Regulação metabólica da acumulação de prolina em folhas de cajueiro expostas ao estresse salino

• Ano de defesa: 2003
• Autor(a) principal: Rocha, Iza Marineves Almeida da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Prolina; Estresse salino; Cajueiro
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/47535

In spite of increasing research interest, the biochemical mechanisms of Pro accumulation in plants upon salinity are not fully known yet. In the current study, attempts were made to check the hypothesis that leaf Pro accumulation of salinized cashew can arrives from increase in availability of secondary precursors (A, Band C) and maintenance of activity of enzymes from NI-h assimilation (GS, GOGAT and GDH), both together with ornithine-aminotransferase activity. This study has comprised three distinct parts. In the first, a leaf disc system was tested for their effectiveness as a study method. In the second, the Glu and Om kinetic and efficacy on Pro accumulation were compared in three systems: leaf discs, integer leaf of aerial part free of roots and leaf of intact plants. And, in the third, the activities of GS, GOGAT, GDH and OAT either on NaCl or PEG 6000 were determined upon different systems: leaf extract free of cells, leaf discs and leaf from intact plants. ln the current work, the results had compared been with changes occurring in the concentrations of precursors Gln, Glu, Orn, Arg and of free ammonia. The experiments were carried out under controlled conditions of luminosity, temperature and air moisture. The results indicate leaf disc system to be the one more adequate to realize the more direct responses of NaCl on metabolism; however, it aiso shows to be able to study precursors and Pro uptake kinetic and accumulation and to study enzyme lesponses to NaCl and PEG 6000.Om was seen to be more able than Glu to induce Pro accumulation. The NaCl stress seems induce primarily accumulation of ammonia alongside Glu; apparently, it would stimulate the activity of GS/GOGAT/GDH via, and weight is added for the role of GS in supplying Glu to synthesize Pro precursors Glu and Om. Theprolina dehydrogenase activity was very low; therefore, a low Pro oxidation itself has aiso contributed for its accumulation. The results allow hypothesize that Pro accumulation in leaf of cashew come mainly from metabolic imbalance in the pool of free amino acids, and that maintenance of flow and levels of intermediaries and precursors is essential to retain activity of enzymes of Pro synthesis.