Dissertations / Theses on the topic 'Rhizosphere'
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Burton, C. C. "Phosphomonoesterase and phosphodiesterase activities in rhizosphere and non-rhizosphere soil." Thesis, University of Kent, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378637.
Full textDartnall, A. M. "Cyanogenesis and the rhizosphere." Thesis, University of Kent, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383179.
Full textBergfield, William Alan. "Rhizosphere bacteria and benomyl interactions /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3036805.
Full textLevy, Avram. "Modelling rhizosphere interactions of Burkholderia species." University of Western Australia. School of Biomedical and Chemical Sciences, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0123.
Full textYeates, G. "Microbial population dynamics of the rhizosphere." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334939.
Full textMacey, Michael. "Characterisation of methylotrophs in the rhizosphere." Thesis, University of East Anglia, 2017. https://ueaeprints.uea.ac.uk/66855/.
Full textDeery, Sarah Jane. "Monitoring rhizosphere microbial communities of tomato." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12759/.
Full textCurnow, Philip Kenneth. "Influence of root exudates on rhizosphere pseudomonads." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286230.
Full textSheta, Omar T. "Phytoremediation and rhizosphere manipulation using different amendments." Thesis, University of Glasgow, 2006. http://theses.gla.ac.uk/2147/.
Full textGiles, Madeline E. "Where does denitrification occur in the rhizosphere?" Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=192249.
Full textPires, Ana Cecília da Cruz. "Mangrove rhizosphere effect on sediment Archael communities." Master's thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/3491.
Full textOs mangais são económica e biologicamente importantes. Sendo, contudo, cada vez mais ameaçados. Com o intuito de recuperar estes ecossistemas, têm sido desenvolvidos programas de reabilitação. Todavia, geralmente, estes programas não consideram a importância e os possíveis efeitos das interacções entre microrganismos e plantas no ecossistema dos mangais, devido ao número limitado de estudos em ecologia microbiana neste ecossistema. Sabe-se que as raízes de espécies de plantas terrestres influenciam a composição das comunidades bacterianas do solo. Por sua vez, os microrganismos podem contribuir no crescimento e saúde das plantas. Este estudo teve como objectivos desenvolver um sistema primers para reacção em cadeia da polimerase -electroforese em gel com gradiente desnaturante (PCRDGGE) para o domínio Archaea e o género Nanoarchaeum e determinar se as raízes de plantas de mangal (Rhizophora mangle e Laguncularia racemosa) afectam a composição das comunidades de Archaea e Nanoarchaeum que habitam o solo que está sob a influência das raízes de mangal (efeito “rizosfera”). As comunidades de Archaea e Nanoarchaeum foram analisadas por métodos moleculares, como a PCR e o DGGE. Foi desenvolvido um sistema de primers para PCR-DGGE adequado para o domínio Archaea e para o género Nanoarchaeum com base em novas sequências do gene 16S rRNA recentemente publicadas. Os perfis de DGGE foram analisados com a análise de similaridades (ANOSIM), o método de escalonamento multidimensional não paramétrico (MDS) e o índice de Shannon-Wiener. Os resultados de MDS e ANOSIM sugerem que existem diferenças significativas entre as amostras de sedimento e as amostras de rizosfera de R. mangle e L. racemosa. Por sua vez, a análise de MDS sugere que as raízes de L. racemosa afectam mais a composição da comunidade de Archaea do sedimento do que as raízes de R. mangle. Pelo contrário, os resultados de MDS e ANOSIM sugerem que as plantas de L. racemosa e R. mangle não exercem qualquer efeito na composição de Nanoarchaeum e que não existem diferenças entre as amostras de sedimento e as de rizosfera. A diversidade das populações de Archaea e Nanoarchaeum foi estimada pelo índice de Shannon-Wiener; e mostrou que a diversidade de Archaea era mais elevada do que anteriormente descrito em sedimentos marinhos. Com o propósito de completar este estudo algumas bandas dominantes das amostras de rizosfera vão ser clonados e sequenciados, vão ser criadas bibliotecas de clones para Nanoarchaeum e serão efectuadas análises de pirosequenciação às comunidades de Archaea.
Mangrove forests are economically and biologically important; however, they are also increasingly threatened. In order to recuperate these ecosystems, rehabilitation programs have been developed. However, in general these programs have no knowledge about the importance of plant-microbe interactions in mangrove ecosystem. This happens also because the limited numbers of studies on microbial ecology in this ecosystem. Therefore, they do not consider the possible effects of plant-microbe interactions in mangrove reforestation approaches. It is known that roots of terrestrial plant species influence the composition of soil bacterial communities. In turn, microorganisms can contribute to plant growth and health. In this study we aimed to develop a polymerase chain reaction -denaturing gradient gel electrophoresis (PCRDGGE) primer system suitable for Archaea domain and Nanoarchaeum genus and to determine if roots of mangrove plants (Rhizophora mangle and Laguncularia racemosa) affect the composition of Archaea and Nanoarchaeum communities inhabiting the sediment under influence of mangrove roots (rhizosphere effect). Archaea and Nanoarchaeum communities were analyzed using molecular methods, such as PCR and DGGE. A PCR-DGGE primer system suitable for Archaea domain and Nanoarchaeum genus was developed based on new 16S rRNA gene sequences recently published. DGGE profiles were analyzed with analysis of similarities (ANOSIM), non-metric multidimensional scaling (MDS) and Shannon-Wiener index. Both MDS and ANOSIM results suggest that there are significant differences between bulk and rhizosphere samples of R. mangle and L. racemosa. In turn, MDS analyses suggest that roots of L. racemosa affect more the composition of Archaea community from bulk sediment than roots of R. mangle. On the opposite, ANOSIM statistics and MDS analyses suggest that L. racemosa or R. mangle plants do not influence the nanoarchaeal composition and that there are no differences between bulk and rhizosphere samples. Diversity of Archaea and Nanoarchaeum populations was estimated by using the Shannon-Wiener index; and showed that diversity of Archaea was higher than previously reported in marine sediments. With the purpose to complete this study some dominant bands of rhizosphere samples will be cloned and sequenced, clone libraries for Nanoarchaeum will be generated and pyrosequencing analysis of archaeal communities will be performed.
Obeidy, Carole. "Effet de la végétation sur la mobilité de l’arsenic dans la rhizosphère." Thesis, Saint-Etienne, EMSE, 2011. http://www.theses.fr/2011EMSE0608/document.
Full textThe pollution of soils with Arsenic (As) is an increasing environmental concerns in several countries in the world: USA, Canada, Mexico, China, Vietnam and France. Recently, the emergence of green technologies sush as “phytoremediation” is considered an attractive soil remediation strategy due to its low cost and soil preservation. For this reason, the understanding of interactions between plants and As at the soil-root interface is necessary in order to accelerate phytoremediation implementation and to test its effectiveness. Hence the aim of this work was to study the effect of four plant species Holcus lanatus, Dittrichia viscosa, Plantago lanceolata and Lotus corniculatus on As mobility in a natural As contaminated soil (up to 2000 mg kg-1). First, we compared and characterized the tolerance behaviour of the four selected species to As and their accumulation capacity in hydroponic and in natural soil conditions. Then, the study of As mobilization in the rhizosphere was conducted by using two approaches "rhizopot-rhizons” and "root mat”. We identified by the “rhizopot-rhizons” approach, some interesting correlations between As and the monitored parameters (NO3-, SO42-, Ca, Mg, P, pH, COD) over the vegetative growing period. We observed several processes affecting As mobilization in the rhizosphere (alkalization / acidification, anionic competition ...). The advantage of this approach is that the plants have grown normally without growth substrate pretreatment (artificial contamination, addition of nutrient solutions ...).Whereas, the "root mat" approach allowed the identification of some organic anions in the root system of P. lanceolata and highlighted the role of phosphorus on As mobilization due mainly toto the easy roots collection at the end of experiment
Lecomte, Solène. "Anaerobic respiration diversification in Agrobacterium fabrum C58." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1231.
Full textAnaerobic respiration may be an essential trait in lifestyle, environment colonization and survival. Until now, the only confirmed anaerobic respiration in Agrobacterium spp. is denitrification. Interestingly, this pathway is unequally widespread among Agrobacteria. These observations led me to my hypothesis which is anaerobic respiration and notably denitrification could explain the coexistence of Agrobacteria and their distribution in specific niches in the rhizosphere. My thesis was undertaken to explore the anaerobic respiration strategies of Agrobacterium spp. and to relate them to niche adaptation. The objectives of my thesis were to (1) characterize all the genes involved in denitrification in A. fabrum C58 in vitro, (2) explore the genes of denitrification that are needed during maize root colonization and (3) discover new anaerobic respirations that occur during maize root colonization (Figure 16). Mutational analysis is the classic way to determine the involvement of a gene in specific pathway. However, this method implies an a priori view and solid knowledge on target genes and cannot be applied for every situation. We have to develop a more adapted method to identify essential genes involved in growth in specific anaerobic conditions. - Denitrification genes in A. fabrum C58 in vitro. To complete denitrification pathway in A. fabrum C58 and identify all the genes and regulators involved in the denitrification function, we adopted two strategies: Firstly, an a priori view to (1) identify the nitrate reductase involved in the first step of denitrification and (2) validate the role of a non-coding RNA in denitrification control. To do so, we constructed a mutant of napA of A. fabrum C58 and a mutant of the non-coding RNA NopR and we evaluated their growth and capacity to produce N2O under anoxic conditions. Secondly, to identify all the genes involved in denitrification, we constructed a mutant transposon library of C58 and tested its growth under denitrification conditions in vitro in the presence of either nitrate or nitrite. - Role of A. fabrum C58 denitrifying genes in the root colonization of maize. It is well known that Transposon-sequencing (Tn-Seq) is a very powerful method to determine genes required for bacterial growth in the presence of their host. To determine denitrifying genes involved in root colonization under anaerobic conditions, we used the library constructed in C58 and performed in planta assays. The mutant library was inoculated on maize plants grown on fertile-ground and cultured under flooded conditions miming anaerobic conditions. Sequencing the recovered A. fabrum C58 cells will evidence the genes involved in this anaerobically specific niche colonization. - Discovery of new anaerobic respiration pathways in A. fabrum C58. To discover new anaerobic respiration pathways, we set-up growth assays of C58 under anoxic conditions in the presence C and N sources as terminal electrons acceptors. Interestingly, by culturing WT and NapA-deficient strains in contact with maize root under anoxic conditions (Chapter 1), we showed growth of both strains, suggesting that root exudates serve as terminal electrons acceptors for anaerobic growth of C58. To determine which maize exuded compounds can serve as TEAs, primary metabolites were identified by HPLC and some were tested as TEAs under the set-up conditions
Goddard, Victoria Jane. "Population dynamics of fluorescent pseudomonads in the rhizosphere." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298609.
Full textBiran, Gemma Louisa. "Rhizosphere dynamics of Meloidogyne incognita and Verticillium chlamydosporium." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619510.
Full textMeharg, Andrew Alexander. "Factors affecting rhizosphere carbon-flow in Lolium perenne." Thesis, University of Aberdeen, 1989. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU031803.
Full textRogers, Michael. "PCR-SSCP analysis of microbial communities in a model system." Thesis, University of Kent, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270818.
Full textGeorge, Tim. "Enhanced phosphorus acquisition by Tithonia diversifolia and other potential agroforestry species." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326188.
Full textNaseby, David Craig. "Soil enzymes as indicators of perturbations in the rhizosphere." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/844143/.
Full textOsborne, Meave Catherine. "The spatial ecology of phytopathogenic zoospores in the rhizosphere." Thesis, University of Aberdeen, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369560.
Full textHale, Christopher Charles. "Characterisation of plant (Brassica spp.) and microbial rhizosphere functions." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/102344/.
Full textPacheco, Adriana. "Contribution of methanotrophic groundwater and rhizosphere bacteria to phytoremediation." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013836.
Full textRandima, Livhuwani Priscilla. "Rhizosphere microbial diversity in PAH's contaminated and uncontaminated soil." Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-11302009-195201/.
Full textZamberlin, Mary Frances. "Rhizosphere : Gilles Deleuze and minor American literature and thought /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/6622.
Full textMaboreke, Hazel Ruvimbo. "Effect of plant-parasitic nematodes on rhizosphere interactions in oaks." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17783.
Full textThis thesis investigated the response of Pedunculate oak to the plant-parasitic nematode Pratylenchus penetrans, using RNA-sequencing, stable isotope labelling and fatty acid analyses. Insight into rhizosphere interactions was gained by employing beneficial biotic partners (ectomycorrhizal fungi, rhizosphere helper bacteria), fungal grazers (Collembola) and multitrophic environments. Microbial biomass and community structure as well as oak fitness were assessed. The effects of root-feeding nematodes on oak were largely governed by the endogenous rhythmic growth of the tree. The nematodes triggered a stronger response during shoot flush, e.g. activation of multi-layered defence mechanisms and repression of photosynthesis, as compared to root flush where pathogen-related signalling was repressed. With the presence of the mycorrhizal symbiont plant defence was attenuated and stress tolerance enhanced, indirectly promoting the growth of rhizosphere microorganisms. The helper bacteria fostered the ectomycorrhizal fungus, which in turn stimulated plant growth, counteracting the negative effects of nematodes. Plant-parasitic nematodes and Collembola grazers had independent roles in plant carbon allocation patterns, with nematodes hampering whilst Collembola enhancing the flux of recent photoassimilates to Gram-positive bacteria. Lastly, increasing trophic diversity of the soil fauna in the rhizosphere of oaks was crucial for the maintenances of a microbial community equilibrium that promotes plant growth. In sum, this study highlights the importance of endogenous resource allocation pattern of plants in determining the outcome of belowground biotic interactions. Therefore such plant traits should be considered as important drivers for rhizosphere processes in future studies. Moreover, taking into account the rhizosphere main players in studies on parasitic nematode-plant interactions will result in a more realistic picture and thus more effective nematode management.
Münch, Christiane. "Die Bedeutung der wurzelassoziierten Mikroorganismen für die Stickstoffumsetzungen in Pflanzenkläranlagen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2003. http://nbn-resolving.de/urn:nbn:de:swb:14-1067340834875-91707.
Full textStevens, Daryl Philip. "Uptake of fluorides by the plant root." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phs8442.pdf.
Full textZysko, Agnieszka. "Bacterial responses to changes in phosphorus supply in Ryegrass Rhizosphere." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518478.
Full textKeeble, Alison. "Interaction between mycorrhiza, rhizosphere bacteria and take-all on wheat." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342050.
Full textAvery, Lisa Marie. "The influence of UV-B radiation on rhizosphere microbial communities." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247141.
Full textAlegria, Terrazas Rodrigo. "Defining the host genetic control of the barley rhizosphere microbiota." Thesis, University of Dundee, 2019. https://discovery.dundee.ac.uk/en/studentTheses/4ca9658f-c69d-4c23-b1b2-46d0ef40339d.
Full textTkacz, Andrzej. "Plant genotype, immunity and soil composition control the rhizosphere microbiome." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/48113/.
Full textWakeford, Tom. "The molecular ecology of a legume rhizosphere : patterns and mechanisms." Thesis, University of York, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273883.
Full textLee, Nathan Robert William. "Long Term Glyphosate Effects on Roundup Ready Soybean Rhizosphere Microorganisms." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1525689141453883.
Full textPorteous, Fiona. "Use of lux-marked rhizobacteria to investigate rhizosphere C-flow." Thesis, University of Aberdeen, 1998. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU112116.
Full textMoritsuka, Naoki. "STUDIES ON THE DYNAMICS OF SOIL NUTRIENTS IN THE RHIZOSPHERE." Kyoto University, 2001. http://hdl.handle.net/2433/150333.
Full text0048
新制・課程博士
博士(農学)
甲第9148号
農博第1209号
新制||農||831(附属図書館)
学位論文||H13||N3579(農学部図書室)
UT51-2001-K355
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 小﨑 隆, 教授 櫻谷 哲夫, 教授 關谷 次郎
学位規則第4条第1項該当
Devau, Nicolas. "Processus rhizosphériques déterminant la disponibilité en phosphore : apport de la modélisation mécaniste géochimique." Thesis, Montpellier, SupAgro, 2010. http://www.theses.fr/2010NSAM0019.
Full textRoot-induced chemical processes are recognized as a major strategy developed by plants to enhance phosphorus (P) availability and thus to promote P acquisition. However, the exact influence of these root-induced chemical processes is still poorly understood and quantified. The present study aimed at investigating the influence of root-induced chemical processes, especially root-induced pH changes, on P availability in the rhizosphere. In this work, we used a set of mechanistic adsorption models (« 1-pK triple plane », ion-exchange and Nica-Donnan) within the framework of the component additive approach in order to simulate the effects of root activity on P availability. First, we described the effects of pH on P availability in several soils unaffected by roots, a Chromic Cambisol and a Luvisol. The Luvisol showed different concentrations in inorganic P because of a long-term fertilisation trial. In the rhizosphere of durum wheat (Triticum tu rgidum durum L.) grown on these two soils, we found that calcium (Ca) uptake, in addition to P uptake and root-induced alkalisation, controlled to various extents the changes of soil P availability. Calcium uptake markedly increased P availability by decreasing the promoting effect of Ca adsorption on P adsorption. The relative influence of these three root processes depended on the solution composition (especially concentration of Ca and pH). Our simulations showed the relationship between changes in P availability and the speciation of adsorbed P onto the different soil minerals. Soil mineralogy, especially the relative abundance of illite vs. Fe oxides, controlled the influence of root processes by regulating the contribution of soil minerals to P adsorption. By identifying a novel root-induced processes, namely the Ca uptake, and describing its influence on P availability, our results demonstrate the ability of surface complexation models to predict the effects of root-i nduced processes on P availability in soils
Ndanga, Mbakop Éliane. "Effet de la végétation dans le processus d'oxydation passive du méthane par les biosystèmes des sites d'enfouissement." Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/7547.
Full textAbstract : The passive CH[subscript 4] oxidation Biosystems are a cost-effective technology for the reduction of landfills fugitive CH[subscript 4] emissions in the atmosphere. As part of the final cover, they are made up of a sequence of soil layers capable to develop methanotrophic bacteria for passive CH[subscript 4] oxidation into CO[subscript 2], in the presence of molecular oxygen. The ability of biosystems to reduce CH[subscript 4] emissions was related to several meteorological and environmental parameters, including vegetation. The main objective of this project is to determine the effect of vegetation on CH[subscript 4] oxidation by biosystems. Studies of the CH[subscript 4] oxidation efficiencies of vegetated column under controlled conditions prevailing in the laboratory and under the partially controlled conditions in the field, followed by the study of the CH[subscript 4] oxidation kinetics of the preconditioned rhizospheric soil, were carried out. Four columns were tested, including: white clover (Trifolium repens L.), timothy grass (Phleum pratense L.), a mixture of both (mixture) and bare soil (control biosystem). The results of the column study showed that up to a loading of 100 g CH[subscript 4]/m[superscript 2]/d, plant species did not influence the results, and the CH[subscript 4] oxidation efficiencies were in the vicinity of ~ 100%. Beyond this value, the efficiencies were still high, and a statistically significant difference was observed between plant species. Bare soil was the most efficient while the mixture and white clover were the least in the laboratory and the field respectively. However, differences in efficiencies between the columns were not high and the oxidation rates continued to increase throughout the test, suggesting that the maximum oxidation capacity of the biosystems tested may have never been fully attained. The kinetics study also showed that vegetation did not have significant effect on CH[subscript 4] oxidation rate. These observations do not corroborate what is reported in technical literature on the positive effect of vegetation. Nevertheless, the findings of this study were adequacy with the analysis of the profiles of efficiencies, root biomass and physico-chemical characteristics of soils. Moreover, a significant effect of vegetation on the degree of water saturation in Biosystems was also observed. The latter was associated with the mechanism of water content regulation through plant roots. The main limitations of this study concerned the duration of the tests and the number of plant species. In summary, for the plant species studied herein, it was shown that the vegetation is not a key factor for enhancing CH[subscript 4] oxidation in biosystems. Moreover, the study of the kinetics of CH[subscript 4] oxidation showed that better oxidation rate were obtained in a moderately pre-exposed rhizospheric soil compared to bare soils, to never before pre-exposed or very pre-exposed rhizospheric soils to CH[subscript 4].
Bressan, Mélanie. "Effets des exsudats racinaires d'une plante Brassicaceae sur les microorganismes rhizophériques : influence de la production d'un glucosinolate exogène chez Arabidopsis thaliana : utilisation d'une approche par traçafe de l'ADN (DAN-SIP)." Aix-Marseille 2, 2009. http://theses.univ-amu.fr.lama.univ-amu.fr/2009AIX22057.pdf.
Full textA specificity of Brassicaceous plants is the production of sulphur secondary metabolites called glucosinolates that can be hydrolyzed into glucose and biocidal products. These metabolites are toxic to a wide range of microorganisms and particularly soil-borne pathogens. The aim of this study was to investigate the role of glucosinolates and their breakdown products as a factor of selection on rhizosphere microbial community associated to living Brassicaceae. We used a DNA-stable isotope probing approach to focus on the active microbial populations involved in root exudates degradation in rhizosphere is achieved. After checking its genetic construction and its phenotype, the transgenic Arabidopsis thaliana line CYP79A1, producing an exogenous glucosinolate, were grown under enriched 13CO2 atmosphere on natural soil with the wild type plant associated. In our conditions, roots of the transgenic plant line presented the expected altered profile of glucosinolates as well as other minor additional modifications compared to the wild type. In rhizospheric soil, hydrolysis products of these metabolites could not be successfully detected, probably because of very small quantities and rapid degradation. We hypothesized that a gradient of concentration of all these compounds set up from plant roots to rhizospheric soil. After harvest, to analyze the structure and composition of soil microbial community, DNA from rhizospheric soil was separated by density gradient centrifugation. Bacterial (alphaproteobacteria, betaproteobacteria, gammaproteobacteria and acidobacteria), archaeal and fungal community structure were analyzed by DGGE fingerprints of amplified 16S and 18S rRNA gene sequences. Specific populations were characterized by sequencing DGGE fragments. In rhizosphere, we pointed out for the first time several active microbial populations, in all tested taxa, which specifically used A. Thaliana root exudates as carbon source. The comparison of the structure and composition of microbial community between the 2 plant types showed that the modifications of glucosinolate content in transgenic plant significantly influenced microbial community on roots and active populations in the rhizosphere. Alphaproteobacteria, particularly Rhizobiaceae, and fungal communities were mainly impacted by these Brassicaceous metabolites, in both structure and composition. Different mechanisms, direct or indirect, could be promoted to explain this impact: compounds toxicity, trophism interaction, competition, specific signal. Our results showed that even a minor modification in plant root could have important repercussions on soil microbial communities. Possible consequences on specific microbial functions implicated in ecosystems equilibrium should be then evaluated
Wouterlood, Madeleine. "Carboxylates in the rhizosphere of chickpea (Cicer arietinum) in relation to P acquisition." University of Western Australia. School of Plant Biology, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0029.
Full textDelafuente, Leonardo. "Characterization of the ecological and physiological basis of superior rhizosphere colonization by 2,4-diacetylphloroglucinol-producing fluorescent Pseudomonas genotypes." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Fall2005/l%5Fdelafuente%5F1082405.pdf.
Full textHart, Timothy David. "Diffusion of ions and water through microbial polysaccharides in the rhizosphere." Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/842747/.
Full textDevine, Gary J. "Detecting pathogens and beneficial microorganisms in the tomato rhizosphere using microarrays." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665477.
Full textTurner, Thomas. "Metatranscriptomic analysis of community structure and metabolism of the rhizosphere microbiome." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/49600/.
Full textBraga, Lucas Palma Perez. "Disentangling the influence of earthworms on microbial communities in sugarcane rhizosphere." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/64/64133/tde-26052017-100757/.
Full textAo longo dos últimos 150 anos muitos estudos têm demonstrado a importância das minhocas para o crescimento de plantas. Porém o exato mecanismo envolvido neste processo ainda é muito pouco compreendido. Muitas funções importantes necessárias para o crescimento de plantas podem ser realizadas pela comunidade microbiana da rizosfera. Para investigar a influência das minhocas na comunidade microbiana da rizosfera, foi desenvolvido um experimento de macrocosmo com cana-de-açúcar com e sem Pontoscolex corethrurus (EW+ e EW-, respectivamente) seguindo diversos procedimentos por 217 dias. No Segundo capítulo da tese é demonstrado que no tratamento EW+, as concentrações de N2O dentro do solo (15 cm profundidade) e a abundância relativa dos genes óxido nitroso redutase (nosZ) foram elevadas no solo e na rizosfera, sugerindo que microrganismos do solo foram capazes de consumir a emissão de N2O induzida pelas minhocas. O sequenciamento do DNA total revelou que aproximadamente 70 funções microbianas no solo e na rizosfera apresentaram diferenças entre os tratamentos EW+ e EW-. No geral, genes associados a biossíntese e proliferação de células foram enriquecidos em EW+, sugerindo uma influencia positiva por parte das minhocas. Na rizosfera EW+, funções associadas a simbiose entre planta e microrganismos foram relativamente enriquecidas comparado com rizosfera EW-. Modelos de rede de interação ecológica revelam menor número de diversificação de nichos e aumento de funções importantes como um efeito derivado da influência das minhocas. A biomassa das plantas foi aumentada no tratamento EW+ e a população de minhocas proliferou. Considerando que as minhocas contribuíram com o aumento de nutrientes, foi avaliado no capítulo três a resposta do resistoma presente nas comunidades microbianas dos solos do experimento. Mecanismos de resistência contra compostos antimicrobianos parecem ser características obrigatórias para a ecologia e evolução de procariotos. Entretanto, a maior parte dos estudos sobre genes de resistência tem sido conduzida em condições artificiais utilizando fontes antropogênicas de antibióticos em comunidades microbianas muito específicas como por exemplo o microbioma animal. Para resolver por que e como a resistência evolui, é importante estudar genes de resistência a antibióticos (GRA) (i.e., resistoma) no seu ambiente natural e entender seu papel ecofisiologico no ambiente. Os resultados demonstraram que minhocas influenciaram a mudança na composição de GRA no solo e na rizosfera. Tratamentos EW+ apresentaram maior número de correlações negativas entre ARG e grupos taxonômicos. A medida de centralidade diferencial (DBC=nBCEW+ - nBCEW-) comparando os modelos de rede de interações obtidos mostrou que a composição e o nível de importância dos indivíduos mais influentes é alterado nos tratamentos EW+ comparado com EW-. Além disso, por meio de uma análise de redundância (RDA) foi demonstrado que as alterações na abundancia relativa de GRA podem ser explicadas pelas alterações verificadas em grupos taxonômicos
Murphy, Conor. "Investigation of rhizosphere priming effects for N mineralisation in contrasting soils." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=228575.
Full textLloyd, Davidson A. "Effects of rhizosphere priming and microbial functions on soil carbon turnover." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9278.
Full textColocho, Hurtarte Luis Carlos. "Plant Nitrogen status driving soil organic matter mineralization in the rhizosphere." Universidade Federal de Viçosa, 2016. http://www.locus.ufv.br/handle/123456789/10440.
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Os fatores que regulam a dinâmica do Carbono (C) e Nitrogênio (N) do solo na rizosfera são ainda pouco compreendidos. A mineralização de C na rizosfera pode ser fortemente influenciada pelo estado nutricional da planta, a concentração de CO2 na atmosfera e a temperatura do ambiente, entre outros. Em este estudo, avaliamos o status nutricional de N em plantas de Eucalyptus spp. e sua influência na dinâmica do C e do N n a rizosfera. Realizamos um experimento usando um rhizobox dividido em dois compartimentos. No compartimento de cima plantas foram cultivadas e areia lavada e supridas com uma solução nutritiva contendo todos o nutrientes e a mesma solução porém sem N . No compartimento inferior o contato das raízes com o solo foi limitado usando uma membrana de nylon com abertura de 5 μm. Observamos uma maior razão raiz:parte aérea e maiores concentrações de CO2 no solo das plantas com deficiência de N. As raízes das plantas deficientes em N, apresentaram maiores concentrações em relação as plantas não deficientes em N, de citrato e tallose, e menores concentrações de sucrose e aminoácidos. A análise de C e N da fração de matéria orgânica ligada aos minerais , junto com os dados obtidos pela termoquimolise indicam um aumento na mineralização de C e uma modificação na dinâmica do N. Devido a impossibilidade de contato físico direto com o solo, pela presença da membrana de nylon, a única forma de modificar o solo seria então pela exsudação de compostos pelas raízes. O contrastante conteúdo de aminoácidos e açúcares na raiz, junto com os dados do extrato da solução do solo e de mineralização de C, indica que a composição destes exsudatos diferiu em razão da deficiência de N. Enquanto as plantas deficientes em N exsudaram mais ácidos orgânicos, as plantas com ótimo status nutricional foram capazes de exsudar compostos energeticamente ricos. Os dados de δ13C da matéria orgânica ligada aos minerais indica que as plantas deficientes em N afetaram um maior volume de solo que as plantas supridas de N. Tudo isto mostra que, diferentes mecanismos de efeito priming foram dominantes, dependendo do status nutricional da planta. Em plantas deficiente de N, a mineralização de C no solo foi dominada pelo mecanismo chamado de “mineração de N”, enquanto no solo das plantas supridas de N o mecanismo dominante foi a “estequiometria microbiana”. Este trabalho demostra pela primeira vez, ao nosso saber, a atuação de diferentes mecanismos de efeito priming n a mesma planta, sobre diferente status de N . Assim ressaltando, a importância do manejo de nutrientes na dinâmica do C da rizosfera.
The factors that regulate the dynamics of soil Carbon (C) and Nitrogen (N) in the rhizosphere are still poorl y understood. The soil C mineralization in the rhizosphere ca n be heavil y influenced by plant’s nutritional status, atmospheric CO2 concentration and temperature, among others. In this study, we assess the influence of Eucalyptus spp. N status on the C and N dynamics in the rhizosphere. We performed an experiment us ing two compartment rhizobox. In the upper compartment, plants were cultivated in washed sand and supplied with a solution containing all nutrients or all nutrients but N. The lower compartment limited the contact of the roots with the soil using a 5 μm mesh nylon membrane. We observed a higher root-shoot ratio for the N deficient plants and an increase in its soil CO2 concentration. The roots of the –N planted treatment had higher concentrations of citrate and tallose and lower concentration of sucrose and aminoacids, when compared to the +N planted treatment. The C and N anal ysis of the mineral associated organic matter fraction, together with the thermochemol ysis data showed an increase in C mineralization in both planted treatments and changes in N dynamics. As the roots had no physical contact with the soil due to the nylon membrane, the changes in the soil must have been consequence of root exudation. The contrasting sugar and aminoacid root content, together with the citrate concentration in soil solut ion extract and the C mineralization data, indicate that exudate composition changed due to the plants N status. The data indicates that the plants in the –N treatment exudated more organic acids than the plants of the +N treatment. Still the exudate comp osition of the plants with the +N treatment may had a higher energetic content and thus affected differentl y the soil microbial communities. The δ13C data indicate that the N deficient plants affected a higher volume of soil than the plants of the +N treatment. All this together shows different priming mechanisms were dominant due to the plants N status. As the plants were N deficient, the mineralization of soil C was driven by the “N-mining” mechanism while in the soil of the +N planted treatment the dominant mechanism was “microbial stoichiometry”. This work demonstrates, to our knowledge, by the first time using the same plants, different priming mechanisms due to the plants N status. Thus highlighting, the importance of plants nutrient management in the rhizosphere C dynamics.
Betencourt, Elodie. "Interactions entre céréale et légumineuse en association et acquisition de phosphore du sol : processus rhizosphériques sous-jacents." Thesis, Montpellier, SupAgro, 2012. http://www.theses.fr/2012NSAM0018/document.
Full textThe aim of the study was to elucidate the implication of rhizospheric processes on plant speciesinteractions for phosphorus (P) acquisition between a cereal and a legume, when intercropped. Weproposed that root-induced acidification of the rhizosphere by the intercropped legume due to N2-fixation as a mechanism of facilitation in neutral to alkaline soils. Thus, the study focused on rootinducedchanges of pH. The effects of initial soil P availability and distance between roots ofintercropped species were also tested. In order to achieve our goals, experiments in the field and incontrolled condition for several cropping devices were conducted. Durum wheat and differentlegumes were grown as sole crops and intercropped on the same soil for all the experiments. Weused a neutral soil (Luvisol) presenting three contrasted fertilization rates from the field of a longtermP fertilizer trial. We demonstrated that cereal-legume can be used to enhance P availability, andeven more so in low P soils, through managing rhizospheric interactions to optimize P acquisition ofintercropped species. Soil characteristics are also a key factor determining the influence of thoserhizospheric processes. In our studied soil root-induced changes of pH substantially enhanced Pavailability in the rhizosphere either through acidification or alkalization. Thus the legume but alsothe cereal may facilitate the acquisition of the intercropped species. Interactions involving pH canaffect P availability over distance of several millimeters and ultimately enhance P acquisition ofplants in the surrounding of the facilitative species.Key words: intercrop, facilitation, rhizosphere, availability, phosphorus, pH, root
Gautier, Antoine. "Rôles du porte-greffe et du greffon dans la réponse à la disponibilité en phosphore chez la Vigne." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0257/document.
Full textGrapevine is grown in a grafted system, combining the fruit production qualities of the European species (Vitis vinifera) and the phylloxera tolerance of American species (Vitis spp.). However, the use of American rootstocks affects the development, the physiology, and the water and mineral status of the scion. Particularly, the genetic background of grapevine rootstocks appears to be involved in the regulation of phosphorus (P) content of the scion. Phosphorus is an essential nutrient for plant growth, involved in the composition of many cellular components, as well as in the control of metabolic pathways via its role in energy transfer and the regulation of enzymatic activity. Despite its importance, P is one of the most limiting mineral elements for plant growth because of its poor availability in the soil. The objective of this work is to determine mechanisms involved in the control of P nutrition in grapevine, by comparing two rootstocks V. riparia cv. Riparia Gloire de Montpellier (RGM) and V. rupestris x V. berlandieri cv. 1103 Paulsen (1103P) known to confer low and high concentrations of P to their scion respectively. The results show that 1103P is more efficient at acquiring P than RGM, with a higher developed root system allowing greater soil exploration as well as a higher efficiency of P acquisition. In addition, this rootstock shows better use of its reserves of P in perennial parts to optimize the growth of the shoot. However, the ability of genotypes to increase the assimilable P in the rhizosphere does not seem to be different. Finally, the effect of grafting, and more particularly of the scion genotype, has been studied, demonstrating the capacity of V. vinifera to alter the development and root functioning of the rootstock. These results contribute to our understanding of the mechanisms regulating the mineral nutrition in grapevine and highlight the role of the genetic background of the rootstock, as well as its regulation by the scion