Dissertations / Theses: 'Legume, symbiosis, nitrogen fixation'

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Webster, Gordon. "The interaction between rhizobia and the non-legume Parasponia andersonii." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283646.

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Ng, Ying-sim. "Symbiotic nitrogen fixation by native woody legumes (leguminosae) in Hong Kong, China." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41897122.

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Ng, Ying-sim, and 吳英嬋. "Symbiotic nitrogen fixation by native woody legumes (leguminosae) in Hong Kong, China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41897122.

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Ott, Thomas. "Functional genomics of nodulins in the model legume Lotus japonicus." Phd thesis, [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975678981.

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Miloud, Youssra. "Etude du potentiel bénéfique des souches de Rhizobium pour Medicago truncatula : symbiose, solubilisation du phosphate et lutte contre la verticilliose." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0123/document.

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En raison de leur capacité à former une symbiose avec des bactéries du sol appelées Rhizobium, ces bactéries fixent l’azote atmosphérique et leurs plantes-hôtes n’ont donc pas besoin de fertilisant azoté, les légumineuses jouent un rôle important dans l'agriculture. En outre, certaines souches de Rhizobium ont la capacité de solubiliser le phosphate, fournissant ainsi du phosphore assimilable aux plantes hôtes. Une aptitude à lutter contre certains agents pathogènes a aussi été démontrée dans plusieurs études. La présente étude évalue l’efficacité symbiotique de rhizobiums tunisiens, leur capacité à solubiliser le phosphate, et leur aptitude à lutter contre la verticilliose ainsi que d’autres champignons pathogènes chez Medicago truncatula. Trente-six isolats de rhizobiums prélevés sur des nodules racinaires de M. truncatula provenant de différentes régions de Tunisie ont été obtenus pour ce travail. Environ 60% de ces isolats étaient capables de solubiliser le phosphate in vitro. Dans une seconde étape, trois rhizobiums solubilisant le phosphate et un isolat incapable de solubiliser le phosphate in vitro ont été utilisés pour des essais en phytotron afin de voir l’effet de la présence des rhizobiums sur les paramètres de croissance des plantes en présence de phosphate inorganique sous forme de CaHPO4 et rocheux sous forme brute. Les résultats de l’essai montrent que les plantes de la lignée A17 traitées au CaHPO4, ont tendance à produire plus de nodules et de biomasse aérienne que la lignée F83005.5 et que la forme du phosphate utilisé, soluble ou non soluble, affecte les paramètres étudiés. L'inoculation de quatre lignées de M. truncatula avec 16 isolats de rhizobium sélectionnés auparavant a montré une interaction significative entre les isolats et les lignées pour la symbiose visible par la formation de nodules. Tous les isolats de rhizobium testés ont augmenté la biomasse aérienne des plantes, réduit la biomasse racinaire et entraîné une teneur plus élevée en azote mais l’effet dépendait de l’isolat de rhizobium et de la lignée de M. truncatula utilisés. Enfin, ces isolats ont été testés pour leur capacité à protéger des plantes de M. truncatula contre une maladie racinaire, la verticilliose. Des activités antagonistes in vitro contre divers champignons pathogènes dont Verticillium et Fusarium ont également été recherchées permettant d’identifier un isolat efficace pour la lutte biologique. Les résultats de cette étude suggèrent que des isolats de rhizobium sélectionnés pourraient être utilisés comme biofertilisants dans les sols pauvres pour réduire l'utilisation d'engrais chimiques azotés et phosphorés mais pas pour lutter contre la verticilliose Because of their ability to form a symbiosis with soil bacteria called Rhizobium, legumes play an important role in agriculture. These bacteria fix atmospheric nitrogen; hence their host plants do not need nitrogen fertilizers. In addition, some strains of Rhizobium have the ability to solubilize phosphate, thus providing phosphorus to host plants. An ability to control certain pathogens has also been demonstrated in several studies. The present study evaluates the symbiotic efficiency of Tunisian rhizobia, their ability to solubilize phosphate, and their ability to control Verticillium wilt and other pathogenic fungi in Medicago truncatula. Thirty-six rhizobial isolates were obtained from root nodules of M. truncatula from different parts of Tunisia were used in this work. About 60% of these isolates were able to solubilize phosphate in vitro. In a second step, three phosphate solubilizing rhizobia and one isolate unable to solubilize phosphate in vitro were used for phytotron assays to see the effect of the presence of rhizobia on plant growth parameters in the presence of soluble and insoluble forms of phosphate. The results of the experiment show that A17 plants treated with CaHPO4, tend to produce more nodules and shoot biomass than F83005.5 and that the phosphate form used, soluble or non-soluble, affects parameters studied. Inoculation of four M. truncatula lines with 16 previously selected rhizobial isolates showed significant interaction between isolates and lines for symbiotic abilities as visualised by nodule formation. All rhizobial isolates tested increased above-ground biomass, reduced root biomass, and increased nitrogen content with strains effects of plant genotype and bacterial isolate. Finallly, these isolates were tested for their ability to protect M. truncatula plants against Verticillium wilt, and to inhibit the growth of pathogenic fungi such as Verticillium and Fusarium in vitro. However, no isolate could be identified as effective for biological control. The results of this study suggest that selected rhizobial isolates could be used as biofertilizers in poor soils to reduce the use of nitrogen and phosphorus fertilizers but not to control Verticillium wilt

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Kleinert, Aleysia. "The functional responses of phosphate-deficient lupin nodules as mediated by phosphoenolpyruvate carboxylase and altered carbon and nitrogen metabolism." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5184.

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Thesis (PhD (Plant biotechnology))--University of Stellenbosch, 2010. ENGLISH ABSTRACT: In soils, the concentration of available phosphate (P) for plants is normally very low (ca. 1 µM in the soil solution), because most of the P combines with iron, aluminium and calcium to form relatively insoluble compounds. Inorganic P (Pi)-deficiency is thought to be one of the limiting factors of nitrogen fixation due to the high energy requirement for nitrogenase function of plants taking part in nitrogen fixation. Pideficiency has important implications for the metabolic Pi and adenylate pools of plants, which influence respiration and nitrogen fixation. An alternative route of pyruvate supply during Pi stress has been proposed involving the combined activities of phosphoenolpyruvate carboxylase (PEPc), malate dehydrogenase (MDH) and NAD-malic enzyme (ME) supplying pyruvate to the mitochondrion during Pi stress. Previously, three isoforms of PEPc were isolated from lupin nodules and roots, with two forms being nodule specific. The aim of this project was to determine the effect of Pi stress on these PEPc isoforms in Lupinus luteus at transcript and protein expression level with a view to produce genetically modified crops for nutrient-poor soils. Cytosolic P levels were measured over a time course to give an indication of temporal development of P stress in nodules. The changes in enzyme activities of PEPc, MDH and PK (pyruvate kinase) under P stress were measured and the downstream effect on amino and organic acid pools were analysed. Two novel PEPc isoforms, LUP1 (AM235211) and LUP2 (AM237200) were isolated from nodules, followed by transcriptional and protein expression analyses. Nodules under P stress had lower amounts of metabolically available Pi and as P stressed developed, the amount of Pi decreased. This decline in Pi levels was associated with lower growth, but higher biological nitrogen fixation (BNF). A greater proportion of root-nodule respiration was devoted to nutrient acquisition than to new growth. A typical P-stress response is higher anaplerotic carbon fixation via PEPc. However, in this study, no significant differences were found for PEPc, MDH or PK in P-stressed plants compared to P-sufficient plants which would lead to an increase in organic acids. An increase in key amino acids was reported along with unchanged levels of organic acids. These levels of organic and amino acid are in congruence with the increases in BNF under P-starvation. No significant differences were found in expression of PEPC1 or PEPC2 at 12 and 20 days for both P-sufficient and P-stressed plants which further supported the lack of engagement of the PEPc-MDH-ME bypass. PEPc activity appeared not to be regulated by gene expression or phosphorylation indicating that other posttranslational modifications such as a decrease in protein degradation may be of importance. AFRIKAANSE OPSOMMING: Die konsentrasie van fosfaat (P) beskikbaar vir opname deur plante vanuit die grond is gewoonlik baie laag (in die omgewing van 1 µM) aangesien die P onoplosbare komplekse vorm met katione soos yster, aluminium en kalsium. ‘n Tekort aan anorganiese P (Pi) word gereken as een van die beperkende faktore van stikstofbinding as gevolg van die hoë energie behoefte wat nitrogenase plaas op plante wat van gefikseerde stikstof gebruik maak. Hierdie P-tekort het ook belangrike betrekking op die metaboliese fosfaat- en adenilaatpoele wat weer op hul beurt respirasie en stikstofbinding beÏnvloed. ‘n Alternatiewe roete van pirovaatvoorsiening aan mitochondria tydens fosfaatstres is voorgestel wat bestaan uit die aktiwiteite van fosfoenolpirovaat karboksilase (PEPc), malaat dehidrogenase en NAD-malaat ensiem. Vantevore is drie isovorme van PEPc uit Lupinus luteus wortelknoppies en wortels geïsoleer, met twee van die isovorme wat wortelknoppie-spesifiek was. The doel van hierdie projek was om die invloed van P-tekort op die transkripsie en proteien uitdrukkingsvlak van hierdie PEPc isovorme te bepaal met die doel van gemodifiseerde gewasse vir arm gronde ingedagte. Sitoplasmiese P konsentrasies is gemeet oor tyd om ‘n aanduiding te gee van die ontwikkeling van P-tekort oor tyd. Veranderinge in ensiemaktiwiteite van PEPc, MDH en pirovaatkinase (PK) is gemeet gedurende P-tekort as ook die moontlike effek van hierdie ensiemaktiwiteite op aminosuur en organiese suur poele. Twee nuwe PEPc isovorme, LUP1 (AM235211) en LUP2 (AM237200) is uit wortelknoppies geïsoleer en gekarakteriseer. Transkripsie en proteïenuitdrukking is geanaliseer. Wortelknoppies wat P-tekort behandeling ontvang het, het laer vlakke van metabolise beskikbare Pi gehad en soos die P-tekort ontwikkel het oor tyd, het die Pi vlakke gedaal. Hierdie afname in vlakke van Pi was geassosieer met laer groei, maar met ‘n toename in biologiese stikstofbinding. ‘n Groter proporsie van respirasie is toegestaan aan minerale opname as aan nuwe groei. ‘n Tipiese reaksie op P-tekort is hoër anaplerotiese koolstofbinding via PEPc. Alhoewel, in hierdie studie is geen gevind betekenisvolle verandering gevind in die aktiwiteite van PEPc, MDH en PK nie in plante wat P-tekort ervaar het nie. Verhoogde aktiwiteit van hierdie ensieme sou verhoogde organise suur konsentrasies tot gevolg hê. ‘n Toename in aminosuur konsentrasies is gevind tesame met onveranderde vlakke van organiese sure. Hierdie toename in aminosure word onderskryf deur die verhoogde biologiese stikstofbinding tydens P-tekort. Geen betekenisvolle verskille is gevind in die geenuitdrukking van pepc1 en pepc2 by beide 12 en 20 dae van P-tekort nie, wat verder die afwesigheid van die PEPc- MDH-ME alternatiewe roete beaam het. Dit blyk dat PEPc aktiwiteit nie deur geenuitdrukking of proteïenfosforilering beheer word nie, maar eerder dat ander posttranslasie modifikasies soos ‘n verlaagde afbraak van proteïen ‘n rol speel.

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Liu, Shengbin. "The roles of the NOOT-BOP-COCH-LIKE genes in plant development and in the symbiotic organ identity." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASB005.

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Les gènes NODULE-ROOT de Medicago truncatula, BLADE-ON-PETIOLE d’Arabidopsis thaliana et COCHLEATA de Pisum sativum font partie d'un clade spécifique NOOT-BOP-COCH-LIKE1 (NBCL1) hautement conservé et qui appartient à la famille de gènes NON-EXPRESSOR OF PATHOGENESIS RELATED PROTEIN1 LIKE. Chez les légumineuses, les membres du clade NBCL1 sont connus comme les principaux régulateurs de l'identité des organes symbiotiques (nodules). Les membres du clade NBCL2 (MtNOOT2) jouent également un rôle clé dans l'établissement et le maintien de l'identité de l’organe symbiotique, en redondance avec les gènes NBCL1. Il a également été démontré que ces gènes végétaux NBCL sont impliqués dans l'abscission. Les gènes NBCL sont également conservés chez les plantes monocotylédones chez lesquelles ils contrôlent différents aspects du développement. Ce travail de thèse vise à mieux comprendre les rôles des gènes NBCL1 et NBCL2 dans le développement des plantes légumineuses et chez Brachypodium et à découvrir de nouveaux acteurs moléculaires impliqués dans la régulation de l'identité des nodules dépendante de NBCL1, en utilisant de nouveaux mutants d'insertion TILLING et Tnt1 chez deux espèces de légumineuses (Medicago et Pisum). En outre, nous avons utilisé les mutations KO CRISPR chez Brachypodium pour mieux comprendre leur rôle chez les plantes monocotylédones. Ce travail de thèse a permis d'élucider les nouvelles fonctions des gènes NBCL1 dans le développement des tiges et l'architecture des plantes. Nous avons également révélé que les membres du clade NBCL2, spécifique aux légumineuses, fonctionnent de manière redondante avec le clade NBCL1 et jouent des rôles importants dans le développement des feuilles, des stipules, des inflorescences et des fleurs. De plus, nous avons montré un rôle dans le développement, l'établissement et le maintien de l'identité des nodosités, et par conséquent dans le succès et l'efficacité de l'association symbiotique. Dans cette thèse, nous avons également exploré les rôles des gènes NBCL BdUNICULME4 et BdLAXATUM-A, dans le développement de B. distachyon à l'aide de doubles mutants. Nous avons confirmé les résultats précédents et révélé une nouvelle fonction pour ces deux gènes dans l'architecture des plantes, la formation des ligules et des inflorescences, ainsi que dans la teneur en lignine. Ce travail de thèse a finalement permis l'identification et la caractérisation de nouveaux mutants pour les gènes de M. truncatula ALOG (Arabidopsis LSH1 et Oryza G1). Les protéines ALOG sont des partenaires d'interaction potentiels pour les NBCLs. Nous avons montré que certains membres ALOG jouent un rôle important dans le développement des nodules et des organes aériens. Dans l'ensemble, ce travail de thèse suggère qu'au cours de l'évolution, le programme de développement des nodules a été recruté à partir de programmes de régulation préexistants pour le développement et l'identité des nodosités The Medicago truncatula NODULE-ROOT, the Arabidopsis thaliana BLADE-ON-PETIOLE, and the Pisum sativum COCHLEATA genes are members of a highly conserved NOOT-BOP-COCH-LIKE1 (NBCL1) specific clade that belongs to the NON-EXPRESSOR OF PATHOGENESIS RELATED PROTEIN1 LIKE gene family. In legumes, the members of this NBCL1 clade are known as key regulators of the symbiotic organ identity. The members of the NBCL2 clade (MtNOOT2) also play a key role in the establishment and maintenance of the symbiotic nodule identity, redundantly with NBCL1 while without significant phenotype alone. These NBCL plant genes were also shown to be involved in abscission. In addition, NBCL genes are also conserved in monocotyledon plants in which they also control different aspects of development. The present thesis work aims to better understand the roles of the NBCL1 and NBCL2 genes in development in both legume and Brachypodium plants and to discover new molecular actors involved in the NBCL1-dependent regulation of the nodule identity using novel TILLING and Tnt1 insertional mutants in two legume species, Medicago, and Pisum. In addition we used CRISPR knock-out mutations in Brachypodium to better understand their roles in monocotyledon plants. This thesis work unraveled new functions of the NBCL1 genes in plant shoot development and plant architecture. We also revealed that the members of the legume-specific NBCL2 redundantly function with NBCL1 sub-clade and play important roles in leaf, stipule, inflorescence and flower development. In addition we showed a role in nodule development, identity establishment and maintenance, and consequently in the success and efficiency of the symbiotic association. In this thesis, we also explored the roles of the highly conserved NBCL genes, BdUNICULME4 and BdLAXATUM-A, in the development of B. distachyon using double mutants. We confirmed previous results and reveal a new function for these two genes in plant architecture, ligule and inflorescence formation, and also lignin content. This thesis work has finally allowed the identification and the characterization of new mutants for M. truncatula ALOG (Arabidopsis LSH1 and Oryza G1) genes. ALOG proteins are potential interacting partners for NBCL. We showed that some ALOG members play important roles in nodule and aerial organ development. Altogether, this thesis work suggests that during evolution, the nodule developmental program was recruited from pre-existing regulatory programs for nodule development and identity

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Costa, Carlos Germano Ferreira. "CaracterizaÃÃo fenotÃpica de rizÃbios de solo rizosfÃrico de leguminosas nativas do semi-Ãrido cearense." Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=6932.

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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico Os diferentes solos e manejos culturais afetam o equilÃbrio entre solo e organismos endÃgenos, os quais, por sua vez afetam a sustentabilidade do solo. Desse modo acredita-se que a diversidade dos organismos do solo tenha uma relaÃÃo estreita com a diversidade de outros organismos, tanto na superfÃcie, quanto no prÃprio solo e que as interaÃÃes dessa diversidade microbiana possam levar a uma alteraÃÃo de funÃÃo reduzindo ou ampliando a sustentabilidade dos ecossistemas. InteraÃÃes mutualÃsticas sÃo muito comuns na natureza e desempenham importante papel em muitos processos de diversos ecossistemas. Desse modo, a identificaÃÃo dos padrÃes da estrutura espacial e abundÃncia de microrganismos Ã um elemento importante e, necessÃrio para identificar esse processo.AssociaÃÃes mutualÃsticas entre plantas e organismos do solo sÃo essenciais para a sobrevivÃncia e crescimento das plantas na maioria dos ecossistemas terrestres. Assim, o uso combinado de leguminosas e microrganismos na reabilitaÃÃo de solos deteriorados Ã um processo efetivo na reestabilizaÃÃo dos ciclos de nutrientes nesse sistema, pois a estrutura alimentar do solo pode afetar o desenvolvimento da vegetaÃÃo. O mutualismo entre rizÃbios e leguminosas Ã possÃvel de manipulaÃÃo experimental. Diferente de alguns mutualistas, rizÃbios podem crescer e ser cultivados em meios seletivos. AlÃm disso, seu comportamento mutualista dentro dos nÃdulos pode ser manipulado e monitorado de modo nÃo invasivo. objetivo deste trabalho foi avaliar a diversidade de estirpes nativas de rizÃbio e a relaÃÃo com algumas espÃcies de leguminosas arbÃreas nativas ocorrentes na Reserva Particular do PatrimÃnio Natural (RPPN) Serra das Almas (05Â 00â a 05Â 20â S e 40Â 48 a 41Â 12â W) no estado do CearÃ (Brasil),em uma Ãrea de caatinga no municÃpio de CrateÃs-Ce, dista 390 Km de Fortaleza, entre cotas de 300 a 350 m de altitude, e que caracteriza-se pro apresentar clima semi Ãrido e pluviosidade mÃdia de 881 mm anuais distribuÃda de Janeiro a Abril. Foram identificadas oito espÃcies de leguminosas arbÃreas, que apresentaramassociaÃÃes com rizÃbios: Anadenanthera colubrina var. cebil (Griseb)Altschu (Angico), Bauhinia cheilantha (Bong.) Stend (MororÃ), Poincianella pyramidalis (Tul.) L.P. Queiroz (Catingueira), Erythrina velutina Willd. (Mulungu), Mimosa caesalpiniifolia Benth (SabiÃ), Minosa acustistipula (Mart.) Benth (Juremabranca), Mimosa tenuiflora (Willd.) Poir (Jurema-preta), Amburana Cearensis (AllemÃo) A.C. Smith (Emburana). Foram coletados nÃdulos e solo rizosfÃrico para a identificaÃÃo de bactÃrias diazotrÃficas, em dois perÃodos, na estaÃÃo chuvosa e na seca. Foi realizado o cultivo destes rizÃbios nas plantas-isca, Macropitillium atropurpureum (DC) Urban, Vigna unguiculata (L., Walp.), Cajanus cajan var. flavus DC e Mimosa pudica L, bem como a caracterizaÃÃo cultural caracterizaÃÃo cultural de estirpes de rizÃbio isolados, testes de tolerÃncia a nÃveis crescentes de NaCl e a altas temperaturas.Verificou-se que 92,42% dos isolados apresentara crescimento rÃpido e 52,24% acidificaram o meio 79. Um total de 84,93% isolados possuem tolerÃncia a altas temperaturas (45Â C), e 90,75% isolados apresentaram tolerÃncia Ãs concentraÃÃes salinas a 5%.Os resultados obtidos demonstraram que hÃ relaÃÃo entre a tolerÃncia Ã salinidade e Ã temperatura quando avaliado in vitro para os isolados testados

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Metcalf, Sarah Jean. "Symbiotic nitrogen fixation and establishment of six Montana native legumes species." Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/metcalf/MetcalfS0805.pdf.

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Yates, Ronald John. "Symbiotic interactions of geographically diverse annual and perennial Trifolium spp. with Rhizobium leguminosarum bv. trifolii /." Murdoch University Digital Theses Program, 2008. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20100330.93305.

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Mansur, Irdika. "Diversity of rhizobia nodulating the tree legumes Acacia mangium and Paraserianthes falcataria and their interaction with arbuscular mycorrhizal fungi in young seedlings." Thesis, University of Kent, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310199.

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Kadel, Khem L. "Forward Genetic Characterization of Medicago truncatula Tnt1 Insertion Mutants Defective in Nodule Development and Symbiotic Nitrogen Fixation." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc801877/.

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Legumes are unique plants because they form special structures “nodules”, via symbiotic relationships with rhizobial bacteria present in the soil. Once rhizobia mature inside nodules, they fix atmospheric nitrogen providing a source of bioavailable nitrogen to the plant. To discover novel genetic components involved in the legume-rhizobia symbiosis by using forward genetic screening, we have isolated Medicago truncatula Tnt1 insertion mutants in the R108 ecotype, which are defective in nodule development and symbiotic nitrogen fixation in response to Sinorhizobium meliloti. Out of three mutants NF11044, NF11217 and NF8324, one of the mutants showed brown nodules and Fix- phenotype that is defective in symbiotic nitrogen fixation. The other two mutants showed white nodules and Fix- phenotype, also indicator of defects in symbiotic nitrogen fixation. To identify the underlying mutation causing the phenotype, we have developed molecular genetic markers by obtaining genomic sequences flanking the Tnt1 insertions by TAIL-PCR and Illumina sequencing. To carry out co-segregation analysis, back-crossed BC1F2 segregating populations were obtained. These are being phenotyped, genotyped and analyzed for co-segregation of the phenotype with the Tnt1 genetic markers. Back-crossing also has the effect of reducing the Tnt1 insertions, which are not linked to the nodulation defective phenotypes. Out of the three mutants, NF8324 harbors exactly the same insertion as in the rsd-1 Tnt1 mutant NF11265. The defect in NF11217 is caused by a Tnt1 insertion in the previously described PLC gene; the site of this insertion is close to that found in a different mutant, NF0217. For mutant NF11044, we developed linkage markers that place the defective locus on chromosome 7. To further characterize co-segregation in NF11044, a mapping population has been created by crossing the mutant with other ecotypes: A17 and A20. We tested mutants and wild type plants with linkage marker A20 X NF11044 BC1F2 that segregates 3:1(wild type: mutant). The recombination frequency ratio is similar as compared to back-crosses to ecotype R108. However, we did not observe mutant phenotypes in the A17 X NF11044 BC1F2 population. Future identification of the defective gene and functional characterization of it once it is identified will be carried out to better understand the mechanism of nodule organogenesis and symbiotic nitrogen fixation.

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Huang, Ying-Sheng. "Evidence for Multiple Functions of a Medicago Truncatula Transporter." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699903/.

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Legumes play an important role in agriculture as major food sources for humans and as feed for animals. Bioavailable nitrogen is a limiting nutrient for crop growth. Legumes are important because they can form a symbiotic relationship with soil bacteria called rhizobia that results in nitrogen-fixing root nodules. In this symbiosis, rhizobia provide nitrogen to the legumes and the legumes provide carbon sources to the rhizobia. The Medicago truncatula NPF1.7/NIP/LATD gene is essential for root nodule development and also for proper development of root architecture. Work in our lab on the MtNPF1.7/MtNIP/LATD gene has established that it encodes a nitrate transporter and strongly suggests it has another function. Mtnip-1/latd mutants have pleiotropic defects, which are only partially explained by defects in nitrate transport. MtNPF1.7/NIP/LATD is a member of the large and diverse NPF/NRT1(PTR) transporter family. NPF/NRT1(PTR) members have been shown to transport other compounds in addition to nitrate: nitrite, amino acids, di- and tri-peptides, dicarboxylates, auxin, abscisic acid and glucosinolates. In Arabidopsis thaliana, the AtNPF6.3/NRT1.1( CHL1) transporter was shown to transport auxin as well as nitrate. Atchl1 mutants have defects in root architecture, which may be explained by defects in auxin transport and/or nitrate sensing. Considering the pleiotropic phenotypes observed in Mtnip-1/latd mutant plants, it is possible that MtNPF1.7/NIP/LATD could have similar activity as AtNPF6.3/NRT1.1(CHL1). Experimental evidence shows that the MtNPF1.7/NIP/LATD gene is able to restore nitrate-absent responsiveness defects of the Atchl1-5 mutant. The constitutive expression of MtNPF1.7/NIP/LATD gene was able to partially, but not fully restore the wild-type phenotype in the Atchl1-5 mutant line in response to auxin and cytokinin. The constitutive expression of MtNPF1.7/NIP/LATD gene affects the lateral root density of wild-type Col-0 plants differently in response to IAA in the presence of high (1mM) or low (0.1 mM) nitrate. MtNPF1.7/NIP/LATD gene expression is not regulated by nitrate at the concentrations tested and MtNPF1.7/NIP/LATD does not regulate the nitrate-responsive MtNRT2.1 gene. Mtnip-1 plants have an abnormal gravitropic root response implicating an auxin defect. Together with these results, MtNPF1.7/NIP/LATD is associated with nitrate and auxin; however, it does not act in a homologous fashion as AtNPF6.3/NRT1.1(CHL1) does in A. thaliana.

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Walker, Simon A. "Aspects of signalling and development during the Rhizobium-legume symbiosis." Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323389.

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15

Salo, Lucinda Faith. "COMPETITION BETWEEN STRAINS OF RHIZOBIA FOR NODULATION OF LEUCAENA LEUCOCEPHALA (LEGUME)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275326.

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16

Jayasundara, H. P. S. "Productivity, dinitrogen fixation and nitrogen transfer in some legume based cropping systems." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386547.

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17

McCauley, Ann Michelle. "Nitrogen fixation by annual legume green manures in a semi-arid cropping system." Thesis, Montana State University, 2011. http://etd.lib.montana.edu/etd/2011/mccauley/McCauleyA0811.pdf.

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There is renewed interest within agriculture to improve and sustain soil fertility. Legume crops can provide an alternative nitrogen (N) input to a cropping system through biological N fixation. The contribution of N from legume cropping systems depends on the quantity of N fixed and soil processes that influence soil N availability. The primary objectives of this project were 1) to evaluate the effect of planting and termination time on biomass production and N fixation by two legume green manure crops; and 2) to investigate the role of soil P availability on legume growth and N fixation. A two-yr dryland field study was conducted with three treatments: legume (field pea and lentil), planting time (spring and summer [2010 only]), and termination time (flower, intermediate [2009 only], and pod). Two methods, Â¹âµ N natural abundance and N difference, were used to quantify N fixation. In 2009, N fixed by spring-planted lentil was higher by pod than flower (P=0.03). There was no difference in N fixed by spring-planted pea among termination times, likely because of reduced precipitation during the middle of the growing season. In 2010, both spring-planted crops fixed more N by pod than flower (P<0.01) and more N was fixed by spring-planted crops than summer-planted crops (P<0.01). A greenhouse study was conducted in an unsterilized, low P soil (8 mg kg-soil -Â¹) with three treatments: legume crop (field pea or lentil), P fertilizer (0, 4, or 8 mg P kg -Â¹), and arbuscular mycorrhizae fungus (AMF) inoculum (AMF-, AMF+). Shoot biomass was sampled at flower, and N fixation was estimated with Â¹âµ N natural abundance method. Fertilization increased biomass yield and tissue N and P uptake for both crops (P<0.01) and increased N fixed by pea (P<0.01). Inoculation with AMF had little effect on measured parameters; however, there was an increase in pea biomass and N uptake in the AMF+ versus AMF- treatments at the 4P rate. Several variables that affect N fixation in semi-arid cropping systems were identified in this project, however further research assessing the effect of other soil and environmental conditions on N fixation and the cycling of fixed N in an agroecosystem is needed.

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18

Salehin, Mohammad. "Molecular and Functional Characterization of Medicago Truncatula Npf17 Gene." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc407747/.

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Legumes are unique among plants for their ability to fix atmospheric nitrogen with the help of soil bacteria rhizobia. Medicago truncatula is used as a model legume to study different aspects of symbiotic nitrogen fixation. M. truncatula, in association with its symbiotic partner Sinorhizobium meliloti, fix atmospheric nitrogen into ammonia, which the plant uses for amino acid biosynthesis and the bacteria get reduced photosynthate in return. M. truncatula NPF1.7 previously called MtNIP/LATD is required for symbiotic nitrogen fixing root nodule development and for normal root architecture. Mutations in MtNPF1.7 have defects in these processes. MtNPF1.7 encodes a member of the NPF family of transporters. Experimental results showing that MtNPF1.7 functioning as a high-affinity nitrate transporter are its expression restoring chlorate susceptibility to the Arabidopsis chl1-5 mutant and high nitrate transport in Xenopus laevis oocyte system. However, the weakest Mtnip-3 mutant allele also displays high-affinity nitrate transport in X. laevis oocytes and chlorate susceptibility to the Atchl1-5 mutant, suggesting that MtNPF1.7 might have another biochemical function. Experimental evidence shows that MtNPF1.7 also functions in hormone signaling. Constitutive expression of MtNPF1.7 in several species including M. truncatula results in plants with a robust growth phenotype. Using a synthetic auxin reporter, the presence of higher auxin in both the Mtnip-1 mutant and in M. truncatula plants constitutively expressing MtNPF1.7 was observed. Previous experiments showed MtNPF1.7 expression is hormone regulated and the MtNPF1.7 promoter is active in root and nodule meristems and in the vasculature. Two potential binding sites for an auxin response factors (ARFs) were found in the MtNPF1.7 promoter. Chromatin immunoprecipitation-qRT-PCR confirmed MtARF1 binding these sites. Mutating the MtARF1 binding sites increases MtNPF1.7 expression, suggesting a mechanism for auxin repression of MtNPF1.7. Consistent with these results, constitutive expression of an ARF in wild-type plants partially phenocopies Mtnip-1 mutants’ phenotypes.

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19

Horak, Rachel Elizabeth Ann. "Controls on nitrogen fixation and nitrogen release in a diazotrophic endosymbiont of shipworms." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37238.

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Nitrogen fixation is an ecologically important microbial process that can contribute bioavailable combined N to habitats low in N. Shipworms, or wood-boring bivalves, host N2-fixing and cellulolytic symbiotic bacteria in gill bacteriocytes, which have been implicated as a necessary adaptation to an N-poor C-rich (wooden) diet. Shipworm symbionts are known to fix N within the gill habitat and newly fixed N is subsequently incorporated into non-symbiont containing host tissue. The presence of N2-fixation in gill bacteriocytes presents a conundrum because N2-fixation is tightly regulated by oxygen in most other diazotrophic microbes. Also, the direct evidence of new N being incorporated into the host tissue indicates that there are potentially complex nutrient cycles in this symbiosis, which have not been investigated. We used the cultivated symbiont Teredinibacter turnerae, which has been isolated from many shipworm species, as a model organism to elucidate controls on N2-fixation and N release in the shipworm symbiosis. Our results indicate that headspace oxygen concentration does not control biomass specific N2-fixation and respiration activity in T. turnerae, but it does influence the magnitude of the growth rate and timing of culture growth. Also, we examined the controls of oxygen on inorganic nutrient uptake rates, and documented a small amount of dissolved inorganic nitrogen release. While the N budget is only partially balanced, we provide indirect evidence for the allocation of fixed N to the excretion of exopolymeric substances and dissolved organic nitrogen; future studies that measure these additional N sinks are necessary to close the N budget. Although there are limitations of using pure cultures to investigate a complex symbiotic system, this study provides direct experimental evidence that T. turnerae has adaptations that are conducive to N2-fixation in gill bacteriocytes.

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Westhoek, Annet. "Resource allocation in the legume-rhizobia symbiosis : an integration of modelling and experimental approaches." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:66ed2e7d-85d3-4090-a822-28609ea866c7.

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The symbiosis between plants of the legume family and nitrogen-fixing rhizobia underpins global food security. Legume crops are a major source of protein in human diets, either directly or indirectly as feed for livestock. Application of inoculant rhizobial strains is common practice in many areas, as plant growth is often nitrogen limited and the symbiosis can significantly enhance yields. However, rhizobial strains and outcomes of the symbiosis vary widely. This variation has also been studied by evolutionary biologists interested in the stability of mutualisms. They proposed that plants may prevent establishing symbioses with ineffective strains (partner choice), or provide them with fewer resources (sanctioning). I studied both mechanisms, combining modelling and experimental approaches. Mathematical modelling was used to predict how plants should allocate resources to maximise growth rates, depending on rhizobial nitrogen provision and carbon requirements and on soil nitrogen conditions. The use of marked mutant strains â easily distinguishable and differing in a single rhizobial characteristic â overcame previous experimental difficulties. It was found that pea (Pisum sativum L.) plants are not able to exert partner choice, but do sanction in a more complex way than was previously established. In line with model predictions, resources were preferentially allocated to the single â best available â strain, so that resources allocated to an intermediate-fixing strain depended on whether or not a strain providing more nitrogen was available. Contrary to model predictions, there was no indication of discrimination based on rhizobial carbon requirements. The results cannot be explained by resource allocation in proportion to nitrogen received, and indicate systemic integration of information from different nodules. I formulate a hypothesis about the underlying plant regulatory mechanisms, and discuss implications of the results for selecting inoculant strains and enhancing yields in the field. Future work will rely on further integration of theoretical and applied methods and perspectives.

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21

Rovere, Martina. "Étude fonctionnelle de la famille des facteurs de transcription ERF-VIIs chez Medicago truncatula : régulateurs clés de l’adaptation au manque d’oxygène." Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4037/document.

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Les légumineuses sont connues pour leurs capacités à établir une relation symbiotique avec des bactéries du sol fixatrices de l'azote atmosphérique. Cette interaction aboutit à la formation d'un nouvel organe au niveau des racines, la nodosité, au sein duquel le symbiote convertit l'azote atmosphérique (N2) en ammoniac, qui peut être directement consommé par les plantes. A l’intérieur de cette nodosité, la concentration en oxygène (O2) est maintenue à un très faible niveau car la réaction de réduction du N2 par l’enzyme bactérienne nitrogénase est inhibée par des traces d’oxygène. Un mécanisme de perception directe de l'O2 impliquant des membres de la famille des facteurs de transcription « Ethylene Responsive Factors » (ERFs) du groupe VII a récemment été découvert chez Arabidopsis thaliana. Ces facteurs de transcription (FT) possèdent une extrémité N-terminale caractéristique avec un résidu de cystéine à la seconde position. Dans des conditions normales d'O2, les FT sont conduit à la dégradation suivant une voie spécifique du protéasome. En condition de stress hypoxique, les TFs sont stabilisés et peuvent activer l’expression des gènes de réponse à l'hypoxie. Il a été démontré que la présence d’O2 et de NO était nécessaire pour déstabiliser ces protéines, et qu'une réduction de la disponibilité de l'un ou l'autre des gaz est suffisante pour protéger le résidu cystéine N-terminale de l'oxydation. L’objectif de cette thèse a été d'étudier le rôle de la famille ERF-VII dans la perception et l'adaptation au manque d'O2 chez M. truncatula. Des travaux ont aussi été menés pour déterminer l’importance du NO dans le fonctionnement en microoxie de la nodosité. Quatre gènes codant pour des facteurs de transcription de la famille ERF-VII ont été identifiés dans le génome de M. truncatula. La caractérisation de cette famille au niveau transcriptionnel a révélé que seul MtERF-B2.2 était induit par le stress hypoxique et au cours du développement des nodosités. Les trois autres, MtERF-B1.1, MtERF-B1.11 et MtERF-B2.3, sont constitutivement exprimés dans les feuilles, les racines et les nodosités. Pour étudier la stabilité de la protéine MtERF-B2.1, l’orthologue de RAP2.12 principal ERF-VII décrit dans la perception de l’O2 chez Arabidopsis, en fonction de la disponibilité de O2/NO, nous avons réalisé une protéine de fusion entre l’extrémité N-terminale de notre protéine et la protéine rapporteur luciférase. Les résultats obtenus sur des protoplastes d'Arabidopsis montrent l’implication la partie N-terminale de MtERF-B2.1 dans la régulation de la stabilité de la protéine, mais en contradiction avec les résultats obtenus en plantes composites de M. truncatula. La fonction de MtERF-B2.1 et MtERF-B2.11 a également été étudiée dans le cadre de la réponse au stress hypoxique et au cours du processus de nodulation en utilisant une stratégie d'interférence ARN. Des racines transgéniques dérégulées sur l’expression de MtERF-B2.1 et MtERF-B2.11 ont montré un défaut d’activation de plusieurs gènes de réponses à l'hypoxie tels que l’alcool déshydrogénase (ADH1) ou la pyruvate décarboxylase (PDC1). Ces racines transgéniques ARNi-MtERF-B2.1/B2.11 sont également affectées dans l'interaction symbiotique avec une réduction significative de la capacité de nodulation et de l'activité de fixation de l'azote dans les nodules matures. En conclusion, ces travaux révèlent que le mécanisme de détection d'O2 est médié par les ERF-VII dans les nodosités de M. truncatula et que ce mécanisme, associé aux cibles moléculaires régulées en aval, participe au développement de cet organe et au maintien de la capacité de fixatrice de celui-ci. De plus, les résultats indiquent que MtERF-B2.1/B2.11 sont des régulateurs positifs du métabolisme anaérobie et que les gènes associés au cycle hémoglobine-NO sont susceptibles d'activer d'autres voies de génération d'ATP Legume crops are known for their capacities to establish a symbiotic relationship with nitrogen fixing soil bacteria. This mutualism culminates in the formation of a new plant organ, the root nodule, in which the symbiont converts atmospheric nitrogen (N2) into ammonia, which can be directly consumed by plants. In nodules, bacterial nitrogenase enzyme is inhibited by traces of oxygen (O2) so different mechanisms maintain this organ at low O2 level. At the same time, nodules need to maintain a high ATP level to support the nitrogenase activity, which is highly energy demanding. Thus, a balance between a tight protection from O2 and an efficient energy production, referred as the “O2 paradox” of N2-fixing legume nodules, has to be reached. In Arabidopsis thaliana, a direct oxygen sensing mechanism has recently been discovered involving members of the ethylene responsive factors (ERFs) group VII. These transcription factors (TFs) possess a characteristic N-terminal amino acid with a cysteine residue at the second position that, under normal O2 conditions, leads to protein degradation following a specific pathway called the N-end rule pathway. Furthermore, it was shown that both O2 and nitric oxide (NO) are required to destabilize the ERFs VII and that a reduction in the availability of either gas is sufficient to stabilize these proteins. Therefore, the goal of this thesis was to investigated the role of ERF-VII family in O2 sensing and adaptation to hypoxia in M. truncatula, model plant for legumes, and to understand how NO interacts with O2 in hypoxic signalization in the microoxic environment that characterizes the nodule. We identified four genes belonging to the ERF-VII TF family in the M. truncatula genome, which present a strong similarity with ERF-VII of Arabidopsis. The characterization of this family at the transcriptional level revealed that only MtERF-B2.2 is up-regulated by hypoxia stress and during nodule development. The three others, MtERF-B1.1, MtERF-B1.11 and MtERF-B2.3 are found constitutively expressed in leaves, roots and nodules. To investigated the protein stability of MtERF-B2.1, the closest orthologous to AtRAP2.12 described as O2-sensors in Arabidopsis, in function of O2/NO availability, we realized a fusion protein with the luciferase reporter protein. Our results on Arabidopsis protoplasts indicated that the N-terminal part of MtERF-B2.1 drives its O2-dependent degradation by the N-end rule pathway. The function of MtERF-B2.1 and MtERF-B2.11 was also investigated both in response to hypoxia stress and during the nodulation process using an RNA interference strategy. Silencing of MtERFB2.1 and MtERF-2.11 showed a significant lower activation of several core hypoxia-responsive genes such as ADH1, PDC1, nsHb1 and AlaAT. These double knock-down transgenic roots were also affected in symbiotic interaction with a significant reduction of the nodulation capacity and nitrogen fixation activity in mature nodules. Overall, the results reveal that O2 sensing mechanism is mediated by ERF-VIIs in M. truncatula roots and nodules and that this mechanism, together with downstream targets, is involved in the organ development and ability to efficiently fix nitrogen. Furthermore, results indicated that MtERF-B2.1/B2.11 are positive regulator of the anaerobic metabolism and the Hb-NO cycle– related genes likely in order to activate alternative ATP generation pathways

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22

Radic, S. "Studies on Calcified Seaweed, Legume Yeild and Nitrogen Fixation in acid soils in the Falkland Islands." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527893.

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23

Lemes, Hamawaki Raphael. "EVALUATION OF DI-NITROGEN FIXATION IN EARLY AND LATE DEVELOPMENTAL STAGES OF SOYBEAN (Glycine max [L.] Merr.)." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/dissertations/1592.

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Nitrogen (N) is present in proteins, enzymes, cell structures, purines and pyrimidines in DNA and RNA molecules, photosynthetic pigments, and several other types of molecules in all living organisms. Nonetheless, even though N makes up more than 78% of the atmosphere, it is reported to be the most frequent deficient nutrient in plants. Nitrate (NO3-) and ammonium (NH4+) are the N forms absorbed by plants from soil, but legume crops can establish symbiotic relationships with rhizobia bacteria, and fix N2 from the atmosphere. In soybean, increasing yield and protein content are raising the crop's N requirement; therefore, enhanced N2 fixation is seen as a reliable path to avoid the use of N fertilizers. In this study, the objective was to perform a comprehensive screening in greenhouse and field conditions of soybean genotypes for traits related to N2 fixation. The purpose was to identify among the soybean genotypes different N2 fixation profiles at early and late stages, as well as to investigate their capacity to accumulate above-ground N and supply carry-over N to following crops. The results showed different profiles among the soybean genotypes for early and late N2 fixation capacity, both in greenhouse and field evaluations. Different traits were correlated to either early or late N2 fixation activity. Soybean and winter-rye shoot dry mass were evaluated in the field to assess above-ground N accumulation and carry-over N, respectively. Soybean genotypes were identified with specific capacities to accumulate N in above-ground biomass or supply N to winter-rye. The patterns of N2 fixation identified in this study, as well as the different abilities to accumulate N above-ground or supply N to following crops, could assist in the selection of superior lines with improved N2 fixation capacity.

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24

Abdel-Lateif, Khalid. "Flavonoids and actinorhizal symbiosis : Impact of RNA interference-mediated silencing of chalcone synthase gene on symbiosis between Casuarina glauca and Frankia." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20244/document.

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Les deux systèmes nodulaires symbiotiques les plus importants au niveau agronomique et environnemental sont, d'une part, les symbioses Rhizobium-légumineuses qui concernent environ 14 000 espèces, et d'autre part, les symbioses entre les plantes actinorhiziennes (environ 200 espèces) et l'actinomycète du sol Frankia. La plupart des plantes actinorhiziennes sont capables de fixer des quantités d'azote comparable à celles des Légumineuses ; ce sont généralement des plantes pionnières capables de coloniser des environnements pauvres en éléments minéraux. Elles représentent donc un atout écologique important. Si la symbiose Rhizobium-légumineuse est très étudiée, les mécanismes moléculaires à l'origine de la formation des nodules actinorhiziens restent actuellement peu connus. Ainsi, chez les Légumineuses, les flavonoïdes sont des molécules-clefs du processus de nodulation, alors que chez les plantes actinorhiziennes, l'implication des flavonoïdes dans la nodulation reste imprécise. L'objectif de cette thèse était de comprendre l'implication des flavonoïdes au cours de l'interaction symbiotique entre l'arbre actinorhizien tropical Casuarina glauca et son symbiote Frankia. L'analyse d'une base de données d'unigènes couplée à celle de données d'expression de puces à ADN a permis l'identification de huit genes de C. glauca impliqués dans la voie de biosynthèse des flavonoïdes. L'étude de leur expression dans les racines par PCR quantitative au cours d'une cinétique d'infection de C. glauca par Frankia a montré que les transcrits de la chalcone isomerase et de l'isoflavone reductase s'accumulaient très tôt après l'inoculation, suggérant ainsi une implication des isoflavonoïdes dans la symbiose actinorhizienne. Nous avons alors utilisé une stratégie d'ARN interférent pour réduire l'expression du gène de la chalcone synthase, la première enzyme de la voie de biosynthèse des flavonoïdes. La réduction de l'expression du gène de la chalcone synthase a provoqué une réduction significative du taux de flavonoïdes dans les racines ainsi qu'une très forte diminution du taux de nodulation chez les plantes transformées. Une restauration du taux de nodulation a pu être obtenu en présence de naringenin, une molécule centrale de la voie de biosynthèse des flavonoïdes.Nos résultats apportent donc, pour la première fois, une évidence directe de l'implication forte des flavonoïdes au cours de la nodulation des plantes actinorhiziennes Nitrogen-fixing root nodulation, confined to four plant orders, encompasses more than 14,000 Leguminosae species, and approximately 200 actinorhizal species forming symbioses with rhizobia and Frankia bacterial species, respectively. Most actinorhizal plants are capable of high rates of nitrogen fixation comparable to the nitrogen fixing symbiosis between legumes and Rhizobium. As a consequence, these plants are able to grow in poor and disturbed soils and are important elements in plant community worldwide. The basic knowledge of the symbiotic interaction between Frankia and actinorhizal plants is still poorly understood, although it offers striking differences with the Rhizobium-legume symbiosis. In the symbiosis between legumes and Rhizobium, flavonoids are key molecules for nodulation. In actinorhizal plants, the involvement of flavonoids in symbiosis is poorly understood, but because of the similarities of the infection process between some actinorhizal plants and legumes, flavonoids were proposed to act as plant signals for the bacteria Frankia. The objective of this thesis was to investigate the involvement of flavonoids during the actinorhizal nodulation process resulting from the interaction between the tropical tree Casuarina glauca and the actinomycete Frankia.Eight C. glauca genes involved in flavonoid biosynthesis were identified from a unigene database and their expression patterns were monitored by quantitative real-time PCR during the nodulation time course. Our results showed that chalcone isomerase and isoflavone reductase transcripts accumulated preferentially early after inoculation with Frankia, suggesting thus for the first time that isoflavonoids are implicated in actinorhizal nodulation. To go deeper in the understanding of the role of these molecules in actinorhizal symbiosis, we used RNA interference strategy to silence chalcone synthase, the enzyme that catalyzes the first committed step of the flavonoid pathway. Knockdown of chalcone synthase expression led to a strong reduction of specific flavonoids levels and resulted in a severely impaired nodulation. Nodule formation could be rescued by supplementation of plants with naringenin, which is an upstream intermediate in flavonoid biosynthesis. Our results provide, for the first time, direct evidence of a strong implication of flavonoids during actinorhizal nodulation

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25

Sajid, G. Mustafa. "Hydrogen Uptake Genes and Nitrogen Fixation Efficiency of Rhizobium Species in Symbiosis With Alfalfa, Chickpea and Pigeonpea." DigitalCommons@USU, 1991. https://digitalcommons.usu.edu/etd/3458.

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The plasmids pDN211 and pDNll, isolated from the gene bank of the Rhizobium japonicum strain I-110, have been reported to complement two different Nif+ Hup· (nitrogen fixation positive and hydrogen uptake negative) mutants. A 5.9-kb Hindiii DNA fragment of the cosmid pHU52, isolated from the gene bank of R. japonicum strain 122DES, has been reported to code for the two polypeptide subunits of uptake hydrogenase. To determine homology between the structural genes of uptake hydrogenase of the two strains, a Southern blot of the Hindiii restriction fragments of the plasmids pDN211 and pDN11 was hybridized to the 5.9-kb Hindiii fragment. A 6.0-kb HindIII DNA fragment of pDN11 was observed to be homologous to the hup DNA probe. Thus, the hup genes of the two Rhizobium strains are conserved. Colony hybridization with the 5.9-kb DNA as the probe was used to detect the homologous hup genes in alfalfa-, chickpea- and pigeonpea- Rhizobium species. These Rhizobium species were also successfully derepressed for uptake hydrogenase in free living conditions. It was found that 30% of the alfalfa-, 30% of the chickpea- and 21% of the pigeonpea- Rhizobium strains tested were Hup+ as determined by the methylene blue (MB) reduction assay. All but one strain of alfalfa- (Celpril Ind. 3623) and one strain of pigeonpea- Rhizobium (IC3282) that showed strong homology to the hup DNA probe also exhibited MB reduction activity. The Hup+ strains of alfalfa- and pigeonpea- Rhizobium produced significantly higher yields as compared to the Hup- strains, whereas those of the chickpea-Rhizobium strains produced significantly lower yields as compared to the Hup- strains. Two of the alfalfa-Rhizobium strains, USDA1024 and CmRm~, exhibited Hup activities greater than any reported previously for this bacterial species. The cosmid-borne hup genes of R. japonicum were successfully expressed in all strains tested but the enzyme activities were very low in alfalfa-Rhizobium compared to those in chickpea- and pigeonpea-Rhizobium species. The relative efficiency of N2-fixation was significantly increased by the transfer of hup genes into the chickpea- and pigeonpea- Rhizobium strains.

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26

Salem, Hassan Samy. "Phylogenetic Analysis of the Symbiotic Nostoc Cyanobacteria as Assessed by the Nitrogen Fixation (Nifd) Gene." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1282030524.

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27

Christophersen, Helle Martha. "Putative dicarboxylate and amino acid transporters in soybean (Glycine max L.) : a molecular characterisation." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0134.

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[Truncated abstract] Some plants, such as legumes, are able to use atmospheric nitrogen as a nitrogen source due to the nitrogen-fixing bacteria residing in specialised root structures called nodules. The exchange of carbon and nitrogen between the host plant (legume) and the nitrogen- fixing micro-symbiont is vital for biological nitrogen fixation. In particular, transport of C4-dicarboxylates, mainly malate, from the plant to the micro-symbiont, and the reverse transport of fixed nitrogen in the form of ammonium are essential for symbiotic nitrogen fixation. In the legume nodule, the symbiosome membrane (SM) surrounds the bacteroid and all exchanges of metabolites and nutrients that occur between the plant and the micro-symbiont must cross this membrane. Recently it has been established that cycling of amino acids across the SM is also critical for optimal symbiotic nitrogen fixation. Therefore to fully understand this agriculturally significant phenomenon, the mechanisms facilitating these exchanges need to be investigated. The major aim of this study was to increase the understanding of nutrient exchange within the nodule at the molecular level by isolating and characterising genes encoding transporters responsible for malate and amino acids transport in soybean (Glycine max, L.), with particular interest in genes significantly or highly expressed in nodules. A combination of molecular and biochemical techniques was used to achieve this. ... Southern blot analysis showed that a small gene family of up to five members encodes these proteins in soybean. A full-length cDNA, designated GmAAP5, was isolated that encodes a novel, putative amino acid transporter. Molecular characterisation of this cDNA and that of GmAAP1 (GenBank Accession no: AY029352), a previously identified putative amino acid transporter gene, was done. Expression analyses showed relatively high expression of GmAAP5 in soybean nodules compared to that in leaf and root tissues, while GmAAP1 showed uniformly high expression in root, leaf and nodule tissues. Phylogenetic analysis of the deduced amino acid sequences of known functional AAPs from dicotyledonous plants revealed that GmAAP1 is most closely related to AAP2 from V. faba, while GmAAP5 is more closely related to AAPs from non-leguminous plants than from leguminous plants. Based on the functional characterisation of the AAPs with which GmAAP1 and GmAAP5 cluster, it is likely that both transporters are neutral and acidic amino acid transporters within the AAP subfamily.

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28

Bashore, Sarah L. aity. "Characterization of a Spontaneous Phaseolus Vulgaris Mutant with the Ability to Selectively Restrict Nodulation." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1155747948.

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29

Perry, Clarice Lorraine. "Specialized Replication Operons Control Rhizobial Plasmid Copy Number in Developing Symbiotic Cells." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/6167.

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The rhizobium – legume symbiosis is a complex process that involves genetic cooperation from both bacteria and plants. Previously, our lab described naturally occurring accessory plasmids in rhizobia that inhibit this cooperation. A transposon mutagenesis was performed on the plasmids to detect the genetic factor that blocked nitrogen fixation. Several of the plasmids were found to possess a replication operon that when disrupted by transposon insertion, restored symbiotic function. This study describes an in-depth investigation into one of those plasmids, pHRC377, and into its replication operon. The operon, which we have called repA2C2, comes from the repABC family of replication and partitioning systems commonly found in alphaproteobacteria. In this study we show that this operon is not necessary for pHRC377 replication in LB culture or free living cells, but is necessary for plasmid amplification in the plant, specifically during rhizobial differentiation into nitrogen fixing bacteroids. We also show how the other repABC type operons on pHRC377 function in relation to plasmid maintenance and copy number during endoreduplication and how they do not have the same phenotypic effect as repA2C2.

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Sampson, Helen G. (Helen Grace). "Biomass and protein yields, N2-fixation and N transfer in annual forage legume-barley (Hordeum vulgare L.) cropping systems." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68257.

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In this study, six annual legumes and the perennial, red clover (Trifolium pratense L.) were monocropped (MC) and intercropped (IC) with barley in a field study with three N levels, 0, 30 and 60 kg N ha$ sp{-1}$. At O kg N ha$ sp{-1}$, N$ sb2$-fixation and N transfer were estimated by the $ sp{15}$N isotope dilution (ID) method. At 60 kg N ha$ sp{-1}$, a direct $ sp{15}$N labelling method was employed to study N transfer. The hypotheses were that the annual species would be more productive within one growing season than red clover, that increased N levels would increase herbage dry matter (DM) and crude protein (CP), that the proportion of N derived from N$ sb2$-fixation in IC-legumes would be higher than that of MC-legumes and that within intercrops there would be evidence of N transfer. In neither year was the total DM yield of red clover, MC or IC, less than the rest of the legumes. In 1991, the total DM yield of intercrops responded to 30 kg N ha$ sp{-1}$; in neither year did the estimated total CP yield of MC-legumes or intercrops respond to N levels. Only in 1992 was there evidence of N$ sb2$-fixation and the proportion of N derived from fixation by IC-legumes was 145% higher than that of MC-legumes. Only the $ sp{15}$N direct labelling method gave evidence of N transfer, to associated legume and barley plants in 1991, and to associated legume plants in 1992.

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VanYperen, Ryan D. "Gene Networks Involved in Competitive Root Colonization and Nodulation in the Sinorhizobium meliloti-Medicago truncatula Symbiosis." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/6177.

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The rhizobia-legume symbiosis is the most agriculturally significant source of naturally fixed nitrogen, accounting for almost 25% of all biologically available nitrogen. Rhizobia-legume compatibility restrictions impose limits on symbiotic nitrogen fixation. In many cases, the molecular basis for symbiotic compatibility is not fully understood. The signals required for establishing a symbiotic partnership between nitrogen-fixing bacteria (e.g. Sinorhizobium meliloti) and leguminous plants (e.g. Medicago truncatula) have been partially characterized at the molecular level. The first stage of successful root colonization is competitive occupation of the rhizosphere (which is poorly understood). Here, the bacteria introduce themselves as potential symbiotic partners through the secretion of glycolipid "Nod" factors. In response, the host facilitates a more exclusive mode of colonization by the formation of a root nodule – a new organ capable of hosting dense intracellular populations of symbiotic rhizobia for nitrogen fixation. This dissertation reports the exhaustive identification of S. meliloti genes that permit competitive colonization of the M. truncatula rhizosphere, and includes a mechanistic study of one particular bacterial signaling pathway that is crucial for both rhizosphere colonization and nodulation. I have made use of Tn-seq technology, which relies on deep sequencing of large transposon mutant libraries to monitor S. meliloti genotypes that increase or decrease in relative abundance after competition in the rhizosphere. This work included the collaborative development of a new computational pipeline for performing Tn-seq analysis. Our analysis implicates a large ensemble of bacterial genes and pathways promoting rhizosphere colonization, provides hints about how the host plant shapes this environment, and opens the door for mechanistic studies about how changes in the rhizosphere are sensed and interpreted by the microbial community. Notable among these sensory pathways is a three-protein signaling system, consisting of FeuQ, FeuP, and FeuN, which are important for both rhizosphere colonization and nodule invasion by S. meliloti. The membrane-bound sensor kinase FeuQ can either positively or negatively influence downstream transcription of target genes by modulating the phosphorylation state of the transcriptional activator FeuP. FeuN, a small periplasmic protein, inhibits the positive mode of FeuPQ signaling by its direct interaction with the extracellular region of FeuQ. FeuN is essential for S. meliloti viability, underscoring the vital importance of controlling the activity of downstream genes. In summary, I have employed several powerful genetic, genomic, computational, and biochemical approaches to uncover a network of genes and pathways that coordinate root colonization and nodulation functions.

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NASCIMENTO, Luciana Remigio Santos. "Diversidade de isolados bacterianos e sua influência na FBN em diferentes coberturas vegetais." Universidade Federal Rural de Pernambuco, 2013. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5226.

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Submitted by (lucia.rodrigues@ufrpe.br) on 2016-08-09T11:44:35Z No. of bitstreams: 1 Luciana Remigio Santos Nascimento.pdf: 1138104 bytes, checksum: 750c8fb90c94f33a3d5dd34960ecc781 (MD5) Made available in DSpace on 2016-08-09T11:44:35Z (GMT). No. of bitstreams: 1 Luciana Remigio Santos Nascimento.pdf: 1138104 bytes, checksum: 750c8fb90c94f33a3d5dd34960ecc781 (MD5) Previous issue date: 2013-02-27 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES The diversity of soil microorganisms interact directly with the vegetation cover. Legumes play a fundamental role in soil fertility by adding nitrogen contributing to the maintenance and balance of the ecosystems. The main scope of this study was to evaluate the effect of vegetation on rhizobia diversity for effective nodulation and N2 fixation in the tree legumes: leucena (Leucaena leucocephala (Lam.) De Wit.) and sabiá (Mimosa caesalpiniifolia Benth.) grown in a Luvisol from the semiarid region of Pernambuco state, Brazil. Samples were collected in the field in soil submitted to different vegetation cover (leucena, sabiá, preserved caatinga, savannah and intercropping maize-beans). A greenhouse experiment was carried out with the soil samples grown leucena and mimosa tree legumes. The isolates obtained from the root nodules were morphologically characterized and grouped to study the diversity, by the construction of dendrograms and calculate the diversity index. The capacity of nitrogen fixation by leucena and mimosa was assessed by means of the natural abundance of 15N. There was a great diversity among bacterial isolates regarding their morphological and physiological characteristics showing a diverse population varying with the different vegetation cover. Soils with vegetation cover less disturbed showed the best results in biological nitrogen fixation and leucena displayed the highest percentage of N2 fixation evaluated by the natural abundance of 15N, especially in soils under savannah vegetation and preserved caatinga. A diversidade de microrganismos do solo está diretamente relacionada com a cobertura vegetal. As leguminosas desempenham um papel fundamental na fertilidade do solo pela adição de nitrogênio contribuindo para a manutenção e equilíbrio dos ecossistemas. O principal objetivo deste estudo foi avaliar o efeito da vegetação na diversidade de rizóbio para nodulação eficaz e fixação de N2 em leguminosas arbóreas: leucena (Leucaena leucocephala (Lam.) De Wit).) e sabiá (Mimosa caesalpiniifolia Benth.) cultivadas em um Luvissolo do semiárido do estado de Pernambuco, Brasil. Amostras foram coletadas em campo em solo submetido a diferentes coberturas vegetais (leucena, sabiá, caatinga preservada, capoeira e consorciação de milho e feijão). Foi realizado um experimento em casa de vegetação com as amostras de solo cultivadas com as espécies de leguminosas arbóreas leucena e sabiá, como plantas isca para isolar rizóbios. Os isolados de rizóbios obtidos a partir de nódulos radiculares foram caracterizados morfologicamente e agrupados de modo a estudar a diversidade, pela construção de dendrogramas e de índice de diversidade. A capacidade de fixação de nitrogênio por leucena e sabiá foi avaliada por meio da abundância natural de 15N. Houve uma grande diversidade entre os isolados bacterianos em relação as suas características morfofisiológicas mostrando uma população diversificada, variando de acordo com as diferentes coberturas vegetais. Solos com a vegetação menos perturbada apresentaram os melhores resultados em fixação biológica de nitrogênio. As plantas de leucena apresentaram o maior percentual de fixação do N2 avaliado pela abundância natural de 15N, especialmente em solos sob vegetação de capoeira e caatinga preservada.

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Castelli, Joanne Maree. "Characterisation of putative transporters maintaining iron homeostasis in symbiotic soybeans." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0020.

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[Truncated abstract] Nitrogen fixation is a feature of the symbiotic association between legumes and rhizobia, which occurs within the symbiosomes of root nodules and involves the conversion of atmospheric N2 to ammonia to be used by the plant in exchange for carbon compounds. Exchange of other nutrients is controlled by plant-synthesised proteins on the symbiosome membrane. Iron is a component of symbiotically important proteins, so is essential for nitrogen fixation. Low soil iron leads to decreased plant yields, whilst in other environments plants may accumulate iron to toxic levels. Knowledge of iron acquisition, transport and storage mechanisms is important to elucidate the role of iron transporters in the maintenance of iron homeostasis in the plant. This study provides evidence that iron has a profound effect in the Bradyrhizobium japonicum-Glycine max symbiosis on the development of the nodule, and on the development of the symbiotic soybean plant itself. cDNAs encoding four putative iron transporters in soybean; GmDmt1, GmYSL1, GmCCC1;1 and GmCCC1;2, were identified, isolated and characterised in this study. GmDmt1 is localised to the symbiosome membrane. Expression of GmDmt1 occurs in nodules, roots and leaves and increases in response to iron starvation. GmDmt1 rescues growth and enhances 55Fe(II) uptake in the iron transport deficient yeast strain fet3fet4, with uptake following Michaelis-Menten kinetics, resembling the situation in isolated symbiosomes. Competition experiments using fet3fet4 indicated that GmDmt1 is able to transport other divalent cations, including zinc, copper and manganese, and is also able to complement a zinc transport deficient yeast mutant. ... These results suggest the divalent metal transporter GmDmt1, the putative iron chelate transporter GmYSL1 and the putative vacuolar iron transporters GmCCC1;1 and GmCCC1;2 act together to maintain iron homeostasis in symbiotic soybeans. The possible interactions and regulation of these proteins and their roles in the acquisition, transport and utilisation of iron in symbiotic soybeans are discussed.

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Mortimer, Peter E. "The C-economy, nutritional benefits and symbiotic performance of dual inoculated Phaseolus vulgaris (L.) plants, under variable nutrient conditions." University of the Western Cape, 2010. http://hdl.handle.net/11394/8207.

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Philosophiae Doctor - PhD The tripartite symbiosis between Phaseolus vulgaris, arbuscular-mycorrhiza and the nodule bacteria, Rhizobia have been the focus of many studies ranging over a number of decades, however these studies have failed to answer certain questions relating the role of the symbionts in regard to host nutrition and the subsequent influence of these symbionts on the host C- economy. There is little doubt over the synergistic benefits involved in the dual inoculation of bean plants, as well as the resultant C-costs of maintaining the 2 symbionts, yet the specific contribution of the individual symbionts to the hosts overall nutrient and C-economy remain to be clarified. Thus the aim of this thesis is to help clarify these points by determining the symbiont induced photosynthetic, respiratory and nutritional changes taking place in the host. This was achieved by a series of experiments in which nodulated bean plants were split into two categories-those with and without AM colonized roots. These plants were then exposed to a range of growing conditions, including hi and low P, and a series of N treatments, ranging from zero N through to 3 mM NH/. Under these differing nutrient conditions growth, photosynthetic, respiratory, nutrient and amino acid responses were monitored, thus allowing for the determination of the symbionts influence on the host and the hosts reliance on the respective symbionts. Host reliance was noted most strongly under nutrient limiting conditions. Under low P treatment AM was the dominant symbiont as far as host C was concerned, allowing for the early establishment of the AM, thus ensuring the uptake of P for both host and nodule development. High P affected AM colonization to a greater extent than it did nodule dry weight and conversely the addition of N~ + led to a greater decrease in nodule dry weight than it did AM colonization. In spite of this decline, AM benefited the host by improving host N nutrition and relieving N-feedback inhibition of the export amino acid asparagine on BNF. These AM induced benefits did come at a cost to the host though, the dual inoculated plants had higher below ground respiratory costs and subsequently higher photosynthetic rates to compensate for the increased demand for C. The higher photosynthetic rates associated with dual inoculation were as a result of symbiont induced sink stimulation and not due to the improved nutrition of the host, as shown by the photosynthetic and nutrient response ratios. However, the respiratory costs associated with the uptake of soil nutrients were lower in AM colonized roots, thus showing an increased efficiency in nutrient gain by AM colonized roots. This improvement in host N nutrition as a result of AM colonization, coupled with the lower respiratory costs of AM nutrition led to the conclusion that under certain growing conditions nodules can become redundant and possibly parasitic.

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Silva, Humberto Ant?o de Sousa e. "Efeito de Alum?nio, Molibd?nio e de Estirpes de Riz?bio em Arachis pintoi." Universidade Federal Rural do Rio de Janeiro, 2007. https://tede.ufrrj.br/jspui/handle/tede/540.

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Made available in DSpace on 2016-04-28T14:58:56Z (GMT). No. of bitstreams: 1 2007-Humberto Antao de Sousa e Silva.pdf: 1812876 bytes, checksum: fc5dddb0fe3112c5b22807ccdce3e05b (MD5) Previous issue date: 2007-02-14 Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior In a modern cattle-breeding using pastures that allows a gain of weight is an essential factor. The Arachis pintoi is an option to a good alimentary diet and to the recuperation of degraded pastures, due to its potential in biological fixation of nitrogen and resistance to acid soil with high contents of aluminium. Experiments were conducted in greenhouse and growth chamber condition, in order to study the behavior of Arachis pintoi (Amarillo cv., Belmonte cv. and accession BRA-031534) in its relation to inoculation with rhizobial strains, aluminium tolerance and Mo influence. Strains CIAT-5067, CIAT-5083, CIAT-5087, BR-1432 e BR-1433 were used in inoculation experiments. In experiments with aluminium were used: a) A simple nutritive solution, initially with rates 10μM, 20μM, 40μM, 80μM and 160μM, and later 2μM, 4μM, 8μM, 16μM e 32μM, b) A complete nutritive solution with rates 20μM, 40μM, 80μM, 160μM and 320μM at Amarillo cv. and access BRA-031534 propagated by seeds and at the Amarillo and Belmonte cv. and access BRA-031534 vegetatively propagated. In the experiment with Mo, four rates of molybdenum (0g.ha-1, 50g.ha-1, 100g.ha-1 e 200g.ha-1), three levels of pH (4,0; 5,0 e 6,0) and two collection dates (49 days and 78 days) were used. The plants inoculated with CIAT strains, presented a good response to nodulation especially in relation to Belmonte cv., and with the same effectiveness of native strain. It was observed deleterious effect of nitrogen in the number of nodules. The results in simple nutritive solution had shown reduction in growth and dry mass of the root and a reduction evaluated in 27% by the relative root length between the concentration of 16μM and the control. In these experiments were observed responses to the concentration of aluminium, with appearance of mucilage and darkening of the primary root. In studies involving complete nutritional solution, Amarillo cultivar and accession BRA-031534 propagated by seeds had had reduction in the growth of the primary root and in relative length of the root in relation to the control. In the concentrations of 320μM and 160μM, a reduction of 51% and 49% respectively, in the Amarillo cultivar and access BRA-031534. It was also observed in this study with the Amarillo cultivar, roots with tip dark in the concentrations of 160μM and 320μM, and increase in the number of secondary roots from the concentration of 80μM. Pyrocatecol violet dyes seems to be promising in allowing a visualization of aluminum effects to Amarillo cultivar and accession BRA-031534. The aluminum in vegetative propagation influenced the cultivars and accession tested. Belmonte cultivar formed a higher number of adventitious roots when compared with Amarillo cv and accession BRA-031534, and with a concentration of 80μM a reduction in the adventitious roots length of the tested cultivars and access occurred. The molybdenum application promote answer in the second harvest in the pH 6,0 being obtained a larger number of nodules in the concentration of 200g.ha-1.The pH intervened in the nodulation. Na pecu?ria moderna, o uso de pastagens que permitem um bom ganho de peso ? um fator imprescind?vel. A leguminosa Arachis pintoi apresenta-se como uma op??o tanto para uma dieta alimentar eficiente, como para recupera??o de pastagens degradadas devido ao seu potencial em fixa??o biol?gica de nitrog?nio e resist?ncia a solos ?cidos com teor elevado de alum?nio. Com a finalidade de estudar o comportamento do Arachis pintoi em rela??o ? inocula??o com estirpes de riz?bio, toler?ncia ao alum?nio e a influ?ncia do molibd?nio, foram conduzidos experimentos em condi??es de casa de vegeta??o e c?mara de crescimento. Nos experimentos de inocula??o utilizaram-se as estirpes CIAT-5067, CIAT-5083, CIAT-5087, BR-1432 e BR-1433. Nos experimentos com alum?nio foram utilizadas: a) Solu??o nutritiva simples, (10μM, 20μM, 40μM, 80μM e 160μM) e (2μM, 4μM, 8μM, 16μM e 32μM), na cultivar Amarillo. b) Solu??o nutritiva completa (20μM, 40μM, 80μM, 160μM e 320μM) na cultivar Amarillo e acesso BRA-031534 propagadas por sementes e nas cultivares Amarillo, Belmonte e acesso BRA-031534 propagadas vegetativamente. No experimento com molibd?nio, foi utilizada a cultivar Amarillo, quatro dosagens de molibd?nio (0gha-1, 50g.ha-1, 100g.ha-1 e 200g.ha-1), tr?s n?veis de pH (4,0; 5,0 e 6,0) e duas ?pocas de coleta (49 e 78 dias). Nos experimentos de sele??o de estirpes, as plantas inoculadas com as estirpes CIAT, apresentaram uma boa resposta ? nodula??o principalmente em rela??o ? cultivar Belmonte, e com a mesma efetividade que as estirpes nativas. Na cultivar Belmonte foi observado efeito delet?rio do nitrog?nio no n?mero de n?dulos por planta. Os resultados obtidos nos experimentos com Al, em solu??o nutritiva simples mostraram uma redu??o no crescimento, redu??o na massa seca da raiz e uma redu??o avaliada em 27% pelo comprimento radicular relativo entre as concentra??es de 16μM e o controle. Ocorreram nestes experimentos respostas ?s concentra??es de alum?nio, com aparecimento de mucilagem e escurecimento da raiz prim?ria. Nos estudos envolvendo solu??o nutritiva completa, as pl?ntulas da cultivar Amarillo e do acesso BRA-031534 propagadas por sementes tiveram redu??o no crescimento da raiz prim?ria e no comprimento relativo da raiz em rela??o ? testemunha. Nas concentra??es de 320μM e 160μM, observou-se uma redu??o de 51% e 49% respectivamente, na cultivar Amarillo e no acesso BRA-031534. Tamb?m foi observado na cultivar Amarillo, ra?zes com as extremidades escurecidas nas concentra??es de 160μM e 320μM e aumento no n?mero de ra?zes secund?rias a partir da concentra??o de 80μM. O corante violeta de pirocatecol parece promissor em permitir uma visualiza??o dos efeitos do alum?nio para a cultivar Amarillo e acesso BRA-031534. O alum?nio influenciou as cultivares e acesso testados com a cultivar Belmonte formando um maior n?mero de ra?zes advent?cias que a cv Amarillo e o acesso BRA-031534. A partir da concentra??o de 80μM, ocorreu uma redu??o no comprimento das ra?zes advent?cias das cultivares e acesso testados. A aplica??o de molibd?nio foi eficiente na segunda colheita no pH 6,0 sendo obtido um maior n?mero de n?dulos na concentra??o de 200g.ha-1. O pH interferiu na nodula??o.

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Kuntz, Veronica L. "The relationship between Sarracenia oreophila and an endophytic Burkholderia." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41094.

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Plant growth-promoting bacteria (PGPB) have been studied in many agriculturally interesting plants, but never in pitcher plants. Sarracenia oreophila (the green pitcher plant) is an endangered species in Georgia, Alabama, and North Carolina (Rice 2010). With the help of Dr. Jim Spain's lab, a previous student in Dr. Gerald Pullman's lab discovered evidence that nitrogen-fixing bacteria (Burkholderia spp.) live within these pitcher plants. This study aims to determine whether these nitrogen-fixing bacteria confer a benefit to their host plants by providing fixed nitrogen. To do this, pitcher plants were inoculated with the Burkholderia and grown on a control medium, a medium without sugar (as the sugar causes the bacteria to grow until they hinder the plants), various media that are missing nitrogen-containing compounds usually provided in growth media, and a medium completely lacking nitrogen. These plants were compared to control plants on the same media that had not been inoculated with Burkholderia. The plants' biomass and root growth were measured. The data suggest that Burkholderia may stimulate plant biomass growth when sufficient nitrogen is present and there may be a nitrogen-threshold that needs to be met in order to sustain the Burkholderia-Sarracenia symbiosis. Also, the Burkholderia has a negative effect on roots grown in high-nitrogen media, possibly due to competition for nutrients.

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37

SILVA, Emmanuella Vila Nova da. "Interrelação bactérias (MHB) e FMA : estratégia para estimular a eficiência simbiótica e micorrização de sabiá." Universidade Federal Rural de Pernambuco, 2012. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/4948.

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Submitted by (lucia.rodrigues@ufrpe.br) on 2016-07-05T12:16:24Z No. of bitstreams: 1 Emmanuella Vila Nova da Silva.pdf: 1939037 bytes, checksum: f521d3bf721007766ec42ccf2f7454a6 (MD5) Made available in DSpace on 2016-07-05T12:16:24Z (GMT). No. of bitstreams: 1 Emmanuella Vila Nova da Silva.pdf: 1939037 bytes, checksum: f521d3bf721007766ec42ccf2f7454a6 (MD5) Previous issue date: 2012-03-07 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES The use of plants symbiotically associated with N2 fixing bacteria and mycorrhizal fungi (AMF) provides an efficient strategy to accelerate the recovery of impacted areas and reduces its costs considerably. The term "mycorrhiza helper bacteria” (MHB) has been introduced and discussed due to the synergistic effect that this dual combination promotes to plants. They are bacteria associated with roots and AMF that selectively promote the establishment of symbiosis with fungi. Thus, the objectives were to verify the AMF activity in the area with native vegetation in the Pernambucano semiarid, municipality of Sertânia; determine glomerospores number and the most probable number (MPN) of infective propagules; quantify the content of glomalin-related protein in the soil and determine the feasibility of bacteria (MHB) co-inoculation and AMF mixture in “sabiá” (Mimosa caesalpiniifolia Benth) aiming at obtaining combinations and compatibility of symbiotic pairs, as well as to evaluate the mycorrhizal efficiency and colonization. The experiments were conducted in greenhouse of the Agronomic Institute of Pernambuco (IPA). 10 composite soil samples were collected with points were defined at random. Samples were homogenized and analyzed for physical and chemical characteristics. Composite samples were used for direct count (DC) and propagation of AMF for indirect count (IC) of spores, using trap- cultures and sorghum (Sorghum bicolor L. Moench) and peanut (Arachis hypogea L.) as host plants (experiment I). To determine the MPN of infective propagules of AMF in the Haplic Luvisol was used a system of serial dilution: 0, 1:10, 1:100 and 1:1000 with five replicates each, with maize (Zea mays L.) as host plant (experiment II). In the experiment III were used pots with Haplic Luvisol soil (8 kg pot-1) at pH 6.0 and the plant used was the “sabiá”. On seeding, inoculation with Burkholderia sabiae (BR 3405) and co-inoculation with BR3405 + MHB were performed and each seed was inoculated with 2 mL of specific medium for each of MHB bacteria and for the BR3405 containing 108 CFU mL-1. In the inoculation with AMF mixture was used 4 g pot-1 in the form of propagule containing approximately 670 spores. Plants were harvested at 110 days after planting (DAP) and the following variables were evaluated: shoot dry mass (SDM), root (RDM), RDM/SDM ratio, plant height (PH) on periods of 45, 90 and 110 days, root length (RL), total N accumulated in SDM (Nat), strains efficiency (E) and mycorrhizal colonization. The experimental design was randomized blocks, with 9 x 2 factorial arrangement plus an absolute control (AC) - without inoculation; MHB strains and one control treatment inoculated only with Burkholderia sabiae with and without AMF (AMF mixture) with 3 blocks . The experimental results show that the MPN of AMF infective propagules found in the city of Sertânia was 23 propagules cm-3. Soil proteins related to easily extractable glomalin (PSRGFE) and soil proteins related to total glomalin (PSRGT) were approximately 0.46 and 0.26 mg g soil-1, respectively. The AMF colonization combined with the bacteria was positive, as in the case of RL, treatments with BR 3405 + Azospirillum amazonenses (Y2) and BR 3405 + Herbaspirillum seropedicae (Z67) showed significant difference by the Tukey test (p <0.05) compared to the factor with and without AMF. Thereby ensuring that, in the presence of MHB bacteria there was increase in root length of “sabiá” plants. Strains efficiency showed better results when bacteria were in the presence of AMF and the treatment BR 3405 + Paenibacillus brasilensis (24) + AMF showed the best response. The treatments that received AMF were higher compared to the others on the variables SDM, RDM, E, Nac, coming to present on average 84% of root colonization. A utilização de plantas associadas simbioticamente, com bactérias fixadoras de N2 e fungos micorrízicos arbusculares (FMA), constitui uma estratégia eficiente para acelerar a recuperação de áreas impactadas além de reduzir consideravelmente os custos com a mesma. O conceito de “mycorrhiza helper bacteria (MHB)” tem sido introduzido e discutido devido ao efeito sinergístico que essa dupla associação promove às plantas. São bactérias associadas com raízes e FMA que, seletivamente, promovem o estabelecimento da simbiose com os fungos. Deste modo, os objetivos deste trabalho foram verificar a atividade de FMA em área com vegetação nativa do semiárido Pernambucano, no município de Sertânia; determinar o número de glomerosporos e o número mais provável (NMP) de propágulos infectivos; quantificar o teor de proteínas do solo relacionadas à glomalina; determinar a viabilidade da co-inoculação entre bactérias (MHB) e mistura de FMA em sabiá (Mimosa caesalpiniifolia Benth) visando obter combinações e compatibilidade de pares simbióticos, assim como avaliar a eficiência e colonização micorrízica. Os experimentos foram conduzidos em casa de vegetação na Sede do Instituto Agronômico de Pernambuco (IPA). Foram coletadas 10 amostras compostas de solo, sendo os pontos definidos aleatoriamente. As amostras foram homogeneizadas e analisadas quanto às características físicas e químicas. Amostras compostas foram utilizadas para contagem direta (CD) e multiplicação de FMA para contagem indireta (CI) de esporos, com o uso de culturas-armadilha, empregando sorgo granífero (Sorghum bicolor L. Moench) e amendoim (Arachis hypogea L.) como plantas hospedeiras (experimento I). Para a determinação do NMP de propágulos infectivos de FMA no Luvissolo Háplico foi utilizado um sistema de diluição em série: 0, 1:10, 1:100 e 1:1000, com 5 repetições cada e, tendo o milho (Zea mays L.) como planta hospedeira (experimento II). No experimento III foram utilizados vasos com o solo Luvissolo Háplico (8 kg vaso-1) com pH 6,0 e a planta utilizada foi a sabiá. Na semeadura, foi efetuada inoculação com Burkholderia sabiae (BR 3405) e co-inoculação com BR3405 + MHB contendo 108 UFC mL-1. Na inoculação com a mistura do FMA, foram utilizados 4 g vaso-1 em forma de propágulo, contendo aproximadamente 670 esporos. A colheita foi realizada 110 dias após plantio (DAP) e foram avaliadas as seguintes variáveis: massa seca da parte aérea (MSPA), raiz (MSR), relação MSR/MSPA, altura de planta (AP) nos períodos de 45, 90 e 110 dias, comprimento da raiz (CR), N total acumulado na MSPA (Nac), eficiência das estirpes (E%) e colonização micorrízica. O delineamento experimental adotado foi em blocos casualizados, com arranjo fatorial 9 x 2 mais uma testemunha absoluta (TA) – sem inoculação; estirpes de MHB e um tratamento controle inoculado apenas com Burkholderia sabiae com e sem FMA (mistura de FMA) com 3 blocos. Os resultados dos experimentos mostram que o NMP de propágulos infectivos de FMA encontrados no município de Sertânia foi de 23 propágulos cm-3. As proteínas do solo relacionadas à glomalina facilmente extraível (PSRGFE) e as proteínas do solo relacionadas à glomalina total (PSRGT) ficaram em torno de 0,46 e 0,26 mg g solo-1, respectivamente. A colonização dos FMA em conjunto com as bactérias foi positiva, como no caso do CR, os tratamentos com BR 3405 + Azospirillum amazonenses (Y2) e BR 3405 + Herbaspirillum seropedicae (Z67) apresentaram diferença significativa pelo teste de Tukey (p<0,05) em relação ao fator com e sem FMA. Confirmando deste modo que, na presença das bactérias MHB houve aumento no comprimento do sistema radicular das plantas de sabiá. A eficiência das estirpes obteve os melhores resultados quando as bactérias estavam em presença de FMA e o tratamento BR 3405 + Paenibacillus brasilensis (24) + FMA foi o que obteve melhor resposta. Os tratamentos que receberam os FMA foram superiores em relação aos demais nas variáveis MSPA, MSR, E, Nac, chegando a apresentar uma média em torno de 84% de colonização radicular.

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Pandharikar, Gaurav. "Symbiose fixatrice d'azote versus nutrition minérale azotée : conséquence sur l'interaction entre Medicago truncatula et le puceron du pois Acyrthosiphon pisum." Electronic Thesis or Diss., Université Côte d'Azur, 2020. http://theses.univ-cotedazur.fr/2020COAZ6005.

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Les symbiotes jouent un rôle crucial dans le phénotype de leur hôte et dans son adaptation à l'environnement. Cependant, jusqu'à récemment, les interactions plantes-insectes étaient étudiées sans tenir compte de la présence de bactéries symbiotiques chez les partenaires impliqués. De nouvelles découvertes ont démontré que les communautés racinaires et aériennes des plantes sont liées. Dans ce contexte, mon doctorat s'interroge sur la façon dont les interactions entre les espèces végétales et les insectes sont modulées par leurs symbiotes respectifs. Dans un premier temps, j'ai analysé le rôle de la symbiose fixatrice d'azote (NFS) chez la légumineuse Medicago truncatula (A17) dans l’interaction avec des lignées de pucerons du pois Acyrthosiphon pisum portant différents endosymbionts facultatifs (FS). Pour ce faire, j'ai comparé la croissance de plantes de M. truncatula inoculées avec la bactérie nodulante Sinorhizobium meliloti (NFS) ou arrosées avec une solution de nitrate (non inoculées ; NI) infestées par des lignées de pucerons du pois provenant d’un même clone génétique (YR2) soit sans FS ou avec Hamiltonella defensa, Serratia symbiotica ou Regiella insecticola. La croissance des plantes NSF et NI est réduite par l'attaque des pucerons, tandis que la croissance des pucerons (mais pas leur survie) a été fortement réduite sur les plants NFS. En présence de pucerons la capacité de fixation d'azote des plantes NFS est réduite suite à l’induction d’une sénescence précoce des nodules. Enfin, chez les plantes NFS, toutes les lignées de pucerons ont déclenché l'expression du gène Pathogenesis-Related-1 (PR1), un marqueur de la voie salicylique (SA), et du gène Proteinase inhibitor (PI), un marqueur de la voie jasmonique (JA), tandis que chez les plantes NI, seule l'expression de PR1 a été déclenchée. Ainsi, le statut symbiotique de la plante influence clairement les interactions plante-puceron et la réponse de la plante à l’infestation, alors que le statut symbiotique du puceron ne fait que moduler l'amplitude de cette réponse. Il a été démontré que le génotype de la plante et du puceron sont tous deux importants dans le résultat de leur interaction, j'ai donc étudié plus en détail comment la NFS affecte l'interaction entre différents génotypes de plantes et de pucerons. Pour cela, j'ai utilisé trois génotypes différents d’A. pisum dépourvus de FS (LL01, YR2, T3-8V1) et deux génotypes de M. truncatula (A17 et R108) en présence ou en absence S. meliloti. La performance de chaque génotype de puceron sur les deux génotypes de plantes et l'effet des différents génotypes de pucerons sur la croissance des plantes et la capacité de fixation de l'azote des plantes de SNF ont été mesurés. Nous avons également estimé la réponse de défense médiée par le génotype de M. truncatula déclenchée par les différents génotypes de pucerons en utilisant différents gènes marqueurs des voies de défense JA et SA. J'ai constaté que les génotypes plantes-insectes ainsi que la présence de S. meliloti affectent de manière significative les interactions plantes-aphides. Ainsi, les interactions génétiques interspécifiques entre la plante hôte et les pucerons ainsi que leur statut symbiotique peuvent influencer la dynamique de la population et la structure de la communauté. Ces résultats montrent que l'interaction plante-insecte est fortement influencée par la génétique des espèces et par leur statut symbiotique, ajoutant un nouveau niveau de complexité qui reste à explorer Symbionts play a crucial role in shaping their host phenotype and driving its adaptation to the environment. However, until recently plant-insect interactions were studied disregarding the symbiotic bacterial presence in the involved partners. New findings have now demonstrated that above- and belowground plant communities are linked through biotic interactions. In this context, my PhD questions how the interaction between plant-insect species are modulated by their respective symbionts. In the first part of my work I have analysed the effect of the nitrogen fixing symbiosis (NFS) in the leguminous Medicago truncatula (A17) in interaction with pea aphid Acyrthosiphon pisum lines bearing different facultative endosymbionts (FS). For this, first I have compared the growth of M. truncatula plants either inoculated with the nodules inducing bacteria Sinorhizobium meliloti (NFS) or supplemented with nitrate (non-inoculated; NI), infested with pea aphid lines derived from the same genetic clone (YR2) and bearing either no FS or Hamiltonella defensa, Serratia symbiotica or Regiella insecticola. As expected, growth of both NFS and NI plants was reduced by the aphid attack, while aphid growth (but not survival) was strongly reduced on NFS compared to NI plants. Interestingly, most aphid lines decreased the plant nitrogen fixation capacity of NFS plants by inducing an early nodule senescence. Finally, in NFS plants all aphid lines triggered the expression of Pathogenesis Related Protein 1 (PR1), a marker of the salicylic (SA) pathway, and of Proteinase Inhibitor (PI), a marker of the jasmonic (JA) pathway, while in NI plants only PR1 expression was triggered. Thus, the plant symbiotic status influences clearly the plant–aphid interactions and the plant response while the aphid symbiotic status only modulates the response amplitude. Since both plant and aphid genotypes are important in the outcome of their interaction, I further studied how plant symbiosis affect the plant-insect genotype x genotype interaction. For this, I used three different pea aphid genotypes devoid of FS (LL01, YR2, and T3-8V1) and two M. truncatula genotype (A17 and R108) combinations in the presence or absence of rhizobacteria. The performance of each aphid genotype on both plant genotypes and the effect of different aphid genotypes on the plant growth and nitrogen fixation capacity of NFS plants were measured. We also estimated M. truncatula genotype-mediated defence response triggered by the different aphid genotypes using multiple gene markers of the JA and SA defence-pathways. I found that the plant-insect genotypes as well as the rhizobacteria presence significantly affect plant-aphid interactions. These results show that the outcome of the plant-insect interaction is strongly impacted by the genotype of the species and by their symbiotic status, rising a new level of complexity that remains to be explored

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Aït-Salem, Elhosseyn. "Etude de la signalisation contrôlant l’accommodation intracellulaire au cours de la symbiose Medicago/Sinorhizobium The Multiple Faces of the Medicago-Sinorhizobium Symbiosis Control of the ethylene signaling pathway prevents plant defenses during intracellular accommodation of the rhizobia." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS096.

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Les légumineuses en milieu carencé en azote, établissent une relation symbiotique avec les bactéries du sol appelées rhizobia. Cette interaction conduit à la formation d’un nouvel organe racinaire, la nodosité. Au sein de celle-ci, les rhizobia se différencient en bactéroïdes fixant l’azote atmosphérique au profit de la plante. La colonisation massive et chronique des cellules symbiotiques de nodosités par les rhizobia ne déclenche aucune réaction de défense visible. Au laboratoire nous avons isolé deux mutants symbiotiques développant des réactions de défense dans les nodosités de Medicago truncatula indiquant qu’il existe un contrôle strict de l’immunité dans cet organe. L’objectif de cette thèse est de comprendre comment l’immunité symbiotique contrôle les voies de signalisation hormonales de défense afin d’héberger le partenaire symbiotique et de trouver de nouveaux outils pour mieux comprendre les mécanismes de défense. Pour cela, des approches moléculaires, pharmacologiques et génétiques sont utilisées. Les résultats obtenus dans cette thèse suggèrent que les mécanismes de défense adoptés par M. truncatula varient en fonction de l’écotype de la plante. L’écotype A17 exploite deux voies de résistance : la voie de la sénescence et la voie des réactions de défense. Cependant, l’écotype R108 n’exploite que la voie des réactions de défense. Ce travail suggère également que chez M. truncatula A17, la protéine SymCRK réprime la voie de signalisation de l’acide jasmonique qui conduit au déclenchement de la sénescence, tandis que la protéine DNF2 réprime principalement la voie de signalisation de l’acide salicylique qui conduit au déclenchement des réactions de défense et aussi réprime secondairement la voie acide jasmonique. Chez M. truncatula R108, les deux protéines SymCRK et DNF2 contrôlent les voies de signalisation de l’acide salicylique et de l’éthylène, avec DNF2 contrôlant préférentiellement la voie acide salicylique et SymCRK contrôlant préférentiellement la voie éthylène. Cette thèse suggère aussi l’implication des protéines R dans le contrôle de l’accommodation intracellulaire des rhizobia. Un gène CNL-5 semble être impliqué dans le contrôle de l’infection des cellules symbiotiques, et deux autres gènes CNL-4 et TNL-2 semblent être impliqués dans le contrôle de l’efficacité de l’infection. Finalement, cette thèse a permis d’isoler une souche bactérienne E. adhaerens, capable se comporter comme un symbiote ou comme un pathogène pour plusieurs espèces de Medicago When grown under limited nitrogen resources, legumes establish a symbiotic relationship with soil bacteria called rhizobia. This interaction leads to the formation of a new root organ, the nodules. Within nodules, rhizobia differentiate into bacteroids and fix atmospheric nitrogen for the plant. The massive and chronic colonization of nodule symbiotic cells by the rhizobia does not trigger any visible defense reactions. In the laboratory, we previously isolated two symbiotic mutants developing defense reactions in Medicago truncatula nodules, indicating a strict control of the nodule immunity. The thesis project aimed first to understand the relationship between symbiotic genes and immunity mediated by defense hormones and second to find new tools to help to better understand nodules defense mechanisms. For this, molecular, pharmacological and genetic approaches were used. The results obtained in this thesis suggest that the defense mechanisms adopted by M. truncatula vary depending on the plant ecotypes. The A17 ecotype uses two resistance pathways; senescence and defense reactions. While, the R108 ecotype uses defense reactions pathway to fight against rhizobia. This work also suggests that in M. truncatula A17, the SymCRK protein represses jasmonic acid signalling. This work also suggests that in M. truncatula A17, the SymCRK protein represses the jasmonic acid signaling pathway involved in senescence triggering. In contrast, the DNF2 protein mainly represses the salicylic acid signaling pathway involved in defense reactions and also represses the JA pathway. In M. truncatula R108, the two proteins SymCRK and DNF2 control salicylic acid and ethylene signaling pathways involved in triggering defense reactions. DNF2 controls the salicylic acid pathway more than the ethylene signaling pathway, while, SymCRK controls more the ethylene pathway than the salicylic acid signaling pathway in nodules. This thesis also suggests the involvement of R proteins in the control of intracellular accommodation of rhizobia. The intracellular receptor CNL-5 appears to be involved in controlling the infection of symbiotic cells and the receptors CNL-4 and TNL-2 genes appear to be involved in controlling the infection efficacy of the symbiotic cells. Finally, this thesis allowed the identification of a new bacterial strain E. adhaerens, capable of behaving as a symbiont or as a pathogen for several Medicago species. This can be used as a tool to study the nodules defense induction and to understand the rhizobia intracellular accommodation in symbiotic cells

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Soares, Pablo Guenther. "Efeito da inoculação com rizóbio no estabelecimento, crescimento inicial e abundância natural de 15N em leguminosas (Fabaceae) arbóreas nativas plantadas por semeadura direta." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-09052007-151411/.

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O presente estudo teve como objetivo avaliar o efeito da inoculação com rizóbio no estabelecimento, crescimento inicial e em alguns aspectos da dinâmica de N em folhas de leguminosas (Fabaceae) arbóreas nativas plantadas por semeadura direta no campo, em área de mata ciliar no Estado de São Paulo. Foi avaliada a emergência de plântulas (% em relação ao número de sementes plantadas) até os 3 meses após a semeadura (MAS) e o crescimento em altura aos 13 MAS. O fracionamento isotópico do N foliar também foi avaliado, pelo método da abundância natural do 15N, além da concentração de N e a razão C/N foliar. Acacia polyphylla foi usada como planta-referência não-fixadora de N2. Em relação ao desenvolvimento inicial, houve grande variação entre as espécies estudadas. Acacia polyphylla e Enterolobium contortisiliquum apresentaram taxa de germinação mediana e rápido crescimento. Mimosa bimucronata e Parapiptadenia rigida tiveram crescimento relativamente rápido, porém baixo potencial germinativo. Erythrina speciosa e Poecilanthe parviflora, com crescimento lento, apresentaram germinação elevada no campo. As espécies fixadoras de N2 mostraram δ15 N médio de 2,7‰, enquanto que a referência Acacia polyphylla se mostrou cerca de 4,0‰ mais enriquecida em 15N . Erythrina speciosa e Ormosia arborea apresentaram os menores valores de δ15N, enquanto que Parapiptadenia rigida, enriquecida em 15N, mostrou estar obtendo N exclusivamente do solo. Poecilanthe parviflora, Mimosa bimucronata e Enterolobium contortisiliquum apresentaram valores intermediários de δ15N, com grande variação entre os indivíduos amostrados. A concentração de N nos tecidos foliares variou entre 1,5% e 3,6%. De forma geral, esta variável não mostrou relação direta com o δ15N das plantas. A menor razão C/N foi observada em Enterolobium contortisiliquum e Erythrina speciosa, seguida por M. bimucronata. Nas condições experimentais locais, as plantas não responderam à inoculação com rizóbio em nenhum dos parâmetros avaliados (estabelecimento, crescimento inicial, δ15N, concentração de N e razão C/N). As espécies de crescimento mais lento e com alta incidência de herbivoria observados no campo (E. speciosa e O. arborea) foram também as que apresentaram δ15N na faixa considerada como de ocorrência da fixação biológica de nitrogênio. Os resultados indicam, para as outras espécies, maior aquisição de N proveniente do solo. The aim of this work was to assess the effect of rhizobia inoculation on the establishment, early growth and some aspects of N dynamics in direct-seeded native legume (Fabaceae) trees in a riparian zone of São Paulo State, Southeastern Brazil. Seedling emergency (% of total planted seeds) was evaluated until three months after sowing (MAS), and the height of the trees were measured at 13 MAS. Isotopic N fractionation was also assessed by the 15N natural abundance method, as well as foliar N content and C/N ratio. Acacia polyphylla was used as a non-N2-fixing reference plant. Acacia polyphylla and Enterolobium contortisiliquum grew most rapidly, with moderate germination rate. Mimosa bimucronata and Parapiptadenia rigida were fast-growing but with low establishment rate. Erythrina speciosa and Poecilanthe parviflora showed low growing rate, but high germination potential. The N2-fixers showed an average foliar δ15N of 2,7‰, while the reference-plant was 4,0‰ more <sup15>N enriched. Erythrina speciosa and Ormosia arborea showed the lowest δ15N values. The high δ15N of Parapiptadenia rigida probably indicated that it is obtaining N exclusively from the soil. Poecilanthe parviflora, Mimosa bimucronata and Enterolobium contortisiliquum showed intermediate δ15N values, with strong variations among the sampled individuals. Foliar N concentrations varied from 1,5% to 3,6%. In general, N concentrations were not correlated with foliar δ15N . The lowest C/N ratio was observed on E. contortisiliquum and E. speciosa , followed by M. bimucronata. In this field trial conditions, rhizobia inoculation did not show differences in all surveyed parameters (establishment, early growth, foliar δ15N, total N content and C/N ratio of trees). The slow-growing species, E. speciosa and O. arborea , that also had a high herbivore attack observed in the field, showed foliar δ15N in the biological N2 fixation range. The results suggested, for the other species, a larger soil N acquisition.

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Magne, Kévin. "The roles of the NOOT-BOP-COCH-LIKE genes in the symbiotic organ identity and in plant development." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS482/document.

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L’association symbiotique entre les légumineuses et les rhizobia aboutit à la formation de la nodosité fixatrice d’azote. Cet organe symbiotique généré de-novo permet l’hébergement intracellulaire des rhizobia qui, grâce à leurs activités nitrogénase,réduisent l’azote atmosphérique en ammonium, une forme de l’azote directement assimilable par la plante hôte.Les mécanismes moléculaires sous-jacents à la reconnaissance entre les deux partenaires symbiotiques, au processus d’infection et à l’organogénèse de la nodosité sont bien décrits, cependantl’établissement et la maintenance de l’identité de cet unique organe souterrain restent incompris.Les gènes NODULE-ROOT de Medicago truncatula, BLADEON-PETIOLE d’Arabidopsis thaliana et COCHLEATA de Pisumsativum sont membres du clade spécifique très conservé NOOTBOP-COCH-LIKE1 (NBCL1) qui fait partie de la famille des gènesNON-EXPRESSOR OF PATHOGENESIS RELATED PROTEIN1-LIKE. Chez les légumineuses, les membres de ce clade NBCL1 sont connus comme étant des régulateurs clés de l’identité de l’organe symbiotique.Mon travail de thèse a eu pour but d’améliorer la compréhension des rôles des gènes NBCL1, à la fois chez des espèces formant des nodosités indéterminées et déterminées, ainsi que de découvrir de nouveaux acteurs moléculaires impliqués dans l’identité de la nodosité dont la régulation est dépendante des gènesNBCL1, essentiellement par l’utilisation de mutants TILLING, Tnt1et LORE1 originaux chez trois espèces de légumineuses: la luzerne tronquée, le petit pois et le lotier.Ce travail rapporte essentiellement l’identification et la caractérisation de nouveaux mutants affectés dans des gènes qui font partie d’un second sous-clade NBCL2 spécifique des légumineuses.Nous avons révélé que les membres de ce sous-clade spécifique des légumineuses NBCL2 jouent d’importants rôles dans le développement de la nodosité, dans l’établissement et la maintenance de l’identité de la nodosité et par conséquence dans le succès et l’efficacité de l’association symbiotique.Ce travail suggère aussi qu’au cours de l’évolution, le programme de développement de la nodosité a recruté des mécanismes de régulations préexistants afin de réguler le développement de la nodosité et son identité, tel que le module de régulation impliquant des interactions entre des protéines NBCL et des facteurs de transcriptions basic leucine zipper de type TGACG. Nous avons identifié le facteur de transcription MtPERIANTHIA-LIKE, comme un premier partenaire protéique interagissant avec des protéines NBLC dans un contexte de nodosité symbiotique. Les gènes NBCL sont aussi impliqués dans les réseaux de régulations qui contrôlent le développement et le déterminisme de nombreux organes végétatifs et reproductifs aériens et sont également impliqués dans la capacité d’abscission de ces organes.Finalement, ce travail thèse a eu pour objectif d’explorer les rôles de ces gènes NBCL très conservés, dans le développement de la graminée non-domestiquée, Brachypodium distachyon The symbiotic interaction between legumes andrhizobia results in the formation of a symbiotic nitrogen fixingnodule.This de-novo generated symbiotic organ allows the intracellularaccommodation of the rhizobia which reduces through theirnitrogenase activity the atmospheric nitrogen in ammonium, anitrogen form usable by the host plant.The molecular mechanisms underlying the symbiotic partnersrecognition, the infection process and the nodule organogenesis arewell described, however the identity establishment and maintenanceof this unique underground organ remain mis-understood.The Medicago truncatula NODULE-ROOT, the Arabidopsisthaliana BLADE-ON-PETIOLE and the Pisum sativumCOCHLEATA genes are members of a highly conserved NOOTBOP-COCH-LIKE1 (NBCL1) specific clade that belongs to theNON-EXPRESSOR OF PATHOGENESIS RELATED PROTEIN1-LIKE gene family. In legumes, the members of this NBCL1 cladeare known as key regulators of the symbiotic nodule identity.The present thesis work aims to better understand the roles of theNBCL1 genes, in both indeterminate and determinate nodule formingspecies and to discover new molecular actors involved in theNBCL1-dependent regulation of the nodule identity essentially usingnovel TILLING, Tnt1 and LORE1 insertional mutants in three legumespecies, Medicago, Pisum and Lotus.This thesis work has allowed the identification and thecharacterization of new mutants for genes belonging to a secondarylegume-specific NBCL2 sub-clade. We revealed that the members ofthis legume-specific NBCL2 sub-clade play important roles in noduledevelopment, identity establishment and maintenance, andconsequently in the success and in the efficiency of the symbioticassociation.This thesis work also shows that during evolution, the noduledevelopmental program has recruited pre-existing regulatorymechanisms for the nodule development and identity, such as theregulatory module involving interactions between NBCL proteins andTGACG type basic leucine zipper transcription factors. We identifiedthe transcription factor, MtPERIANTHIA-LIKE, as a first interactingpartner of NBCL proteins in a context of root nodule symbiosis.NBCL genes are also involved in the regulatory networks thatcontrol the development and the determinacy of many abovegroundvegetative and reproductive organs and were also shown as involvedin their abscission ability.In this thesis we also explored the roles of these highly conservedNBCL genes in the development of the non-domesticated grass,Brachypodium distachyon

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Nagymihály, Marianna. "Ploidy-dependent changes in the epigenome of symbiotic cells correlate with specific patterns of gene expression." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS399/document.

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Les légumineuses peuvent interagir avec les bactéries du sol de la famille des Rhizobiaceae. Cette interaction aboutit à la formation d'un organe spécialisé appelé nodosité. Au sein des cellules symbiotiques des nodosités, les rhizobia sont capables de fixer l'azote atmosphérique et de la convertir en ammoniac, qui est une source d'azote assimilable par les plantes. Chez la Légumineuse Medicago truncatula, les cellules symbiotiques produisent une large famille de peptides riches en cystéines appelées (NCRs) spécifiquement exprimés dans les nodosités. Ces NCRs induisent la différenciation des bactéroïdes qui se traduit par un allongement cellulaire couplé à une forte endoréplication du génome (les bactéroïdes deviennent polyploïdes) contribuant ainsi à une augmentation importante de la taille des cellules, ainsi qu’une perméabilité membranaire accrue et une perte de toute capacité reproductrice. Les peptides NCRs ressemblent à des défensines, des peptides antimicrobiens, acteurs clés de l’immunité innée. L'analyse de l'expression de 334 gènes NCR dans 267 différentes conditions expérimentales en utilisant la base de données MtGEA (Medicago truncatula Gene Expression Atlas) a révélé que l'ensemble des gènes NCR testés (sauf quatre) n'est exprimé que dans les nodosités, ils ne sont pas exprimés dans d’autres organes de la plante, ni lors d’une infection par des agents pathogènes. De plus l’expression des NCRs n’est induite en réponse à aucune interaction biotique ou abiotique testée ou à des facteurs Nod. Les gènes NCR sont activés en vagues successives au cours de l’organogenèse nodulaire et ce profil temporel est en corrélation avec une localisation spatiale spécifique de leurs transcrit de la zone apicale à la partie proximale de nodosités. En outre, nous avons montré que les NCRs ne sont pas induites pendant la sénescence des nodules. Ces analyses expérimentales ensemble avec des calculs d’entropie de Shannon, une métric pour la spécificité d’expression, montrent que les gènes NCR sont parmi les gènes les plus fortement et le plus spécifiquement exprimés chez M. truncatula. Ainsi, l'expression des NCRs est soumise à une régulation extrêmement stricte et ils sont activés exclusivement pendant l’organogenèse et au cours du développement nodulaire dans les cellules symbiotiques polyploïdes. Cette analyse a suggéré l'implication de la régulation épigénétique des gènes NCR. La formation des cellules symbiotiques s'exerce par une endoreplication et est associée à une reprogrammation transcriptionnelle. En utilisant le tri par cytométrie en flux des noyaux, en fonction de leur contenu en ADN, nous avons montré que les vagues transcriptionnelles sont en correlation avec les niveaux croissants de ploïdie et resultent des modifications épigénétiques durant les cycles d’endoréplication. Nous avons étudié la méthylation de l'ADN génomique et l'accessibilité à la chromatine, ainsi que la présence des marqueurs répresseurs (H3K27me3) ou activateurs transcriptionnels (H3K9ac) sur des gènes spécifiques des nodosités. La méthylation différentielle de l'ADN n'a été trouvée que dans un petit sous-ensemble de gènes symbiotiques spécifiques aux nodosités. Néanmoins, plus que la moitié des gènes NCR était différentiellement méthyles. D'autre part, l'expression des gènes était corrélée avec la décondensation de la chromatine (ouverture), un enrichissement du marqueur H3K9ac et une diminution du marqueur H3K27me3. Nos résultats suggèrent que l’endoréplication, pendant la différenciation cellulaire dans les nodosités, fasse partie des mécanismes qui lèvent l’inactivation transcriptionnelle des gènes spécifiques des nodosités, ceci résultant de modifications des codes épigénétiques au niveau de la chromatine Legume plants are able to interact with soil bacteria from the Rhizobiaceae family. This interaction leads to the development of a specialized organ called root nodule. Inside the symbiotic nodule cells, rhizobia are capable to fix atmospheric nitrogen and convert it to ammonia, which is a usable nitrogen source for the plant. In the legume Medicago truncatula the symbiotic cells produce high amounts of Nodule-Specific Cysteine-Rich (NCR) peptides which induce differentiation of the rhizobia into enlarged, polyploid and non-cultivable bacterial cells. NCRs are similar to innate immunity antimicrobial peptides. The NCR gene family is extremely large in Medicago with about 600 genes. The expression analysis of 334 NCR genes in 267 different experimental conditions using the Medicago truncatula Gene Expression Atlas (MtGEA) revealed that all the NCR genes except five are exclusively expressed in nodules. No NCR expression is induced in any other plant organ or in response to biotic, abiotic stress tested or to Nod factors. The NCR genes are activated in consecutive waves during nodule organogenesis, which correlated with a specific spatial localization of their transcripts from the apical to the proximal nodule zones. Moreover, we showed that NCRs are not induced during nodule senescence. According to their Shannon entropy, a metric for tissue specificity, NCR genes are among the most specifically and highest expressed genes in M. truncatula. Thus, NCR gene expression is subject to an extreme tight regulation since they are only activated during nodule organogenesis in the polyploid symbiotic cells. This analysis suggested the involvement of epigenetic regulation of the NCR genes. The formation of the symbiotic cells is driven by endoreduplication and is associated with transcriptional reprogramming. Using sorted nodule nuclei according to their DNA content, we demonstrated that the transcriptional waves correlate with growing ploidy levels and investigated how the epigenome changes during endoreduplication cycles. We studied genome-wide DNA methylation and chromatin accessibility as well as the presence of repressive H3K27me3 and activating H3K9ac histone tail modifications on selected genes. Differential DNA methylation was found only in a small subset of symbiotic nodule-specific genes, including over half of the NCR genes, while in most genes DNA methylation was unaffected by the ploidy levels and was independent of the genes’ active or repressed state. On the other hand, expression of these genes correlated with ploidy-dependent opening of the chromatin and in a subset of tested genes with reduced H3K27me3 levels combined with enhanced H3K9ac levels. Our results suggest that endoreduplication-dependent epigenetic changes contribute to transcriptional reprogramming in differentiation of symbiotic cells

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Lajudie, Philippe de. "Contribution a l'etude de deux symbioses fixatrices d'azote : medicago sativa, legumineuse temperee, sesbania rostrata, legumineuse tropical." Paris 11, 1988. http://www.theses.fr/1988PA112066.

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Dans une premiere partie, on etudie les partenaires bacteriens : recherche de plasmides, essais de mutagenese par insertion de transposon, isolement et caracterisation de bacteriophages specifiques des souches isolees de s. Rostrata. Rhizobium meliloti, en association avec m. Sativa, possede des plasmides de type prme (130 a 300 kb) et des megaplasmides (1500 kb) qui portent les genes symboliques. Dans une deuxieme partie, on etudie le partenaire vegetal : proteines solubles des nodules et des tissus non infectes analysees par electrophorese sur gel et par western blotting, puis au niveau transcriptionnel, expression des genes de la plante par isolement des arn poly a et traduction in vitro

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Debelle, Frédéric. "Etude de genes de rhizobium meliloti controlant la nodulation specifique de medicago sativa." Toulouse 3, 1988. http://www.theses.fr/1988TOU30194.

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La mutagenese par le transposon tn5 d'un fragment de 30 kb du megaplasmide psym de r. Meliloti, a permis de mettre en evidence 3 regions portant des genes de nodulation dont on etudie les proteines correspondantes. Le transfert a r. Trifolii d'un plasmide portant les genes nodfeg et nodh de r. Meliloti rend la souche hybride capable de noduler la luzerne mais inapte a noduler le trefle

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Lullien, Valérie. "Expression des genes vegetaux pendant la differenciation des nodosites de luzerne (medicago sativa)." Toulouse 3, 1987. http://www.theses.fr/1987TOU30238.

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Analyse des polypeptides obtenus par traduction in vitro d'arn messagers extraits de racines non nodulees, de nodosites fixatrices d'azote ou de nodosites non fixatrices. Etude de l'expression des genes codant pour les leghemoglobines et analyse de l'organisation de ces genes chez medicago sativa, des hybrides somatiques, et chez des legumineuses apparentees. Utilisation de sondes d'adn isolees d'autres especes de plantes pour suivre l'expression des genes codant pour des proteines connues pour jouer un role dans la symbiose (glutamine synthetase) ou les interactions plantes-microorganismes (phenylalanine ammonia-lyase, chalcone synthase, extensine)

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Simonsen, Anna. "The Evolutionary and Ecological Consequences of Partner Variation in the Mutualism between Legumes and Symbiotic Nitrogen Fixing Bacteria." Thesis, 2013. http://hdl.handle.net/1807/35998.

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A fundamental goal in ecology and evolutionary biology has been to understand how microevolutionary forces affect the origin and maintenance of mutualisms over ecological and evolutionary time scales. Mutualistic partners vary in the reciprocal benefits they provide, yet the role of partner variation on microevolutionary forces that impact the maintenance of mutualisms is unclear. Using the mutualism between legumes and nitrogen fixing symbionts, my dissertation investigated the ecological and evolutionary consequences of variation in partner quality. In the first experiment, I demonstrate how insect herbivory can change the costs and benefits of associating with exploiters, and that some degree of exploitation from non-beneficial rhizobia can reduce insect herbivory, thus removing the fitness advantage of associating purely with beneficial rhizobia. In the second study, I examine how rhizobia genotype modifies competition between hosts grown in kin and non-kin groups. I show that lower fitness in plant kin groups can simply be a by-product of genetic variance in plant size and non-linear relationships between plant size and fitness. I further show that the symbiotic community can change difference in fitness between kin and non-kin groups independent of these by-product effects. In my last chapter, I provide the first empirical evidence that an important mechanism for mutualism stability-- the ability for hosts to preferentially associate with beneficial rhizobia-- is genetically variable and can evolve in response to exploitation. I also show that host preference for beneficial rhizobia can be maintained in legume populations, even in the absence of exploitation. My dissertation provides insight into the potential evolutionary dynamics of stabilizing mechanisms by suggesting that the agents of selection that affect the level of host exploitation can come from biotic factors other than the exploiters themselves. My dissertation has also shown that inclusion of other ecological interactions, such as herbivory, can provide valuable perspective on fitness effects of symbionts on their hosts, and can even change our fundamental assumptions about the effects of exploitation on host fitness, which has formed the backbone of mutualism theory.

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Jung, Rüdiger. "Stickstoff-Fixierleistung von Luzerne (Medicago sativa L.), Rotklee (Trifolium pratense L.) und Persischem Klee (Trifolium resupinatum L.) in Reinsaat und Gemenge mit Poaceen." Doctoral thesis, 2003. http://hdl.handle.net/11858/00-1735-0000-000D-F264-C.

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Thies, Janice E. "Modeling ecological determinants of the symbiotic performance of introduced rhizobia in tropical soils." Thesis, 1990. http://hdl.handle.net/10125/9987.

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Tewari, Surya Roshni. "The relation between mode of legume nitrogen nutrition, yield determinants and N assimilation efficiency." Thesis, 1995. http://hdl.handle.net/10125/9270.

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Rädecker, Nils. "Coral Bleaching – Breakdown of a Nutrient Exchange Symbiosis." Diss., 2019. http://hdl.handle.net/10754/655942.

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For millions of years, the nutrient exchange symbiosis between corals and their endosymbiotic algae has formed the foundation of the ecological success of coral reefs. Yet, in recent decades anthropogenic climate change is increasingly destabilizing this symbiosis, and thus the reefs that rely on it. High-temperature anomalies have caused mass mortality of corals due to repeated coral bleaching, the expulsion or digestion of symbionts by the host during stress. Hence, in-depth knowledge of the cellular processes of bleaching is required to conceive strategies to maintain the ecological functioning of coral reefs. In this thesis, we investigated the role of symbiotic nutrient cycling in the bleaching response of corals. For this, we examined the mechanisms that underlie the functioning of the symbiosis in a stable state and how heat stress affects these metabolic interactions during coral bleaching. Our findings reveal that the functioning of the coral – algae symbiosis depends on the resource competition between host and symbionts. In a stable state, symbiotic competition for ammonium limits nitrogen availability for the algal symbiont, thereby ensuring symbiotic carbon translocation and recycling. During heat stress, however, increased metabolic energy demand shifts host metabolism from amino acid synthesis to degradation. The resulting net release of ammonium by the host, coupled with the stimulated activity of associated nitrogen-fixing microbes, substantially increases nitrogen availability for algal symbionts. Subsequently, stimulated algal growth causes selfish retention of carbon, thereby further reducing energy availability for the host. This positive feedback loop disturbs symbiotic nutrient recycling, eventually causing the collapse of carbon translocation by the symbiont. Hence, heat stress causes shifts in metabolic interactions, which directly and indirectly destabilizes the symbiosis, and ultimately undermines the ecological benefits of hosting algal symbionts for corals. In summary, this thesis shows that integrating symbiotic nutrient cycling into our conceptual understanding of coral bleaching is likely to improve our ability to predict coral bleaching in light of environmental conditions and may ultimately help to conceive new strategies to preserve coral reef functioning.

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Dissertations / Theses on the topic 'Legume, symbiosis, nitrogen fixation'

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