarins, physalins, essential oil, saponins, triterpenoids and tannins by TLC, and triterpenes and aromatic compounds of low NMR 1H intensity. Given these results it is concluded that P.pubescens has anatomical features that help differentiate it from other species of the genus, and that it synthetizes a wide variety of secondary metabolites also that the cutting is the best method of propagation, independent of substrate type.
32
White, Sean D. „Internal pressurisation and convective flow in two species of emergent macrophyte; Typha domingensis and Phragmites australis /“. Title page, contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phw5877.pdf.
Der volle Inhalt der Quelle
33
Swarts, Nigel. „Integrated conservation of the rare and endangered terrestrial orchid Caladenia huegelii H.G. Reichb /“. Connect to this title, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0044.
Der volle Inhalt der Quelle
34
Prusak, Anne C. „Activated and constitutive chemical defenses in freshwater plants“. Thesis, Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-06072004-131334/unrestricted/prusak%5Fanne%5Fc%5F200405%5Fms.pdf.
Der volle Inhalt der Quelle
35
Lisovenko, M. „Nanobionic plants“. Thesis, Sumy State University, 2014. http://essuir.sumdu.edu.ua/handle/123456789/45220.
Der volle Inhalt der QuelleAnnotation:
Plants have many valuable functions: They provide food and fuel, release the oxygen that we breathe, and add beauty to our surroundings. Now, a team of MIT researchers wants to make plants even more useful by augmenting them with nanomaterials that could enhance their energy production and give them completely new functions, such as monitoring environmental pollutants.
36
Truskina, Jekaterina. „The role of auxin in cell differentiation in meristems“. Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN033/document.
Der volle Inhalt der QuelleAnnotation:
L'auxine régule la croissance et le développement des plantes grâce aux facteurs de transcription de la famille des "AUXIN RESPONSE FACTOR" (ARF). Chez Arabidopsis thaliana en particulier, ARF5, 6, 7, 8 et 19 activent l'expression de gènes cibles en réponse à l'auxine. Ces cinq ARF activateurs contrôlent de façon plus ou moins redondante des processus divers au cours du développement de la plante, notamment la régulation des croissances au niveau des méristèmes racinaires et aériens ainsi que la formation des racines latérales ou des méristèmes axillaires.Chacun de ces cinq ARF activateurs présente des patrons d'expression uniques dans chacun des tissus racinaires et aériens, en association avec leurs fonctions particulières. Il est probable que cette expression tissu-spécifique trouve son origine dans un contrôle différencié de leur transcription. Dans cette étude, des régulateurs amonts de la transcription de ARF5, 6, 7, 8 et 19 ont été identifiés par une méthode haut-débit de crible simple hybride en levure (Y1H). Une procédure d'expression transitoire en protoplastes a permis de confirmer que l'expression de chaque ARF activateur est contrôlée par des régulateurs spécifiques, dont la majorité se comportent comme des répresseurs de la transcription des ARF in planta. Parmi les régulateurs identifiés, les facteurs de transcription ont été étudiés grâce à des mutants pour préciser les interactions in planta. Ces mutants montrent des phénotypes développementaux typiques de perturbations de l'auxine dans les racines et les tiges : altérations des cinétiques de croissance, de l'émergence des organes latéraux ou de réponses à l'auxine et modification de l'expression des ARF activateurs.Par ailleurs, ce travail aborde également les dialogues entre les voies de signalisation de l'auxine et des cytokinines, et en particulier le rôle de ces interactions dans le développement des racines et des tiges. Une des interactions identifiées dans le crible Y1H est la répression de ARF7 par CRF10, un gène membre de la famille des "Cytokinin Response Factors". Nous avons mis en évidence l'importance de cette interaction pour le maintien de l'architecture du méristème apical racinaire, pour la sénescence des feuille et pour la réponse phototropique à la lumière bleue dans les hypocotylesAuxin regulates plant growth and development through the transcription factors of the AUXIN RESPONSE FACTOR (ARF) gene family. Most notably in Arabidopsis thaliana ARF5, 6, 7, 8 and 19 activate expression of target genes in response to auxin. These five ARF activators control both variable and overlapping processes during plant development including regulation of growth at the root and the shoot apical meristems, lateral root and axillary shoot formation. Each of the five ARF activators shows unique tissue-specific expression patterns in the root and the shoot associated with their distinct functions. This tissue-specific expression is likely derived from the differences in the control of ARF activator transcription. In this study the upstream regulators of ARF5, 6, 7, 8 and 19 transcription were identified. This was achieved by utilizing a high-throughput yeast one-hybrid (Y1H) method. The transient protoplast assay revealed that each ARF activator is controlled by specific transcriptional regulators and that the majority of these regulators are repressors of ARF transcription in planta. Mutants of the regulatory transcription factors were utilized to additionally investigate the interactions in planta. These mutants display auxin-related developmental phenotypes in the root and the shoot including alternations in growth kinetics, emergence of lateral organs, responses to auxin and altered expression of ARF activators. Furthermore, this study additionally focuses on cross-talk between the auxin and cytokinin signaling pathways and its role in root and shoot development. One of the interactions identified in the Y1H screen is a repression of ARF7 by CRF10, a member of the Cytokinin Response Factors gene family. The importance of this interaction in maintaining architecture of the root apical meristem, in leaf senescence and in the phototropic response to blue light in hypocotyls is studied
37
Damgaard, Christian. „Evolutionary ecology of plant-plant interactions : an empirical modelling approach /“. Aarhus University Press, 2004. http://www.elib.se/library/ebook_detail.asp?id_type=ISBN&lib=DK&id=8779348750.
Der volle Inhalt der Quelle
38
Brickman, Jacklyn E. „Experiments in Biological Planet Formation and Plants: Nourishing Bodies, Nourishing Planets“. The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595340630648528.
Der volle Inhalt der Quelle
39
Bartomeus, Roig Ignasi. „Integration and impacts of invasive plants on plant-pollination networks (Integración e impactos de las plantas invasoras sobre las redes de plantas y polinizadores)“. Doctoral thesis, Universitat Autònoma de Barcelona, 2008. http://hdl.handle.net/10803/3697.
Der volle Inhalt der QuelleAnnotation:
Nota: el text d'aquesta tesi és en anglès i castellàLas especies invasoras son aquellas que transportadas e introducidas por el ser humano en lugares fuera de su área de distribución natural, han conseguido establecerse y dispersarse en la región de destino. Las especies invasoras pueden producir cambios en las poblaciones de las especies nativas e incluso conducir a su extinción local. Las comunidades invadidas por plantas exóticas pueden sufrir diversos impactos, siendo la competencia por los recursos ambientales, los cambios en las propiedades del suelo o en el régimen de perturbaciones los más estudiados. Sin embargo, los efectos sobre otros niveles tróficos han recibido menos atención, aunque cada vez hay más estudios referentes al efecto sobre los herbívoros y los mutualismos. La mayoría de estudios sobre el impacto de las plantas invasoras en las interacciones de polinización han considerado interacciones entre pares de especies. Dado que las plantas suelen interactuar con varios polinizadores y los polinizadores visitar varias especies de plantas, las especies invasoras tienen el potencial de perturbar, no sólo interacciones puntuales, sino toda la red de interacciones. No obstante, se ha realizado poca investigación sobre las repercusiones de las invasiones a nivel de toda la comunidad de polinizadores y plantas. Esta tesis estudia la forma en que los sistemas de plantas y polinizadores se ven afectados por especies de plantas invasoras. Hemos estudiado tres especies de plantas invasoras, Carpobrotus aff acinaciformis, Opuntia stricta e Impatiens glandulifera para caracterizar su integración e impactos sobre la red de interacciones nativa. Los polinizadores nativos, sobre todo aquellos con un espectro de visitas generalistas, proporcionan una vía de integración para las plantas invasoras. Tanto C. acinaciformis como O. stricta dependen de los polinizadores para la reproducción sexual en el área de introducción, aunque C. acinaciformis se ve levemente limitado por el polen. La competencia por los polinizador con las plantas nativas depende de la especie estudiada, así, encontramos competencia con O. stricta, facilitación con C. acinaciformis y no encontramos un efecto en I. glandulifera. En el caso de existir facilitación por las visitas, hemos visto que el polen invasor tiene muy pocas posibilidades de interferir en la reproducción de las plantas nativas al depositarse en muy baja frecuencia en los estigmas de las especies nativas. Finalmente, cuando evaluamos la importancia del paisaje en I. glandulifera, los efectos producidos por la invasión resultan ser independientes del los efectos del paisaje. Las redes planta-polinizador son complejas e involucran una gran cantidad de interacciones, por eso es difícil predecir el impacto de las especies invasoras. Sin embargo, el hecho de que las tres plantas estudiadas estén causando importantes cambios sobre las redes invadidas indica lo importante que es tener en cuenta sus efectos tanto para comprender para la biología de las interacciones mutualistas, como para futuras estrategias de conservación.
Invasive species are species transported and introduced by humans outside their natural range. This species are established and dispersed in the new habitats. Invasive species can produce changes in native species populations and even lead to its local extinction. Invaded communities can suffer different impacts, like competition for environmental resources, changes in soil properties or in the disturbance regime. However, the effects on other trophic levels have received less attention. Most studies on the impact of invasive plants and its interactions with pollinators have only considered interactions between pairs of species. Since plants tend to interact with several pollinators and the pollinators visit several species of plants, invasive species have the potential to disrupt not only particular interactions, but the entire network of interactions. However, there has been little research on the impact of invasions in the community of pollinators and plants. This thesis explores how the systems of plants and pollinators are affected by invasive plant species. We studied three invasive species, Carpobrotus aff acinaciformis, Opuntia stricta and Impatiens glandulifera to characterize their integration and impacts on the network of native interactions. The native pollinators, especially generalists, provide an integration way for invasive plants. Both C. acinaciformis and O. stricta depend on pollinators for sexual reproduction in the introduced area. However, C. acinaciformis is slightly limited by pollen. The competition for pollinators with native plants depends on the context, thus, we found competition processes with O. stricta, facilitation with C. acinaciformis and we did not find any effects on I. glandulifera. In the case of C. acinaciformis that facilitated visits to natives, we saw that the invasive pollen has very little chance of interfering with the reproduction of native plants and is deposited in very low frequency in the stigmas of native species. Finally, when we evaluate the importance of the landscape context in I. glandulifera, the impact of the invasion appear to be independent from the effects of the landscape. Plant-pollinator networks are complex and involve large numbers of interactions, so it is difficult to predict the impact of invasive species. However, the fact that the three studied plants produce major changes in the networks is very significant.
Les espècies invasores són aquelles que transportades i introduïdes per l'ésser humà en llocs fora de la seva àrea de distribució natural, han aconseguit establir-se i dispersar-se en la regió de destinació. Les espècies invasores poden produir canvis en les poblacions de les espècies nadives i fins i tot conduir a la seva extinció local. Les comunitats envaïdes per plantes exòtiques poden sofrir diversos impactes, sent la competència pels recursos ambientals, els canvis en les propietats del sòl o en el règim de pertorbacions els més estudiats. No obstant això, els efectes sobre altres nivells trófics han rebut menys atenció, encara que cada vegada hi ha més estudis referents a aquest efecte sobre els herbívors i els mutualismes. La majoria d'estudis sobre l'impacte de les plantes invasores en les interaccions amb els polinitzadors han considerat interaccions entre parells d'espècies. Atès que les plantes solen interactuar amb diversos polinizadors i els polinizadors visitar diverses espècies de plantes, les espècies invasores tenen el potencial de pertorbar, no només interaccions puntuals, sinó tota la xarxa d'interaccions. No obstant això, s'ha realitzat poca investigació sobre les repercussions de les invasions a nivell de tota la comunitat de polinizadors i plantes. Aquesta tesi estudia la forma que els sistemes de plantes i polinizadores es veuen afectats per espècies de plantes invasores. Hem estudiat tres espècies invasores, Carpobrotus aff acinaciformis, Opuntia stricta i Impatiens glandulifera per caracteritzar la seva integració i impactes sobre la xarxa d'interaccions nadiva. Els polinizadors nadius, sobretot aquells amb un espectre de visites generalistes, proporcionen una via d'integració per a les plantes invasores. Tant C. acinaciformis com O. stricta depenen dels polinizadors per a la reproducció sexual en l'àrea d'introducció, encara que C. acinaciformis es veu lleument limitat pel pol·len. La competència pels polinizadors amb les plantes nadives depèn de l'espècie estudiada, així, vam trobar competència amb O. stricta, facilitacio amb C. acinaciformis i no trobem un efecte en I. glandulifera. En el cas d'existir facilitació per les visites, hem vist que el pol·len invasor té molt poques possibilitats d'interferir en la reproducció de les plantes nadives al dipositar- se en molt baixa freqüència en els estigmes de les espècies nadives. Finalment, quan vam avaluar la importància del paisatge sobre comunitats envaïdes per I. glandulifera, els efectes produïts per la invasió resulten ser independents de l'els efectes del paisatge. Les xarxes planta-polinizador són complexes i involucren una gran quantitat d'interaccions, per això és dificil predir l'impacte de les espècies invasores. De tota manera, el fet que les tres plantes estudiades produeixin importants canvis en aquestes xarxes és molt significatiu.
40
Lindqvist, Hans. „Plant vitality in deciduous ornamental plants affected by lifting date and cold storage /“. Alnarp : Swedish University of Agricultural Sciences, 2000. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=009416344&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
Der volle Inhalt der Quelle
41
Helson, Julie Elizabeth. „Tropical host plant-insect relationships as guides to medicinally-active plants“. Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98723.
Der volle Inhalt der QuelleAnnotation:
Previous studies have shown that: (1) plant defensive compounds may have medicinal properties; and (2) defensive compounds present in aposematic insects are often sequestered from their host-plant(s). This study addresses whether aposematic insects can be used as guides to detect plants containing medicinally-active compounds. First, ten tropical medicinally-active plants and ten non-active plants, selected using previous ICBG bioassay results, were observed regularly to determine their insect populations. Aposematic insects were found more frequently on active than non-active plants ( X2=8.167, P=0.01). Second, three aposematic insects feeding on Tithonia diversifolia were examined chemically to determine the fate of the plant's pharmaceutically-active compounds. They were not found to sequester or excrete these compounds. Therefore, using aposematic insects could increase the likelihood of finding plants with medicinally-active compounds; however, these insects may not necessarily utilize these compounds for defensive purposes. The underlying basis for this significant association between aposematic insects and medicinally-active plants requires further investigation.
42
Pauw, Anton. „Mite-plant mutualism: leaf domatia of African plants house beneficial mites“. Thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/25735.
Der volle Inhalt der Quelle
43
Van, Blerk Justin. „Rodents and Restionaceae : sex-specific plant-animal interactions in dioecious plants“. Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20541.
Der volle Inhalt der QuelleAnnotation:
Differing plant canopy structures between the sexes of the dioecious Cannomois congesta (Restionaceae) were found to be the result of the destructive pre-dispersal seed predation methods used by the four-striped grass mouse (Rhabdomys). Mature, reproductive culms on female plants were felled down (mid way along the culm) in large numbers by Rhabdomys in order for it to access the seeds held terminally on culms. Male plants were largely unaffected due to their lack of seeds. Seeds acquired through culm-felling by Rhabdomys were all eaten shortly after their discovery, leading to significant seed mortality each year and reducing the rate of seed dispersal by ants (myrmecochory). I studied the physiological effects of culm-felling by Rhabdomys in C. congesta. Firstly I investigated nutrient resorption from senescing culms and considered the effects of reproductive effort (higher in females) and sex-specific nutrient losses. I found that nutrient resorption from mature culms was highly efficient in both sexes. Culm-felling by Rhabdomys lead to the loss of pre-senescent culm tissue in females and therefore lead to the loss of a significant proportion of potentially resorbed nutrients. Nutrient resorption was found not to be flexible as a strategy to compensate for higher reproductive costs/nutrient-losses in females. This was possibly due to nutrient resorption occurring near is physiological maximum. Plant photosynthetic performance was also investigated using stable isotopes and gas exchange and was found to be similar in both C. congesta sexes throughout the year. The influence of culm-felling by Rhabdomys on female micro-climate also did not appear to have a significant influence on photosynthetic performance between sexes. There was a general lack of evidence to suggest compensatory physiological changes or reductions in fitness (photosynthetic capacity/growth/reproduction) in females due to higher reproductive costs/nutrient-losses. The lack of physiological differences and the fact that females supported a greater number of culms relative to males suggested that other compensatory mechanisms could exist. Phenological differences were discovered and could be important in allowing flexibility between sexes to best use available resources for their specific sexual requirements. Another possibility is that compensatory growth occurred in females at the cost of rhizome-stored nutrients. This has been shown to occur in graminoids after high levels of herbivory (Bryant et al 1983).
44
Nasim, Muhammad. „Response of rice plants to plant growth regulators under saline conditions“. Thesis, University of Aberdeen, 2003. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU164162.
Der volle Inhalt der QuelleAnnotation:
Responses of rice to plant growth regulators on germination and seedling growth under NaCl salinity were studied to identify possible means of increasing salinity tolerance. Gibberellic acid (GA) promoted germination processes and a-amylase activity and increased plumule but reduced radicle growth after emergence. GA partitioned more metabolites towards the plumule than the radicle. Chlormequat (CCC) showed no beneficial effects and abscisic acid (ABA) inhibited germination under saline conditions. Overall there was no large difference in the performance of three rice varieties, BR29, IR8 and Pokkali in germination. Artificially aged seeds showed increased sensitivity to salinity and GA produced similar effects on germination of artificially aged rice seeds as on unaged seeds. Seed pre-treatment with GA was as effective in promoting germination under saline conditions as applying GA in the germination media. GA with low Ca promoted germination and plumule growth as well as radicle growth. GA increased plant height and fresh weight of seedlings under saline conditions, however it did not show a large positive effect on rice seedlings. CCC had no beneficial effects on rice seedlings. ABA showed possible beneficial effects on rice seedlings as it reduced Na+ uptake and increased K+ and Ca2+ uptake. GA in combination with ABA appeared to adapt rice plants better to saline conditions. GA in combination with low Ca also promoted rice growth under saline conditions.
45
Rosso, Stefano. „Power Plant Operation Optimization Economic dispatch of combined cycle power plants“. Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264350.
Der volle Inhalt der QuelleAnnotation:
As electricity production from renewable sources increases, higher flexibility is required by fossil fuel generation to cope with the inherent fluctuations of solar and wind power. This results in shorter operating cycles and steeper ramps for the turbines, and more uncertainty for the operators. This thesis work applies mathematical optimization and statistical learning to improve the economic dispatch of a combined cycle power plant composed by two separate blocks of two gas turbines and one steam turbine. The goal is to minimize the input fuel to the gas turbines while respecting a series of constraints related to the demand the plant faces, power generation limits etc. This is achieved through the creation of a mathematical model of the plant that regulates how the plant can operate. The model is then optimized to reduce fuel consumption at a minimum. Machine learning techniques have been applied to sensor data from the plant itself to realistically simulate the behavior of the turbines. Input-Output curves have been obtained for power and exhaust heat generation of all the turbines using ordinary least squares on monthly data with a ten minutes sampling rate. The model is cross-validated and proven statistically valid. The optimization problem is formulated through generalized disjunctive programming in the form of a mixed-integer linear problem (MILP) and solved using a branch-and-bound algorithm. The output of the model is a one-week dispatch, in fifteen minutes intervals, carried out for two months in total. Lower fuel consumption is achieved using the optimization model, with a weekly reduction of fuel consumed in the range of 2-4%. A sensitivity analysis and a correlation matrix are used to highlights the demand and the maximum available capacity as critical parameters. Results show that the most efficient machines (alternatively, the ones with highest available capacity) should be operated at maximum load while still striving for an efficient utilization of the exhaust gas.När elproduktionen från förnybara källor ökar krävs högre flexibilitet av fossil bränsleproduktion för att hantera fluktuationerna från sol- och vindkraft. Detta resulterar i kortare driftscykler och brantare ramper för turbinerna och mer osäkerhet för operatörerna. Detta avhandlingsarbete tillämpar matematisk optimering och statistisk inlärning för att förbättra det ekonomiska utnyttjandet av en kombicykel i ett kraftverk som består av två separata block med två gasturbiner och en ångturbin. Målet är att minimera bränsleförbrukningen hos gasturbinerna samtidigt som man tar hänsyn till en serie av villkor relaterade till efterfrågan som anläggningen står inför, kraftproduktionsbegränsningar etc. Detta uppnås genom skapandet av en matematisk modell för anläggningen som reglerar hur anläggningen kan fungera. Modellen är sedan optimerad för minsta möjliga bränsleförbrukning. Maskinteknik har använts på sensor data från själva anläggningen för att realistiskt simulera turbinernas beteende. In och utdata kurvor har erhållits för kraftproduktion och avgasvärmeproduktion med hjälp av ordinary least squares (OLS) med månads data och med en tio minuters samplingshastighet. Modellen är korsvaliderad och bevisad statistiskt giltig. Optimeringsproblemet formuleras genom en generaliserad disjunktiv programmering i form av ett mixed-integer linear problem (MILP) och löses med hjälp av en Branch-and-Bound algoritm. Resultatet från modellen är en veckas värden, med femton minuters intervall, totalt i två månader. Lägre bränsleförbrukning uppnås med hjälp av optimeringsmodellen, med en vecka minskad bränsleförbrukning i intervallet 2-4%. En känslighetsanalys och en korrelationsmatris används för att visa efterfrågan och den maximala tillgängliga kapaciteten som kritiska parametrar. Resultaten visar att de mest effektiva maskinerna (alternativt de med högsta tillgängliga kapacitet) bör drivas med maximal belastning medan de fortfarande strävar efter ett effektivt utnyttjande av avgaserna.
46
Zuefle, Marion E. „The impact of non-native woody plants on the native herbivorous insect community of northern Delaware“. Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 75 p, 2006. http://proquest.umi.com/pqdweb?did=1163239621&sid=7&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Der volle Inhalt der Quelle
47
Underwood, Angela Marie Spano Folkerts Debbie R. „Larvae of Sarcophagidae (Insecta Diptera) and their relationship with the pitcher plants (Sarraceniaceae: Sarracenia) of southeastern U.S. bogs /“. Auburn, Ala, 2009. http://hdl.handle.net/10415/1889.
Der volle Inhalt der Quelle
48
Tonello, Kelly Cristina. „Comportamento ecofisiologico de clones de Eucalyptus“. [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256936.
Der volle Inhalt der QuelleAnnotation:
Orientador: Jose Teixeira FilhoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola
Made available in DSpace on 2018-08-15T15:44:54Z (GMT). No. of bitstreams: 1 Tonello_KellyCristina_D.pdf: 3209931 bytes, checksum: ad807b85c48d80b43bb9c5e89fb27160 (MD5) Previous issue date: 2010
Resumo: O crescimento e o desenvolvimento dos vegetais é conseqüência de vários processos fisiológicos controlados pelas condições ambientais e características genéticas de cada espécie vegetal. Este estudo teve por objetivo caracterizar o comportamento ecofisiológico da transpiração (E) e condutância estomática (Gs) de dois clones de Eucalyptus grandis x Eucalyptus urophylla (C041 e P4295) sob diferentes condições de disponibilidade hídrica no solo e em função de variáveis ambientais como radiação global (Rg), radiação fotossinteticamente ativa (Qleaf) e déficit de pressão de vapor da atmosfera (DPV). As aferições foram realizadas ao longo do período de fevereiro de 2007 a agosto de 2008 em três escalas de estudo designadas como vaso, parcela e bacia hidrográfica. Medidas de potencial hídrico antemanhã (?pd) foram realizadas para o acompanhamento das disponibilidades hídricas no solo. Após o conhecimento do comportamento ecofisiológico dos clones em função das variáveis ambientais e ?pd, buscou-se relacionar as respostas obtidas na escala vaso com as escalas parcela e bacia hidrográfica por meio de modelos ecofisiológicos desenvolvidos para a mudança de escala ao nível de folha. De acordo com os resultados, as variáveis ecofisiológicas estiveram diretamente associadas às variáveis ambientais e ao ?pd tanto para o clone C041 quanto para o clone P4295. Foram observados entre os clones comportamentos ecofisiológicos distintos quando associados à Qleaf, DPV e ?pd. Os clones apresentaram-se diferentes na amplitude de resposta de E e Gs em função de Qleaf e DPV entre as escalas, porém, observou-se a mesma tendência de comportamento, com exceção da relação Gs x DPV para o clone C041, entre escala vaso e parcela/bacia hidrográfica. Os modelos propostos para a mudança de escala de folha para folha mostraram-se satisfatórios, principalmente nas relações envolvendo a radiação fotossinteticamente ativa. Contudo, não apresentaram bons resultados para a extrapolação das respostas ecofisiológicas de Gs em função do DPV
Abstract: The growth and development of plants is a consequence of several physiological processes controlled by environmental conditions and genetic characteristics of each plant species. This study aimed to characterize the ecophysiological behavior of transpiration (E) and stomatal conductance (Gs) of two clones of Eucalyptus grandis x urophylla (C041 and P4295) under different soil water conditions and according to environmental variables such as global radiation (Rg), photosynthetic active radiation (Qleaf) and a vapor pressure deficit of the atmosphere (VPD). The measurements were performed during the period February 2007 to August 2008 on three scales of study designated as a pot, plot and watershed. Predawn leaf water potential (?pd) measurements were performed to monitor water availability in the soil. After the knowledge of the ecophysiological behavior of the clones on the basis of environmental variables and ?pd, sought to link the responses obtained in the pots scale with pot and watershed through ecophysiological models developed for scaling up leaf from leaf. According to the results, the ecophysiological behavior were directly associated with environmental variables and the ?pd both to the C041 as for P4295. Were observed among different clones ecophysiological behavior when associated with Qleaf, VPD and ?pd. The clones were different in amplitude of E and Gs as function of Qleaf and VPD between the scales, however, showed the same pattern of behavior, except for Gs x VPD for clone C041 between pot and plot / watershed scale. The proposed models for the scaling up from leaf to leaf were satisfactory, especially in relationships involving the Qleaf. However, they not provided good results for the extrapolation of ecophysiological responses of Gs as a function of VPD
Doutorado
Agua e Solo
Doutor em Engenharia Agrícola
49
Soares, Natalia Costa [UNESP]. „Variação intra-específica na fenologia de espécies de sub-bosque de floresta Atlântica e sua relação com variáveis microambientais“. Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/87852.
Der volle Inhalt der QuelleAnnotation:
Made available in DSpace on 2014-06-11T19:23:02Z (GMT). No. of bitstreams: 0
Previous issue date: 2011-04-29Bitstream added on 2014-06-13T18:50:12Z : No. of bitstreams: 1
soares_nc_me_rcla.pdf: 2043945 bytes, checksum: 87d8fa88bf79cb92e1c9e75b4726f821 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Variação intra-específica na fenologia de espécies de sub-bosque de Floresta Atlântica e sua relação com variáveis microambientais - Fatores abióticos, como a umidade relativa, temperatura e luz, influenciam o estabelecimento, desenvolvimento e reprodução das espécies vegetais florestais. Entretanto é necessária a coleta de parâmetros estruturais, microclimáticos e microambientais para a caracterização dos ambientes nos quais as plantas se desenvolvem. Neste contexto, o presente trabalho objetivou avaliar a influência de fatores do microambiente na resposta fenológica de espécies vegetais componentes do sub-bosque de floresta Atlântica, em Ubatuba, SP. Procuramos responder as seguintes perguntas: i) As plantas de sub-bosque podem ser agrupadas em relação aos ambientes de luz: borda natural, clareira e interior sombreado da floresta?; ii) Existem variações intra-específicas na fenologia das espécies de sub-bosque de Floresta Atlântica de acordo com o ambiente de luz em que foram agrupadas?; iii) A intensidade das respostas fenológicas (número de estruturas reprodutivas produzidas) está relacionada aos locais de luz?; iv) Outras condições microclimáticas, como temperatura e umidade relativa, e microambientais, como a densidade da vegetação, também influenciam a fenologia das espécies? Para tanto a fenologia e a produção de estruturas reprodutivas de quatro espécies abundantes do sub-bosque foram acompanhadas de janeiro de 2009 a abril de 2010. Indivíduos foram selecionados em ambientes previamente determinados como borda natural (beira de rio), clareira e interior de floresta atlântica. Medidas periódicas das variáveis microclimáticas (temperatura, umidade relativa, PAR) e microambiental (abertura do dossel) próximas aos indivíduos amostrados foram realizadas. Medidas estruturais...
Phenological intraspecific variation of Atlantic Forest understory species and its relation to microenvironmental variables - Abiotic factors such as humidity, temperature and light influence the establishment, development and reproduction of forest plant species. However, it is necessary to collect structural, microclimatic and microenvironmental parameters to characterize the environments in which plants grow. In this context, this study evaluated the influence of the microenvironment in the phenological response of understory plant species components of the Atlantic Forest in Ubatuba, São Paulo State. We tried to answer the following questions: i) Can the understory species be grouped in relation to natural edge, gaps and interior microenvironments? ii) Do exist intraspecific variations in the phenology of understory species of Atlantic forest in accordance with the light environment in which they were grouped? iii) Do the intensity of phenological responses (number of reproductive structures produced) related to local condictions of light?; iv) Do other microclimatic (such as temperature and relative humidity) and microenvironmental (density vegetation) conditions also influence the phenology of species? The phenology and reproductive structures production of four abundant species of the understory were followed from January 2009 to April 2010. Individuals were selected in environments previously determined as natural edge (riverside), gap and interior. We performed periodic measurements of microclimatic (temperature, relative humidity and PAR) and microenvironmental variables (canopy openness) near the sampled individuals. Structural measures (CAS, CAP, plant height, crown height from the ground and crown size) and microenvironment characterization (canopy height, understory vertical density, distance... (Complete abstract click electronic access below)
50
Sangwan, Veena. „Temperature sensing in plants“. Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37831.
Der volle Inhalt der QuelleAnnotation:
It is now well established that cold-triggered calcium influx mediates cold-induced gene expression and development of freezing tolerance (cold acclimation). In this thesis, cold signaling events both upstream and downstream of calcium influx were examined.First, it was shown that the studies on calcium mediation of cold acclimation in alfalfa cell suspension cultures could be applied to intact seedlings of Arabidopsis. Calcium chelators and channel blockers caused a strong reduction in the cold-induced accumulation of kin1 and kin2 transcripts, suggesting that calcium influx was an essential event during cold signaling and that the source of calcium for this influx was largely the calcium-rich cell wall. Evidence suggesting the involvement of calcium-dependent protein kinases (CDPKs) was also obtained.
Second, the nature of events upstream of calcium influx was explored. For this study, transgenic Brassica napus seedlings possessing both the endogenous cold-inducible BN115 gene and the coding part of beta-glucuronidase (GUS) gene placed under the control of the BN115 promoter were used. Thus cold-activation of the BN115 promoter drove the expression of both BN115 at the transcriptional level and the GUS enzyme activity at the translational level. Cold-activation of BN115 was inhibited by chemicals which cause membrane fluidization, cytoskeletal stabilization and inhibition of Ca2+ influx, and mimicked at 25°C by chemicals causing membrane rigidification, cytoskeletal destabilization and Ca2+ influx. Inhibitors of protein and lipid kinases prevented cold-activation of BN115, but inhibition of protein phosphatases activated BN115 at 25°C.
Third, given the increasing importance of mitogen-activated protein kinases (MAPKs) in signal transduction, the nature of molecular mechanisms that lead to cold-activation of a previously reported MAPK, SAMK, was investigated. During this study, the first plant MAPK activated by heat shock was discovered and named HAMK (Heat-shock-activated MAPK). It was shown that cold-activation of SAMK is mediated by cold-induced membrane rigidification, whereas the heat shock-activation of HAMK occurs through heat shock-induced membrane fluidization. Whereas activation of both SAMK and HAMK is blocked by an actin microfilament stabilizer, it is mimicked at 25°C by chemical destabilizers of microtubules or actin microfilaments. All of these events are inhibited by blocking the influx of extracellular Ca 2+. Cold-activation of SAMK and heat-activation of HAMK was prevented by treatment of cells with inhibitors of CDPKs. Thus, cold and heat shock are sensed by structural changes in the plasma membrane, which transduces the signal via cytoskeletal rearrangements to the opening of calcium channels, leading to Ca2+ influx, activation of CDPKs and activation of distinct MAPK cascades.