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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
371

Characterization of the biological function of AtEXO70E2

Yin, Zhao 01 February 2018 (has links)
Exocyst positive organelle (EXPO) is a newly discovered double membrane organelle involved in exocytosis and likely other vesicle trafficking processes. EXPO is likely generated from the ER, fused with plasma membrane and released a single membrane vesicle to cell exterior. The Arabidopsis protein Exo70E2 was found to be associated with EXPO and therefore is considered as a marker of EXPO and might play a role in EXPO-mediated vesicle trafficking. Understanding the biological function of AtExo70E2 (abbreviated as E2 in this thesis) will be very helpful in unraveling the function of EXPO. The aim of this work was to use various molecular, genetic and physiological approaches to determine the possible role of Arabidopsis Exo70E2 in biological pathways. By using the Exo70E2pro:GUS line, the expression pattern of Exo70E2 was determined. Exo70E2 was expressed mainly in roots, especially in root tips and epidermal cells in the division and elongation zones of roots. Its expression level was induced when the seedlings were treated with Flg22, a peptide derived from bacterial flagillin protein that induces the plant defense response. The tissue subcellular localization of Exo70E2 was also studied using the 35S:Exo70E2-eYFP and Exo70E2pro:Exo70E2-GFP reporter lines. The GFP fusion protein was found primarily in the epidermal cells of roots even in the 35S:Exo70E2-eYFP lines. For phenotypic analysis resulting from mutations of the Exo70E2 gene, I obtained three T-DNA insertion mutant lines and generated its overexpression lines. The two mutant alleles, e2-2 and e2-3 are in the Columbia ecotype background and further characterized. e2-2 which has a T-DNA insertion in an exon is likely a knock out line as Exo70E2 gene transcript could not be detected. e2-3, which carries a T-DNA insertion in its promoter region, was found to accumulate a higher level of the transcript, suggesting that the insertion causes its enhanced expression of Exo70E2. There was no obvious difference between wild type and e2-2 in their phenotypes under different conditions tested in this study. However, e2-3 had a retarded growth phenotype when grown in soil or on MS medium. The seedlings of e2-3 on MS medium also had a yellowish color although such a phenotype was not obvious when they were grown in soil. When supplementing the MS medium with sucrose, glucose or mannitol, the growth of e2-3 was more reduced compared to wild type under these conditions. However, on the medium with NaCl or under phosphate deficiency, the yellowish phenotype of e2-3 was rescued and the mutant seedlings became relatively healthier than the seedlings under the regular MS medium. A proteomics approach was taken to compare protein secreted from the seedlings of wild type and the mutants. Proteins secreted by seedlings to the liquid medium were collected, concentrated and subjected to MS analysis. Comparison of the profiles of secreted proteins between the wild type and the mutants leaded to identification of candidate proteins whose secretion might be affected by the mutation. My study indicates that Exo70E2 and EXPO are involved in transporting proteins (likely also metabolites) to the exterior of cells and the rhizosphere and might play an important role in stress responses.
372

The role and position of diel [Ca2+]cyt oscillations in the Arabidopsis thaliana circadian clock

Witterick, Eleanor January 2013 (has links)
Cytosolic free calcium (Ca2+cyt) is a ubiquitous second messenger in eukaryotes. In Arabidopsis thaliana, diurnal or circadian (diel) rhythms in [Ca2+]cyt have been widely documented. There is evidence to suggest that these diel [Ca2+]cyt oscillations modulate different signalling pathways, including photoperiodic signal transduction, gating responses to endogenous and environmental stimuli and feed-back entrainment of the core circadian clock itself. However, direct evidence for the role of Ca2+ in clock entrainment or as an output from the clock is lacking, and the question of the functional role of diel [Ca2+]cyt oscillations remains open. The role of diel [Ca2+]cyt rhythms in A. thaliana and their relationship relative to the central molecular oscillator was investigated. While it was found that diel [Ca2+]cyt oscillations persist throughout the life cycle of A. thaliana, I found no indication that diel [Ca2+]cyt rhythms are involved in photoperiodic signalling. Furthermore, I demonstrated that normal diel [Ca2+]cyt oscillations persist even in the absence of a functioning core circadian clock, indicating that, contrary to the accepted view, diel [Ca2+]cyt oscillations are not directly controlled by the core circadian clock, but are more probably generated by a non-transcriptional oscillator. In silico analysis of the amino-acid sequences of the 12 core clock proteins revealed that TOC1 contains a putative EF-hand and may therefore provide a route into the molecular oscillator for diel [Ca2+]cyt signals. The TOC1 sequence was altered to eliminate the Ca2+ coordinating residues but attempts to express this protein in E. coli, N. benthamiana and Baculovirus were unsuccessful. Complementation of the A. thaliana toc1-1 mutant with transgenes containing the endogenous TOC1 promoter sequence upstream of the wild type or the altered TOC1 sequences were also unsuccessful. A series of experiments were conducted to provide empirical data for Boolean Logic models of circadian rhythmicity that would enable further characterisation of the potential link between diel [Ca2+]cyt oscillations and TOC1.
373

Tvorba konstruktů pro studium funkce DRM1 u Arabidopsis thaliana

Veselá, Petra January 2014 (has links)
The aim of the study called Creating of constructs for study of function DRM1 in Arabidopsis thaliana was to create a construct harbouring the gene of interest DRM1 (dormancy-associated protein), and other components necessary for successful transgenosis, by which will be transformed Arabidopsis thaliana plants in order to study the function of this gene in the plant organism. DRM1 function has not been identified yet, but the gene was annotated as putative dormancy-associated protein. The final gene cassette, containing DRM1 gene under promoter for the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), was inserted into the vector pGreen II giving the recombinant plasmid pWell17A whose completeness was verified by restriction analysis. The Rubisco promoter ensure DRM1 gene overexpression in transgenic plants and on the basis of this overexpression is determined DRM1 gene function.
374

Ovlivnění odpovědi rostlin na teplotní stres modulovanými hladinami cytokininů - fenomická a protemická analýza

Vícha, Daniel January 2015 (has links)
Cytokinins are important group of phytohormones regulating many physiological processes ranging from cell division to programmed cell death. This thesis is focused on effects of cytokinin levels in response to heat stress in Arabidopsis thaliana. Analysis of transgenic plants with regulated expression of ipt and HvCKX showed that cytokinins and their optimal levels play important role in the morphological alterations induced by heat stress. Seedlings with increased and decreased levels of cytokinins exhibit inhibition of petioles growth, decreased length of blades of true leaves and reduced leaf area. To obtain insights into molecular events underlying early response to heat stress LC-MS analysis of whole proteom was performed. Analysis revealed 57 differentialy regulated proteins in response to heat stress in Columbia ecotype. On the cellular level, most of the proteins were located in cytosol (47 %) nebo plastids (32 %). Coparative analysis between wild-type seedlings and seedlings with decreased level of cytokinins confirmed 31 proteinInfluencing plant responses to temperature stress modulating cytokinin levels - fenomic and proteomic analysiss regulated by cytokinins in response to heat stress. Among these proteins, desarurase 7 and Tudor SN1 protein were previously found as important factors in response to heat stress.
375

Alterações fisiológicas causadas pelo arsênio, genotoxidade e importância do mecanismo mismatch repair no reparo do DNA em Arabidopsis thaliana / Physiological changes caused by arsenic, genotoxicity and importance of mismatch repair mechanism in DNA repair in Arabidopsis thaliana

Barbosa, Alice Pita 02 April 2013 (has links)
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-03-29T11:03:04Z No. of bitstreams: 1 texto completo.pdf: 3774617 bytes, checksum: 197f3ca5359c93c3476e850581110d85 (MD5) / Made available in DSpace on 2017-03-29T11:03:04Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3774617 bytes, checksum: 197f3ca5359c93c3476e850581110d85 (MD5) Previous issue date: 2013-04-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O arsênio (As) é um elemento não só tóxico, mas também altamente genotóxico aos seres vivos. Muitas lacunas precisam ser preenchidas com relação aos processos causadores de toxidade do As em plantas, bem como os mecanismos de tolerância e sensibilidade a este metalóide. Para isso, plantas de Arabidopsis thaliana (WT, mutantes msh2 e transgênicas repórteres em mutações) e Allium cepa foram expostas a 0, 2, 8 e 16 mg As L -1, durante cinco dias, em sistema hidropônico ou em meio de cultura. As plantas acumularam grandes teores de As nas raízes e apresentaram elevado fator de translocação para a parte aérea, e também alterações no acúmulo de nutrientes. Os sintomas visuais se intensificaram com o aumento da concentração de As na solução nutritiva. As raízes adquiriram coloração escura e aspecto gelatinoso, danificado e aumento no comprimento e densidade dos pêlos; a parte aérea apresentou aumento dos teores de antocianinas e sinais de senescência precoce, bem como alterações na espessura de tecidos. O estresse oxidativo e a redução dos teores de fósforo foram apontados como os principais efeitos do As capazes de causar toxidez, evidenciando os danos indiretos deste elemento no organismo. Foram verificadas importantes alterações fotossintéticas, bem como indícios de danos ao processo de respiração celular devido o aumento da expressão de genes codificantes de oxidases alternativas. Também foram observadas alterações nos teores de açúcares em folhas jovens, maduras e raízes. O As promoveu fragmentação do DNA nos ápices radiculares de A. cepa e aumento das taxas de mutação pontual e de recombinação-não homóloga em A. thaliana. O significativo aumento da expressão dos genes msh2 e msh7, codificadores de enzimas-chave do processo mismatch repair, que realiza o reparo de bases danificadas ou erroneamente inseridas no DNA, sugeriu a importância deste mecanismo no combate à genotoxidade do As em A. thaliana. Isso foi confirmado pela maior sensibilidade observada nas plantas mutantes msh2 ao As, detectada visualmente via aumento da peroxidação de lipídios. Observou-se inibição da atividade da protease caspase-3, associada ao processo de morte celular programada, reforçando a capacidade de inibição da atividade enzimática pelo As. / Arsenic (As) is not only a toxic element, but also highly genotoxic to living organisms. Several gaps in our understanding of As toxicity in plants need to be filled, including the mechanisms that result in tolerance and sensitivity to this metalloid. For this reason Arabidopsis thaliana plants (WT, msh2 mutants and transgenic reporters in mutation process) and Allium cepa were exposed to 0, 2, 8 e 16 mg As L -1, for five days, in a hydroponic system or in culture medium. The plants accumulated large amounts of As in roots and presented a high translocation factor to the shoot, and also showed changes in nutrient accumulation. The visual symptoms have intensified with the increasing of As concentration in the nutritive solution. Roots showed dark coloration and a damaged and gelatinous aspect, with increased roots hair length and density. The shoots showed accumulation of anthocyanins and signs of early senescence, as well as changes in tissue thickness. Oxidative stress and reduction of phosphorus concentration in tissues have been implicated as the main cause of toxicity, evidencing the indirect damage from this element in the organism. Important changes in photosynthesis were observed, as signs of damage to respiration, due to increased expression of alternative oxidase genes. Thus, changes in the levels of synthesis and utilization of sugars by plants were observed. As promoted DNA fragmentation in A. cepa and increased rates of point mutation and nonhomologous recombination. The significant increase in the expression pattern of the msh2 and msh7 genes, which encode key enzymes in DNA repair process, suggests the importance of this mechanism in defense against As genotoxicity in A. thaliana. This was confirmed by the greater sensitivity observed in msh2 mutants to As as indicated by visual symptoms and by an increase in lipid peroxidation. Inhibition of the activity of the caspase-3 protease was also observed, evidencing the As capacity of enzyme activity inhibition. / Tese enviada pela secretaria do curso por e-mail, em 28-03-17.
376

Functional characterization of the mitochondrial adenine nucleotide transporter (ADNT1) in Arabidopsis thaliana under dark-induced senescence / Caracterização functional do transportador mitochondrial de nucleotídeos de adenina (ADNT1) em plantas de Arabidopsis thaliana submetidas à condição de senescência induzida pela escuridão

Pereira, Paula da Fonseca 28 February 2013 (has links)
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-03-29T11:17:16Z No. of bitstreams: 1 texto completo.pdf: 905568 bytes, checksum: 94c53779a921ceebf36267e09ef933a1 (MD5) / Made available in DSpace on 2017-03-29T11:17:16Z (GMT). No. of bitstreams: 1 texto completo.pdf: 905568 bytes, checksum: 94c53779a921ceebf36267e09ef933a1 (MD5) Previous issue date: 2013-02-28 / Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Ao contrário de outros transportadores de ADP/ATP, ADNT1 é o único que medeia um antiporte um de ATP preferencialmente por AMP, e, em menor grau, por ADP. Um trabalho prévio sugere que a expressão ADNT1 é maior em pontas de raízes e em tecidos senescentes. Considerando a elevada expressão de ADNT1 em tecidos senescentes, nos propusemos a investigar o papel do ADNT1 durante o processo de senescência induzida pelo escuro. Sob estas condições, plantas mutantes de Arabidopsis thaliana deficientes na expressão do transportador ADNT1 exibiram uma senescência antecipada em relação ao tipo selvagem, como evidenciado tanto pelo fenótipo visual das plantas após o crescimento em longos períodos de escuridão, como pela perda de clorofilas e da capacidade fotossintética. O tratamento prolongado de escuro levou, em geral, a um declínio mais rápido nos mutantes do que nos do tipo selvagem nos teores de clorofila e nos níveis de sacarose e de proteínas. Por outro lado, os níveis de aminoácidos totais e de alguns intermediários do ciclo TCA, como malato, fumarato e isocitrato geralmente aumentaram significativamente nos mutantes no final do tratamento de escuro. As razões NADH/NAD + e NADPH/NADP+ também se apresentaram maiores nos mutantes em comparação com o tipo selvagem, com a progressão da escuridão. Além disso, as plantas mutantes apresentaram sintomas de senescência precoce em comparação ao tipo selvagem, mesmo sob condições tidas como não estressantes. Estes dados demonstram, assim, que ADNT1 não é funcionalmente redundante aos previamente caracterizados transportadores de ADP/ATP, especialmente durante a falta de carbono, e reforçam a função potencial de ADNT1 no fornecimento da energia necessária para suportar o crescimento de tecidos vegetais heterotróficos. / Unlike other ADP/ATP carriers, ADNT1 is the only one that mediates an antiport of ATP, AMP, and, to a lesser extent, ADP and the corresponding deoxyadenine nucleotides. Previous work observed that ADNT1 expression is much stronger in root tips and senescing tissues. Considering the high expression of ADNT1 in senescing tissues, we have investigated the role of ADNT1 during the process of dark-induced senescence. Under these conditions, Arabidopsis thaliana mutants deficient in the expression of ADNT1 transporter displayed a similar, yet milder, early onset of senescence as evidenced both by the visual phenotype of plants following growth in extended periods of darkness and the loss of chlorophyll and photosynthetic competence. The extended dark treatment led in general to a more rapidly decline in the mutants than in the wild type in the levels of sucrose and protein. By contrast, the levels of total amino acids and TCA cycle intermediates malate, fumarate and isocitrate generally increased significantly in the mutants at the end of dark treatment. The NADH/NAD + and NADPH/NADP+ ratios also increased in mutants in comparison to the wild type with progression of the darkness. Additionally, the mutant plants exhibited symptoms of early senescence in comparison to the wild type even under optimal conditions. Altogether the data obtained demonstrate that ADNT1 is not functionally redundant to the previously characterized ADP/ATP carriers, especially during carbon starvation and reinforce the potential function for ADNT1 in the provision of energy which is required to support growth in heterotrophic plant tissues. / Não foi localizado o cpf do autor. Tese enviada pela secretaria do curso por e-mail, em 28-03-17.
377

Reconstituição da via de sinalização antiviral mediada por NIK1 de Arabidopsis em tomateiros / Reconstitution of the Arabidopsis NIK1-mediated antiviral signaling in tomato

Ávila, Larissa Gabriela Morais de 21 July 2017 (has links)
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2018-04-19T17:29:27Z No. of bitstreams: 1 texto completo.pdf: 1046673 bytes, checksum: 303cdb874bd37b4e599895a7138301a8 (MD5) / Made available in DSpace on 2018-04-19T17:29:27Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1046673 bytes, checksum: 303cdb874bd37b4e599895a7138301a8 (MD5) Previous issue date: 2017-07-21 / Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Recentemente, uma nova camada de defesa antiviral foi caracterizada em Arabidopsis thaliana, que é mediada pelo receptor NIK (NSP-Interacting Kinase) e protege a planta contra begomovirus. Quando a planta é infectada por um vírus, NIK1 oligomeriza com outro receptor imune ou com NIK1 para transfosforilar um ao outro e consequentemente, ativar o domínio cinase de NIK1. NIK1 é capaz de se ligar a proteína ribossomal L10 (RPL10), e é capaz de mediar sua fosforilação e subsequente translocação ao núcleo, onde RPL10 interage com LIMYB (L10-interacting Myb domain-containing protein) para regular negativamente a expressão de genes de proteínas ribossomais, levando a supressão global da tradução. Os mRNAs virais não são capazes de escapar ao mecanismo de regulação de tradução do hospedeiro, aumentando assim a resistência contra begomovirus. A proteína viral NSP interage com NIK1 e inibe sua atividade cinase, aumentando a patogenicidade do begomovírus em seu hospedeiro. Foi demonstrado em trabalhos anteriores que o mutante NIK1-T474D é um excelente alvo para engenharia genética, pois é constitutivamente ativada em linhagens transgênicas. Nesse trabalho, primeiramente foi realizado a reconstrução in silico da via de sinalização antiviral mediada por NIK1 em tomateiro, identificando possíveis componentes homólogos dessa via. Em seguida, foi examinada a possibilidade do duplo mutante T474D-T469A de conferir resistência contra begomovírus em linhagens transgênicas de tomateiro. Além disso, a linhagem transgênica NIK1-T474D-T469A foi transformada com o componente a jusante da via de sinalilzação antiviral, LIMYB de Arabidopsis, e examinamos o efeito da reconstituição dessa via de defesa durante a infecção viral. Os resultado dessa investigação indicam que a expressão de NIK1-T474D/T469A em linhagens transgênicas de tomateiro foi efetiva para suprimir a expressão de genes ribossomais, indicando que o duplo mutante é constitutivamente ativado em tomateiro. Além disso, a expressão de LIMYB em combinação com NIK1-T469A/T474D promoveu um efeito aditivo na repressão dos genes de proteínas ribossomais, possivelmente revelando uma melhorestratégia para obtenção de resistência a begomovírus. Para averiguar essa hipótese, as linhagens transgênicas foram desafiadas com os begomovírus de tomateiro ToYSV e ToSRV e a infecção foi monitorada por meio de sintomatologia e quantificação do DNA viral. Os resultados demonstraram que a expressão de NIK1-T469A/T474D em combinação com LIMYB é potencialmente um alvo melhor para modificar geneticamente genótipos suscetíveis. / Recently, a new layer of antiviral defenses was characterized in Arabidopsis thaliana, which is mediated by the immune receptor NIK (NSP-Interacting Kinase) and protects plants against begomoviruses. Upon virus infection, NIK1 oligomerizes with itself or another immune receptor to transphosphorylate one another and to activate the NIK1 kinase domain. Activated NIK1 mediates the phosphorylation of the ribosomal protein L10 (RPL10) and subsequent translocation to the nucleus, where RPL10 interacts with LIMYB (L10-interacting Myb domain-containing protein) to down-regulate the expression of ribosomal protein genes, leading to global translation suppression. The viral mRNAs are not able to escape this host translation regulatory mechanism enhancing host resistance against begomoviruses. The viral protein NSP interacts with NIK1 and inhibits its kinase activity, increasing the pathogenicity of begomoviruses by their hosts. We have previously demonstrated that the NIK1 mutant T474D is an excellent target for engineering begomovirus resistance because it is constitutively activated in transgenic lines. In this investigation, we first reconstructed in silico the NIK1-mediated antiviral signaling in tomato by identifying the tomato homologs of the components of the signaling pathway. Then, we examined the property of the double mutant T474D-T469A to confer resistance against begomoviruses in tomato transgenic lines. Furthermore, we overexpressed the downstream component of NIK1 antiviral signaling, LIMYB from Arabidopsis, in the T474D-T469A transgenic lines and examined the effect of reconstituting the antiviral pathway on begomovirus infection. Our results indicated that expression of T474D/T469A in transgenic lines was effective to suppress the expression of ribosomal protein genes, indicating that this double mutant is constitutively activated in tomato. Furthermore, expression of LIMYB in combination with T469A/T474D promoted an additive effect in ribosomal protein gene repression, possibly uncovering a better strategy to acquire begomovirus resistance. To examine this hypothesis, we challenged the transgenic lines with the tomato-infecting begomoviruses ToYSV and ToSRV and monitored the infection by symptomatology and quantitation of viral DNA.Our results demonstrated that expression of T469A/T474D in combination with LIMYB holds the potential to be a better target for engineering begomovirus resistance in susceptible genotypes. / Ficha catalográfica com erro: Morais de Ávila, Larissa Gabriela.
378

Elucidating the function of the suppressor of ppi1 locus 2

Broad, William January 2017 (has links)
No description available.
379

Superexpressão do gene dehidrina de Arachis duranensis em plantas transgênicas de Arabidopsis thaliana

Oliveira, Thaís Nicolini de 15 April 2016 (has links)
Dissertação (mestrado)—Universidade de Brasília, Departamento de Botânica, Programa de Pós-Graduação em Botânica, 2016. / Submitted by Nayara Silva (nayarasilva@bce.unb.br) on 2016-06-24T15:55:06Z No. of bitstreams: 1 2016_ThaísNicolinideOliveira.pdf: 2383809 bytes, checksum: 92976f3067a5cb3679dc9f4bedc9119f (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2016-07-07T21:13:20Z (GMT) No. of bitstreams: 1 2016_ThaísNicolinideOliveira.pdf: 2383809 bytes, checksum: 92976f3067a5cb3679dc9f4bedc9119f (MD5) / Made available in DSpace on 2016-07-07T21:13:20Z (GMT). No. of bitstreams: 1 2016_ThaísNicolinideOliveira.pdf: 2383809 bytes, checksum: 92976f3067a5cb3679dc9f4bedc9119f (MD5) / Espécies silvestres têm sido exploradas como fonte de alelos de tolerância para o melhoramento genético vegetal de várias culturas. O parental silvestre do amendoim, Arachis duranensis, é um genótipo que apresenta alta adaptabilidade ao déficit hídrico e foi utilizado em um ensaio de dry drown para sequenciamento do transcriptoma. A análise in silico e a validação por RT-qPCR de genes diferencialmente expressos auxiliaram na identificação de genes candidatos associados à resposta a seca. Dentre eles, uma proteína LEA mostrou-se positivamente regulada mediante a esse estresse. Sabe-se que proteínas LEA se comportam como chaperonas e são encontradas em abundância em tecidos sob dessecação, diante disso, o objetivo desse trabalho foi caracterizar, clonar e introduzir esse gene via transgenia em planta modelo (Arabidopsis thaliana) para compreender os efeitos da sua superexpressão. O gene foi inserido em plantas de A. thaliana, ecotipo Columbia 0, utilizando o método de floral dip e os eventos em homozigose (geração T3) foram testados. As linhagens foram plantadas em placas de meio MS com 150 mM de NaCl e 200 mM de manitol, separadamente, além de outro grupo que foi plantado em meio MS e colocado em temperaturas extremas (-18°C por uma hora e 37°C por oito horas). Foram calculadas as taxas de sobrevivência e o teor de açúcares solúveis totais de cada amostra/ensaio. O teste de seca também foi feito, onde a irrigação foi suspensa por 15 dias e foram feitas análises de área foliar, teor relativo de água e coexpressão de genes relacionados à tolerância a seca. Nos ensaios com NaCl e manitol não houveram diferenças entre as linhagens e as plantas não transformadas, além de ter sido observado desenvolvimento reduzido das plantas. Nos ensaios com temperaturas extremas as linhagens mantiveram seus teores de açúcares iguais ao controle enquanto as não-transformadas (NT) aumentaram seu teor de açúcares solúveis totais apenas no tratamento de calor e sem diferença significativa na taxa de sobrevivência entre as linhagens e NT. No ensaio com seca houve maior desenvolvimento da área foliar em algumas linhagens quando comparadas às plantas NT. Na análise de teor relativo de água as linhagens mostraram maiores teores relativos de água quando comparado à NT, sob condição de rega controlada e após 15 dias sem irrigação, sendo uma linhagem com maior teor significativo. Esse evento foi selecionado para a análise de expressão gênica de três genes coexpressos com a Dehidrina. Houve aumento da expressão dos três genes em diferentes situações, tanto pelo fato da planta superexpressar a AdDHN quanto pela indução da seca. Os resultados sugerem que esse gene possa conferir uma melhor resposta aos estresses abióticos. _________________________________________________________________________________________________ ABSTRACT / Wild species have been exploited as a source of tolerance alleles for plant breeding of various cultures. Arachis duranensis, a wild parental of the cultivated peanut, is a genotype which has high adaptability to drought and has been used in a dry down test for sequencing the transcriptome. In silico analysis and validation by RT-qPCR differentially expressed genes assisted in the identification of candidate genes associated with drought response. Among them, an LEA protein was positively regulated in response to this stress. It is known that LEA proteins behave as chaperones and are found in abundance in tissues under desiccation, therefore, the aim of this study was to characterize, clone and introduce this gene via genetic modification in the model plant Arabidopsis thaliana, to understand the effects of its overexpression. The gene was inserted into plants of A. thaliana, ecotype Columbia 0, using the floral dip method and homozygous lines (T3 generation) were assayed. The lines were sown on MS medium plates containing either 150 mM NaCl or 200mM mannitol, and another group that was grown in MS medium and placed at extremes temperatures (-18°C for one hour and 37°C for eight hours). Survival rates were calculated and the total soluble sugar content of each sample/test. The dry test was also done where irrigation was suspended for 15 days and analyses were made of leaf area, relative water content, and co-expression of genes related to drought tolerance. In assays with NaCl and mannitol, there were no differences between lines and non-transformed (NT) have been observed in addition to reduced development of plants. In assays with extreme temperatures, lines maintained their sugar content in levels equal to control while non-transformed (NT) increased their total soluble sugar content only under heat treatment, and no significant difference in survival rate between the lines and NT. In assay for drought, there was a greater leaf area development in some lines than in NT plants, while the relative water content analysis of the strains showed higher relative contents of water when compared to NT under controlled irrigation condition and after 15 days without irrigation, with one line showing a significant content. This line was selected for the gene expression analysis of ascorbate peroxidase, galactinol synthase and DREB. There was increased expression of the three genes in different situations, because the plant overexpresses the AdDHN and because the drought induction. The results suggest that AdDHN may give a better response to abiotic stresses.
380

PTP85, a dual-specificity protein tyrosine phosphatase, is involved in the osmotic stress signaling in arabidopsis

Liu, Rui 01 January 2010 (has links)
No description available.

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