Nos frutos, a cor é fundamental para a aceitabilidade inicial do consumidor, especialmente para os chamados \"pequenos frutos\" como morangos e framboesas, sendo um critério tradicional para a apreciação e seleção do estado de maturação. Em framboesas (Rubus idaeus), as pesquisas têm focado a síntese de antocianinas, os pigmentos mais abundantes nesta espécie. Seus precursores provem da via de biossíntese dos fenilpropanóides, porém os fatores que regulam a atividade dessa via metabólica ainda são pouco conhecidos. Sabe-se que alguns hormônios como o etileno, o ácido indol-3-acético (AIA), o ácido abscísico (ABA) e o metil-jasmonato (MJ) estão relacionados à inibição da síntese ou aumento no acúmulo destes flavonóides. Neste contexto, o objetivo do trabalho é avaliar o efeito destes fatores hormonais sobre a biossíntese de antocianinas em framboesas da cultivar (cv.) Autumn Bliss. Foram avaliados os efeitos dos hormônios sobre as características físico-químicas e fisiológicas dos frutos (açúcares solúveis, ácidos orgânicos, respiração, síntese de etileno, cor), conteúdo de compostos fenólicos e flavonóides. Também foram quantificados os níveis de AIA livre, ABA e MJ e a expressão relativa das enzimas antocianidina sintase (ANS), dihidroflavonol redutase (DFR) e do fator de transcrição MYB10, regulador da transcrição de genes da via de biossíntese de antocianinas em framboesas. As alterações mais significativas foram observadas no tratamento com MJ, para o qual os frutos apresentaram acentuada produção de etileno (sem efeito sobre a respiração) e também na cor, mais acentuada nos frutos maduros deste grupo em comparação com os frutos do grupo controle. O MJ também induziu aumento nos níveis de expressão relativa de MYB, ANS e DFR, nos dois primeiros dias pós-colheita. Outro grupo que se destacou foi o tratado com AIA por apresentar inibição na síntese de antocianinas e compostos fenólicos, a qual foi correlacionada à inibição da transcrição do MYB e ANS. O ABA por sua vez, inibiu o acúmulo de transcritos da DFR, de forma correlata ao menor acúmulo de antocianinas. Exceto pelo ACC, que não produziu efeitos significativos em nenhum dos parâmetros avaliados, os resultados indicam que o metabolismo de antocianinas deve ser regulado por múltiplos sinais hormonais. / The color is fundamental for the fruits, for the initial acceptability of the consumers, is a factor that influence the appreciation and selection of the maturity stage, especially for berries, like strawberries and raspberries. In raspberries (Rubus idaeus), the research have focused on the anthocyanin biosynthesis, the pigments most frequent on this species. Their precursors came from the phenylpropanoid pathway but the factors that regulate this metabolic pathway remain unclear. There are evidences that some phytohormones as ethylene, indole-3-acetic acid (IAA) abscisic acid (ABA) and methyl jasmonate (MJ) are related to the inhibition or increase of these flavonoids on fruits. In this context, the aim of this study is to evaluate the effect of these phytohormones on the anthocyanin pathway in raspberries Autumn Bliss. It was evaluated the effects of these phytohormones in some physico-chemical and physiologic characteristics of these fruits (soluble sugars, organic acids, respiration, ethylene biosynthesis, color), phenolic compounds and flavonoid content. Also, it was quantified the auxin, ABA and MJ levels, and the relative transcript levels of anthocyanidin synthase (ANS), dihydroflavonol 4-reductase (DFR) and the transcriptional factor MYB10, a transcriptional regulator of the anthocyanin pathway in raspberries. The most significant alterations were observed on MJ treatment, in which the ethylene production in berries reach the highest levels (without effect on the respiration) and the most intense red color on ripe fruits in comparison with the control group. MJ also induced the increase on relative expression of MYB, ANS and DFR two days after harvest prior to the anthocyanin accumulation. Other noticeable effect was detected in the IAA group in which anthocyanin synthesis and phenolic compound content were inhibited and related to the inhibition of MYB and ANS transcription. ABA inhibited the DFR transcript accumulation, related to the delay in anthocyanins synthesis in relation to control group. Except by ACC, that did not have significant effects in any of the evaluated parameters, the results suggest that the anthocyanin metabolism might be regulate for multiple hormonal signs.

Le système racinaire des arbres peut établir des symbioses ectomycorhiziennes (ECM) avec des champignons rhizosphériques. La mise en place de la symbiose est accompagnée d'une stimulation de la formation des racines latérales (RLs), et d'une modification de la croissance racinaire. Ces processus développementaux conduisent à la formation de racines courtes typiques des ECMs. Il a été montré que l'auxine est une phytohormone clef dans la formation des RLs ainsi que dans la croissance racinaire. Notre projet s'est focalisé sur l'étude de la régulation des voies de l'auxine dans la racine de peuplier en réponse à L. bicolor. Dans cette étude, nous avons mis en évidence un arrêt de croissance des RLs et des racines adventives du peuplier Populus tremula x P. alba, après deux semaines de co-culture avec L. bicolor. De plus, nous avons aussi montré que cet arrêt n'est pas conditionné par la présence du réseau de Hartig. Une analyse de l'expression globale des gènes de peuplier dans la mycorhize a été réalisée au cours de la formation de la mycorhize. Cette analyse, couplée à des observations du gradient auxinique via le patron d'expression du promoteur DR5, montre que la signalisation auxinique est affectée dans l'organe symbiotique. La quantification de l'auxine (acide indole 3-acétique, AIA) et des métabolites associés a permis de mettre en évidence un environnement symbiotique riche en auxine dans la mycorhize, qui pourrait expliquer les modifications de la signalisation auxinique. De plus, un changement de la conjugaison et de la dégradation de l'AIA est détecté dans la racine, ainsi qu'une dégradation de l'AIA dans les hyphes de L. bicolor. En parallèle, une analyse fonctionnelle de PtaPIN9, un orthologue de AtPIN2, responsable du transport basipète de l'auxine à l'apex racinaire chez Arabidopsis thaliana, a été réalisée au cours de la mycorhization avec L. bicolor. L'immunolocalisation de PtPIN9 dans les racines de peuplier a montré une localisation similaire à AtPIN2, dans les cellules épidermiques. Les lignées transgéniques ayant une modification de l'expression de ce gène ne répondent pas à L. bicolor en terme de stimulation de RLs. Dans les racines mycorhizées, PtaPIN9 n'est plus observée, mais les modifications de l'expression de PtaPIN9 ne modifient ni l'arrêt de croissance racinaire, ni la formation du réseau de Hartig. Ces résultats montrent des modifications majeures des voies de l'auxine du peuplier par le champignon symbiotique L. bicolor. Cette étude ouvre des perspectives sur la compréhension du rôle de l'auxine dans le développement racinaire ainsi que dans le contexte des interactions plantes-microorganismes / Root systems of host trees are known to establish the ectomycorrhizal (ECM) symbiosis with rhizospheric fungi. This mutualistic association leads to modifications of root development that including a stimulation of lateral host roots, and a modification in root growth. The phytohormone auxin (Indole-3-acetic acid, IAA) is known to regulate LRs formation and root growth. Our research focussed on auxin pathways in poplar root in response to L. bicolor. In this study, our data showed that the poplar-Laccaria bicolor interaction leads to the arrest of LRs and adventitious root growth after two weeks of interaction. We also showed that this arrest is not regulated by the Hartig net. Differential auxin responses were analyzed by using an auxin-responsive DR5::GUS marker line and revealed a loss of auxin response in ECM roots. An oligoarray-based transcript profiling of poplar roots in contact with L. bicolor highlights a differential expression of auxin asociated genes in ECM. Measurement of auxin metabolite in ECM and in the free living partners revealed an IAA accumulation, an activation of the IPyA (Indol-3-Pyruvic Acid) dependant IAA biosynthesis pathway in both partners, as well as changes in IAA conjugation pathways in poplar and in IAA degradation pathways in L. bicolor. Our findings illustrate the impact of L. bicolor colonization on root auxin metabolism and response, and also suggest a role of auxin as a signal in the formation of ECM and in the regulation of ECM function. In parallel, PtaPIN9 function analysis in response to L. bicolor has been performed. PtaPIN9 immunolocalization in poplar roots showed similar localization to AtPIN2 in epidermis cells. Transgenic lines having a modification in PtaPIN9 expression, did not formed new LRs in respond to L. bicolor. In ECM roots, the loss of PtaPIN9 signal is observed but modifications of PtaPIN9 expression did not modify the root growth arrest and the Hartig net formation. These results show major changes in auxin associate pathways in poplar root by the symbiotic fungus L. bicolor, during the formation of the mycorrhiza root. Our results offer perspectives on the role of auxin in root development and in the context plants-microbes interactions

L’auxine est une hormone fondamentale dans le développement et la physiologie de la plante. L’obtention des plantes conditionnelles pour ABP1 a permis la mise en évidence de son importance dans la signalisation de l’auxine. Ainsi ABP1 agirait d’une part sur l’endocytose de vésicules à clathrine au niveau de la membrane plasmique et d’autre part sur la stabilité des Aux/IAAs. Ce dernier résultat suggère qu’une voie de signalisation en aval d’ABP1 permet de modifier l’homéostasie de la voie de régulation transcriptionnelle de l’auxine, la voie SCFTIR/AFBs.Mon travail de thèse a consisté à caractériser les plantes inactivées pour ABP1 lors de la croissance à l’obscurité dans la plante modèle Arabidopsis thaliana. Mon étude montre qu’ABP1 contrôle l’expansion cellulaire en jouant sur la plasticité pariétale. J’ai ainsi pu mettre en évidence une modification de la proportion de formes fucosylées des chaînes latérales des xyloglucanes, le principal hémicellulose de la paroi primaire chez Arabidopsis. Cette modification de la fucosylation des xyloglucanes requiert des changements d’expressions géniques médiés ce qui conforte l’existence d’une voie de signalisation reliant ABP1 à la voie SCFTIR/AFBs.En parallèle, j’ai mené une approche génétique de recherche de suppresseurs du phénotype lié à l’inactivation d’ABP1 à l’obscurité. Parmi les dix lignées validées, j’ai d’ores et déjà identifié le gène DCL3 comme étant impliqué dans la suppression du phénotype ss12k et mis en évidence l’implication de la voie d’extinction de gènes par l’intermédiaire de petits ARNs non codant (voie RdDM) dans le contrôle de l’expansion cellulaire. / Auxin is a key hormone concerning the control of plant physiology and the impact on plant development. Conditional plants for ABP1 allowed the post embryonic studies and have contributed to demonstrate the involvement of ABP1 in a broad range of cellular and developmental responses including the clathrin-dependent endocytosis and the regulation of Aux/IAAs homeostasis. These datas revealed that an ABP1-dependent pathway is acting on transcriptional regulation by modulating the SCFTIR/AFBs signaling pathway. I took advantage of the phenotype of dark grown seedlings to study cell expansion in ABP1 loss of function background. ABP1 knockdown induced modifications of fucosylated form of xyloglucan side chains that are the main hemicellulose in Arabidopsis primary cell wall. All data converge to show that this effect results from alterations of expression of cell wall related genes via the modulation of the SCFTIR/AFBs pathway. In parallel, I used a suppressor approach to discover new signaling components downstream of ABP1. Characterisation of one of the suppressor leads to the identification of a loss of function allele of DCL3. This data demonstrates the involvement of the RNA directed DNA methylation pathway downstream of ABP1.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-08-09T11:45:20Z No. of bitstreams: 1 2011 - Anelise Dias.pdf: 15332435 bytes, checksum: 2029d6acb53e3ead830aa60dc2c29a5a (MD5) / Made available in DSpace on 2016-08-09T11:45:20Z (GMT). No. of bitstreams: 1 2011 - Anelise Dias.pdf: 15332435 bytes, checksum: 2029d6acb53e3ead830aa60dc2c29a5a (MD5) Previous issue date: 2011-09-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / A collection of 189 bacterial isolates, obtained from organic system of vegetable production, was characterized aiming to selection of cabbage growth promoting strains. Isolatings were performed from rhizosphere of vegetables and soil after harvest of cultivated species. The vast majority of the strains showed biochemical profiles identical to Pseudomonas (fluorescent group). While profiles identical to Burkholderia, Stenotrophomonas and Acinetobacter constituted other groups of representatives. Characterization of isolates took into account the capacity for synthesis of compounds possibly involved in mechanisms to stimulate plant growth, namely: biofilms, siderophores, acyl homoserine lactones (AHLs), indole-3-acetic acid (IAA) and indole related compounds, as well as solubilization of calcium phosphate. A total of 94 isolates were evaluated in the greenhouse for their ability to promote the growth of cabbage (Brassica oleracea var. acephala) in pots containing unsterilized loam soil. In addition, consortia were evaluated between components of the collection and rhizobia for the same purpose. In addition, it compared the effects of application of certain producing IAA isolates and the application of synthetic IAA on the growth of cabbage. Laboratory experiments showed that in vitro, 100% of the isolates formed biofilm, 71% synthesized siderophores, 31% produced AHLs, 95% produced IAA and 74% solubilized P. However, bioassays in the greenhouse showed that only 12% of the isolates induced significant responses to promote the growth of cabbage. Of these, a subgroup composed of 10 strains of rhizobacteria given increments in growth parameters of both the biomass and the root system of vegetables. Biofilms, siderophores, IAA and solubilization of P were common characteristics of the subgroup. No synergistic effect was observed among isolates in consortia, although it was found that the two strains of rhizobia consortium promoted the growth of inoculated plants. The isolates R1132 and S311 were higher than the application of synthetic IAA. The results suggested the potential of 12 bacteria to promote plant growth and increase production of cabbage / Uma cole??o de 189 isolados bacterianos, provenientes de sistema org?nico de produ??o de hortali?as, foi caracterizada com vistas ? sele??o de estirpes promotoras do crescimento de couve. Os isolamentos foram realizados a partir da rizosfera de hortali?as e do solo ap?s colheita das esp?cies cultivadas. A grande maioria das estirpes apresentou perfil bioqu?mico id?ntico a Pseudomonas (grupo fluorescente). Enquanto perfis id?nticos a Burkholderia, Acinetobacter e Stenotrophomonas constitu?ram outros grupos de representantes. A caracteriza??o dos isolados levou em conta a capacidade de s?ntese de compostos possivelmente envolvidos em mecanismos de est?mulo ao crescimento de plantas, a saber: biofilmes, sider?foros, acil-lactonas homoserinas (ALHs), ?cido indol-3-ac?tico (AIA) e compostos ind?licos relacionados, al?m da solubiliza??o de fosfato de c?lcio. Um total de 94 isolados foi testado na casa de vegeta??o quanto ? capacidade de promover o crescimento de couve (Brassica oleraceae var. acephala) em vasos contendo solo distr?fico n?o esterilizado. Paralelamente, foram avaliados cons?rcios entre componentes da cole??o e riz?bios para igual finalidade. Em adendo, foram comparados os efeitos da aplica??o de determinados isolados produtores de AIA e da aplica??o de AIA sint?tico sobre o crescimento da couve. Os experimentos de laborat?rio indicaram que, in vitro, 100% dos isolados formaram biofilme, 71% sintetizaram sider?foros, 31% produziram AHLs, 95% produziram AIA e 74% solubilizaram P. No entanto, os bioensaios na casa de vegeta??o evidenciaram que apenas 11% dos isolados bacterianos induziam respostas significativas de promo??o do crescimento da couve. Desses, um subgrupo formado por 10 estirpes de rizobact?rias conferiu incrementos nos par?metros de crescimento, tanto da biomassa a?rea quanto do sistema radicular da hortali?a. Biofilmes, sider?foros, AIA e solubiliza??o do P foram caracter?sticas comuns do subgrupo. N?o foi observado efeito sin?rgico entre os isolados em cons?rcios, embora tenha sido verificado que as duas estirpes de riz?bios consorciadas promoveram o crescimento das plantas inoculadas. Os isolados R1132 e S311 foram superiores ? aplica??o do AIA sint?tico. Os resultados obtidos sinalizaram o potencial de 12 bact?rias que promover o crescimento das plantas e incrementar a produ??o de couve.

Os frutos do tomateiro (Solanum lycopersicum) apresentam elevada diversidade fenotípica, grande parte da qual deve-se a mutações em cinco genes, SUN (SUN), OVATE (O), LOCULE NUMBER (LC), FRUIT SHAPE 8.1 (FS8.1) e FASCIATED (FAS). Enquanto mutações em LC, O e FAS são responsáveis pela alteração no número de lóculos no fruto, mutações em FS8.1, SUN e O resultam em frutos mais alongados, sendo a última mutação o foco de estudo do presente trabalho. Apesar de ovate ser uma mutação importante tanto do ponto de vista agronômico quanto biológico, não é conhecido ainda o efeito exato da nova classe de gene regulatório codificado por esse locus. Por promover a drástica alteração no formato do fruto, característica esta que pode influenciar a preferência do consumidor, essa mutação é de grande interesse agronômico. Sob o ponto de vista biológico, o maior conhecimento da função desse gene resultaria em um maior entendimento do processo de frutificação. A análise de duplos mutantes ovate DR5::GUS e ovate ARR5::GUS mostrou que essa mutação altera o padrão de resposta a auxina e citocinina, respectivamente, durante o desenvolvimento do fruto. Além disso, foram realizados estudos que mostraram seu impacto no teor de sólidos solúveis, produtividade, tempo de prateleira, teor de matéria seca, peso das sementes e partenocarpia. Tais resultados não somente contribuíram para um melhor entendimento do efeito gênico da nova classe de genes regulatórios codificado por OVATE, como também fornecem importantes implicações agronômicas, já que a mutação ovate vem sendo utilizada na obtenção de variedades e híbridos do tipo \"grape\". / The fruits of tomato (Solanum lycopersicum) present a high phenotypic diversity, most of which can be attributed to mutations in five genes: SUN (SUN), OVATE (O), LOCULE NUMBER (LC), FRUIT SHAPE 8.1 (FS8.1) and FASCIATED (FAS). Whereas mutations in LC, O and FAS alter fruit locule number, mutations in FS8.1, SUN and O result in elongated fruits. The latter is the focus of the present work. ovate is a biologically and agronomically relevant mutation, however, the exact effect of the new class of regulatory gene it represents is unknown. The drastic alteration in fruit shape produced by the mutation can influence consumer preference, thus rendering it agronomically important. Biologically, a thorough characterization of its gene function would result in deeper understanding of fruit formation. Crosses to the marker lines DR5::GUS and ARR5::GUS showed that ovate alters the response pattern of auxin and cytokinin, respectively, during fruit development. Furthermore, studies are described showing its effect on total soluble solids content, yield, shelf life, dry mass rate, seed weight and parthenocarpy. The results contribute not only to a better understanding of the effect of the new class of regulatory genes encoded by OVATE, but also have important agronomic implications, given that the ovate mutation has been used in the obtention of \'grape/plum\' tomato varieties and hybrids.

The Arabidopsis chitinase-like1 (Atctl1) mutant, pom1 is compromised in primary cell wall development, resulting in short roots when grown on high sucrose and shortened hypocotyls when grown in darkness. To better understand this phenotype and the evolution of AtCTL1 and its homologue, AtCTL2, we obtained a large number of CTL sequences and determined the phylogenetic relationships among them. Since microarray analysis had suggested a change in auxin response or homeostasis in pom1, I used the auxin reporter DR5::GUS in the pom1 background to assess changes in distribution. To assess whether the biochemical functions of AtCTL1 homologues in Arabidopsis and other plants are conserved, I transformed pom1 with AtCTL2 and CTLs from poplar (Populus trichocarpa x Populus deltoides clone H-11) and from Picea glauca (spruce) and assessed rescue of the pom1 phenotype. To further understand CTL expression and function, Arabidopsis and poplar CTL promoter::GUS fusions were also expressed in Arabidopsis, PopCTL1 overexpressed in Arabidopsis, and CTL expression down regulated in poplar by RNAi. Our results indicate that CTL genes represent an ancient family encoding proteins of conserved biochemical function. In dicots, represented by Arabidopsis and poplar) duplicated CTL genes are differentially expressed in conjunction with primary and secondary cell wall development, respectively. Mutation of these genes results in improperly formed primary walls in certain cell types in the case of AtCTL1, and an impairment in the differentiation of vascular bundles for AtCTL2. Overexpression of PopCTL1 in Arabidopsis seems to over stimulate the differentiation of vascular bundles, and our studies show that auxin distribution is altered in the Atctl1 mutant. Down regulation of PopCTL1 and PopCTL2 in poplar appears to phenocopy aspects of these mutations, resulting in secondary cell walls that appear to have less deposition of lignin and an accelerated production of secondary xylem respectively. While specific biochemical function(s) of CTL genes were not studied, potential functions are discussed.

The Arabidopsis chitinase-like1 (Atctl1) mutant, pom1 is compromised in primary cell wall development, resulting in short roots when grown on high sucrose and shortened hypocotyls when grown in darkness. To better understand this phenotype and the evolution of AtCTL1 and its homologue, AtCTL2, we obtained a large number of CTL sequences and determined the phylogenetic relationships among them. Since microarray analysis had suggested a change in auxin response or homeostasis in pom1, I used the auxin reporter DR5::GUS in the pom1 background to assess changes in distribution. To assess whether the biochemical functions of AtCTL1 homologues in Arabidopsis and other plants are conserved, I transformed pom1 with AtCTL2 and CTLs from poplar (Populus trichocarpa x Populus deltoides clone H-11) and from Picea glauca (spruce) and assessed rescue of the pom1 phenotype. To further understand CTL expression and function, Arabidopsis and poplar CTL promoter::GUS fusions were also expressed in Arabidopsis, PopCTL1 overexpressed in Arabidopsis, and CTL expression down regulated in poplar by RNAi. Our results indicate that CTL genes represent an ancient family encoding proteins of conserved biochemical function. In dicots, represented by Arabidopsis and poplar) duplicated CTL genes are differentially expressed in conjunction with primary and secondary cell wall development, respectively. Mutation of these genes results in improperly formed primary walls in certain cell types in the case of AtCTL1, and an impairment in the differentiation of vascular bundles for AtCTL2. Overexpression of PopCTL1 in Arabidopsis seems to over stimulate the differentiation of vascular bundles, and our studies show that auxin distribution is altered in the Atctl1 mutant. Down regulation of PopCTL1 and PopCTL2 in poplar appears to phenocopy aspects of these mutations, resulting in secondary cell walls that appear to have less deposition of lignin and an accelerated production of secondary xylem respectively. While specific biochemical function(s) of CTL genes were not studied, potential functions are discussed.

Rice is a very important culture in the South of Brazil, with productivity mean of 6 t ha-1, requiring large amounts of nitrogen. The biological nitrogen fixation (BNF) has already been established for legumes and in gramineous plants, microrganisms of the genus Azospirillum, Herbaspirillum, Gluconacetobacter and Burkholderia have potential to BNF and growth-promoting substances production. The aim of this work was to evaluate the influence of inoculation with diazotrophic bactéria above the performance of rice in the field. Diazotrophic bacteria were measured and isolated of nine rice cultivars in Rio Grande do Sul State. Using the NFb medium ((Azospirillum brasilense/lipoferum), JNFb (Herbaspirillum), JMV (Burkholderia), LGI (Azospirillum amazonense) and LGI-P (Gluconacetobacter), 58 isolates were obtained. From these, 10 isolates obtained in NFb medium (I-02, I-08, I-14, I-20, I-26, I-31, I-36, I-42, I-48 e I-54) and A. brasilense and A. lipoferum were evaluated in vitro the N2-fixing ability and indolacetic acid production. All for BNF, A. brasilense and A. lipoferum showed greater values (41,08 e 46,82 μg N mL-1, respectively) in relation to all the isolates evaluated (7,20 a 12,99 μg N mL-1). For indolacetic acid production, the I-31 isolate was the greatest producer (13,47 μg mL-1). In experiment of greenhouse A. brasilense e A. lipoferum were used I-14, I-31, I-54 isolates, and the rice cultivars IRGA-417, IRGA-419 e IRGA-420. In nutritive solution, A. lipoferum and I-54 isolate associated with IRGA-420 rice were the major producers of dry mass (13,11 e 13,22 mg plant -1, respectively) and in soil the greater values were for A. brasilense (20,40 mg plant-1) and the I-31 isolate (16,00 mg planta-1). In the fields, the populations of diazotrophic bacteria were evaluated and the parameters of rice growth as lenght, fresh and dry mass, lenght and weight of roots, total N-content of aerial parts and productivity of grains. The collections were performed on the 40, 90 e 120 day after seedling (DAS). Doses of 0, 60 and 120 kg N ha-1 and inoculant with Azospirillum brasilense or I-31 isolate inoculant were used. At the 135 DAS the harvest was proceeded. The population of endophytic bactéria in the different rice-growing stages was obtained in culture medium, revealing great numbers present in the roots. Verified an increase at the yield of rice grains of 26,91% was verified when inoculated with A. brasilense and 17,78% when inoculated with I-31, both without the use of the N-fertilizer. In the reccommended dose for rice at 120 120 kg N ha -1, the yield of inoculated rice with A. brasilense increased 31,85% over uninoculated control and unfertilizer-N. The data obtained allow to conclude that there is a possibility to use endophytic diazotrophics bacteria isolated from regional cultivars evaluated in vitro as microrganisms towards inoculants, permitting the reducing of costs from N-fertilizer and the maintenance of rice productivity. / O arroz é uma cultura importante no sul do Brasil, com produtividade de 6 t.ha-1, demandando grandes quantidades de nitrogênio. A fixação biológica de nitrogênio (FBN) já está estabelecida entre leguminosas, e entre as gramíneas, microrganismos dos gêneros Azospirillum, Herbaspirillum, Gluconacetobacter e Burkholderia apresentam potencial para FBN e produção de substâncias promotoras de crescimento. O objetivo deste trabalho foi avaliar a influência da inoculação de bactérias diazotróficas sobre o desempenho do arroz em campo. Foram quantificadas e isoladas bactérias diazotróficas de nove cultivares de arroz irrigado do Estado do Rio Grande do Sul. Utilizando os meios NFb (Azospirillum brasilense/lipoferum), JNFb (Herbaspirillum), JMV (Burkholderia), LGI (Azospirillum amazonense) e LGI-P (Gluconacetobacter), foram obtidos 58 isolados. Destes, 10 isolados obtidos em meio NFb (I-02, I-08, I-14, I-20, I-26, I-31, I-36, I-42, I-48 e I-54) e A. brasilense e A. lipoferum foram avaliados in vitro quanto à sua capacidade de FBN e produção de ácido indolacético. Quanto a FBN, A. brasilense e A. lipoferum apresentaram maiores valores (41,08 e 46,82 μg N mL-1, respectivamente) em relação a todos os isolados avaliados. Para produção de ácido indolacético, o isolado I-31 foi o maior produtor (13,47 μg mL-1). No experimento em câmara de crescimento utilizaram-se A. brasilense e A. lipoferum,os isolados I-14, I-31 e I-54 e as cultivares de arroz IRGA-417, IRGA-419 e BR-IRGA-420. Em solução nutritiva A. lipoferum e o isolado I-54 associados ao arroz BR-IRGA-420 foram os maiores produtores de massa seca (13,11 e 13,22 mg planta -1, respectivamente) e em solo os maiores valores foram para A. brasilense (20,40 mg planta-1) e o isolado I-31(16,00 mg planta-1). No campo foram avaliadas as populações de bactérias diazotróficas e os indicadores de crescimento do arroz, como altura, massa fresca e seca, comprimento e peso radiculares, N-total da parte aérea e rendimento em grãos. As coletas realizaram-se aos 40, 90 e 120 dias após a semeadura (DAS). Foram utilizadas doses de N de 0, 60 e 120 kg ha-1 e inoculantes contendo Azospirillum brasilense ou isolado I-31. Aos 135 DAS procedeu-se à colheita. A população de bactérias diazotróficas endofíticas nos diferentes estágios do arroz foi obtida em de meios de cultivos específicos, revelando grande número nas raízes. Verificou-se um incremento no rendimento em grãos do arroz de 26,91% quando inoculado com A. brasilense e 17,78% quando inoculado com I-31, ambos sem utilização de adubo nitrogenado. Na dose de N recomendada para o arroz, de 120 kg ha-1, o rendimento do arroz inoculado com A. brasilense aumentou 12,84% e o isolado I-31 aumentou 31,85% sobre o tratamento sem inoculação e sem adubação nitrogenada. Os dados obtidos permitem concluir que existem possibilidades de se utilizar bactérias diazotróficas endofíticas isoladas de cultivares da região e avaliadas in vitro como microrganismos para inoculantes, permitindo a redução dos custos de adubação nitrogenada e a manutenção da produção de arroz.

Os frutos do tomateiro (Solanum lycopersicum) apresentam elevada diversidade fenotípica, grande parte da qual deve-se a mutações em cinco genes, SUN (SUN), OVATE (O), LOCULE NUMBER (LC), FRUIT SHAPE 8.1 (FS8.1) e FASCIATED (FAS). Enquanto mutações em LC, O e FAS são responsáveis pela alteração no número de lóculos no fruto, mutações em FS8.1, SUN e O resultam em frutos mais alongados, sendo a última mutação o foco de estudo do presente trabalho. Apesar de ovate ser uma mutação importante tanto do ponto de vista agronômico quanto biológico, não é conhecido ainda o efeito exato da nova classe de gene regulatório codificado por esse locus. Por promover a drástica alteração no formato do fruto, característica esta que pode influenciar a preferência do consumidor, essa mutação é de grande interesse agronômico. Sob o ponto de vista biológico, o maior conhecimento da função desse gene resultaria em um maior entendimento do processo de frutificação. A análise de duplos mutantes ovate DR5::GUS e ovate ARR5::GUS mostrou que essa mutação altera o padrão de resposta a auxina e citocinina, respectivamente, durante o desenvolvimento do fruto. Além disso, foram realizados estudos que mostraram seu impacto no teor de sólidos solúveis, produtividade, tempo de prateleira, teor de matéria seca, peso das sementes e partenocarpia. Tais resultados não somente contribuíram para um melhor entendimento do efeito gênico da nova classe de genes regulatórios codificado por OVATE, como também fornecem importantes implicações agronômicas, já que a mutação ovate vem sendo utilizada na obtenção de variedades e híbridos do tipo \"grape\". / The fruits of tomato (Solanum lycopersicum) present a high phenotypic diversity, most of which can be attributed to mutations in five genes: SUN (SUN), OVATE (O), LOCULE NUMBER (LC), FRUIT SHAPE 8.1 (FS8.1) and FASCIATED (FAS). Whereas mutations in LC, O and FAS alter fruit locule number, mutations in FS8.1, SUN and O result in elongated fruits. The latter is the focus of the present work. ovate is a biologically and agronomically relevant mutation, however, the exact effect of the new class of regulatory gene it represents is unknown. The drastic alteration in fruit shape produced by the mutation can influence consumer preference, thus rendering it agronomically important. Biologically, a thorough characterization of its gene function would result in deeper understanding of fruit formation. Crosses to the marker lines DR5::GUS and ARR5::GUS showed that ovate alters the response pattern of auxin and cytokinin, respectively, during fruit development. Furthermore, studies are described showing its effect on total soluble solids content, yield, shelf life, dry mass rate, seed weight and parthenocarpy. The results contribute not only to a better understanding of the effect of the new class of regulatory genes encoded by OVATE, but also have important agronomic implications, given that the ovate mutation has been used in the obtention of \'grape/plum\' tomato varieties and hybrids.

Les cellules eucaryotes possèdent un territoire membranaire dit « électrostatique » qui est définit par la présence de phospholipides négativement chargés sur la face cytosolique des membranes. Cette propriété permet le recrutement de protéine cytosolique contenant des motifs/domaines positivement chargés au niveau des membranes via des interactions électrostatiques. Nous nous sommes demandés si le territoire électrostatique est présent chez les cellules végétales et quel est son organisation ? Quels sont le(s) lipide(s) anionique(s) impliqués dans son maintien ? Et quel est son (ces) rôle(s) dans la signalisation et le développement des plantes ? Premièrement, nous avons mis en avant que la membrane plasmique est le compartiment intracellulaire le plus électronégativement chargé (Simon, Platre et al., 2016 Nature Plants). Ce champ électrostatique est gouverné par trois lipides anioniques différents, l’acide phosphatidique, la phosphatidylserine et le phosphatidylinositol-4-phosphate. Nous avons montré que cette propriété unique de la membrane plasmique permet de réguler des voies de signalisation hormonale, tel que celle de l’auxine et des brassinostéroïdes. Notamment, la phosphatidylserine régule la dynamique spatiotemporelle des petites GTPases de la famille Rho. En réponse à l’auxine, ce lipide permet de regrouper les protéines Rho dans des domaines membranaires. La formation de ces domaines est requise pour l’activité de ces protéines permettant de contrôler l’endocytose, la dynamique du cytosquelette mais également régule la morphogenèse cellulaire ainsi que la réponse gravitropique de la racine. / The « electrostatic territory» is part of the eukaryotic membrane organization and is defined by the enrichment of negatively charged phospholipids at the membrane cytosolic face. This feature is involved in the membrane recruitment of cytosolic proteins, which contain positively charged motifs and/or domains. In this work, we used Arabidopsis thaliana as a model and explored the existence of an electrostatic territory in plant cells. We found that the plasma membrane is the most anionic intracellular membrane (Simon, Platre et al., 2016 Nature Plants). This electrostatic field is maintained by lipid cooperation between, phosphatidic acid, phosphatidylserine and phosphatidylinositol-4-phosphate. The cell surface unique feature is involved in the regulation of hormonal signalling such as auxin and brassinosteroids pathways. We found that phosphatidylserine tunes the spatiotemporal dynamics of small GTPases from the Rho family. During auxin response, PS is required to cluster Rho into specialized membrane domains. We show that nanocluster formation is required for Rho-mediated auxin signaling including the regulation of endocytosis, cytoskeleton organization, morphogenesis and the root gravitropic response.