Made available in DSpace on 2014-08-20T13:25:37Z (GMT). No. of bitstreams: 1 dissertacao_daniela_da_hora_farias.pdf: 867696 bytes, checksum: 75997246f8d586086ba6e82e5a50c2ed (MD5) Previous issue date: 2012-02-10 / Blueberries are temperate fruit species of great economic importance that has stood out in Southern Brazil. The objectives of this study were to evaluate the influence of arbuscular mycorrhizal fungi (AMF) on the production of plantlets of blueberry, as well as isolate and identify these fungi from the orchards in the South - RS. Samples were collected from soil and roots in experimental and commercial of blueberry orchards in the municipalities Pelotas, Morro Redondo and Jaguarão and ecological indexes used as a measure populations in orchards in the study and principal components analysis to assess the physical and chemical soil in relation to the AMF. We identified 18 different morphotypes of spores. The percentages of root colonization with AMF were high, ranging from 40 to 80%. Since the varieties in commercial orchard located in the city of Morro Redondo city were the most colonized in relation to others. The greatest number of spores found in O'Neal in the orchard from Micaela. The relative abundance and the highest Shannon diversity index (H ') and richness (R) were found in the older areas of cultivation, old orchard at Embrapa (EPV) and the commercial orchard in the Morro Redondo city (MR). The relative frequency shows the prevalence of species of the genus Glomus and Acaulospora in all orchards. The dominance evaluated by the Simpson index (Is) showed the same trend as the Shannon diversity and richness. Among the chemical parameters of soil, there was a high correlation of AMF species with varying pH, V (%), P and sand. AMF isolates for the production of seedlings were provided by Bank of species of the Department of Horticulture and Forestry at UFRGS. Were tested four species of AMF (Glomus clarum, Glomus etunicatum, Gigaspora margarita and Scutellospora heterogama) on the production of cultivars Woodard and Bluegem. The AMF would have positive effects in the nursery, particularly Gigaspora margarita which provided better nutrition, and higher biomass of plants growing Woodard and Glomus etunicatum Bluegem for cultivation. The efficiency of the mycorrhizal symbiosis of blueberry cultivars, depends on the interaction specifies AMF X host. / O mirtilo é uma espécie frutífera de clima temperado de grande importância econômica que vem se destacando na região Sul do Brasil. Os objetivos desse trabalho foram avaliar a influência de fungos micorrízicos arbusculares (FMA) na produção de mudas micropropagadas de mirtilo, assim como isolar e identificar esses fungos oriundos dos pomares da região Sul - RS. Foram coletadas amostras de solo e raízes em pomares comerciais e experimentais de mirtilo dos municípios de Pelotas, Morro Redondo e Jaguarão e utilizados índices ecológicos como forma de avaliar as populações nos pomares em estudo e a análise de componentes principais para avaliar os atributos físicos e químicos do solo em relação aos FMAs. Foram identificadas 18 diferentes morfotipos de esporos de FMA. As porcentagens de colonização radicular com FMA foram elevadas, variando de 40 a 80%. Sendo que as variedades localizadas no pomar comercial do município do Morro Redondo foram as mais colonizadas em relação às demais. O maior número de esporos foi encontrado na variedade O‟Neal no pomar comercial da Micaela. A abundância relativa e os maiores índices de diversidade Shannon (H‟) e riqueza (R) foram encontrados nas áreas mais velhas de cultivo, pomar velho experimental da Embrapa (EPV) e do pomar comercial do município Morro Redondo (MR). A frequência relativa demonstra a prevalência de espécies do gênero Glomus e Acaulospora em todos os pomares. A dominância avaliada pelo índice de Simpsom (Is) apresentou a mesma tendência da diversidade de Shannon e da riqueza. Entre os parâmetros químicos do solo, houve uma alta correlação das espécies de FMA com as variáveis pH, V(%), P e areia. Os isolados de FMAs para a produção de mudas foram cedidos pelo banco de espécies do Departamento de Horticultura e Silvicultura da UFRGS. Testaram-se quatro espécies de FMAs (Glomus clarum, Glomus etunicatum e Scutellospora heterogama e Gigaspora margarita) sobre a produção de mudas das cultivares Woodard e Bluegem. Os FMAs proporcionaram efeito positivo na produção das mudas, em especial Gigaspora margarita que proporcionou melhor nutrição e maior incremento na biomassa nas plantas da cultivar Woodard e o Glomus etunicatum para a cultivar Bluegem. A eficiência da simbiose dos FMAs em cultivares de mirtilo, depende da interação especifica FMA X hospedeiro.

Les endosymbioses racinaires sont des associations bénéfiques établies entre les racines des plantes et des micro-organismes du sol. Ces symbioses ont un intérêt agronomique et écologique puisque les plantes fournissent à leurs partenaires microbiens une niche écologique et des sucres issus de la photosynthèse et en retour, les micro-organismes associés aux racines vont fournir à la plante des nutriments minéraux qui sont actuellement apportés dans l’agriculture conventionnelle sous forme d’engrais. Durant ma thèse, j’ai particulièrement étudié la symbiose endomycorhizienne à arbuscules (AMS). Elle implique des champignons du groupe des Gloméromycètes et plus de 80 % des plantes terrestres. Ainsi cette symbiose est la plus répandue sur terre connue à l’heure actuelle. Plusieurs étapes importantes pour l’établissement de l’AMS ont été définies. La première de ces étapes est la reconnaissance mutuelle entre le champignon endomycorhizien et la plante hôte. Le champignon est capable de percevoir les plantes par les exsudats racinaires qu’elles sécrètent dans la rhizosphère. Dans le mélange complexe de molécules que sont les exsudats racinaires, des phytohormones appelées strigolactones activent le métabolisme des champignons endomycorhizien, la ramification des leurs hyphes et la production de molécules fongiques appelée facteurs Myc. La perception des facteurs Myc par la plante active des processus permettant la colonisation des racines par le champignon. Ce dialogue moléculaire entre champignons endomycorhiziens et plantes hôtes reste toutefois méconnu. Des molécules de type Lipo-chitooligosaccharides (LCO) ou chito-oligosaccharides (CO) ont été identifiées dans les exsudats de spores ou d’hyphes de champignons et activent la voie de signalisation symbiotique chez les plantes mais leurs rôles respectifs dans l’établissement de l’AMS restent mal compris. Du côté de la plante, des récepteurs potentiels aux LCOs et aux COs sont codés par les gènes de la famille des Lysin Motif Receptor-Like Kinase (LysM-RLK) qui sont capables de lier les constituants structuraux des LCOs et des COs. Cependant aucune preuve n’avait été apportée, au commencement de ma thèse, permettant de conclure sur le rôle des LCOs, des COs, et des LysM-RLKs dans la mise en place de l’AMS. C’est ce que je me suis attachée à démontrer durant ma thèse. Pour cela, j’ai travaillé sur une dicotylédone (la tomate : Solanum lycopersicum) et sur une monocotylédone (Brachypodium distachyon, un modèle pour le blé). Pour identifier les récepteurs aux LCOs dans ces plantes et déterminer leur rôle dans l’AMS nous avons mis en place des techniques de génétique inverse. Nous avons ensuite déterminé l’affinité de ces récepteurs pour les LCOs. Ainsi, nous avons montré que la perception des LCOs dans la tomate est importante pour la mise en place de l’AMS. Par ailleurs, je me suis intéressée à la symbiose entre des bactéries du type rhizobium et des plantes principalement de la famille des légumineuses. La mise en place de cette symbiose nécessite la synthèse de LCOs par les rhizobia et leur perception par la plante via des récepteurs de la famille des LysM-RLKs. Ces similarités que la symbiose rhizobium-légumineuses partage avec l’AMS nous ont conduits à poser la question de savoir si les récepteurs de LCOs impliqués dans l’AMS (beaucoup plus ancienne que la symbiose rhizobium-légumineuse) ont été recrutés durant l’évolution pour jouer un rôle dans la symbiose rhizobium-légumineuse. J’ai pu montrer que les récepteurs de LCOs impliqués dans l’AMS chez les espèces non-légumineuses susmentionnées sont fonctionnels l’établissement de la symbiose rhizobium-légumineuse chez une légumineuse. / Root endosymbioses are beneficial associations established between plant roots and soil microorganisms. These symbioses have an agronomic and ecological interest as plants provide their microbial partners with an ecological niche and carbohydrates from photosynthesis. In return, the root-associated microorganisms provide the plant with minerals that are currently being delivered in conventional agriculture as fertilizers. During my thesis, I particularly studied the arbuscular mycorrhizal symbiosis (AMS). It involves fungi of the Glomeromycota group and more than 80 % of land plants. This is the currently known most widespread symbiosis on earth. Important steps for the AMS establishment have been defined. The first step is the mutual recognition between the endomycorrhizal fungus and the host plant. Fungi can perceive plants through the root exudates. In the complex mixture of molecules in the root exudates, phytohormones called strigolactones activate the endomycorrhizal fungal metabolism, the branching of their hyphae and the production of fungal molecules called Myc-Factors. Myc-Factors are perceived by the plant and activate a signaling pathway allowing root colonization by the fungus. However, parts of the molecular dialogue between endomycorrhizal fungi and host plants remain unknown. Lipo-chitooligosaccharide (LCO) or chito-oligosaccharides (CO) molecules have been found in exudates of fungal spores or hyphae and were shown to activate the plant symbiotic signaling pathway, however their respective roles in the AMS establishment are unclear. Putative plant receptors for LCOs and COs are encoded by genes from the Lysin Motif Receptor-Like Kinase family (LysM-RLK) which are able of binding the structural LCO and CO components. However, at the beginning of my PhD, we had no evidence allowing to conclude about the involvement of LCOs, COs, or LysM-RLKs in the AMS establishment. During my thesis, I aimed to understand the role the LCOs and their plant receptors in AMS. For this, I used on a dicotyledon (the tomato: Solanum lycopersicum) and on a monocotyledon (Brachypodium distachyon that is a model for wheat). In order to identify the LCO receptors in these two species, I used a reverse genetic approach. Then I determined these receptors affinity for various LCO structures. I showed that in tomato, LCO perception is important for AMS establishment. In addition, I have studied the symbiosis between rhizobium-type bacteria and plants of the legume family. Interestingly, the establishment of this symbiosis requires LCO synthesis by rhizobia and LCO perception by the plant via receptors of the LysM-RLK family. The fact that rhizobium-legume symbiosis shares similarities with the AMS led us to ask whether the LCO receptors involved in AMS (a much more ancient symbiosis than the rhizobium-legume symbiosis) have been recruited during evolution for a role in the rhizobium-legume symbiosis. I demonstrated that the LysM-RLKs involved in AMS in the above mentioned non-legume species are functional for the rhizobium-legumes establishment in a legume species.