O aumento contínuo das emissões de gases causadores do efeito estufa resulta em níveis elevados de aquecimento do planeta. Estes efeitos, relacionados à mudança do clima, representam impactos na saúde humana, na produção de alimentos, nos ecossistemas e no abastecimento hídrico. Com o abastecimento hídrico afetado, as águas de menor qualidade para fins de irrigação, tornam-se importantes fontes hídricas para produção de alimentos. Dessa forma, objetivou-se estudar a tolerância da mini melancia à salinidade, bem como a resposta da cultura ao incremento de CO2 atmosférico, sob irrigação salina e não salina. O primeiro experimento foi realizado na Escola Superior de Agricultura Luiz de Queiroz (ESALQ-Piracicaba), em casa de vegetação. Cultivaram-se plantas de mini melancia, cv. Smile, irrigadas com água de diferentes condutividades elétricas- CEa (1, 2, 3, 4 e 5 dSm-1) com o objetivo de estudar a tolerância das plantas, em função do estresse salino. O segundo experimento foi realizado no Centro Nacional de Pesquisa de Informática Agropecuária (CNPTIA-Campinas) em duas câmaras de crescimento. Com objetivo de estudar como o incremento do CO2 atmosférico afeta a tolerância à salinidade da mini melancia cv. Smile. Na primeira câmara de crescimento (C1), cultivaram-se as plantas irrigadas com águas de diferentes condutividades elétricas- CEa (1 e 5 dSm-1), com aumento da concentração atmosférica de CO2 para 800 ppm. Na segunda câmara de crescimento (C2), cultivaram-se as plantas irrigadas com as mesmas condutividades elétricas da C1, entretanto com a concentração de CO2 atmosférico de 400 ppm. A salinidade afetou negativamente e o aumento da concentração de CO2 afetou positivamente a massa e o tamanho dos frutos da mini melancia. Assim, conclui-se que a mini melancia cv. Smile é moderadamente sensível à salinidade e que o aumento da concentração de CO2 atmosférico favorece o desenvolvimento dos frutos irrigados com água salina e não salina. / The continued increase in emissions of greenhouse gas effect inducing gases results in the warming of the planet. These climate change-related effects impact human health, food production, ecosystems and water supply. With the water supply affected, lower quality water becomes a possible water source for food production. Thus, the purpose of this analysis was to study the tolerance of mini watermelon to salinity and the crop response to increasing atmospheric CO2 in saline and non-saline irrigation. The first experiment was conducted at the School of Agriculture \"Luiz de Queiroz\" (ESALQ-Piracicaba), under greenhouse conditions. Mini watermelon plants were cultivated and irrigated with water of different electrical conductivities-ECw (1, 2, 3, 4 and 5 dSm-1) with the purpose of observing the behavior of plants affected by salt stress. The second experiment was carred out at the National Center of Agricultural Informatics Research (CNPTIA-Campinas) in two different growth chambers. In the first growth chamber (C1), the plants were cultivated and irrigated with different electrical conductivities-ECw (1 and 5 dSm-1), with an increase of atmospheric CO2 concentration to 800 ppm. In the second growth chamber (C2), plants were grown and irrigated with the same electrical conductivities as in C1, though the atmospheric concentration was kept at CO2 400 ppm. The salinity negatively affected the mass and the size of the fruits of mini watermelon while the increased CO2 concentration had a positive effect. Thus, it is possible to conclude that the cv. Smile mini watermelon is moderately sensitive to salinity whereas the increasing atmospheric CO2 concentration favors the development of irrigated fruit with both saline and non-saline water.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O estresse salino à apontado como tendo impactos negativos sobre a produÃÃo de cultivares de interesse comercial. Nos Ãltimos anos os estudos tÃm focado na pesquisa e no entendimento dos mecanismos utilizados pelas plantas que toleram esse tipo de estresse naturalmente. Dentre as espÃcies que toleram ao estresse salino encontra-se Anacardium occidentale L. ou popularmente conhecida como Cajueiro. Trabalhos na literatura jà descrevem mecanismos que esse cultivar pode utilizar para suportar a condiÃÃo de estresse. Contudo, estudos adicionais que permitam obter uma visÃo global do processo sÃo requeridos para um melhor entendimento das vias que estÃo envolvidas em resposta ao estresse salino no Cajueiro. O presente trabalho objetivou a avaliaÃÃo da expressÃo global de genes em folhas de Cajueiro CCP76 com base no perfil transcriptÃmico em condiÃÃes normais e de estresse. Para tanto, fez-se induÃÃo do estresse salino com 150 mM de NaCl e as coletas de folhas foram realizadas apÃs 1, 3, 6 e 12 horas da adiÃÃo do sal. O transcriptoma das folhas foi montado utilizando-se o programa Velvet. Por fim, os dados identificados pela ferramenta BLAST foram classificados com base no Gene Ontology (GO) e KEGG Pathways. Os dados obtidos foram utilizados na anÃlise comparativa entre Ãs plantas em estresse salino e o controle. Foram obtidos um total de 9.133.193 e 10.787.002 leituras para condiÃÃo controle e estresse, respectivamente. Os resultados revelaram que os contigs com coberturas maiores que 50 vezes estavam relacionados as vias de produÃÃo de aminoÃcidos, metabÃlitos secundÃrios e enzimas antioxidativas. Tais resultados mostram as mudanÃas metabÃlicas sofridas pela espÃcie em estudo para adequaÃÃo Ãs condiÃÃes de estresse. Em suma, pÃde-se observar de forma eficiente as mudanÃas globais no metabolismo do cajueiro para adaptaÃÃo a condiÃÃo de estresse. Os resultados aumentam as informaÃÃes sobre as possÃveis vias que Anacardium occidentale L. usa para tolerar a condiÃÃo de estresse, alÃm de apontarem para elucidaÃÃo de novos mecanismos usada por tal organismo. Esse à o primeiro trabalho na literatura que analisou os impactos em transcritos nas primeiras horas de estresse salino em cajueiro. / Salt stress is touted as having negative impacts on the production of commercial cultivars interest. In recent years studies have focused on the research and understanding of the mechanisms used by plants to tolerate this kind of stress naturally. Among the species that tolerate salt stress is Anacardium occidentale L. or popularly known as Cashew. Studies in the literature have described the mechanisms that this cultivar can use to support the stress condition. However, additional studies to obtain an overall view of the process are required for a better understanding of the pathways that are involved in response to salt stress in Cashew. This study aimed to evaluate the global gene expression in leaves Cashew CCP76 based on transcriptomic profile in normal and stress condition. As such, there is induction of salt stress with 150 mM NaCl and collections of leaves were performed after 1, 3, 6 and 12 hours of salt addition. The leaves transcriptome assembled using the Velvet program. Finally, the data identified by the BLAST tool and were classified based on Gene Ontology (GO) and KEGG Pathways. The data were used in the comparative analysis between the plants in salt stress and control. A total of 9,133,193 and 10,787,002 reads were obtained for the control condition and stress, respectively. The results showed that contigs with covers greater than 50 times were related pathways for the production of amino acids, secondary metabolites and antioxidative enzymes. These results show metabolic changes undergone by the species under for adaptation to stress conditions. In short, it can be observed efficiently global changes in the metabolism of cashew for adaptation to stress condition. The results augment the information about possible routes that Anacardium occidentale L. uses to tolerate the stress condition, and also point to elucidate new mechanisms used by this organism. This is the first work in the literature that examined the impacts on transcripts in the early hours of salt stress on cashew.

Submitted by (edna.saturno@ufrpe.br) on 2016-06-15T13:07:09Z No. of bitstreams: 1 Aurenivia Bonifacio de Lima.pdf: 158583 bytes, checksum: c8dae3b865cbbb770850897214bbac02 (MD5) / Made available in DSpace on 2016-06-15T13:07:09Z (GMT). No. of bitstreams: 1 Aurenivia Bonifacio de Lima.pdf: 158583 bytes, checksum: c8dae3b865cbbb770850897214bbac02 (MD5) Previous issue date: 2008-02-15 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Physiologic and biochemical aspects of the two corianders cultivate submitted to the salinity were evaluated, have in view the effect on the development and the oxidative nature of the salt stress. Coriander plants of two cultivates (Tabocas and Verdão) were submitted at the tree levels of the NaCl (0, 50 and 100 mol.m-3). Were observed, weekely, the leaves number (LN) and the height (H). The fresh and dry biomass of the shoot (FBS and DBS) and root (FBR and DBR) was quantified and it was calculated the succulency of the shoot (SCS) and roots (SCR) and the absolute growth tax (AGT). Were determinate, still, sodium (Na+), chloride (Cl-) and potassium (K+) ions, free proline (FP), soluble protein (SP), total phenols (TP), total soluble carbohydrate (TSC), sucrose (SUC), reduce sugars (RS) analyze and peroxidase (POX) and poliphenol oxidase (PPO) enzimatic ativity. Data were analysed with the ASSISTAT program. Detrimental effects of NaCl were observed in the growth parameters of both cultivate studied, except in LN and DBR (in the cv. Tabocas). The Na+ and Cl- tenors increased while the K+ decreased, in the shoot and roots. The Na/K relationship reached values of up to 1,5. The FP, SP, TP, TSC, SUC and RS levels increased with the added of NaCl in the nutritious solution, as well as the enzymes activities of the POX and PPO. In general, Verdão cultivate it was the better grew in the salinity conditions imposed. / Aspectos fisiológicos e bioquímicos de cultivares de coentro submetidas à salinidade foram avaliados, tendo em vista o efeito sobre o desenvolvimento e a natureza oxidativa do estresse salino. Plantas de coentro de duas cultivare (Tabocas e Verdão) foram submetidas a três concentrações de NaCl (0, 50 e 100 mol.m-3). Foram observados, semanalmente, o número de folhas (NF) e a altura (ALT). Quantificou-se a biomassa fresca e seca da parte aérea (BFPA) e das raízes (BFR) e calculou-se a suculência da parte aérea (SCPA) e das raízes (SCR) e a taxa de crescimento absoluto (TCA). Determinaram-se, ainda, as concentrações de íons sódio (Na+), cloreto (Cl-) e potássio (K+), prolina livre (PL), proteína solúvel (PS), fenóis totais (FT), carboidratos solúveis totais (CST), sacarose (SAC), açucares redutores (AR) e a atividade enzimática de peroxidase (POX) e polifenoloxidase (PPO). Os dados foram analisados com o programa ASSISTAT. Foram observados efeitos danosos do NaCl nos parâmetros de crescimento em ambas cultivares, exceto no NF e BSR (na cv. Tabocas). Os teores de Na+ e Cl- aumentaram enquanto que os de K+ decresceram, na parte aérea e nas raízes. A relação Na/K alcançou valores de até 1,5. Os concentrações de PL, PS, FT, CST, AR e SAC acresceram com a adição do NaCl à solução nutritiva, bem como as atividades das enzimas POX e PPO. De modo geral, a cv. Verdão foi a que melhor se desenvolveu nas condições de salinidade impostas.

Submitted by (lucia.rodrigues@ufrpe.br) on 2016-08-03T14:52:48Z No. of bitstreams: 1 Jose Benjamin Machado Coelho.pdf: 973299 bytes, checksum: eedb2e1f9cf8814fb63a0c3a9a896d70 (MD5) / Made available in DSpace on 2016-08-03T14:52:48Z (GMT). No. of bitstreams: 1 Jose Benjamin Machado Coelho.pdf: 973299 bytes, checksum: eedb2e1f9cf8814fb63a0c3a9a896d70 (MD5) Previous issue date: 2012-02-24 / Salinization of soils is one of the abiotic stresses which most limits the growth and crop productivity. To withstand salt stress, plants have developed complex mechanisms which contribute to the adaptation to osmotic and ionic stresses. The cowpea, as a species adapted to semiarid conditions, can develop in saline environments without great loss. The quantification of the permanent wilting point constitutes an important information for water management in irrigated soils. Some researchers report that the soil permanent wilting point soil varies not only with soil texture, but also with the cultivated plant species. Two experiments carried out in a greenhouse at UFRPE, in Recife (Brazil), aiming to evaluate the effect of salt stress on plant growth, accumulation of organic solutes, water use and leaf osmotic potential, and determine the physiological wilting point of cowpea. The statistical design was completely randomized with a factorial 2 x 4, composed of two soil textures and four levels of soil electrical conductivity (4, 8 and 12 dS m-1 at 25°C, and the control without addition of salt, with five replications, totalizing 40 plots per experiment. Cowpea [Vigna unguiculata L. (Walp.)], cultivar pele de moça, was used as test crop. The results were subjected to analysis of variance and regression, using the statistical program SAEG. It was concluded that the permanent wilting point of cowpea was lower by the physiological method than as determined by Richards chamber; the osmotic potential of cowpea leaves decreases with increasing of soil salinity; soil salinity caused a reduction of plant height, leaf number and shoot dry biomass of cowpea and, the increase on soil salinity resulted in higher levels of proline and total soluble carbohydrates of cowpea. / A salinização de solos é um dos estresses abióticos que mais limita o crescimento e a produtividade das culturas. Para suportar o estresse salino, as plantas têm desenvolvido mecanismos complexos, que contribuem para a adaptação aos estresses osmótico e iônico. O feijão vigna, por ser uma espécie adaptada às condições semiáridas, consegue se desenvolver em ambientes salinizados sem grandes prejuízos. A quantificação do ponto de murcha permanente constitui-se numa importante informação para o manejo da água em solos irrigados. Alguns pesquisadores relatam que o ponto de murcha permanente do solo varia não apenas com a textura do solo, mas também com a espécie vegetal cultivada. Dois experimentos foram conduzidos em casa de vegetação da UFRPE, em Recife-PE (Brasil), com os objetivos de avaliar os efeitos do estresse salino no crescimento, acúmulos de solutos orgânicos, consumo de água e potencial osmótico foliar, bem como determinar o ponto de murcha permanente fisiológico do feijoeiro vigna. O delineamento estatístico utilizado foi o inteiramente casualizado, com arranjo fatorial 2 x 4, composto por: duas texturas de solos e quatro níveis de condutividade elétrica do solo (4, 8 e 12 dS m-1 a 25ºC, além da testemunha sem a adição de sais), com cinco repetições, totalizando 40 parcelas por experimento. Como cultura teste foi utilizada o feijão vigna [Vigna unguiculata L. (Walp.)], cultivar pele de moça. Os resultados foram submetidos à análise de variância e de regressão, através do programa estatístico SAEG. Concluiu-se que o ponto de murcha permanente do feijoeiro vigna é menor no método fisiológico que o determinado na câmara de Richards; o potencial osmótico das folhas do feijoeiro vigna diminui com o aumento da salinidade do solo; a salinidade do solo ocasiona a redução da altura da planta, do número de folhas e da biomassa seca da parte aérea do feijão vigna e, o aumento dos níveis de salinidade no solo proporciona elevação dos teores de prolina e de carboidratos solúveis totais do feijoeiro vigna.

Made available in DSpace on 2016-12-23T14:37:27Z (GMT). No. of bitstreams: 1 Luciano Bestete Oliveira.pdf: 543242 bytes, checksum: 21c93fc24ac23f97c9e16d4d24b93b6f (MD5) Previous issue date: 2011-08-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The impact of soil salinity on agricultural productivity is a serious problem, especially in arid and semiarid regions, which depend on irrigation to ensure an adequate supply of water for crops. In order to evaluate the soil chemical properties, development and production of corn from the use of different electrical conductivity of irrigation water, was mounted in an experiment in a completely randomized split plot with three 4 x 5 repetitions. The plots consisted of five levels of salinity of irrigation water with a conductivity of 0.1, 0.8, 1.6, 2.4 and 3.2 dS m-1 and the plots, four phenological stages corresponding vegetative growth, flowering, grain filling and physiological maturity. In each phenological phase, tests were carried out, the crop growth and soil chemical properties and the end of the experiment was determined to grain production. The application of irrigation water with different electrical conductivity reduced the dry mass of roots, shoots, leaf area, number and grain weight per plant of maize cultivar and soil PL6880 increased the availability of the calcium and sodium as well as the values of electrical conductivity of soil saturation and sodium saturation, sum of bases, cation exchange capacity and effective potential, followed by a decrease in pH value, content of aluminum and aluminum saturation. The levels of phosphorus, potassium, magnesium and potential acidity were not affected / O impacto da salinidade do solo sobre a produtividade agrícola é um sério problema, principalmente em regiões áridas e semiáridas, que dependem da irrigação para garantir um adequado suprimento de água para as culturas. Com o objetivo de avaliar os atributos químicos do solo, desenvolvimento e produção de milho decorrentes do uso de diferentes condutividades elétricas da água de irrigação, foi montado um experimento no delineamento inteiramente casualizado no esquema de parcelas subdivididas 5 x 4 com três repetições. As parcelas constituíram-se em cinco níveis de salinidade da água de irrigação com condutividade de 0,1; 0,8; 1,6; 2,4 e 3,2 dS m-1 e nas subparcelas, quatro fases fenológicas da cultura correspondentes ao crescimento vegetativo, floração, enchimento de grãos e maturação fisiológica. Em cada fase fenológica, foram realizadas as análises, do crescimento da cultura e dos atributos químicos do solo e ao final do período experimental foi determinada a produção de grãos. A aplicação de água de irrigação com diferentes condutividades elétricas reduziu a massa seca das raízes, da parte aérea, a área foliar, o número e peso de grãos por planta da cultivar de milho PL6880 e no solo aumentou a disponibilidade dos teores de cálcio e sódio, bem como os valores da condutividade elétrica do solo, saturação por bases e saturação por sódio, soma de bases, capacidade de troca de cátions potencial e efetiva, seguindo-se a diminuição nos valores do pH, teor de alumínio e saturação por alumínio. Os teores de fósforo, potássio, magnésio e acidez potencial não foram afetados

Submitted by Mario BC (mario@bc.ufrpe.br) on 2017-04-18T13:02:05Z No. of bitstreams: 1 Joao Paulo Rodrigues da Silva.pdf: 4322694 bytes, checksum: 73622fb6c482c2976842cc2ad9b5745a (MD5) / Made available in DSpace on 2017-04-18T13:02:05Z (GMT). No. of bitstreams: 1 Joao Paulo Rodrigues da Silva.pdf: 4322694 bytes, checksum: 73622fb6c482c2976842cc2ad9b5745a (MD5) Previous issue date: 2015-10-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The use of tolerant to salinity cultivars and techniques that promotes good agricultural yields in saline soils is important. The objective was to evaluate the activation of defense responses to salt stress induced by halo-priming in plant cowpea cultivars, coming from pre-conditioned seeds. The experiment was carried out in randomized completely design in a greenhouse in a factorial 3x4 and 2x3x3, with three repetitions. The plot was represented by a pot, size 3 dm3, with one plant per pot. Were used two (2) levels salinity: E0, with 0 mmol NaCl and E1 with 60 mmol NaCl in the nutrient solution; three (3) halo-priming levels: HP0, no priming, HP1 immersion in solution with 30 mmol NaCl for 2 hours and HP2, immersion in 60 mmol NaCl for 2 hours; and four (4) cultivars, C1: Canapu, C2: Epace 10; C3: IPA 206 and C4: IPA Miranda 207. The treatment salt stress (E1) started 20 days after planting. They were made germination index evaluation (GI) and emergence speed index (ESI), before the start of the salt stress treatments. After the salt stress treatments, at 60 days after planting, the following biometric evaluations (plant height, stem diameter, dry weight of shoot and root dry weight), percentage reduction evaluation of shoot and chemical evaluations of sodium and potassium. Statistical analysis was done using analysis of variance and average comparison tests, using the electronic program SISVAR. Better results were seen for germination speed index in the Miranda IPA 207 and IPA 206 cultivars when subjected to halo-priming. The height of the main branch was significantly reduced in salt stress situation. The treatments with the presence of halo-priming increased the average stem diameter in Epace 10 and IPA 206 cultivars. The halo-priming with 30 mmol of NaCl for 2 hours significantly increased the root dry weight of cultivars. For dry weight of shoots to grow Canapu had the highest average under salt stress and absence of halo-priming. To the sodium content in the plant, best responses were observed when using the halo-priming 30 mmol NaCl. To the potassium content to cultivate Canapu showed better responses when used halo-priming 60 mmol NaCl. Conclude that the cultivar Canapu is moderately tolerant to irrigation water with salt concentration of 60 mmol NaCl in the vegetative phase. The halo-priming with a concentration of 30 mmol of NaCl can be given to remediate the salt stress in cultivating Canapu. / O emprego de cultivares tolerantes ao estresse salino e de tecnologias que favoreçam bons rendimentos agrícolas em solos salinos são importantes. O objetivo do trabalho foi avaliar a ativação de respostas de defesa, frente ao estresse salino, induzidas por halo-priming em plantas de cultivares de feijão-caupi, oriundas de sementes pré-condicionadas. O experimento foi montado em delineamento inteiramente casualisado, em casa de vegetação, em esquema fatorial 3x4 e 2x3x3, com 3 repetições. A parcela foi representada por um vaso, volume de 3 dm3, com uma planta por vaso. Foram utilizados dois (2) níveis de salinidade: E0, sem NaCl e E1, com 60 mmol de NaCl na solução nutritiva; três (3) níveis de halo-priming: HP0, ausência de priming, HP1 imersão em solução com 30 mmol NaCl por 2 horas e HP2, imersão em 60 mmol NaCl por 2 horas; e quatro (4) cultivares, C1 Canapu, C2 EPACE 10, C3 IPA 206 e C4 Miranda IPA 207. O tratamento salino (E1) foi iniciado 20 dias após o plantio. Foram feitas avaliações de índice de germinação (IG) e índice de velocidade de emergência (IVE), antes do início dos tratamentos salinos. Após tratamentos salinos, aos 60 DAP, foram feitas avaliações biométricas (altura de planta, diâmetro do caule, massa seca da parte aérea e massa seca de raiz), avaliação de redução percentual de MSPA e avaliações químicas (teores de Sódio e Potássio). Foi feita análises de variância e teste de comparação de média, com utilização do programa eletrônico SISVAR. Plantas das cultivares Miranda IPA 207 e IPA 206, oriundas de halo-priming, obtiveram melhores respostas para IVE. A altura do caule foi reduzida significativamente em situação de estresse salino. Para diâmetro do caule, em condições de estresse salino, foi observada redução da média, nas plantas oriundas de pré-condicionamento halo-priming. Nas plantas cultivadas em condições de estresse, oriundas do halo-priming 30 mmol de NaCl, foi observado menor média para MSR e entre as cultivares a IPA 206, teve maior média. Para massa seca da parte aérea, na condição de estresse salino e ausência de halo-priming, foi observado maior média na cultivar Canapu, comprovando sua tolerância ao estresse salino. Para os teores de sódio na planta, foram observadas melhores respostas quando utilizado o halo-priming de 30 mmol de NaCl. Para o teor de potássio, a cultivar Canapu apresentou melhores respostas quando utilizado o halo-priming de 60 mmol NaCl. Conclui-se que a cultivar Canapu é moderadamente tolerante à água de irrigação com concentração salina de 60 mmol de NaCl na fase vegetativa. O halo-priming com concentração de 30 mmol de NaCl pode ser indicado para remediar o estresse salino na cultivar Canapu.

Salt stress is a severe environmental challenge in agriculture, limiting the quality and productivity of the crops around the globe. Plant growth promoting rhizobacteria (PGPR) is proposed as a friendly solution to overcome those challenges. The desert plant endophytic bacterium, Enterobacter sp. SA187 has shown plant growth promotion and salt stress tolerance beneficial effect on the model plant Arabidopsis thaliana in vitro as well as under the field conditions on different crops. SA187 has a distinguished morphology of yellow colonies (SA187Y) that could be due to carotenoid biosynthesis. However, the bacteria tend to lose the yellow color upon incubation with the plants and the colonies turn to white (SA187W). In comparison to SA187Y, SA187W shows 50% reduction on the beneficial impact on A. thaliana fresh and dry weight of root and shoot system. By counting the CFU/plant, we showed that SA187Y and SA187W both have similar colonization rate in both shoots and roots. Under non-salt conditions, optimal bacterial colonization was observed on day 8 after inocubation, however, under the salt stress condition, the optimal colonization was observed at day 4. Moreover, during the time period of the incubation of the SA187Y with the plants, there was a consistent noticeable loss of the yellow color of the colonies. This change in color is only observed eight days after transfer and the number of white colonies increases with the increase of the incubation time. In addition, SA187W was GFP-tagged by Tn7 transposon system and visualized by confocal laser scanning microscopy. The SA187W-GFP colonies have shown a similar colonization pattern as SA187Y-GFP, bacteria were colonizing the differentiation zone and cell elongation zone in the roots. Finally, the gene expression of the carotenoid biosynthesis pathways genes in SA187Y showed an overall higher gene expression compared to SA187W. In conclusion, the color loss seems to affect the beneficial impact of the bacteria on plants. However, the reduced beneficial impact is not due to the colonization efficiency of bacteria on the plant roots but could be due to a regulation of gene expression of carotenoid biosynthesis.

Here, we embarked a bioprospecting project that focuses on the isolation and characterization of plant root endophytes, collected from the Thar Desert. A total of 381 endophytes were isolated and based on their 16S rRNA gene sequences, genus Bacillus (58 strains) was identified as the major taxon and only endophytes from this genus were isolated from all plant types. Of the 58 Bacillus strains, only 16 strains were selected for screening of plant growth promotion traits such as P and Zn solubilization, indole-3-acetic acid and siderophore production, and antimicrobial activity. Based on the presence of specific plant growth promotion traits 10 strains were shortlisted for further in vitro screening with A. thaliana; to confirm that these bacteria can confer resilience to plants under salt stress conditions. B. circulans (PK3-15 and PK3-109), B. cereus (PK6-15) B. subtilis (PK3-9) and B. licheniformis (PK5-26) displayed the ability to increased the fresh weight of A. thaliana under salt stress conditions by more than 50 % compared to the uninoculated control. An interesting observation was that B. circulans (PK3-109) (shown to produce IAA exopolysaccharide) and B. circulans (PK3-138) (shown to produce IAA) in vitro results were substantially different as B. circulans (PK3-138) decreased the total fresh weight of A. thaliana by 47 %, whilst B. circulans (PK3-109) was one of the best performing strains. Thus, the genomes of these two strains were sequences to unravel the molecular versatility of B. circulans strains, specifically with respect to their interaction with plants. Most of the genome of these strains is identical but the most interesting feature was the presence of 1/ the DegS–DegU two-component system that is known to mediate the salt stress response and DegU also represses toxin wapA similar to antitoxin wapI, and 2/ YxiG, a gene in the unique orthogroup of PK3-109 was found to be linked to WapI. Thus, PK3-138 substantially decreasing the total fresh weight of A. thaliana under salt stress conditions suggests that the toxic activity of a toxin such as WapA is not effectively ameliorated by the antitoxin such as WapI in the absence of a functional YxiG gene.

Arid and semi-arid regions, mostly found in developing countries with exponentially increasing populations, are in chronic lack of water thereby severely limiting agricultural production. Irrigation with saline water, which is available in large quantities, could be an obvious solution, but current crops are all salt sensitive. Although major efforts are underway to breed salt tolerant crops, no breakthrough results have yet been obtained. One alternative could rely on plant-interacting microbiota communities. Indeed, rhizophere and endosphere microbial communities are distinct from those of the surrounding soils, and these specific communities contribute to plant growth and health by increasing nutrient availability or plant resistance towards abiotic and biotic stresses. Here we show that plant microbe interactions induce plant tolerance to multiple stresses. From a collection of strains isolated from the desert plant Indigofera argentea, we could identify at least four different strategies to induce salt stress tolerance in Arabidopsis thaliana. A deep analysis of Enterobacter sp. SA187 showed that it induces Arabidopsis tolerance to salinity through activation of the ethylene signaling pathway. Interestingly, although SA187 does not produce ethylene as such, the association of SA187 with plants induces the expression of the methionine salvage pathway in SA187 resulting in the conversion of bacterially produced 2-keto-4-methylthiobutyric acid (KMBA) to ethylene. In addition, a metabolic network characterization of both SA187 and Arabidopsis in their free-living and endophytic state revealed that the sulfur metabolic pathways are strongly upregulated in both organisms. Furthermore, plant genetic experiments verified the essential role of the sulfur metabolism and ethylene signaling in plant salt stress tolerance. Our findings demonstrate how successful plant microbes of a given community can help other plants to enhance tolerance to abiotic stress, and reveal a part of the complex molecular communication process during beneficial plant-microbe interaction.

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第19085号 / 人博第738号 / 新制||人||177(附属図書館) / 26||人博||738(吉田南総合図書館) / 32036 / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 瀬戸口 浩彰, 教授 加藤 眞, 教授 市岡 孝朗 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DGAM