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Rai, Hardeep Singh. "Molecular phylogenetic studies of the vascular plants." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/3889.
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To investigate vascular-plant phylogeny at deep levels of relationship, I collected and analyzed a large set of plastid-DNA data comprising multiple protein-coding genes and associated noncoding regions. I addressed questions relating to overall tracheophyte phylogeny, including relationships among the five living lineages of seed plants, and within two of the largest living gymnosperm clades (conifers and cycads). I also examined relationships within and among the major lineages of monilophytes (ferns and relatives), including their relationship to the remaining vascular plants. Overall, I recovered three well-supported lineages of vascular plants: lycophytes, monilophytes, and seed plants. I inferred strong support for most of the phylogenetic backbones of cycads and conifers. My results suggest that the cycad family Stangeriaceae (Stangeria and Bowenia) is not monophyletic, and that Stangeria is instead more closely related to Zamia and Ceratozamia. Within the conifers, I found Pinaceae to be the sister-group of all other conifers, and I argue that two conifer genera, Cephalotaxus and Phyllocladus (often treated as monogeneric families) should be recognized under Taxaceae and Podocarpaceae, respectively. Systematic error likely affects inference of the placement of Gnetales within seed-plant phylogeny. As a result, the question of the relationships among the five living seed-plant groups still remains largely unresolved, even though removal of the most rapidly evolving characters appears to reduce systematic error. Phylogenetic analyses that included these rapidly evolving characters often led to the misinference of the “Gnetales-sister” hypothesis (Gnetales as the sister-group of all other seed plants), especially when maximum parsimony was the inference method. Filtering of rapidly evolving characters had little effect on inference of higher-order relationships within conifers and monilophytes, and generally resulted in reduced support for backbone relationships. Within the monilophytes, I found strong support for the majority of relationships along the backbone. These were generally congruent with other recent studies. Equisetaceae and Marattiaceae may be, respectively, the sister-groups of the remaining monilophytes and of the leptosporangiate ferns, but relationships among the major monilophyte lineages are sensitive to the outgroups used, and to long branches in lycophytes.
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Sutherland, Margery Louise. "Recognition of host plants by vascular pathogens." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303155.
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Haig, David. "Applications of allocation and kinship models to the interpretation of vascular plant life cycles." Phd thesis, Australia : Macquarie University, 1990. http://hdl.handle.net/1959.14/23227.
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Thesis by publication.Thesis (PhD) -- Macquarie University, School of Biological Sciences, 1990.
Bibliography: leaves 269-324.
Introduction -- Models of parental allocation -- Sex expression in homosporous pteridophytes -- The origin of heterospory -- Pollination and the origin of the seed habit -- Brood reduction in gymnosperms -- Pollination: costs and consequences -- Adaptive explanations for the rise of the angiosperms -- Parent-specific gene expression and the triploid endosperm -- New perspectives on the angiosperm female gametophyte -- Overview -- Glossary -- Kinship terms in plants -- Literature Cited.
Among vascular plants/ different life cycles are associated with characteristic ranges of propagule size. In the modern flora, isospores of homosporous pteridophytes are almost all smaller than 150 urn diameter, megaspores of heterosporous pteridophytes fall in the range 100-1000 urn diameter, gymnosperm seeds are possibly all larger than the largest megaspores, but the smallest angiosperm seeds are of comparable size to large isospores. -- Propagule size is one of the most important features of a sporophyte's reproductive strategy. Roughly speaking, larger propagules have larger food reserves, and a greater probability of successful establishment, than smaller propagules, but a sporophyte can produce more smaller propagules from the same quantity of resources. Different species have adopted very different size-versus-number compromises. The characteristic ranges of propagule size, in each of the major groups of vascular plants, suggest that some life cycles are incompatible with particular size-versus-number compromises. -- Sex expression in homosporous plants is a property of gametophytes (homosporous sporophytes are essentially asexual). Gametophytes should produce either eggs or sperm depending on which course of action gives the greatest chance of reproductive success. A maternal gametophyte must contribute much greater resources to a young sporophyte than the paternal gametophyte. Therefore, smaller gametophytes should tend to reproduce as males, and gametophytes with abundant resources should tend to reproduce as females. Consistent with these predictions, large female gametophytes release substances (antheridiogens) which induce smaller neighbouring ametophytes to produce sperm. -- The mechanism of sex determination in heterosporous species appears to be fundamentally different. Large megaspores develop into female gametophytes, and small icrospores develop into male gametophytes. Sex expression appears to be determined by the sporophyte generation. This is misleading. As argued above, the optimal sex expression of a homosporous gametophyte is influenced by its access to resources. This is determined by (1) the quantity of food reserves in its spore and (2) the quantity of resources accumulated by the gametophyte's own activities. If a sporophyte produced spores of two sizes, gametophytes developing from the larger spores' would be more likely to reproduce as females than gametophytes developing from the smaller spores, because the pre-existing mechanisms of sex determination would favor production of archegonia by larger gametophytes. Thus, the predicted mechanisms of sex determination in homosporous species could also explain the differences in sex expression of gametophytes developing from large and small spores in heterosporous species.
Megaspores of living heterosporous pteridophytes contain sufficient resources for female reproduction without photosynthesis by the gametophyte (Platyzoma excepted), whereas microspores only contain sufficient resources for male reproduction. Furthermore, many more microspores are produced than megaspores. A gametophyte's optimal sex expression is overwhelmingly determined by the amount of resources supplied in its spore by the sporophyte, and is little influenced by the particular environmental conditions where the spore lands. Gametophytes determine sex expression in heterosporous species, as well as homosporous species. A satisfactory model for the evolution of heterospory needs to explain under what circumstances sporophytes will benefit from producing spores of two distinct sizes. -- In Chapter 4, I present a model for the origin of heterospory that predicts the existence of a "heterospory threshold". For propagule sizes below the threshold, homosporous reproduction is evolutionarily stable because gametophytes must rely on their own activities to accumulate sufficient resources for successful female reproduction. Whether a gametophyte can accumulate sufficient resources before its competitors is strongly influenced by environmental conditions. Gametophytes benefit from being able to adjust their sex expression in response to these conditions. For propagule sizes above the threshold, homosporous reproduction is evolutionarily unstable, because the propagule's food reserves are more than sufficient for a "male" gametophyte to fertilize all eggs within its neighbourhood. A population of homosporous sporophytes can be invaded by sporophytes that produce a greater number of smaller spores which could land in additional locations and fertilize additional eggs. Such'spores would be male-specialists on account of their size. Therefore, both spore types would be maintained in the population because of frequency-dependent selection. -- The earliest vascular plants were homosporous. Several homosporous groups gave rise to heterosporous lineages, at least one of which was the progeniture of the seed plants. The first heterosporous species appear in the Devonian. During the Devonian, there was a gradual increase in maximum spore size, possibly associated with the evolution of trees and the appearance of the first forests. As the heterospory threshold was approached, the optimal spore size for female reproduction diverged from the optimal spore size for male reproduction. Below the threshold, a compromise spore size gave the highest fitness returns to sporophytes, but above the threshold, sporophytes could attain higher fitness by producing two types of spores. -- The evolution of heterospory had profound consequences. Once a sporophyte produced two types of spores, microspores and megaspores could become specialized for male and female function respectively. The most successful heterosporous lineage (or lineages) is that of the seed plants. The feature that distinguishes seed plants from other heterosporous lineages is pollination, the capture of microspores before, rather than after, propagule dispersal. Traditionally, pollination has been considered to be a major adaptive advance because it frees sexual reproduction from dependence on external fertilization by freeswimming sperm, but pollination has a more important advantage. In heterosporous pteridophytes, a megaspore is provisioned whether or not it will be fertilized whereas seeds are only provisioned if they are pollinated.
The total cost per seed cannot be assessed solely from the seed's energy and nutrient content. Rather, each seed also has an associated supplementary cost of adaptations for pollen capture and of resources committed to ovules that remain unpollinated. The supplementary cost per seed has important consequences for understanding reproductive strategies. First, supplementary costs are expected to be proportionally greater for smaller seeds. Thus, the benefits of decreasing seed size (in order to produce more seeds) are reduced for species with small seeds. This effect may explain minimum seed sizes. Second, supplementary costs are greater for populations at lower density. Thus, there is a minimum density below which a species cannot maintain its numbers. -- By far the most successful group of seed plants in the modern flora are the angiosperms. Two types of evidence suggest that early angiosperms had a lower supplementary cost per seed than contemporary gymnosperms. First, the minimum size of angiosperm seeds was much smaller than the minimum size of gymnosperm seeds. This suggests that angiosperms could produce small seeds more cheaply than could gymnosperms. Second, angiosperm-dominated floras were more speciose than the gymnosperm-dominated floras they replaced. This suggests that the supplementary cost per seed of angiosperms does not increase as rapidly as that of gymnosperms, as population density decreases. In consequence, angiosperms were able to displace gymnosperms from many habitats, because the angiosperms had a lower cost of rarity. -- Angiosperm embryology has a number of distinctive features that may be related to the group's success. In gymnosperms, the nutrient storage tissue of the seed is the female gametophyte. In most angiosperms, this role is taken by the endosperm. Endosperm is initiated by the fertilization of two female gametophyte nuclei by a second sperm that is genetically identical to the sperm which fertilizes the egg. Endosperm has identical genes to its associated embryo, except that there are two copies of maternal genes for every copy of a paternal gene. -- Chapter 9 presents a hypothesis to explain the unusual genetic constitution of endosperm. Paternal genes benefit from their endosperm receiving more resources than the amount which maximizes the fitness of maternal genes, and this conflict is expressed as parent-specific gene expression in endosperm. The effect of the second maternal genome is to increase maternal control of nutrient acquisition. -- Female gametophytes of angiosperms are traditionally classified as monosporic, bisporic or tetrasporic. Bisporic and tetrasporic embryo sacs contain the derivatives of more than one megaspore nucleus. Therefore, there is potential for conflict between the different nuclear types within an embryo sac, but this possibility has not been recognized by plant embryologists. In Chapter 10, I show that many previously inexplicable observations can be understood in terms of genetic conflicts within the embryo sac.
Mode of access: World Wide Web.
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Kücükoglu, Melis. "CLE/RLK regulated vascular signalling pathways in plants." Thesis, Umeå University, Plant Physiology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-26276.
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Entire postembryonic production of plant tissues are maintained by meristems. These specialized structures provide a pool of undifferentiated stem cells and a limited population of proliferating cells which are destined for differentiation in order to generate a variety of tissues in the plant body. For the forest trees, a large part of the biomass is produced by a secondary meristem called vascular cambium. Vascular cambium forms a continuous cylinder of meristematic cells in the stem, producing both secondary phloem and secondary xylem or wood. Maintenance and differentiation of meristems are much conserved and strictly regulated for the production of correct tissues and organs. Receptor-like kinases (RLKs) are characterized by the presence of a signal sequence, a putative amino-terminal extracellular domain connected to a carboxyl-terminal intracellular kinase domain with a trans-membrane domain. They control a wide-range of physiological processes, including development, disease resistance, hormone perception, and self-incompatibility. Leucine-rich repeat receptor-like kinases (LRR-RLKs) represent the largest group of RLKs in the Arabidopsis thaliana genome, with more than 200 members.Several LRR-RLKs and their putative ligands CLAVATA3 (CLV3)/ Endosperm Surrounding Region (ESR)-related (CLE) peptides have been found to be involved in the regulation of vascular development. In the current study, the main aim was to study the tissue-specific expression patterns of LRR-RLK genes in A. thaliana by generating promoter::GUS transcriptional fusions. The results confirmed that these genes are expressed in the vasculature of the plants. Moreover, Populus orthologs of the CLE genes were detected by bioinformatic tools as putative ligands of LRR-RLKs and an extensive quantitative Real-Time Reverse Transcriptase PCR (qRT-PCR) analysis was performed to test for significant changes in transcript levels across different tissue types. As a result, a collection of potential candidate genes for vascular development were identified.
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Gersbach, Paul Vincent, University of Western Sydney, and of Science Technology and Environment College. "Aspects of essential oil secretion in vascular plants." THESIS_CSTE_XXX_Gersbach_P.xml, 2001. http://handle.uws.edu.au:8081/1959.7/775.
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A study of some aspects of essential oil secretion in plants was conducted. The first part of the study involved analysis of the volatile terpenoid content and composition of leaf extracts from a range of Australian native plants by gas chromatography and mass spectrometry. Secretory structures were studied by several microscopic imaging techniques including conventional bright and dark field optical microscopy, confocal microscopy, and scanning (SEM) and transmission (TEM) electron microscopy. Three methods were employed for scanning electron microscopy. Sample material was prepared for conventional SEM by chemical fixation and rapid freeze fixation, and fresh material was imaged by environmental SEM. These methods were compared, and the images acquired by environmental SEM were invariably of a superior standard as the biological integrity of the samples was retained throughout, and the samples were free of process-induced artefacts. Several other tests were conducted and results discussed in some detail. In the final part of the study, aspects of essential oil secretion were examined by histochemical methods. The first of these was a new method based on traditional approaches to histochemistry. The monoterpene phenols thymol and carvacrol were located in glandular trichomes of Lamiaceae species by means of a colour-change reaction of the phenols with a nitrosophenol/acid reagent. The second used magnetic resonance imaging by a chemical shift selective method to locate, non invasively, the aromatic monoterpenes thymol and anethole in secretory structures in the fruit of Carum copticum (Apiaceae) and the leaves of Backhousia anisata (Myrtaceae) respectively.Doctor of Philosophy (PhD) (Science)
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Gersbach, Paul V. "Aspects of essential oil secretion in vascular plants /." View thesis, 2001. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20031223.143208/index.html.
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Thesis (Ph.D.) -- University of Western Sydney, 2001."This thesis is presented in fulfilment of the degree of Doctor of Philosophy in Science at the University of Western Sydney, Richmond, New South Wales, Australia" Bibliography : p. 145-163.
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Balogh, Zsuzsanna. "Chemical hydrology of vascular plant growth : role of root-fungus associations." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Summer2006/z%5Fbalogh%5F071806.pdf.
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Bruchmann, Ines [Verfasser]. "Plant endemism in Europe : spatial distribution and habitat affinities of endemic vascular plants / Ines Bruchmann." Flensburg : Zentrale Hochschulbibliothek Flensburg, 2011. http://d-nb.info/1019372133/34.
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Chowdhury, Anurag. "Studies on the diversity and ethnic uses of wetland vascular plants in Terai and Duars of West Bengal, India." Thesis, University of North Bengal, 2015. http://ir.nbu.ac.in/hdl.handle.net/123456789/1871.
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Harrelson, Sarah M. "A floristic survey of the terrestrial vascular plants of Strouds Run State Park, Athens County, Ohio." Ohio : Ohio University, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1113581854.
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Backéus, Ingvar. "Aboveground production and growth dynamics of vascular bog plants in central Sweden." Uppsala : Stockholm : Svenska växtgeografiska sällskapet ; Almqvist & Wiksell International [distributor], 1985. http://catalog.hathitrust.org/api/volumes/oclc/12807002.html.
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Steynen, Quintin John, and University of Lethbridge Faculty of Arts and Science. "Genetic analysis of leaf vascular patterning in Arabidopsis thaliana." Thesis, Lethbridge : University of Lethbridge, University of Lethbridge. Faculty of Arts and Science, 2001, 2001. http://hdl.handle.net/10133/143.
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I have isolated and characterized a recessive mutation in the Forked (FKD) gene that results in the abnormal initiation of vascular bundles in the foliar organs, such that the apices of the vascular bundles initiate freely. Once initiated, the development of Fkd vascular bundles is like wild type, generating an open vascular pattern of similar complexity to the closed venation pattern of wild type. Despite the significant alteration in the vascular pattern, Fkd plants are morphologically indistinct from wild type. fkd mutants do not show altered sensitivity to the effects of auxin and show additive phenotypes with auxin response mutants, suggesting the FKD is part of a pathway acting independently of auxin. The similarity of the open vascular pattern of Fkd plants to that of ancestral vascular plants suggests that acquisition of this pathway may have been critical in the evolution of the closed vascular pattern.x, 55 leaves : ill. ; 28 cm.
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Kowal, Jill. "Fungal interactions with vascular and non-vascular plants : an investigation of mutualisms and their roles in heathland regeneration." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/42788.
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Mycorrhizal mutualisms between aboveground vascular plant communities, which reward their belowground fungal associates with photosynthates in return for growth-limiting nutrients such as phosphate, are widely recognized as stable long-term interactions which helped plants colonize land. Pezoloma ericae (D.J. Read) Baral, an ascomycete mycorrhiza-forming fungus present amongst plants in the Ericales, such as heathers, also forms associations in several families of non-vascular leafy liverworts. Whether there is a mutually beneficial functional relationship between these leafy liverworts and the fungus growing in their rhizoids was previously unconfirmed. Furthermore, an ecological role of this 'shared' mycobiont and its link between vascular (Ericaceae) and non-vascular (liverworts) plants was also unknown. Thus the main questions asked in this dissertation are: 1) Is there a measurable mutually beneficial relationship between a liverwort and its fungal partner?; and, 2) Can liverworts harbouring the ericoid mycorrhiza P. ericae act as inoculum that facilitates the re-establishment of Ericaceae - and henceforth be proposed as a practical tool in a restoration ecology context. This is the first time British species of leafy liverworts are conclusively identified to harbour the ericoid mycorrhizal fungus Pezoloma ericae using molecular identification. I have demonstrated a mutualism occurring between the leafy liverworts and their fungal symbiont in two independent microcosm growth experiments and confirmatory reciprocal trophic exchanges between phosphorus and carbon and the two organisms. Glasshouse experiments demonstrated P. ericae originating from leafy liverwort rhizoids, can repeatedly colonize Ericaceae plant roots. Under realistic ecological circumstances (further tested at two field sites), liverworts delivered mycorrhizal inoculum and improved the resilience and growth of vascular plants. By providing this novel source of mycorrhizal inoculum, symbiotic non-vascular plants can contribute to the restoration of plant communities dominated by Ericaceous plants. This research leads to broader knowledge about the function of ericoid mycorrhizas in ecosystems with multi-trophic non-vascular-fungi-vascular community interactions, both above and below ground.
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Flaig, Jeanette H. "A vascular plant inventory of the eastern San Juan Mountains and vicinity in southern Colorado." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1495959121&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Larson, Jill E. "A floristic inventory of vascular plants of the Carson National Forest and vicinity, north-central New Mexico." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594496631&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Pier, Melanie Dawn. "Vascular plants as indicators of polychlorinated biphenyl contamination in terrestrial Arctic environments." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ59397.pdf.
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Walker, Charles Henry. "Biological and ecological attributes of some endangered vascular plants of southern Illinois /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1324370471&sid=4&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Backéus, Ingvar. "Aboveground production and growth dynamics of vascular bog plants in central Sweden." Doctoral thesis, Uppsala universitet, Matematisk-naturvetenskapliga fakulteten, 1985. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-184355.
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Santos, Leonardo Biral [UNESP]. "Florística vascular da Mata da Pavuna, Botucatu, SP, Brasil." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/87842.
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A Mata da Pavuna é um fragmento de floresta estacional semidecídua em um cânion com afloramento rochoso e solo raso, localizado no município de Botucatu, Estado de São Paulo. Foram amostradas todas as espécies vasculares em estádio reprodutivo e identificadas até o menor nível possível. Foram encontradas 381 espécies em 83 famílias. Fabaceae foi a família com maior número de espécies (44), seguido de Asteraceae (33), Euphorbiaceae (18), Poaceae (17), Malvaceae (14), Bignoniaceae e Solanaceae (12). Em Pteridophyta sensu stricto as famílias mais diversas foram Pteridaceae (oito espécies) e Polypodiaceae (sete). Comparado a outros levantamentos florísticos extensos na Mata Atlântica os resultados ressaltam a elevada diversidade florística local, bem como a presença de espécies típicas de formações xerofíticas sugerindo, inclusive, a ocorrência de um encrave de vegetação seca. Noticiamos também o primeiro registro de Pellaea ovata (Desv.) Weath. (Pteridaceae) para o Brasil
The „Mata da Pavuna‟ is a semideciduous seasonal forest fragment located in a canyon characterized by rock outcrops and shallow soil, in municipality of Botucatu, State of São Paulo. We collected all vascular plants in reproductive stage, and identified them to the lowest taxonomic level possible. We found 381 species in 83 families. Fabaceae was the most diverse family with 44 species, followed by Asteraceae (33), Euphorbiaceae (18), Poaceae (17), Malvaceae (14), Bignoniaceae (12) and Solanaceae (12). In the Pteridophyta sensu lato the most diverse families was Pteridaceae (eight species) and Polypodiaceae (seven). Compared to other comprehensive floristic surveys carried out in the Atlantic Forest these results show the high floristic diversity and the presence of typical xerofitic vegetation species, suggesting the presence of an enclave of dry forest. We reported here the first mention of Pellaea ovata (Desv.) Weath. (Pteridaceae) for Brazil
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Phiri, E. E. "Species occupancy, distribution and abundance : indigenous and alien invasive vascular plants on sub-Antarctic Marion Island." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/47001.
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Thesis (MSc)--Stellenbosch University, 2008.ENGLISH ABSTRACT: Macroecological relationships have rarely been studied at wide spatial scales and across geographic ranges of species in the field in the sub-Antarctic. In this thesis I examined the occupancy, distribution and abundance, and the relationships thereof, of indigenous plants and alien species at broad (island-wide) and fine scales across sub-Antarctic Marion Island. The impacts of alien species and their interactions with indigenous plants were also investigated. I examined the nature of the abundance structure of a cushion-forming, vascular plant, Azorella selago, at the island-wide scale. Moreover, the hypothesis that species reach their highest abundances at the centre of their geographic range and decline in abundance towards the range edges was tested. Azorella selago cushions were counted in 8 m x 8 m quadrats, placed regularly at 1 minute latitude and longitude intervals across Marion Island. Using spatially non-explicit and explicit methods, this study showed that the abundance structure of A. selago had a more complex pattern of high abundance patches and low abundance gaps in its island-wide distribution. Subsequently, the hypothesis of an abundant centre distribution was not supported for A. selago across Marion Island. Rather, there were sharp discontinuities at both the coastal and altitudinal (667 m a.s.l.) limits for the species, between which little pattern in altitudinal abundance structure existed. Mice (Mus musculus) have recently been found to cause extensive structural damage to A. selago. The structural influence of mice on vegetation structure at the landscape scale has largely been overlooked on many sub-Antarctic islands. I mapped the distribution of evidence of mouse damage within the cushions of A. selago across the island using systematic (at 1 minute latitude and longitude intervals) and opportunistic sampling. Approximately 40 % of the systematically sampled sites had evidence of mouse damage to A. selago. Furthermore, a third of cushions in opportunistically sampled sites was damaged. Mouse damage was high in sites of low A. selago abundance, emphasizing that impacts of mice may be greater in low cushion abundance areas. This damage sometimes led to the disintegration of entire cushions. Given that A. selago acts as a nurse plant and supports high abundances of indigenous invertebrates, the impacts of mice on this keystone species may have significant ecological implications. Studies on interactions between alien and indigenous plants are limited within the sub-Antarctic. I examined the fine-scale distributions and co-occurrences of alien plants, Agrostis stolonifera and Sagina procumbens, and the indigenous Acaena magellanica (in 2 m x 2 m plots, subdivided into 0.25 m x 0.25 m quadrats) along rivers on Marion Island. Environmental variables were important for the occurrence of these species. In particular, 42.95 % and 24.82 % of the deviance in the occurrence of A. stolonifera and S. procumbens, respectively, was explained by environmental variables, compared to 17.35 % for A. magellanica. Furthermore, the co-occurrence of A. magellanica with A. stolonifera was significantly influenced by environmental variables. Significant positive spatial associations between A. magellanica and A. stolonifera were found, while the interactions of either species with S. procumbens were either spatially dissociated or random. Therefore, this study highlighted that alien species are responding to different environmental variables and conditions on Marion Island. Sagina procumbens seems to be less sensitive to the island’s environmental conditions and may thus be affecting biodiversity at broader ranges. This thesis provides unparalleled data on the distributions and interactions of indigenous plants and alien species for Marion Island. Alien species are undoubtedly posing significant threats to indigenous plants on the island and this thesis presents insight into interactions of species, specifically plants, an approach underrepresented in the sub-Antarctic to date.
AFRIKAANSE OPSOMMING: Makro-ekologiese verhoudings is selde bestudeer op wye ruimtelike skale en oor geografiese gebiede van spesies in die veld in die sub-Antarktiek. In hierdie tesis het ek die digtheid, bewoning, verspreiding en die verhoudings daarvan, van inheemse plante en uitheemse spesies ondersoek op breë (eiland-wyd) en smal skale oor sub-Antarktiese Marion Eiland. Die impakte van uitheemse spesies en hul interaksies met inheems plante is ook ondersoek. Ek het die aard van die digtheidstruktuur ondersoek van 'n kussing-vormende, vaatplant, Azorella selago, op die eiland-wydte skaal. Bowenal is die hipotese dat spesies hul hoogste digtheid bereik in die sentrum van hul geografies gebied en afneem in digtheid na die grense van die gebied getoets. Azorella selago kussings is getel in 8 m x 8 m kwadrante, wat eweredig geplaas is op 1 minuut breedte- en lengtegraad intervalle oor Marion Eiland. Deur gebruik te maak van ruimtelik nie-eksplisiete en eksplisiete metodes, het hierdie studie getoon dat die digtheidstruktuur van A. selago ‘n meer komplekse patroon van hoë digtheidslaslappe en lae digtheidsgapings in sy eiland-wyd verspreiding het. Vervolgens is die hipotese van 'n digte sentrum verspreiding nie gesteun vir A. selago oor Marion Eiland nie. Daar was eerder skerp diskontinuïteite by beide die kus- en hoërliggende (667 m bo seespieël) grense vir die spesie, waartussen daar ’n oneweredige patroon in digtheidstruktuur bestaan het. Onlangs is bevind dat muise (Mus musculus) uitgebreide struktuele skade aan A. selago veroorsaak. Die struktuele invloed van muise op plantegroei struktuur op landskapskaal is grootliks oor die hoof gesien op baie sub-Antarktiese eilande. Ek het die verspreiding van die bewyse van muisskade binne die kussings van A. selago oor die eiland gekarteer deur gebruik te maak van sistematiese (tot 1 minuut breedte- en lengtegraad intervalle) en opportunistiese opnames. Ongeveer 40 % van die sistematiese opname kwadrante het bewyse van muis skade aan A. selago vertoon. Verder, ‘n derde van die kussings in die opportunistiese opname kwadrante was beskadig. Muisskade was hoog in plotte met lae A. selago volopheid, wat beklemtoon dat impakte van muise groter mag wees in lae kussing digtheid gebiede. Hierdie skade het partykeer gelei tot die verbrokkeling van hele kussings. Gegewe dat A. selago as 'n verpleegsterplant optree en ’n hoë digtheid van inheemse invertebrata ondersteun, mag die impakte van muise op hierdie hoeksteen spesie beduidende ekologiese implikasies tot gevolg hê. Studies oor interaksies tussen uitheemse- en inheemse plante is beperk in die sub-Antarktiese gebied. Ek het die smal-skaal verspreidings ondersoek en medevoorkoms van uitheemse plante, Agrostis stolonifera en Sagina procumbens, en die inheems Acaena magellanica (in 2 m x 2 m kwadrante, subverdeel in 0. 25 m x 0. 25 m kwadrante) langs riviere op Marion Eiland. Omgewingsveranderlikes was belangrik vir die voorkoms van hierdie spesies. In besonder, 42.95 % en 24.82 % van die afwykings in die voorkoms van A. stolonifera en S. procumbens, onderskeidelik, is verduidelik deur omgewingsveranderlikes, vergeleke met 17.35 % vir A. magellanica. Verder, die medevoorkoms van A. magellanica saam met A. stolonifera is beduidend beinvloed deur omgewingsveranderlikes. Beduidende positiewe ruimtelike assosiasies tussen A. magellanica en A. stolonifera is gevind, terwyl die interaksies van beide spesies met S. procumbens was of ruimtelik nie-geassosieerd of lukraak. Daarom het hierdie studie uitgelig dat uitheemse spesies reageer op verskillende omgewingsveranderlikes op Marion Eiland. Sagina procumbens blyk minder sensitief te wees tot die eiland se omgewingsomstandighede en mag dus moontlik biodiversiteit op breër vlakke beïnvloed. Hierdie tesis voorsien onge-ewenaarde data oor die verspreiding en interaksies van inheems plante en uitheemse spesies vir Marion Eiland. Uitheemse spesies hou ongetwyfeld ’n beduidende bedreiging in vir inheems plante op die eiland, en hierdie tesis bied insig in die interaksies van spesies, spesifiek plante – ’n benadering wat swak verteenwoordig was in die sub-Antarktiese gebied tot op hede.
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Phiri, Patrick Samu Mkozokele. "The flora of the Luangwa Valley and an analysis of its phytogeographical affinities." Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329560.
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Cormack, Ryan David, and University of Lethbridge Faculty of Arts and Science. "The unhinged gene is essential for vascular complexity in the leaves of Arabidopsis." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2006, 2006. http://hdl.handle.net/10133/343.
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The complex vasculature seen in the vascular plants provides a scaffolding of
structural support and is responsible for the movement of water, minerals, photosynthate
and some hormones. The auxin canalization model proposes that a positive feedback
mechanism causes auxin-transporting cells to become vascular cells. We have isolated a
leaf-patterning mutant, unhinged (unh), which shows a simplified leaf vascular pattern
with more freely ending veins and fewer secondary veins. Expression of the
ATHB8::GUS reporter construct indicates that the UNH gene acts prior to procambial
patterning of the first presumptive secondary veins. Expression of the auxin responsive
reporter gene DR5::GUS is reduced in unh leaves and roots, indicating that UNH may be
involved in auxin signaling. Increasing the level of auxin in unh leaves through the
addition of auxin transport inhibitors, low concentrations of 2,4-dichlorophenoxyacetic
acid, and through introducing unh into mutants in which auxin transport is defective
partially rescues the unh phenotype, supporting this hypothesis. The unh mutation maps
to a 60kb region near the top of chromosome IV. No other leaf vascular mutant or auxinassociated
mutant have been reported in this area, thus UNH represents a novel
component of leaf vascularization and auxin signaling.xi, 65 leaves : ill. (some col.) ; 29 cm.
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Kull, Matthew Austin. "Abundance patterns for vascular epiphytes in a tropical secondary forest, Costa Rica." Diss., Online access via UMI:, 2007.
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Rembold, Katja [Verfasser]. "Conservation status of the vascular plants in East African rain forests / Katja Rembold." Koblenz : Universitätsbibliothek Koblenz, 2011. http://d-nb.info/101343739X/34.
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Mukhadi, Fulufhelo Licken. "Phenology of indigenous and alien vascular flowering plants on sub-Antarctic Marion Island." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/6890.
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Thesis (MSc)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Species’ seasonal behaviour is of paramount importance in understanding community functioning and dynamics. Recently, plant phenology has further gained significance as a reliable indicator of climate change impacts. Despite the importance of understanding plant dynamics, there are relatively few plant phenological records for the sub-Antarctic region, and where records exist they are often not extensive. Sub-Antarctic Marion Island, typical of Southern Ocean Islands, offers a useful setting for addressing these knowledge gaps. This study documented the vegetative and reproductive phenologies (or aggregate phenological patterns) of twelve indigenous and three alien vascular plant species on the island. The phenological differences among the species and distinct seasonal groupings (e.g. early, intermediate and late species) were examined. I also investigated the phenological differences among the indigenous and alien plant species. Furthermore, the onset of selected reproductive phenophases from the current records was compared with historical records for determining the extent of climate change-related alterations in phenology. Phenological data were collected fortnightly on five, 5 m x 5 m permanent plots per species (except for a few species) for a full growing season. Thus the sample size is n = 5 for all plant species except for Crassula moschata (n = 4), Juncus effusus (n=4) and Rumex acetosella (n=1). Sites of the same species were separated by at least 500 m except for the alien plant, Juncus effusus, where all four known populations were selected despite two of these populations being < 500 m apart. This study indicated that Marion Island plants grow throughout the year with no major peaks except in Azorella selago and Acaena magellanica which showed winter dormancy. However, reproduction in most plant species predominately occurred in spring and summer months. Pringlea antiscorbutica and Poa cookii were the first two species to set flower buds in September while most species dispersed their seeds in summer except for Agrostis magellanica and Crassula moschata which dispersed in early autumn. Distinct from most temperate systems, the reproductive seasonality displayed by Marion Island plant species is explained more by daylength than by temperature, perhaps due to the region’s typical thermal aseasonality. Interestingly, many cooccurring species and/or clades across the Falkland, Kerguelen, Macquarie and South Georgia Islands also showed similar flowering onset date to the Marion Island plants, further confirming their daylength sensitivity. However, other external factors seem to come into play at later events of reproduction. Consequently, fruit maturation time of similar species across the sub-Antarctic islands varied substantially despite the plants having flowered in the same month. Although plant species showed similar reproductive seasonality, there were significant differences among species phenologies i.e. phenophase timing, duration and peak occurrence dates. However, using 95% confidence intervals of Generalized Linear Models weighted means, and/or one-way ANOVA (Tukey post hoc test), three homogenous sets of species (early, late, or intermediate onsets) were identified based on flower bud, flowering and seed dispersal phenophase onset dates. The homogenous species groupings observed for flower buds also remained unchanged during flowering onset except for Cotula plumosa and Callitriche antarctica which switched groups. As for the seed dispersal timing, the pattern was not consistent with that of the flower bud and flowering onset homogenous groupings, except for Acaena magellanica and Agrostis magellanica which remained in the early and late groups, respectively. Conversely, in the case of the timing of other phenophases (pollen release, fruit set and fruit ripening), entire phenophase durations, and peak occurrence dates, species overlapped greatly, resulting in an unbroken progression or continuum of phenology among species. Similarly, the three alien plant species investigated here (Cerastium fontanum, Juncus effusus and Rumex acetosella) showed no consistent phenological differences from the rest of the species. However, a widespread alien plant species on Marion Island, C. fontanum, reproduced for most of the year, although its reproduction peak was in summer months as was the case for the rest of the species. This study also indicated that indigenous plant species have altered their reproductive phenologies since 1965. Although the response was species-specific, the majority of plant species significantly delayed the onset of reproductive activities in 2007 by comparison with 1965. However, it is not clear if the observed species response was caused by the now drier and warmer Marion Island climate or by discrepancies in reporting in the earlier studies and/or sampling differences between the recent and historical records. Therefore, these results should be taken with caution. In conclusion, this research provided a detailed phenological dynamics record for vascular plant species on the island. Over time these records may be used as a basis for monitoring and modelling the impact of climate on plant phenology on the island.
AFRIKAANSE OPSOMMING: Spesies se seisoenale gedrag is van die allergrootste belang in die begrip van gemeenskapsfunksionering en dinamika. Meer onlangs het plant fenologie verdere betekenis verwerf as ‘n betroubare indikator vir die impakte van klimaatsverandering. Ondanks die belangrikheid om plant dinamika te verstaan, is daar relatief min plant fenologiese rekords vir die sub-Antarktiese streek en waar rekords wel bestaan is dit dikwels nie omvangryk nie. Sub- Antarktiese Marion Eiland, tipies van Suidelike Oseaan Eilande, bied ‘n nuttige ligging om hierdie kennis gapings aan te spreek. Hierdie studie het die vegetatiewe en voorplantingsfenologieë (of gesamentlike fenologiese patrone) van elf inheemse en drie uitheemse vaatplantspesies op die eiland gedokumenteer. Die fenologiese verskille tussen die spesies en duidelike seisoenale groeperings (bv. vroeë, intermediêre en laat spesies) is ondersoek. Ek het ook die betekenisvolle fenologiese verskille tussen die inheemse en uitheemse plantspesies ondersoek. Voorts, die aanvang van gekose voortplanting feno-fases van huidige rekords is vergelyk met historiese rekords om die mate van klimaatsverandering verbandhoudende veranderings in die fenologie te bepaal. Fenologiese data is twee weekliks ingesamel op vyf, 5 m x 5 m permanente plotte per spesie (behalwe vir ‘n paar spesies) vir ‘n volle groei seisoen. Dus, die insamelings grootte is n = 5 vir al die plantspesies behalwe vir C. moschata (n = 4), Juncus effusus (n=4) en Rumex acetosella (n=1). Persele vir dieselfde spesies is geskei deur ten minste 500 m, behalwe vir die uitheemse plant, Juncus effusus, waar al vier populasies wat bekend is gekies is, ten spyte daarvan dat twee van hierdie populasies < 500 m uitmekaar is. Hierdie studie het aangedui dat Marion Eiland plante regdeur die jaar groei, met geen belangrike spitstye nie, behalwe in Azorella selago en Acaena magellanica wat ‘n winter rusperiode wys. Hoe ookal, voortplanting in meeste van die plantspesies het hoofsaaklik voorgekom tussen die lente en somermaande. Pringlea antiscorbutica en Poa cookii was die eerste twee spesies om blomknoppe uit te stoot in September, terwyl die meeste spesies hulle sade versprei het gedurende die somer, behalwe vir Agrostis magellanica en Crassula moschata wat versprei het in vroeg herfs. Duidelik van meeste gematigde sisteme, word die voortplanting seisoenaliteit, getoon deur die Marion Eiland plantspesies, verduidelik meer deur daglengte as deur temperatuur, moontlik weens die streek se tipiese termiese a-seisoenaliteit. Interessant, baie spesies en/of afstameling-groeperings wat saam aangtref word dwarsoor die Falkland, Kerguelen, Macquarie en Suid Georgia Eilande wys ook soortgelyke bloei aanvangsdatums as die Marion Eiland plante, nog meer bevestigend van hulle dag-lengte sensitieweteit. Hoe ookal, ander eksterne faktore blyk betrokke te raak by latere gebeure van voortplanting. Gevolglik het vrug rypwordingstyd van dieselfde spesies oor die sub-Antarktiek noemenswaardig verskil, ten spyte daarvan dat die plante in dieselfde maand geblom het. Alhoewel plantspesies dieselfde voortplanting seisoenaliteit gewys het, was daar ‘n noemenswaardige veskil tussen spesie fenologieë, m. a. w. feno-fase tydsberekenning, tydsduur en spits voorkomsdatums. Hoe ookal, deur gebruik te maak van 95% betroubaarheid intervalle van Algemene Lineêre Modelle gewigte gemiddelde en/of een rigting ANOVA (Turkey post hoc toets), is drie homogene stelle van spesies (vroeë, laat en intermediêre aanvang) geïdentifiseer gebasseer op blomknop, bloei en saad verspreiding feno-fase aanvangsdatums. Die homogene spesie groeperings waargeneem op blomknoppe het ook onveranderd gebly gedurende bloei aanvang behalwe vir Cotula plumosa en Crassula antarctica wat groepe geruil het. Vir die saadverspreiding tydsberekenning was die patroon nie konstant met die van die blomknop en bloei aanvang homogene groepe nie, behalwe vir Acaena magellanica en Agrostis magellanica wat in die vroeë en laat groepe respektiewelik gebly het. Omgekeerd, in die geval van tydsberekenning van ander feno-fases (stuifmeel vrysetelling, vrugwerp, vrugrypwording), volledige feno-fase tydsduur en spits voorkomsdatums het spesies grootliks oorvleuel, wat ‘n ongebroke vordering of deurlopendheid van fenologie tussen die spesies tot gevolg het. Ooreenkomstig het die drie uitheemse spesies wat hier ondersoek is (Cerastium fontanum, Juncus effusus en Rumex acetosella) geen bestendige fenologiese verskille van die res van die spesies gewys nie. Hoe ookal, ‘n wydverspreide uitheemse spesie op Marion Eiland, Cerastium fontanum, het deur die meeste van die jaar voortgeplant, hoewel met ‘n voorplanting spits in die somer maande soos die res van die spesies. Hierdie studie dui ook aan dat inheemse plantspesies hulle voortplanting fenologieë verander het sedert 1965. Alhoewel die reaksie spesiespesifiek was, het die meerderheid van die plantspesies hulle voortplanting aanvang aansienlik vertraag gedurende 2007 in vergelyking met 1965. Hoe ookal, dis nie duidelik of die waargeneemde spesie reaksie was as gevolg van die nou droër en warmer Marion Eiland klimaat of deur teenstrydighede in verslagewing gedurende die vroëre studies en/of insameling verskille tussen die onlangse en historiese rekords. Daarom moet hierdie resultate met versigtigheid hanteer word. In samevatting, hierdie navorsing voorsien ‘n gedetaileerde fenologiese dinamieka rekord vir vaatplantspesies op die eiland. Oor tyd kan hierdie rekords gebruik word as basis vir monitering en modellering van die impak van klimaat.
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Del, Olmo Ruiz Mariana. "Diversity, Distributions, and Host Affiliations of Fungal Endophytes Associated with Seedless Vascular Plants." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/243097.
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In this dissertation, I explore the diversity of endophytic fungi associated with above-ground tissues of neotropical ferns, assess factors shaping their community structure in three forests, and explore the contributions of endophytes and related strains to our understanding of the diversity and ecology of a representative genus of Ascomycota. In Appendix A, I report a survey of endophytic fungi from seven species of ferns at La Selva, Costa Rica. Using both species-level and phylogenetic analyses, I compare culturable endophytes as a function of fern taxonomy, frond tissues (blades vs. stalks), habits (terrestrial vs. epiphytic), and vegetation types (arboretum vs. primary and secondary forest) during two consecutive years. Analysis of>500 strains provides a first taxonomic overview of fern endophytes at a community scale and reveals high diversity, host preference, and interannual variation in fungal assemblages. However, when variation due to host species is taken into account, community structure is similar among fern tissue types, habits, and sampling sites over a small spatial scale. In Appendix B, I expand my work to evaluate the abundance, species-level and phylogenetic diversity, and distributions of fern-affiliated endophytes in three neotropical forests (La Selva, Costa Rica; Barro Colorado Island, Panama; Los Tuxtlas, Mexico). My analysis of > 2000 isolates reveals that communities differ significantly among fern species within sites, and among ferns in different sites. Intersite differences in communities are correlated with geographic distance and environmental dissimilarity. My work suggests that extrapolative estimates of fungal diversity should take into account not just host species, but locality and environmental variation as well. In Appendix C I focus on a representative genus of Ascomycota (Lecythophora) to evaluate how multi-locus phylogenetic analyses of endophytes can detect new species. Lecythophora is a geographically widespread genus that includes opportunistic human pathogens, produces novel secondary metabolites, and consists presently of six described species. Multi-locus analysis of 33 newly collected strains suggested seven phylogenetic species that are new to science and highlighted their capacity to inhibit growth of two plant pathogenic fungi. This work shows how recognition of cryptic species even in well-characterized genera has major implications for estimating fungal biodiversity.
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Aidar, Saulo de Tarso. "Implicações da manutenção ou perda da clorofila na tolerância à dessecação de tecidos vegetativos de Anemia flexuosa (Schizaeaceae) e Pleurostima purpurea (Velloziaceae)." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-22052013-150802/.
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O objetivo deste estudo foi identificar características de uso da luz para explicar a distribuição diferencial das espécies tolerantes à dessecação homeoclorófila Anemia flexuosa e peciloclorófila Pleurostima purpurea em ambientes sombreados e expostos, respectivamente, de comunidades vegetais de afloramentos rochosos. A cultivar Oryza sativa IAC 202 foi incluída para comparações. Durante um ciclo completo de desidratação - dessecação - reidratação foram avaliados parâmetros fotossintéticos de trocas gasosas e fluorescência da clorofila a, associados ao conteúdo relativo de água (CRA) e de pigmentos fotossintéticos de plantas intactas sob temperatura e umidade relativa do ar constantes de 25°C e de 55%, respectivamente. As plantas foram submetidas à diferentes densidades de fluxo de fótons fotossintéticos (DFFF de 0, 100 e 400 ?mol fótons m-2s-1) nas fases de desidratação e dessecação, dependendo da espécie. O. sativa foi avaliada somente durante as fases de desidratação e dessecação sob condições ambientais variáveis de casa de vegetação. A diminuição da assimilação líquida de CO2 (A) foi acompanhada pelo aumento da dissipação de calor avaliada pelos coeficientes de extinção nãofotoquímica (qN e NPQ) nas três espécies. Após cessação de A, a eficiência quântica efetiva (?PSII e Fv\"/Fm\"), a taxa de transporte de elétrons (ETR) e o coeficiente de extinção fotoquímica (qP) foram mantidos relativamente altos em P.purpurea, mas cessaram simultaneamente com A em A.flexuosa. Em O.sativa, ?PSII, ETR e qP diminuíram substancialmente após a cessação de A, mas Fv\"/Fm\" foi mantido. A eficiência quântica potencial (Fv/Fm) foi a última variável a diminuir nas três espécies durante a desidratação. Após a reidratação de P.purpurea e A.flexuosa foi observado inicialmente o estabelecimento da respiração e em seguida um balanço levemente positivo de CO2, quando os valores de Fv\"/Fm\", ?PSII, ETR, qP e Fv/Fm de P.purpurea recuperaram quase totalmente, enquanto qN e NPQ diminuíram. A.flexuosa apresentou uma recuperação apenas parcial de Fv\"/Fm\", ?PSII, ETR, qP e Fv/Fm quando o balanço de CO2 se tornou levemente positivo, tendo sido a recuperação ainda menor para o tratamento de desidratação no escuro associado à dessecação na luz. A.flexuosa tolerou a perda de 88% do CRA. O enrolamento foliar durante a desidratação é uma forma de proteção contra a luz no estado dessecado de A.flexuosa. Mesmo no estado dessecado ocorrem processos de interação dos fotossistemas II com a luz em A.flexuosa. P.purpurea baseia sua proteção contra a luz na ativação de processos de dissipação de calor, vias de consumo de elétrons diferentes do ciclo redutivo do CO2 e, em última instância, na perda de clorofilas. Plantas dessecadas de P.purpurea permanecem viáveis no estado desidratado por pelo menos 42 dias. P.purpurea tolerou a perda de 94% do CRA. A recuperação do turgor da parte aérea de P.purpurea ocorre necessariamente pela absorção de água pelas raízes durante a reidratação. Foi evidenciada uma aclimatação de A.flexuosa quando desidratada sob condição de luz. Os resultados não foram conclusivos em relação à sustentação da hipótese, considerando que as diferenças de recuperação observadas para A.flexuosa nos diferentes tratamentos luminosos, em geral, não foram significativas.The aim of this study was to identify characteristics of light use that could explain the differential distribution of homoiochlorophyllous and poikilochlorophyllous desiccation tolerant plants Anemia flexuosa and Pleurostima purpurea, respectively, in shaded and exposed microsites of rock outcrop plant communities. Oryza sativa IAC 202 was included in the study for comparisons. Leaf gas exchanges, fluorescence chlorophyll, relative water content (RWC) and photosynthetic pigment content were evaluated in intact plants under constant temperature and relative humidity of 25°C and 55%, respectively, during a complete cycle of dehydration - desiccation - rehydration. The plants were exposed to different photosynthetic photon flux densities (PPFD of 0, 100 and 400 ?mol photons m-2s-1) during dehydration and desiccation phases, according to species. O.sativa was evaluated only during dehydration and desiccation phases under variable environmental conditions in a greenhouse. In all species, the decrease in CO2 net assimilation (A) was accompanied by increased heat dissipation assessed by nonphotochemical quenching coefficients (qN and NPQ). The effective quantum yield (?PSII and Fv\"/Fm\"), electron transport rate (ETR) and photochemical quenching coefficient (qP) were kept relatively high after A cessation in P.purpurea, but in A.flexuosa ceased simultaneously with A. In O.sativa, ?PSII, ETR and qP decreased substantially after A cessation, but Fv\"/Fm\" was maintained. The potential quantum yield (Fv/Fm) was the last variable to decrease during dehydration in all species. After rehydration, the establishment of respiration was observed initially in P.purpurea and A.flexuosa. Then, a slightly positive CO2 balance was associated with the almost total recovery of Fv\"/Fm\", ?PSII, ETR, qP and Fv/Fm in P.purpurea, while qN and NPQ decreased. A.flexuosa showed only a partial recovery of Fv\"/Fm\", ?PSII, ETR, qP and Fv/Fm when the CO2 balance became slightly positive, and recovery was even lower for the treatment of dehydration in dark associated to desiccation in light. A.FLEXUOSA TOLERATES A LOSS OF 88% OF RWC. Leaf curling during dehydration is also a form of light protection in the dried state in A.flexuosa. Interactions between photosystem II and light occur even in the dried state of A.flexuosa. P.purpurea bases its protection against light activating heat dissipation process, ways of electron consumption different of reductive CO2 cycle and, in last instance, chlorophyll loss. P.purpurea remains viable in dried state for at least for 42 days, and tolerates a loss of 94% of RWC. The shoot rehydration in P.purpurea occurs necessarily by roots water uptake. A.flexuosa showed an acclimation when dried under light conditions. The results were not conclusive regarding the hypothesis, since differences in recovery observed for this species in the different light treatments, in general, were not significant.
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Mallick, Debanshu. "Study on diversity and ecology of vascular plants at medicinal plant conservation areas (MPCAs) in Terai and Duars, West Bengal." Thesis, University of North Bengal, 2022. http://ir.nbu.ac.in/handle/123456789/4799.
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Bowman, G. Brian. "A comparison of vascular, herbaceous plants between disturbed and undisturbed east-central Indiana woodlots." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/941351.
Full textAbstract:
The mode of propagation of a plant species may influence its success in recolonizing a successional forest following agricultural disturbance. It is hypothesized that plants with animal-borne or broadcast-dispersed seed will successfully recolonize, while plants which rely upon vegetative propagules may not repopulate the disturbed area. This hypothesis was tested by comparing vascular, herbaceous plant communities of two forests (one old-growth and one successional) in east-central Indiana. Populations of vascular, herbaceous plant species were inventoried in both forests, and the soil characteristics (organic matter and pH) of both areas were analyzed. The two forests had similar soil organic matter profiles, but the pH of the disturbed forest was significantly lower than that of the undisturbed area. Most vegetatively-propagated plant species were, as predicted, significantly more abundant in the undisturbed forest; the disturbed area had been effectively recolonized by animal-borne and broadcast-dispersed seed plants. This perspective has implications for long-term management of east-central Indiana forests.Department of Natural Resources and Environmental Management
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Vanderplank, Sula E. "The Vascular Flora of Greater San Quintín, Baja California, Mexico." Scholarship @ Claremont, 2010. http://scholarship.claremont.edu/cgu_etd/2.
Full textAbstract:
The plants of San Quintín (Baja California, Mexico) were documented through intensive fieldwork and the collection of herbarium specimens to create a checklist of species. This region is home to a diverse flora with high levels of local endemism and many rare plants. The flora documented in this study was compared to historical records from the region and shows the impact of agriculture and urbanization on the plants, including several extirpated species. A study of the perennial vegetation using a 1 km grid provides species distribution data for 140 native species, which were assessed to highlight areas of significant species richness for native, rare, and endemic taxa. Several non-native plants were also mapped to provide baseline data. Areas of conservation priority for the flora of Greater San Quintín are discussed in light of these combined findings.
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Santos, Leonardo Biral. "Florística vascular da Mata da Pavuna, Botucatu, SP, Brasil /." Rio Claro : [s.n.], 2011. http://hdl.handle.net/11449/87842.
Full textAbstract:
Orientador: Julio Antonio LombardiBanca: Marco Atonio de Assis
Banca: Milton Groppo Junior
Resumo: A Mata da Pavuna é um fragmento de floresta estacional semidecídua em um cânion com afloramento rochoso e solo raso, localizado no município de Botucatu, Estado de São Paulo. Foram amostradas todas as espécies vasculares em estádio reprodutivo e identificadas até o menor nível possível. Foram encontradas 381 espécies em 83 famílias. Fabaceae foi a família com maior número de espécies (44), seguido de Asteraceae (33), Euphorbiaceae (18), Poaceae (17), Malvaceae (14), Bignoniaceae e Solanaceae (12). Em Pteridophyta sensu stricto as famílias mais diversas foram Pteridaceae (oito espécies) e Polypodiaceae (sete). Comparado a outros levantamentos florísticos extensos na Mata Atlântica os resultados ressaltam a elevada diversidade florística local, bem como a presença de espécies típicas de formações xerofíticas sugerindo, inclusive, a ocorrência de um encrave de vegetação seca. Noticiamos também o primeiro registro de Pellaea ovata (Desv.) Weath. (Pteridaceae) para o Brasil
Abstract: The „Mata da Pavuna‟ is a semideciduous seasonal forest fragment located in a canyon characterized by rock outcrops and shallow soil, in municipality of Botucatu, State of São Paulo. We collected all vascular plants in reproductive stage, and identified them to the lowest taxonomic level possible. We found 381 species in 83 families. Fabaceae was the most diverse family with 44 species, followed by Asteraceae (33), Euphorbiaceae (18), Poaceae (17), Malvaceae (14), Bignoniaceae (12) and Solanaceae (12). In the Pteridophyta sensu lato the most diverse families was Pteridaceae (eight species) and Polypodiaceae (seven). Compared to other comprehensive floristic surveys carried out in the Atlantic Forest these results show the high floristic diversity and the presence of typical xerofitic vegetation species, suggesting the presence of an enclave of dry forest. We reported here the first mention of Pellaea ovata (Desv.) Weath. (Pteridaceae) for Brazil
Mestre
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Morris, J. Clay. "The vascular flora of Boiling Spring Lakes Preserve, Brunswick County, North Carolina /." Electronic version (PDF), 2007. http://dl.uncw.edu/etd/2007-3/morrisj/josephmorris.pdf.
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Wulf, Monika, and Thilo Heinken. "Colonization of recent coniferous versus deciduous forest stands by vascular plants at the local scale." Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2010/4608/.
Full textAbstract:
Questions:
1. Are there differences among species in their preference for coniferous vs. deciduous forest?
2. Are tree and shrub species better colonizers of recent forest stands than herbaceous species?
3. Do colonization patterns of plant species groups depend on tree species composition?
Location:
Three deciduous and one coniferous recent forest areas in Brandenburg, NE Germany.
Methods:
In 34 and 21 transects in coniferous and deciduous stands, respectively, we studied the occurrence and percentage cover of vascular plants in a total of 150 plots in ancient stands, 315 in recent stands and 55 at the ecotone. Habitat preference, diaspore weight, generative dispersal potential and clonal extension were used to explain mechanisms of local migration. Regression analysis was conducted to test whether migration distance was related to species’ life-history traits.
Results:
25 species were significantly associated with ancient stands and ten species were significantly more frequent in recent stands. Tree and shrub species were good colonizers of recent coniferous and deciduous stands. In the coniferous stands, all herbaceous species showed a strong dispersal limitation during colonization, whereas in the deciduous stands generalist species may have survived in the grasslands which were present prior to afforestation.
Conclusions:
The fast colonization of recent stands by trees and shrubs can be explained by their effective dispersal via wind and animals. This, and the comparably efficient migration of herbaceous forest specialists into recent coniferous stands, implies that the conversion of coniferous into deciduous stands adjacent to ancient deciduous forests is promising even without planting of trees.
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Demirci, Barbaros. "A Geographic Information Systems Tool Development For Geostatistical Analysis Of Endangered Endemic Vascular Plants Of Turkey." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606098/index.pdf.
Full textAbstract:
Modern information systems strive to provide effective use of resources. Supplied with analysis tools, geographical information systems (GIS) can serve its stakeholders with minimal requirements. In this study, GIS capabilities were employed for Turkish Flora. Data related with the threatened plants that are indigenous to Turkey were gathered from the relevant literature and reshaped into a dataset in which spatial locations were represented in a geographically referenced format. Afterwards, this output was used to investigate the affects of different factors on the distribution patterns of these plants by means of functions of GIS and multivariate analysis. At last, overlay analysis was employed in
order to reveal the congruence between official protection reserves, spatial locations of the plants in danger and areas of importance for other elements of wildlife specifically birds.
Outcomes of the study is three-fold. First of all, a simple algorithm was established which can be used in the formation of a unified database of widely distributed floristic data in Turkey. Geographically referenced data and the analysis results produced in the study is another value added for Turkish botanics. From another perspective, effectiveness of GIS in handling different types of non-standard data were scrutinized. Overlay analysis of locations of the plants and the protection reserves constituted the managerial aspect of the study by pointing large gaps in the actual protection coverage and proposing candidate regions for official reserve
choices of the future. In essence, GIS was deemed to be an effective tool for parties working on non-standard spatial data.
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Bosio, Fabio [UNESP]. "Atividade cambial e o efeito de anelamento no xilema secundário em espécies de cerrado." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/142970.
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000865641.pdf: 1581001 bytes, checksum: 3b640de54758f10bba3e166471a8e8ff (MD5)Este estudo abordou a sazonalidade da atividade cambial e da fenologia vegetativa, a relação existente entre estes dois eventos e a relação destes com fatores climáticos e ambientais, bem como os efeitos de anelamento caulinar na estrutura do xilema secundário em espécies de cerrado. Para o estudo da sazonalidade da atividade cambial, amostras do caule principal de Kielmeyera grandiflora (Wawra) Saddi (Calophyllaceae) foram coletadas mensalmente, entre setembro de 2011 e dezembro de 2012. No mesmo período, foram feitas observações mensais das fases fenológicas vegetativas para avaliar a sazonalidade na produção de folhas e comparar estes dados com a atividade cambial. Para verificar quais os fatores ambientais e climáticos relacionados com a brotação e com o início da atividade cambial, foram calculadas as médias de temperatura e do fotoperíodo, e obtido o somatório da precipitação em uma escala de tempo que variou de 1 a 30 dias antes da brotação e do início da atividade cambial. Em seguida, foi calculado o coeficiente de variação das médias para avaliar a variabilidade entre os anos. Para o estudo do efeito de anelamento caulinar na estrutura do xilema secundário foi montado um experimento em campo com a espécie Aegiphila verticillata Vell. (Lamiaceae). O experimento foi composto por dois grupos, anelamento e controle. No grupo anelamento, a casca e o câmbio vascular foram removidos completamente do caule principal na porção central do tronco, formando um anel completo. O objetivo do anelamento foi interromper o fluxo polar de auxina produzido na copa para avaliar os efeitos dessa interrupção na estrutura do xilema secundário. No grupo controle, o caule não foi anelado. Para identificar o xilema secundário formado antes do anelamento do formado posteriormente ao tratamento foi feita uma incisão na casca, nas porções acima e abaixo do anelamento, até atingir o câmbio vascular. Esta incisão...
This study approached the seasonality in cambial activity and vegetative phenology, the relationship between these events and their relation with wheater and environmental factors, and also the effects of stem girdling in the structure of secondary xylem in Cerrado species. In order to study of seasonality in cambial activity, monthly samples from main stem of Kielmeyera grandiflora (Wawra) Saddi (Calophyllaceae) were collected from September 2011 to December 2012. In the same period, observations of vegetative phenological phases were made to assess the seasonality in leaf production, and to compare these data with cambial activity. In order to certify which environmental and weather features are related with bud opening and onset of cambial activity, it was calculated the mean value of temperature and photoperiod, and obtained the sum of rainfall in a time scale that ranged from 1 to 30 days before bud opening and the onset of cambial activity. After that, the coefficient of variation was calculated to assess the variability between years. In order to evaluate the stem girdling effect in the structure of secondary xylem was conducted an experiment in field with the species Aegiphila verticillataVell (Lamiaceae), composed of two groups, girdling and control. In girdling group, bark and cambium were completely removed from the central portion of main stem, forming a complete ring. The purpose of girdling was to interrupt the polar flow of auxin produced in the crown, and to assess the effect of its disruption in the structure of secondary xylem. In control group, it has not made a girdling in the stem. To distinguish the xylem formed before girdling from xylem formed after the treatment, an incision (03 cm in length) was made in the regions above and below girdling until reaches the vascular cambium. In the same way, in control group an incision in the bark was made at a central point of the ...
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Bosio, Fabio. "Atividade cambial e o efeito de anelamento no xilema secundário em espécies de cerrado /." Botucatu, 2015. http://hdl.handle.net/11449/142970.
Full textAbstract:
Orientador: Carmen Regina MarcatiBanca: Veronica Angylossy
Banca: Patricia Soffiatti
Banca: Silvia Rodrigues Machado
Banca: Fábio Akira Mori
Resumo: - Este estudo abordou a sazonalidade da atividade cambial e da fenologia vegetativa, a relação existente entre estes dois eventos e a relação destes com fatores climáticos e ambientais, bem como os efeitos de anelamento caulinar na estrutura do xilema secundário em espécies de cerrado. Para o estudo da sazonalidade da atividade cambial, amostras do caule principal de Kielmeyera grandiflora (Wawra) Saddi (Calophyllaceae) foram coletadas mensalmente, entre setembro de 2011 e dezembro de 2012. No mesmo período, foram feitas observações mensais das fases fenológicas vegetativas para avaliar a sazonalidade na produção de folhas e comparar estes dados com a atividade cambial. Para verificar quais os fatores ambientais e climáticos relacionados com a brotação e com o início da atividade cambial, foram calculadas as médias de temperatura e do fotoperíodo, e obtido o somatório da precipitação em uma escala de tempo que variou de 1 a 30 dias antes da brotação e do início da atividade cambial. Em seguida, foi calculado o coeficiente de variação das médias para avaliar a variabilidade entre os anos. Para o estudo do efeito de anelamento caulinar na estrutura do xilema secundário foi montado um experimento em campo com a espécie Aegiphila verticillata Vell. (Lamiaceae). O experimento foi composto por dois grupos, anelamento e controle. No grupo anelamento, a casca e o câmbio vascular foram removidos completamente do caule principal na porção central do tronco, formando um anel completo. O objetivo do anelamento foi interromper o fluxo polar de auxina produzido na copa para avaliar os efeitos dessa interrupção na estrutura do xilema secundário. No grupo controle, o caule não foi anelado. Para identificar o xilema secundário formado antes do anelamento do formado posteriormente ao tratamento foi feita uma incisão na casca, nas porções acima e abaixo do anelamento, até atingir o câmbio vascular. Esta incisão...
Abstract: This study approached the seasonality in cambial activity and vegetative phenology, the relationship between these events and their relation with wheater and environmental factors, and also the effects of stem girdling in the structure of secondary xylem in Cerrado species. In order to study of seasonality in cambial activity, monthly samples from main stem of Kielmeyera grandiflora (Wawra) Saddi (Calophyllaceae) were collected from September 2011 to December 2012. In the same period, observations of vegetative phenological phases were made to assess the seasonality in leaf production, and to compare these data with cambial activity. In order to certify which environmental and weather features are related with bud opening and onset of cambial activity, it was calculated the mean value of temperature and photoperiod, and obtained the sum of rainfall in a time scale that ranged from 1 to 30 days before bud opening and the onset of cambial activity. After that, the coefficient of variation was calculated to assess the variability between years. In order to evaluate the stem girdling effect in the structure of secondary xylem was conducted an experiment in field with the species Aegiphila verticillataVell (Lamiaceae), composed of two groups, girdling and control. In girdling group, bark and cambium were completely removed from the central portion of main stem, forming a complete ring. The purpose of girdling was to interrupt the polar flow of auxin produced in the crown, and to assess the effect of its disruption in the structure of secondary xylem. In control group, it has not made a girdling in the stem. To distinguish the xylem formed before girdling from xylem formed after the treatment, an incision (03 cm in length) was made in the regions above and below girdling until reaches the vascular cambium. In the same way, in control group an incision in the bark was made at a central point of the ...
Doutor
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Schoultz, Ashleigh. "An inventory of the vascular flora of Ginn Woods." Virtual Press, 1997. http://liblink.bsu.edu/uhtbin/catkey/1041907.
Full textAbstract:
Ginn Woods, a 161 acre tract of woodlands located in northern Delaware County, contains one of the largest remaining sections of old growth forest in East Central Indiana. Located approximately 15 miles north of Muncie, it has been regularly used by Ball State students and faculty for education and research for over 60 years. Despite this frequent use, little formal botanical exploration has been published. This study presents a comprehensive inventory of the vascular flora found in the woods and documents the composition and sizeclass distribution of the canopy tree species. The 370 species represent 237 genera and 94 families based on family classification by Gleason and Cronquist (1991). A total of 123 species were recorded for the first time in Delaware County. Of the 370 species listed, 56 or 15.1 % are non-native or naturalized species, thus indicating that the native species are dominant. The overstory canopy species are typical of a beech-maple woods with Acer saccharum and Fagus grandifolia as overallco-dominant species. However the importance of Fagus grandifolia varies in the sections known as North, South and Nixon Woods. With the fragmentation of regional ecosystems into isolated forest systems by urbanization and agricultural development, the maintenance and preservation of original communities becomes more difficult. Ginn Woods is one of the few remaining remanents of old growth forests in East Central Indiana and serves as an important reserve of the native flora of this area. The inventory and overstory tree species analysis provided by this study establishes important baseline data to which future studies can be compared.Ball State UniversityMuncie, IN 47306Department of Biology
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Gabaldon, Caballero Carlos. "Molecular and functional characterization of one peroxidase responsible for the lignin biosynthesis in vascular plants = Caracterización molecular y funcional de una peroxidasa responsable de la síntesis de ligninas en plantas vasculares." Doctoral thesis, Universidad de Murcia, 2016. http://hdl.handle.net/10803/369833.
Full textAbstract:
Tesis por compendio de publicacionesZinnia elegans constituye uno de los sistemas modelos más útiles para estudiar la diferenciación en el xilema que incluye la síntesis de la pared celular secundaria, la lignificación de la pared celular, y la muerte celular programada. Además, el cultivo de células del mesófilo de Z. elegans in vitro también se ha utilizado como sistema modelo ya que la diferenciación de las células del mesófilo en traqueidas permite estudiar de manera sencilla la bioquímica y la fisiología de la xilogénesis alejados de la complejidad que imponen los tejidos vegetales. Por otra parte, Z. elegans ha resultado ser una excelente planta modelo para estudiar la implicación de las peroxidasas en la lignificación de la pared celular. Esto es debido a la simplicidad y dualidad del patrón de lignificación mostrado en los tallos e hipocotilos de esta planta y a la naturaleza básica de esta isoenzima de peroxidasa. Sin embargo, esta proteína no solo se expresa en hipocotilos y en tallos sino también en células que se encuentran en diferenciación en traqueidas. Por lo tanto, esta peroxidasa no solo cumple todos los requerimientos catalíticos impuestos para ser la candidata idónea implicada en la lignificación cumpliendo con todas las restricciones impuestas por la etapa de acoplamiento oxidativo de los alcoholes hidroxicinamilicos y polimerización, sino también debido a que su expresión es inherente en la lignificación. De hecho, su naturaleza básica no es excepcional ya que las peroxidasas básicas se expresan diferencialmente durante la lignificación en otros sistemas modelo, mostrando propiedades bioquímicas inusuales y exclusivas tales como la oxidación de las unidades siringilo. Esta Tesis se ha centrado en la realización de las actividades que conducen a un mejor entendimiento de la lignificación en Zinnia, comenzando con el estudio del patrón de lignificación, cómo se sucede este proceso, y la implicación de la peroxidasa, demostrando sus propiedades catalíticas inusuales y cómo esta enzima es regulada por el óxido nítrico (NO) y el H2O2. En relación a la producción de NO y H2O2 en los haces vasculares, utilizando la microscopía confocal láser de barrido, se observó un gradiente espacial de producción de NO inversamente relacionado con el grado de diferenciación del xilema ya que las células del xilema jóvenes, en diferenciación manifestaron una mayor capacidad para producir NO que las células del xilema completamente maduras y diferenciadas. Estos resultados demuestran la fuerte relación entre la producción de NO y la muerte celular programada que se produce durante la diferenciación del xilema y que precede a la lignificación de la pared celular. Además, la producción de NO en los cultivos celulares de mesófilo de Z. elegans que se diferencian a traqueidas, las células del mesófilo mantienen la misma propiedad mostrada por las células del xilema en diferenciación ya que la señal fluorescente se detectó, principalmente, en las células predeterminadas y en las que se encontraban en diferenciación. Por el contrario, las células aisladas del mesófilo que no habían adquirido la capacidad para diferenciarse a traqueidas, manifestaban unos niveles muy débiles de la señal fluorescente que contrastaba con la producción elevada mostrada por las células predeterminadas para diferenciarse a traqueidas. Por otra parte, mediante la utilización conjunta de técnicas de microscopía óptica y electrónica, se realizó un estudio detallado de los sitios de producción de H2O2 en el xilema en lignificación, comprobándose que en las células del xilema en diferenciación y en las células del parénquima adyacentes se localizaba la producción de H2O2 sugiriendo que estas células podrían ser las responsables de la producción de H2O2 que, posteriormente, difunde de célula a célula, a través del espacio intercelular hacia las células del xilema en diferenciación para que tenga lugar la biosíntesis de ligninas en la pared celular secundaria. Una evidencia adicional que apoyó la hipótesis planteada se obtuvo mediante la localización del H2O2 en los cultivos celulares de mesófilo de Z. elegans en diferenciación a elementos traqueales. Utilizando este sistema modelo junto con la microscopía confocal láser y el diacetato de diclorofluoresceína como sonda fluorescente, la producción de H2O2 se localizó mayoritariamente en las células del mesófilo predeterminadas para diferenciarse, detectándose un bajo nivel de H2O2 en las traqueidas completamente diferenciadas.
Zinnia elegans constitutes one of the most useful model systems for studying xylem differentiation, which simultaneously involves secondary cell wall synthesis, cell wall lignification, and programmed cell death. Likewise, the in vitro culture system of Z. elegans has been the best characterized since the differentiation of mesophyll cells into tracheary elements allows study the biochemistry and physiology of xylogenesis free from the complexity that heterogeneous plant tissues impose. Moreover, Z. elegans has resulted in an excellent plant model to study the involvement of peroxidases in cell wall lignification. This has been due to the simplicity and duality of the lignification pattern shown by the stems and hypocotyls, and to the basic nature of the peroxidase isoenzyme. This protein is expressed not only in hypocotyls and stems but also in mesophyll cells transdifferentiating into tracheary elements. Therefore, not only does this peroxidase fulfil all the catalytic requirements to be involved in lignification overcoming all restrictions imposed by the polymerization step, but also its expression is inherent in lignification. In fact, its basic nature is not exceptional since basic peroxidases are differentially expressed during lignification in other model systems, showing unusual and unique biochemical properties such as oxidation of syringyl moieties. This Thesis has focused on the experiments which led to a better understanding of the lignification process in Zinnia, starting with the basic knowledge about its lignin pattern, how lignification takes place, and the involvement of the basic peroxidase in the lignification process, demonstrating its unusual catalytic properties, and how this enzyme is regulated by nitric oxide and H2O2. In relation to the production of NO in the vascular bundles using confocal laser scanning microscopy, a spatial NO gradient inversely related to the degree of xylem differentiation was observed since differentiating xylem cells clearly manifest a higher capacity for NO production than differentiated xylem cells. In addition, the NO production in cultured mesophyll cells which are trans-differentiating in tracheary elements maintain the same property shown by differentiating xylem from the Z. elegans vascular bundles since the fluorescent probe was mainly observed in pro-differentiating thin-walled and differentiating (secondary cell wall forming) tracheary elements. By the contrary, mesophyll cells which have not acquired competence for trans-differentiation showed only background levels of triazolofluorescein green fluorescence. These results confirm that NO formation by tracheary elements is directly related to the early processes of xylem differentiation, which takes place immediately before the late processes of secondary cell wall formation and cell autolysis. On the other hand, a study of both localization and production of H2O2 in the lignifying xylem by the joint use of optical and electronic microscopy and 2,7-dichlorofluorescein diacetate and CeCl3 assays was carried out. Thus, H2O2 production was observed in thin-walled cells surround thick-walled xylem vessels and in the xylem parenchyma cells intercalated between xylem vessels suggesting that these cells could be responsible of H2O2 production and a degree of cell to cell cooperation is produced during lignin biosynthesis. Further evidence that supports this hypothesis was obtained by studying the production and localization of H2O2 during the differentiation of Z. elegans mesophyll cells into tracheary elements. Using this model system and confocal laser scanning microscopy and 2,7-dichlorofluorescein diacetate as fluorescent probe, H2O2 was mainly produced by both differentiating tracheary and parenchyma-like elements being the non-lignifying parenchyma-like cells the main H2O2 source and detecting a low level of H2O2 in the totally differentiated tracheary elements.
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Demars, Benoît Olivier Laurent. "Aquatic vascular plants in nitrate-rich calcareous lowland streams : do they respond to phosphorus enrichment and control?" Thesis, University of Leicester, 2002. http://hdl.handle.net/2381/29832.
Full textAbstract:
The problems of eutrophication in the lowland rivers of Britain have been exacerbated in the past 13 years by the droughts of 1989-92 and 1995-96. Large growths of filamentous algae have smothered aquatic vascular plants (major primary producers) in lowland calcareous streams and phosphorus enrichment has been blamed for a shift in submerged plant species composition and community structure. This study investigated the impact of phosphorus removal from two sewage treatment works (STWs) situated in the River Wensum catchment area, Norfolk, UK. The mesology of aquatic vascular plants was investigated through a survey at 62 sites spread over four river basins: Wensum, Nar, Bure, Wissey. The landscape is predominantly rural (crops and pasture) not rising above 90 metres (OD). The average background concentrations of phosphorus from diffuse sources were: soluble reactive phosphorus (SRP) 13 microg/L, total dissolved phosphorus 24 ug/L and total phosphorus (TP) 53 microg/L. Before phosphorus stripping (1990-1999), the background contributed about 12% of the TP loads (0.08-0.10 kg/ha/year of TP) and after (2000-2001) it was about 34% for two reasons, the phosphorus stripping plus effects due to higher rainfall (0.13-0.18 kg/ha/year of TP). The level of bioavailable phosphorus from the river-bed sediment was highest at sites impacted by both the effluents and weirs associated with mills. Phosphorus removal effectively reduced the TP load contribution of the two STWs from 42% to 18% of the effluents in the whole catchment. However the predicted levels of SRP at mean flow (140-273 microg/L) and 95% exceedance discharge (415-1039 microg/L) dowstream from the STWs, remained very high. An isozyme technique was developed to identify the eight British species of Callitriche L. (water-starworts). This allowed the chorology of Callitriche in the rivers of Norfolk to be determined. Aquatic vascular plant composition, species Natural Combination of Attributes (NCAs - life history trade-offs) and community structure did not respond to the gradient of nutrients (SRP 11-3600 microg/L, nitrate 6.4-12.9 mg/L, ionised ammonia 16-434 microg/L). Species composition did respond, however, to the biogeographical units and distance of the site from the source (surrogate for species probability of colonisation) and channel depth/substrata (species environmental requirements). Even the most obvious geomorphological factors were only weak predictors of the NCAs. Moreover, the NCAs were linked, although only marginally, to the spatial structure of the river network, a surrogate for species probability of dispersal. Therefore the idea of using the species' attribute approach as currently applied to aquatic vascular plants seems falsely optimistic. The lack of dominance within plant communities suggested that demographic processes as well as inter-species competition might have occurred at the local scale as predicted by the patch dynamics concept. However, the different probabilities of colonisation of the sites as well as the regional species pool may dictate the local processes of plant community structure and composition in a directional river network. This study indicates the need for a unification of the niche and demography theories at multiple spatial and temporal scales. The species' demographic dynamics, the catchment- based habitat heterogeneity and the regional species pool should therefore always be taken into account for conservation and management purposes. Wetlands should be preserved and restored as much as possible to maintain the regional species pool which will ensure the persistence of the riverine flora.
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Garrett, Jasmine Jay Tamara, and University of Lethbridge Faculty of Arts and Science. "Autobahn : a gene that has a role in auxin influx in Arabidopsis leaves." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2005, 2005. http://hdl.handle.net/10133/258.
Full textAbstract:
The development of leaf vascular patterns is a highly regulated process. The plant hormone
auxin is critical for vascular patterning: auxin canalization is proposed to cause files of cells to accumulate higher auxin levels and develop into veins. Thus, the response of cells to auxin and transport of auxin are critical to establish proper cell fate. We have characterized a mutation in the Arabidopsis thaliana gene name AUTOBAHN (ABN). abn leaves produce leaves that proliferate disorganized, overlapping veins parallel to the midvein with no differentiation of higher order veins. abn leaves show no normal aspects of the secondary auxin response though double mutant analysis suggest that ABN functions independently of previously characterized auxin response pathways. Wild type plants grown on an influx inhibitor phenocopy abn suggesting that abn is defective in carrier-mediated auxin influx.x, 69 leaves : ill. ; 28 cm.
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Searles, Peter S. "Responses of Sphagnum and Carex Peatlands to Ultraviolet-B Radiation, and a Meta-Analysis of UV-B Effects on Vascular Plants." DigitalCommons@USU, 2000. https://digitalcommons.usu.edu/etd/6578.
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The severity of stratospheric ozone depletion in the temperate and polar latitudes has raised concerns about the sensitivity of terrestrial vegetation and ecosystems to solar ultraviolet (UV-B) radiation. This dissertation examined the responses of plants and microbes to solar UV-B for 3 years in Tierra de! Fuego, Argentina (55° S). This region is under the influence of the Antarctic "ozone hole" during the austral spring. Additionally, a quantitative review of the UV-B literature was conducted using a set of statistical techniques known as meta-analysis.
For the field studies in Tierra de! Fuego, plots were established in a Sphagnum moss peatland and a Carexsedge fen during the spring of 1996. These plots received either near-ambient solar UV-B (90% of ambient) or reduced UV-B (20% of ambient) using specially designed plastic films. At the end of the first field season, no effects of the solar UV-B treatments were apparent on the growth and pigmentation of the plant species in either community The height growth of the moss Sphagnum mageffanicum was less under near-ambient solar UV-B than reduced UV-B during the second and third growing seasons. In contrast, volumetric density of the moss was greater under nearambient UV-B. The growth of the vascular plants did not respond to the solar UV-B treatments even after 3 years although UV-B-absorbing compounds were greater under near-ambient UV-B in some species. Populations of testate amoebae (i.e., shelled amoebae) inhabiting S. magellanicum had greater numbers under near-ambient UV-B than reduced UV-B throughout the 3 years. This response may be an indirect effect of solar UV-B mediated by the direct effect of UV-Bon S. mageffanicum height growth. Fungi on the leaf surfaces of the tree Nothojagus antarctica appeared to be directly inhibited by solar UV-B.
The quantitative literature review of plant field studies simulating stratospheric ozone depletion assessed the effects of elevated UV-B on 10 plant response variables from papers published between 1976 and mid-1999. Modest significant inhibitions of leaf area, aboveground biomass, and plant height were apparent due to increased UV-B using meta-analysis. An increase in UV-B-absorbing compounds appears to be the most robust general response to increased UV-B radiation.
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Zinko, Ursula. "Plants go with the flow : predicting spatial distribution of plant species in the boreal forest." Doctoral thesis, Umeå : Ekologi och geovetenskap, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-315.
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Stierstorfer, Christian. "The vascular plant vegetation in the forest belt of El Hierro (Canary Islands) : with 110 figures, 34 tables, 20 colored plates and 2 tables on 1 folder /." Berlin [u.a.] : Cramer in der Gebr.-Borntraeger-Verl.-Buchh, 2005. http://www.gbv.de/dms/bs/toc/474704858.pdf.
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Öquist, Mats. "Northern peatland carbon biogeochemistry : the influence of vascular plants and edaphic factors on carbon dioxide and methane exchange /." Linköping : Univ, 2001. http://www.bibl.liu.se/liupubl/disp/disp2001/tek729s.pdf.
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Slingerland, Martin Jacob (Marc), and University of Lethbridge Faculty of Arts and Science. "Modelling the auxin-mediated vein formation system in plant leaves." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2007, 2007. http://hdl.handle.net/10133/673.
Full textAbstract:
The plant hormone auxin is involved in a wide range of developmental phenomena in
plants. It carries out many of its effects through a signalling network involving the regulation
of specific genes, including those involved in its own polar transport between cells.
These transporters are able to be redistributed between cell faces, causing the asymmetric
auxin transport that is a key requirement for the formation of vein patterns in leaves.
In this thesis I describe the development of a biochemical kinetics-based model of auxin
signalling and transport in a single cell, which displays biologically plausible responses
to auxin application. The single-cell model then serves as the basis for a multicell model
of auxin-mediated vein formation at a very early stage of leaf formation in Arabidopsis
thaliana.ix, 73 leaves : ill. ; 29 cm.
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Smith, Marthinus Luther. "Investigating the role of pyrophosphate fructose 6-phosphate 1-phosphotransferase in phloem loading." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/1969.
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McMillan, Michele Ann. "The impact of rock climbing on vascular plants, bryophytes, lichens, and land snails of the Niagara Escarpment, Ontario, Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0023/MQ51083.pdf.
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Uys, Lafras. "Coupling kinetic models and advection-diffusion equations to model vascular transport in plants, applied to sucrose accumulation in sugarcane." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1441.
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Thesis (PhD (Biochemistry))--University of Stellenbosch, 2009.ENGLISH ABSTRACT: The sugarcane stalk, besides being the main structural component of the plant, is also the major storage organ for carbohydrates. Sucrose forms the bulk of stored carbohydrates. Previous studies have modelled the sucrose accumulation pathway in the internodal storage parenchyma of sugarcane using kinetic models cast as systems of ordinary differential equations. Typically, results were analysed with methods such as metabolic control analysis. The present study extends those original models within an advection-diffusion-reaction framework, requiring the use of partial differential equations to model sucrose metabolism coupled to phloem translocation. Let N be a stoichiometric matrix, v a vector of reaction rates, s a vector of species concentrations and r the gradient operator. Consider a coupled network of chemical reactions where the species may be advected with velocities, U, or diffuse with coefficients, D, or both. We propose the use of the dynamic system, s + r (Us) + r (Drs) = Nv; for a kinetic model where species can exist in different compartments and can be transported over long distances in a fluid medium, or involved in chemical reactions, or both. Darcy’s law is used to model fluid flow and allows a simplified, phenomenological approach to be applied to translocation in the phloem. Similarly, generic reversible Hill equations are used to model biochemical reaction rates. These are also phenomenological equations, where all the parameters have operationally defined interpretations. Numerical solutions to this formulation are demonstrated with time-courses of two toy models. The first model uses a simple “linear” pathway definition to study the impact of the system geometry on the solutions. Although this is an elementary model, it is able to demonstrate the up-regulation of photosynthesis in response to a change in sink demand. The second model elaborates on the reaction pathway while keeping the same geometry definition as the first. This pathway is designed to be an abstracted model of sucrose metabolism. Finally, a realistic model of sucrose translocation, metabolism and accumulation is presented, spanning eight internodes and four compartments. Most of the parameters and species concentrations used as initial values were obtained from experimental measurements. To analyse the models, a method of sensitivity analysis called the Fourier Amplitude Sensitivity Test (FAST) is employed. FAST calculates the contribution of the possible variation in a parameter to the total variation in the output from the model, i.e. the species concentrations and reaction rates. The model predicted that the most important factors affecting sucrose accumulation are the synthesis and breakdown of sucrose in futile cycles and the rate of cross-membrane transport of sucrose. The models also showed that sucrose moves down a concentration gradient from the leaves to the symplast, where it is transported against a concentration gradient into the vacuole. There was a net gain in carbohydrate accumulation in the realistic model, despite an increase in futile cycling with internode maturity. The model presented provides a very comprehensive description of sucrose accumulation and is a rigorous, quantitative framework for future modelling and experimental design.
AFRIKAANSE OPSOMMING: Benewens sy strukturele belang, is die suikerrietstingel ook die primêre bergingsorgaan vir koolhidrate. Die oorgrote meerderheid van hierdie koolhidrate word as sukrose opgeberg. Studies tot dusver het die metabolisme rondom sukroseberging in die parenchiem van die onderskeie stingellitte as stelsels gewone differensiaalvergelykings gemodelleer. Die resultate is ondermeer met metaboliese kontrole-analise geanaliseer. Hierdie studie brei uit op die oorspronklike modelle, deur gebruik te maak van ’n stromings-diffusie-reaksie-raamwerk. Parsiële differensiaalvergelykings is geformuleer om die metabolisme van sukrose te koppel aan die vloei in die floëem. Gestel N is ’n stoichiometriese matriks, v ’n vektor van reaksiesnelhede, s ’n vektor van spesie-konsentrasies en r die differensiaalvektoroperator. Beskou ’n netwerk van gekoppelde reaksies waar die onderskeie spesies stroom met snelhede U, of diffundeer met koëffisiënte D, of onderhewig is aan beide prosesse. Dit word voorgestel dat die dinamiese stelsel, _s + r (Us) + r (Drs) = Nv; gebruik kan word vir ’n kinetiese model waar spesies in verskeie kompartemente kan voorkom en vervoer kan word oor lang afstande saam met ’n vloeier, of kan deelneem aan chemiese reaksies, of albei. Darcy se wet word gebruik om die vloeier te modeller en maak dit moontlik om ’n eenvoudige, fenomenologiese benadering toe te pas op floëem-vervoer. Eweneens word generiese, omkeerbare Hill-vergelykings gebruik om biochemiese reaksiesnelhede te modelleer. Hierdie vergelykings is ook fenomenologies van aard en beskik oor parameters met ’n duidelike fisiese betekenis. Hierdie omvattende raamwerk is ondermeer gedemonstreer met behulp van numeriese oplossings van twee vereenvoudigde modelle as voorbeelde. Die eerste model het bestaan uit ’n lineêre reaksienetwerk en is gebruik om die geometrie van die stelsel te bestudeer. Alhoewel hierdie ’n eenvoudige model is, kon dit die toename in fotosintese as gevolg van ’n verandering in metaboliese aanvraag verklaar. Die tweede model het uitgebrei op die reaksieskema van die eerste, terwyl dieselfde stelselgeometrie behou is. Hierdie skema is ontwerp as ’n abstrakte weergawe van sukrosemetabolisme. Ten slotte is ’n realistiese model van sukrosevervoer, metabolisme en berging ontwikkel wat agt stingellitte en vier kompartemente omvat. Die meeste parameters en konsentrasies van biochemiese spesies wat as aanvanklike waardes in die model gebruik is, is direk vanaf eksperimentele metings verkry. Die Fourier Amplitude Sensitiwiteits-Toets (FAST) is gebruik om die modelle te analiseer. FAST maak dit moontlik om die bydrae van parameters tot variasie in modeluitsette soos reaksiesnelhede en die konsentrasies van chemiese spesies te bepaal. Die model het voorspel dat sintese en afbraak van sukrose in ’n futiele siklus, asook transmembraan sukrosevervoer, die belangrikste faktore is wat sukrose-berging beïnvloed. Die model het ook getoon dat sukrose saam met ’n konsentrasiegradiënt beweeg vanaf die blare tot by die stingelparenchiem-sitoplasma, van waar dit teen ’n konsentrasiegradiënt na die vogselholte (vakuool) vervoer word. Volgens die realistiese model was daar ’n netto toename in die totale hoeveelheid koolhidrate, ten spyte van ’n toename in die futile siklus van sukrose in die ouer stingellitte. Die model wat in hierdie proefskrif voorgestel word verskaf ’n uitgebreide, omvattende beskrywing van sukroseberging. Voorts stel dit ’n rigiede kwantitatiewe raamwerk daar vir toekomstige modellering en eksperimentele ontwerp.
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Cabena, Lori E. "Vascular land plant isolates from near-shore sediments and implications for stable isotope determination of the paleoatmosphere." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/25882.
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Forster, Paul I. "The pursuit of plants : studies on the systematics, ecology and chemistry of the vascular flora of Australia and related regions /." [St. Lucia, Qld], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18317.pdf.
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