Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-21T00:14:46Z No. of bitstreams: 1 JulianaGabrielaSilvaDeLima_DISSERT.pdf: 2326207 bytes, checksum: 72dd0aa19271777e0700d9c307ad79e7 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-03T21:38:22Z (GMT) No. of bitstreams: 1 JulianaGabrielaSilvaDeLima_DISSERT.pdf: 2326207 bytes, checksum: 72dd0aa19271777e0700d9c307ad79e7 (MD5) / Made available in DSpace on 2017-03-03T21:38:22Z (GMT). No. of bitstreams: 1 JulianaGabrielaSilvaDeLima_DISSERT.pdf: 2326207 bytes, checksum: 72dd0aa19271777e0700d9c307ad79e7 (MD5) Previous issue date: 2016-09-16 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Durante o desenvolvimento p?s-germinativo, o d?ficit h?drico e concentra??es t?xicas de sais podem afetar processos dos tecidos cotiledonares, como o crescimento, a atividade de enzimas e a mobiliza??o das reservas lip?dicas, al?m de gerar um desequil?brio redox celular. No entanto, os estudos geralmente relatam altera??es metab?licas ao longo do desenvolvimento sob estresses aplicados apenas no momento da embebi??o. Visto isso, o objetivo desde estudo foi avaliar as mudan?as fenol?gicas e fisiol?gicas ocasionadas pelos estresses h?drico, induzido por polietilenoglicol (PEG-8000), e salino, induzido por NaCl, aplicados no momento da embebi??o ou durante a fase de transi??o semente-pl?ntula. Adicionalmente, o estudo tamb?m teve como finalidade caracterizar a atividade das enzimas APX, CAT e SOD e a express?o das enzimas APX, CAT, ICL e MLS das pl?ntulas de c?rtamo de pl?ntulas submetidas aos estresses apenas durante a fase de transi??o semente-pl?ntula. Verificou-se que as pl?ntulas sofreram altera??es fenol?gicas e fisiol?gicas diferentes de acordo com o momento de aplica??o do NaCl e do PEG. Os tratamentos realizados durante a transi??o semente-pl?ntula afetaram em menor grau o crescimento das ra?zes, a taxa e o ?ndice de velocidade de germina??o do que a aplica??o de NaCl e PEG no momento da embebi??o. Entretanto, o efeito do PEG sob os par?metros fenol?gicos e fisiol?gicos avaliados foi mais severo em rela??o ao observado para o NaCl independentemente do momento de aplica??o dos tratamentos. Interessantemente, durante a transi??o semente-pl?ntula, os teores de H2O2 e de lip?deos peroxidados nas pl?ntulas controle sofreram intenso aumento durante o estabelecimento. Por?m, ambos os estresses induziram diminui??es nos teores de clorofilas, carotenoides, H2O2 e lip?deos peroxidados, quando comparado ao controle, apesar das plantas submetidas aos tratamentos apresentarem consider?vel diminui??o na atividade da SOD e CAT. Estas redu??es tamb?m ocorreram a n?vel transcricional, uma vez que n?o houve express?o da CAT durante o tratamento com NaCl, sendo observada apenas 72 h ap?s o tratamento com PEG. J? a atividade e express?o da APX se mantiveram altas nas pl?ntulas tratadas, assim como a express?o da MLS. A partir disto, conclu?mos que condi??es estressantes especificamente durante a transi??o semente-pl?ntula podem interferir no processo de sinaliza??o induzido por H2O2 necess?rio ao completo estabelecimento, ocasionando atrasos no in?cio do metabolismo fotossint?tico. Al?m disso, o sistema da APX pode ter um importante papel na manuten??o deste processo. / During seed?s post-germinative development, drought and toxic ionic concentrations affect physiological and metabolic processes of cotyledonary tissues, such as growth, enzyme activity and mobilization of lipid reserves, as well as contribute to a cellular redox imbalance. However, studies generally report metabolic changes throughout the development under stress conditions applied only at the time of soaking. Therefore, this study aimed to evaluate the phenological and physiological changes caused by Poliethyleneglycol induced-osmotic stress (PEG-8000) and NaCl induced-salt stresses applied during soaking or during seed-to-seedling transition. In addition, the present work characterizes the activity of APX, CAT and SOD enzymes and APX, CAT, ICL and MLS mRNA expression of safflower seedlings subjected to stress applied only at the seed-to-seedling transition stage. It was observed that seedlings suffered phenological and physiological changes according to application time of NaCl and PEG treatments. During the seed-to-seedling transition, stress conditions affected root growth, germination rate and germination speed index in lower levels than when they are applied at the time of soaking. PEG-induced osmotic stress exerts more severe effects on the evaluated phenological and physiological parameters, regardless of application time. Interestingly, during seed-to-seedling transition, the H2O2 and lipid peroxidation levels in control seedlings showed an intense increase during establishment. Conversely, both stresses induced decreases in chlorophyll, carotenoids, H2O2, and peroxidized lipid levels when comparing to control, even though stressed plants presented marked reductions in SOD and CAT activities. These reductions were also at the transcriptional level, since CAT mRNA expression was only observed after 72 h of PEG treatment and not observed at all during NaCl treatment. On the other hand, APX activity and expression remained high during both treatments, as well as MLS mRNA expression. Taking into account all the obtained results, we conclude that specific stress conditions during seed-to-seedling transition may interfere in the H2O2 signalization needed to complete establishment, causing delays on the beginning of photosynthetic metabolism. Also, it seems that APX system may have an important role in maintenance of this process.

Made available in DSpace on 2014-12-17T14:03:41Z (GMT). No. of bitstreams: 1 TaffarelMT_DISSERT.pdf: 2213102 bytes, checksum: 779f70cd3a9747e4f3a386630bd3d1cc (MD5) Previous issue date: 2013-04-09 / Funda??o de Apoio ? Pesquisa do Estado do Rio Grande do Norte / Oilseeds are a high-value natural resource, due to its use as a substitute for petroleum. However, the storage time can reduce seed viability and oil quality. Therefore, scientific efforts have been made to provide a increment of storage time, germination rates and plant establishment of high-value oilseeds. The seedling establishment depends of the plant pass over the functional transition stage, characterized by a metabolic change from heterotrophic condition to autotrophic one. The storage oil mobilization is performed by β-oxidation process and the glyoxylate cycle. Also, the functional transition involves acclimation to photosynthetic condition, which generally includes the participation of antioxidant system and the reactive oxygen species, the latter are produced in various reactions of primary and secondary metabolism. In the present study, Catalase was inhibited during the functional transition of sunflower and safflower, after were performed many analyzes to elucidate the effects caused on the SOD and APX antioxidant systems. Also, were checked the changes in expression pattern of the glyoxylate cycle enzymes markers, ICL and MLS. It was observed that after CAT inhibition, the SOD and APX antioxidant systems allow the seedling establishment. Besides, was verified that both oilseeds can be accelerate the reverse mobilization and the photosynthetic establishment when Catalase activity has dramatically decreased / As sementes oleaginosas armazenam ?leos, um recurso natural de alto valor econ?mico devido a sua aplicabilidade como substituto aos derivados do petr?leo. Por?m, o tempo de armazenamento pode inviabilizar a semente provocando a redu??o da qualidade do ?leo e perda da viabilidade da semente. Por este motivo, esfor?os cient?ficos t?m sido realizados para proporcionar um maior tempo de armazenamento e incrementar taxas de germina??o e estabelecimento destas plantas com alto valor econ?mico. O estabelecimento da pl?ntula depende da capacidade do vegetal transpassar a etapa de transi??o funcional, caracterizada pela mudan?a do estado heterotr?fico para o autotr?fico. O consumo das reservas de ?leo depende das vias de β-oxida??o e do ciclo do glioxilato. No entanto, o processo de transi??o envolve a aclimata??o do vegetal ? condi??o de organismo fotossintetizante, que em geral conta com a participa??o fundamental do sistema antioxidante do vegetal devido ? produ??o de esp?cies reativas de oxig?nio em v?rias rea??es do metabolismo prim?rio e secund?rio. Neste estudo, a Catalase foi inibida durante a transi??o funcional de girassol e c?rtamo para analisar os efeitos provocados nos sistemas antioxidantes de APX e da SOD e verificar as modifica??es no padr?o de express?o das enzimas marcadoras do ciclo do glioxilato, ICL e MLS. Constatou-se que diante da inibi??o da Catalase o sistema antioxidante da APX e da SOD permitem o estabelecimento da pl?ntula. Verificou-se tamb?m que as duas oleaginoasas parecem acelerar a mobiliza??o de reservas e o estabelecimento fotossint?tico quando a Catalase tem a atividade drasticamente reduzida