A systematic study of two complexes of closely related species within Eleocharis subg. Limnochloa was conducted to better define poorly understood species and to lay the foundation for a worldwide revision of this group. Research utilized scanning electron microscopy (SEM), study of more than 2300 herbarium specimens and types from 35 herbaria, multivariate analysis, and field studies in the southeast United States and Mexico. Examination of achene gross- and micromorphology using SEM indicated a relationship among the species of the Eleocharis mutata complex (comprising E. mutata, E. spiralis, and E. cellulosa), their distinctness from the E. acutangula complex (comprising E. acutangula s.l. and E. obtusetrigona) and support the placement of all taxa studied within subg. Limnochloa. All species examined shared micromorphological characters typical of subg. Limnochloa. A systematic study of the worldwide morphological variation of E. mutata suggests it is represented by a single taxon throughout its distribution and is native to the New World and probably introduced in tropical Africa. The taxonomic relationship of Eleocharis mutata and E. spiralis was explored using discriminant analysis, PCA and phyto-geography, supporting the recognition of the two taxa as distinct at the rank of species. A systematic study of E. cellulosa suggests it is represented by a single taxon throughout its distribution, with an apparent Caribbean genotype distinguished by the presence of perianth bristles with retrorse spinules. A systematic study of the worldwide variation of E. acutangula s.l. resulted in its segregation into two infraspecific taxa, E. acutangula subsp. acutangula and E. acutangula subsp. breviseta, and two new South American species, E. neotropica and E. steinbachii. Nomenclatural history and lectotypification of certain taxa studied are discussed, and two basyionyms and two synonyms of accepted taxa are lectotypified. A taxonomic treatment is provided that includes a key, detailed descriptions and complete synonymy of each species, line drawings prepared from select specimens examined, and notes on habitat and distribution. Future research goals and needs are discussed.

A systematic study of two complexes of closely related species within Eleocharis subg. Limnochloa was conducted to better define poorly understood species and to lay the foundation for a worldwide revision of this group. Research utilized scanning electron microscopy (SEM), study of more than 2300 herbarium specimens and types from 35 herbaria, multivariate analysis, and field studies in the southeast United States and Mexico. Examination of achene gross- and micromorphology using SEM indicated a relationship among the species of the Eleocharis mutata complex (comprising E. mutata, E. spiralis, and E. cellulosa), their distinctness from the E. acutangula complex (comprising E. acutangula s.l. and E. obtusetrigona) and support the placement of all taxa studied within subg. Limnochloa. All species examined shared micromorphological characters typical of subg. Limnochloa. A systematic study of the worldwide morphological variation of E. mutata suggests it is represented by a single taxon throughout its distribution and is native to the New World and probably introduced in tropical Africa. The taxonomic relationship of Eleocharis mutata and E. spiralis was explored using discriminant analysis, PCA and phyto-geography, supporting the recognition of the two taxa as distinct at the rank of species. A systematic study of E. cellulosa suggests it is represented by a single taxon throughout its distribution, with an apparent Caribbean genotype distinguished by the presence of perianth bristles with retrorse spinules. A systematic study of the worldwide variation of E. acutangula s.l. resulted in its segregation into two infraspecific taxa, E. acutangula subsp. acutangula and E. acutangula subsp. breviseta, and two new South American species, E. neotropica and E. steinbachii. Nomenclatural history and lectotypification of certain taxa studied are discussed, and two basyionyms and two synonyms of accepted taxa are lectotypified. A taxonomic treatment is provided that includes a key, detailed descriptions and complete synonymy of each species, line drawings prepared from select specimens examined, and notes on habitat and distribution. Future research goals and needs are discussed.

Orientador: Maria do Carmo E. do Amaral / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-24T03:33:05Z (GMT). No. of bitstreams: 1 Faria_AparecidaDonisetede_M.pdf: 17935192 bytes, checksum: d71b4d261ddf76c55d2706568524692f (MD5) Previous issue date: 1998 / Resumo: Foi feito o levantamento das espécies pertencentes ao gênero Eleocharis (Cyperaceae) no estado de São Paulo, a partir de material depositado em herbários nacionais e estrangeiros, assim como coletado em trabalho de campo. Caracteres morfológicos dos caules (escapos), bainhas, flores e frutos foram investigados, com a finalidade de auxiliar na caracterização das espécies. Foram registradas 36 espécies e 1 variedade do gênero para o estado de São Paulo e elaboradas chave de identificação, descrição e pranchas com desenhos e fotos das espécies / Abstract: The floristic inventory of the species of Eleocharis (Cyperaceae) ftom São Paulo state, Brazil. was undertaken. The investigation included herbarium specimens ftom several important Herbaria as well as plant collected during intensive field work. The morphology of culms (scapes), leaf sheaths, flowers and ftuits were investigated, in ordem to help with characterization of the species. 36 species and one variety were found. Identification keys, descriptions and ilIustrations of ali taxa are presented. / Mestrado / Mestre em Biologia Vegetal

Les champignons endophytes sont des organismes qui vivent à l’intérieur de plantes sans causer de symptômes de maladie apparents. Ils sont trouvés dans virtuellement toutes plante, et la nature des interactions peut aller de mutualiste à pathogène dépendant des conditions. La diversité et la structure des communautés des champignons endophytes dans les plantes poussant en milieu extrêmement pollué, ainsi que leur rôle potentiel pour améliorer la phytorémédiation, demeurent peu compris. Dans cette étude, nous nous sommes intéressés aux communautés de champignons endophytes de racines de deux espèces de plantes (Eleocharis erythropoda et Populus sp.). Ces espèces poussaient de manière spontanée dans trois bassins de sédimentation d’un ancienne usine pétro-chimique ayant des niveaux de contaminations différents, en utilisant à la fois une approche d’isolation d’organisme ainsi que des analyses de pyroséquençage de l’ITS d’ADN ribosomal. Nos résultats indiquent que les niveaux de contamination ont un effet significatif sur la composition taxonomique des champignons endophytes des racines de E. erythropoda. Une majorité des données de séquences appartiennent à la classe des Dothideomycetes dans les échantillons de forte concentration en hydrocarbures pétroliers, dont une majorité appartient au genre Alternaria. La comparaison des données d’isolation et de pyroséquençage suggère que l’isolation de souches ne permet pas l’obtention des souches les plus représentées dans les données de pyroséquençage. Ces résultats pourront potentiellement aider à l’élaboration de stratégies pour améliorer la phytorémédiation en utilisant les champignons endophytes. / Endophytic fungi are organisms that live inside plant tissues without any apparent disease symptoms. They are found in virtually all plant species and their interactions can vary widely from mutualism to parasitism depending chiefly on environmental conditions and stresses. The diversity and community structure of fungal endophytes in extremely polluted sites and their role in phytoremediation remain largely unexplored. In this study we investigated the community structure of endophytic fungi in roots of two plant species (Eleocharis eryhtropoda and Populus sp.) growing spontaneously in three petroleum-contaminated sedimentation basins of a former petro-chemical plant with different contamination levels. We used both a culture-dependent method of strain isolation as well as a culture-independent method of pyrosequencing of ITS ribosomal DNA. Our results indicate that levels of contamination shape the taxonomic composition of endophytic fungi in E. erythropoda roots. A majority of the reads belonged to the Dothydeomycetes class in smaples from high petroleum-hydrocarbon levels, with the Alternaria genus accounting for the majority of these reads. In addition comparison between culture-dependent and -independent methods showed that strain isolation does not promote the most abundant species found in pyrosequencing. This could help to develop strategies for improving phytoremediation using fungal endophytes.

Nutrient availability, water depth, competition, and soil management effects on cattail (Typha latifolia) growth in wetland systems were examined. Soluble reactive phosphorous (SRP), nitrate-nitrogen (NO3-N), and ammonia-nitrogen (NH3-N) removals were tested at a constructed wetland receiving municipal wastewater effluent. Over all, no significant differences in nutrients occurred between diverse planted and cattail areas. T. latifolia seeds, under the canopy of Eleochoris macrostachya, had low seed germination. Established stands of emergent vegetation can prevent cattail colonization and spread. Germination of T. latifolia at various water depths was tested, and depth impacts on cattail seedling growth and survival were ascertained using various moist soil management techniques in three ponds. Water levels at 0cm and >40cm can adversely impact cattail establishment.

O estudo taxonômico do gênero Eleocharis R. Br. para o Rio Grande do Sul foi desenvolvido através dos métodos tradicionais em taxonomia. Os dados foram obtidos através da bibliografia, revisão de herbários regionais e coleta de exemplares a campo. O gênero está representado no Rio Grande do Sul por 27 espécies: Eleocharis acutangula (Roxb.) Schult., E. bonariensis Nees, E. contracta Maury, E. dunensis Kük., E. elegans (Kunth) Roem. & Schult., E. filiculmis Kunth, E. flavescens (Poir.) Urb., E. geniculata (L.) Roem. & Schult., E. interstincta (Vahl) Roem. & Schult., E. loefgreniana Boeck., E. maculosa (Vahl) Roem. & Schult., E. minima Kunth var. minima, E. montana (Kunth) Roem. & Schult., E. montevidensis Kunth, E. nudipes (Kunth) Palla, E. obtusetrigona (Lindl. & Nees) Steud., E. ochrostachys Steud., E. parodii Barros, E. aff. quinquangularis, E. quinquangularis Boeck., E. rabenii Boeck., E. radicans (Poir.) Kunth, E. sellowiana Kunth, E. squamigera Svenson, E. subarticulata (Nees) Boeck., E. viridans Kük. e Eleocharis sp. O trabalho apresenta descrições, ilustrações, dados sobre distribuição geográfica, habitat e períodos de floração e frutificação das espécies, além de uma chave dicotômica para diferenciá-las. / The taxonomic study of genus Eleocharis R. Br. for Rio Grande do Sul State was developed through of traditional methods of comparative morphology in taxonomy. The data were obtained through bibliography, revision of regional herbaria and field expedition for specimens collection. The genus is represented in Rio Grande do Sul by 27 species: Eleocharis acutangula (Roxb.) Schult., E. bonariensis Nees, E. contracta Maury, E. dunensis Kük., E. elegans (Kunth) Roem. & Schult., E. filiculmis Kunth, E. flavescens (Poir.) Urb., E. geniculata (L.) Roem. & Schult., E. interstincta (Vahl) Roem. & Schult., E. loefgreniana Boeck., E. maculosa (Vahl) Roem. & Schult., E. minima Kunth var. minima, E. montana (Kunth) Roem. & Schult., E. montevidensis Kunth, E. nudipes (Kunth) Palla, E. obtusetrigona (Lindl. & Nees) Steud., E. ochrostachys Steud., E. parodii Barros, E. aff. quinquangularis, E. quinquangularis Boeck., E. rabenii Boeck., E. radicans (Poir.) Kunth, E. sellowiana Kunth, E. squamigera Svenson, E. subarticulata (Nees) Boeck., E. viridans Kük. and Eleocharis sp. Descriptions, illustrations and an analytical key for species are provided, as well as data about their geographic distribution, habitat and flowering/fruiting periods.

O estudo taxonômico do gênero Eleocharis R. Br. para o Rio Grande do Sul foi desenvolvido através dos métodos tradicionais em taxonomia. Os dados foram obtidos através da bibliografia, revisão de herbários regionais e coleta de exemplares a campo. O gênero está representado no Rio Grande do Sul por 27 espécies: Eleocharis acutangula (Roxb.) Schult., E. bonariensis Nees, E. contracta Maury, E. dunensis Kük., E. elegans (Kunth) Roem. & Schult., E. filiculmis Kunth, E. flavescens (Poir.) Urb., E. geniculata (L.) Roem. & Schult., E. interstincta (Vahl) Roem. & Schult., E. loefgreniana Boeck., E. maculosa (Vahl) Roem. & Schult., E. minima Kunth var. minima, E. montana (Kunth) Roem. & Schult., E. montevidensis Kunth, E. nudipes (Kunth) Palla, E. obtusetrigona (Lindl. & Nees) Steud., E. ochrostachys Steud., E. parodii Barros, E. aff. quinquangularis, E. quinquangularis Boeck., E. rabenii Boeck., E. radicans (Poir.) Kunth, E. sellowiana Kunth, E. squamigera Svenson, E. subarticulata (Nees) Boeck., E. viridans Kük. e Eleocharis sp. O trabalho apresenta descrições, ilustrações, dados sobre distribuição geográfica, habitat e períodos de floração e frutificação das espécies, além de uma chave dicotômica para diferenciá-las. / The taxonomic study of genus Eleocharis R. Br. for Rio Grande do Sul State was developed through of traditional methods of comparative morphology in taxonomy. The data were obtained through bibliography, revision of regional herbaria and field expedition for specimens collection. The genus is represented in Rio Grande do Sul by 27 species: Eleocharis acutangula (Roxb.) Schult., E. bonariensis Nees, E. contracta Maury, E. dunensis Kük., E. elegans (Kunth) Roem. & Schult., E. filiculmis Kunth, E. flavescens (Poir.) Urb., E. geniculata (L.) Roem. & Schult., E. interstincta (Vahl) Roem. & Schult., E. loefgreniana Boeck., E. maculosa (Vahl) Roem. & Schult., E. minima Kunth var. minima, E. montana (Kunth) Roem. & Schult., E. montevidensis Kunth, E. nudipes (Kunth) Palla, E. obtusetrigona (Lindl. & Nees) Steud., E. ochrostachys Steud., E. parodii Barros, E. aff. quinquangularis, E. quinquangularis Boeck., E. rabenii Boeck., E. radicans (Poir.) Kunth, E. sellowiana Kunth, E. squamigera Svenson, E. subarticulata (Nees) Boeck., E. viridans Kük. and Eleocharis sp. Descriptions, illustrations and an analytical key for species are provided, as well as data about their geographic distribution, habitat and flowering/fruiting periods.

O estudo taxonômico do gênero Eleocharis R. Br. para o Rio Grande do Sul foi desenvolvido através dos métodos tradicionais em taxonomia. Os dados foram obtidos através da bibliografia, revisão de herbários regionais e coleta de exemplares a campo. O gênero está representado no Rio Grande do Sul por 27 espécies: Eleocharis acutangula (Roxb.) Schult., E. bonariensis Nees, E. contracta Maury, E. dunensis Kük., E. elegans (Kunth) Roem. & Schult., E. filiculmis Kunth, E. flavescens (Poir.) Urb., E. geniculata (L.) Roem. & Schult., E. interstincta (Vahl) Roem. & Schult., E. loefgreniana Boeck., E. maculosa (Vahl) Roem. & Schult., E. minima Kunth var. minima, E. montana (Kunth) Roem. & Schult., E. montevidensis Kunth, E. nudipes (Kunth) Palla, E. obtusetrigona (Lindl. & Nees) Steud., E. ochrostachys Steud., E. parodii Barros, E. aff. quinquangularis, E. quinquangularis Boeck., E. rabenii Boeck., E. radicans (Poir.) Kunth, E. sellowiana Kunth, E. squamigera Svenson, E. subarticulata (Nees) Boeck., E. viridans Kük. e Eleocharis sp. O trabalho apresenta descrições, ilustrações, dados sobre distribuição geográfica, habitat e períodos de floração e frutificação das espécies, além de uma chave dicotômica para diferenciá-las. / The taxonomic study of genus Eleocharis R. Br. for Rio Grande do Sul State was developed through of traditional methods of comparative morphology in taxonomy. The data were obtained through bibliography, revision of regional herbaria and field expedition for specimens collection. The genus is represented in Rio Grande do Sul by 27 species: Eleocharis acutangula (Roxb.) Schult., E. bonariensis Nees, E. contracta Maury, E. dunensis Kük., E. elegans (Kunth) Roem. & Schult., E. filiculmis Kunth, E. flavescens (Poir.) Urb., E. geniculata (L.) Roem. & Schult., E. interstincta (Vahl) Roem. & Schult., E. loefgreniana Boeck., E. maculosa (Vahl) Roem. & Schult., E. minima Kunth var. minima, E. montana (Kunth) Roem. & Schult., E. montevidensis Kunth, E. nudipes (Kunth) Palla, E. obtusetrigona (Lindl. & Nees) Steud., E. ochrostachys Steud., E. parodii Barros, E. aff. quinquangularis, E. quinquangularis Boeck., E. rabenii Boeck., E. radicans (Poir.) Kunth, E. sellowiana Kunth, E. squamigera Svenson, E. subarticulata (Nees) Boeck., E. viridans Kük. and Eleocharis sp. Descriptions, illustrations and an analytical key for species are provided, as well as data about their geographic distribution, habitat and flowering/fruiting periods.

Orientadora: Profa Dra Roseli Frederigi Benassi / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia Ambiental, 2017. / Os alagados construídos são sistemas desenvolvidos para reproduzir as características de áreas alagadas naturais sob condições controladas para tratamento descentralizado de águas residuárias. Assim, o presente trabalho teve por objetivo principal avaliar o desempenho de um sistema piloto de alagados construídos com fluxo subsuperficial horizontal cultivados com macrófitas aquáticas emergentes (Typha sp. e Eleocharis sp.) no tratamento secundário de efluente sanitário. O experimento foi conduzido na Estação de Tratamento de Esgotos de Arujá (SP), e consistiu de um tanque de alimentação e quatro tanques de tratamento. Tanque 1 (T1): sistema de tratamento com Eleocharis sp. (Junco); Tanque 2 (T2): sistema de tratamento com Typha sp. (Taboa); Tanque 3 (T3): sistema de tratamento combinado com Typha sp. e Eleocharis sp. e Tanque 4 (T4): sistema controle (sem plantas), composto apenas de brita, utilizada como material suporte. O tanque de alimentação foi abastecido com esgoto proveniente apenas do tratamento preliminar da ETE (grades e caixa de areia). Os sistemas foram operados em regime de fluxo contínuo com vazão de 0,105 m³ dia-1, TDH de 4,8 dias e TAS de 0,05 m3 m-2 dia-1. Após estabilidade, o sistema foi monitorado por 3 meses: coletas diárias (de segunda à sexta-feira) durante um mês e meio e semanais durante o restante do período, totalizando 33 coletas. Foram realizadas diversas análises físico-químicas no afluente, efluente em tratamento e efluente final, dentre as quais destacam-se: DBO5,20, DQO, COD, SST, SSF e SSV, série N e fósforo total. Todos os quatro sistemas apresentaram eficiências médias de remoção de DBO5,20 (90 ¿ 93%), DQO (86 ¿ 90%), COD (51 ¿ 58%), SST (98%), SSF (98%), SSV (98%), nitrogênio total (22 ¿ 29%) e nitrogênio amoniacal (19 ¿ 31%) estatisticamente iguais (ANOVA p > 0,05). Com relação à eficiência de remoção de fósforo total (47 ¿ 59 %), houve diferença estatística significativa (ANOVA p < 0,05) apenas entre os tanques 2 (Taboa) e 4 (Controle), sendo a eficiência de remoção do tanque 2 superior à do tanque 4. Portanto, tanto os sistemas cultivados com macrófitas quanto o controle (sem plantas) apresentaram desempenhos semelhantes para a remoção de matéria orgânica, sólidos suspensos e nitrogênio. Com base nos resultados obtidos, observou-se o predomínio dos mecanismos de remoção físicos (filtração e sedimentação do material particulado) e microbiológicos (remoção da fração solúvel dos poluentes). Tendo em vista a similaridade de desempenho dos sistemas com e sem macrófitas aquáticas, concluiu-se que as mesmas apresentaram pouca ou nenhuma influência direta na remoção dos poluentes analisados. / Constructed wetlands are artificial systems developed to reproduce the characteristics of natural wetlands under controlled conditions for decentralized wastewater treatment. Thus, this study aimed to evaluate the performance of a constructed wetland system with horizontal subsurface flow cultivated with emergent aquatic macrophytes (Typha spp. e Eleocharis spp.) in the wastewater secondary treatment. The experiment was conducted on a pilot scale installed at the wastewater treatment plant (WWTP) of Arujá (SP) and consisted of one supply reservoir and four treatment tanks. Tank 1 (T1): treatment system with Eleocharis spp. (Spikerushes); Tank 2 (T2): treatment system with Typha spp. (Cattails); Tank 3 (T3): treatment system with both species (Typha spp. and Eleocharis spp.) combined; Tank 4 (T4): control system (unplanted), consisting of only gravel used as supporting media. The supply reservoir was loaded with raw sewage from the preliminary treatment. The systems were operated in a continuous flow with a rate of 0.105 m³ day-1, HRT of 4.8 days and hydraulic rate of 0.05 m3 m-2 day-1. Once stabilized, the system was monitored for 3 months: on a daily basis (from Monday to Friday) for one month and a half, and on a weekly basis during the rest of the period, completing 33 collections. A variety of physical and chemical analysis were carried out in the influent, effluent during and after the treatment. The main analyses were BOD5,20, COD, DOC, TSS, FSS, VSS. All four systems presented average removal efficiencies statistically equivalents (ANOVA, p > 0,05) for the variables: BOD5,20 (90 ¿ 93%), COD (86 ¿ 90%), DOC (51 ¿ 58%), TSS (98%), FSS (98%), VSS (98%), total nitrogen (22 ¿ 29%) and ammonia nitrogen (19 ¿ 31%). Regarding the removal efficiency of total phosphorus (47 ¿ 59%), there was a significant statistical difference (ANOVA, p < 0,05) only between tanks 2 (Cattails) and 4 (Control), where tank two presented a better performance. Therefore, both the planted and unplanted systems presented similar performance for the removal of organic matter, suspended solids and nitrogen. Based on the results obtained, it can be inferred that there is a predominance of physical (filtration and sedimentation of particulate matter) and microbiological (removal of dissolved fraction) removal mechanisms. Based on the similar performance of both the planted and unplanted systems, it was concluded that the aquatic macrophytes had little or no direct influence on the pollutants removal.

Les champignons mycorhiziens arbusculaires (CMA) appartiennent au phylum Glomeromycota. Ces champignons forment une association symbiotique (obligatoire pour les champignons) avec plus de 80 % des espèces de plantes vasculaires, incluant la plupart des plantes cultivées. Cette symbiose mycorhizienne arbusculaire, très répandue dans la nature, a été retrouvée dans presque tous les écosystèmes terrestres aussi bien dans des déserts chauds et froids que dans des forêts tropicales ou tempérées. L’emploi d’outils de biologie moléculaire et des fossiles ont permis d’estimer la date de l’origine de la symbiose mycorhizienne arbusculaire à environ 450 millions d’années avant notre ère. Cette date coïncide avec l’apparition des premières plantes terrestres primitives. Il existe plusieurs types de mycorhizes impliquant différents champignons et différentes plantes hôtes. Ces différents faits suggèrent que les plantes vasculaires et les champignons mycorhiziens à arbuscules ont co-évolué, et que les Glomeromycota ont influencé la capacité des plantes à coloniser le milieu terrestre. Plusieurs études ont montré que les contaminants organiques peuvent influer négativement cette relation mutuellement bénéfique qu'entretiennent la plante et le champignon conduisant à une diminution de la croissance du CMA mais aussi à une modification des interactions au sein de la communauté de CMA elle-même. Ainsi, mon projet de maîtrise vise à quantifier la diversité mycorhizienne arbusculaire de deux espèces de plante Eleocharis obtusa et Panicum capillare qui poussent dans un bassin hautement contaminé par des hydrocarbures pétroliers de façon très hétérogène et étudier les structures des communautés des CMA dans des échantillons de sol rhizosphérique et de racines de celles-ci. L'un des résultats important de mon étude est la découverte d’une très grande diversité des CMA associés à E. obtusa et P. capillare dans ce milieu contaminé. En effet, pas moins de 26 unités taxonomiques opérationnelles (OTU) de champignons mycorhiziens à arbuscules ont été recensés. La quasi-totalité des familles de Glomeroycota sont représentées à l'exception de Ambisporaceae, Geosiphonaceae et Pacisporaceae. Ainsi, le genre Diversispora domine la communauté des CMA par son abondance relative, cependant le genre Claroideoglomus est le plus abondant des genres des CMA. Ensuite, mon projet a déterminé l'influence de la plante hôte sur la composition de la communauté de CMA. D'après l'analyse de la diversité alpha, les plantes présentent une structure de diversité différente. Les valeurs de Local Contributions to beta Diveristy (LCBD) élevées étaient souvent liées à un site avec un grand nombre de taxons de CMA. En utilisant une analyse en composante principale (ACP), j’ai constaté que les échantillons récoltés en 2011 auraient sensiblement la même composition en OTU. J’ai pu observer également une variation de la communauté des OTU de CMA d'une année à l'autre pour les plantes. La rhizosphère des plantes récoltées la même année avait une communauté d'OTU similaire globalement, pourtant au niveau racinaire, j’ai observé une spécificité chez des certains OTU. Cette étude fournit une vue d’ensemble de la diversité des CMA associés à des végétaux localisés dans les sédiments très polluées. Elle suggère aussi que les CMA peuvent être des candidats microbiens potentiellement importants dans la restauration des sols contaminés par le pétrole. / The arbuscular mycorrhizal fungi (AMF) belong to phylum Glomeromycota, a group of early divergent fungal lineage. These fungi form a mutualistic symbiotic association with more than 80% of vascular plant species, including most important crops. The arbuscular mycorrhizal symbiosis is widespread and has been found in almost all terestrial ecosystems on earth such as hot and cold deserts, as well as tropical and temperate forests. The use of molecular biology tools and fossil records dated back the origin of arbuscular mycorrhizal symbiosis to 460 million years ago, which coincides with the emergence of terrestrial plants. There are several types of mycorrhizas depending on fungal groups and host plants. It has been suggested that vascular plants and AMF have co-evolved and that Glomeromycota helped plant ancestors to colonize the land. It has been reported that organic contaminants can negatively impact this mutually beneficial symbiosis between plant and fungi reducing the growth of the AMF and changing the structure of AMF communities. The objective of my master project was to determine the diversity of arbuscular mycorrhizal fungi associated with two plant species, Eleocharis obtusa and Panicum capillare, which spontaneously growing a highly petroleum hydrocarbons contaminated basin with an heterogeneous pattern of contamination, and to describe the structures of their communities in their rhizosphere soils and roots. My results revealed an unexpected high diversity of AMF OTUs associated with two plant species. Indeed, we identified 26 OTUs of AMF. This diversity covered the most important families of Glomeroycota except Ambisporaceae, Geosiphonaceae and Pacisporaceae. Genus Diversispora dominated the AMF community by its relative abundance, however the genus Claroideoglomus was the most represented in the samples. My study determined the influence of the host plant on the composition of the AMF community. Based on the analysis of the α diversity, we found that the rhizospheric soil and root samples showed different community structures between the two plants species. β diversity analysis showed that high Local Contributions to β Diveristy (LCBD) values (high uniqueness of species composition) were often linked to the sample with a large number of AMF taxa. Using a principal component analysis (PCA), we found that the samples collected in 2011 have approximately the same composition of OTUs. It is likely that a turnover of AMF OTU and 4 plants may occur from one year to another. This study provides an overview of the diversity of AMF associated with plants located in heavily polluted sediments. It also suggests that AMF may be potentially important microbial candidates in the remediation of oil-contaminated soils.