Análise proteômica em sementes condicionadas de eucalipto submetidas a estresse salino

Abstract

The physiological conditioning is an important technique which induces greater tolerance of seeds to abiotic stresses such as hydric, salt, oxidative, as well as that caused by extreme temperatures. The signalling pathways and cellular responses of these kind of stresses are often similar. Then, when activating one of these pathways, the conditioning favours a defense response and tolerance of seeds to a subsequent stress in a quick and intense way. In this work, we aimed to induce greater tolerance of seeds of Eucalyptus urophylla and of the hybrid E. urophylla x E. grandis to salt stress through osmotic conditioning performed with polyethylene glycol. We tested two osmotic potentials (-1.0 and -1.5 Mpa) for 1 and 3 days. Subsequently, seeds were germinated under salt stress in NaCl solution at potentials of 0.0 (control), -0.5, -0.75 and -1.0 Mpa at 25oC under constant light. The treatment of E. urophylla was found to be more tolerant to salt stress, showing higher germination percentages under all tested potentials. In addition, the osmotic conditioning at -1.0 Mpa for three days was found to be the most indicated to induce greater tolerance to germination under the most acute stress. Thus, these treatments were selected for proteomic analysis. Total proteins were isolated and separated by the 2D gel electrophoresis from the following six samples: one of dry seeds, one of seeds conditioned at -1.0 Mpa for three days, and four of seeds in the germination process (in water and at -1.0 Mpa in NaCl, these for 6 hours and for 6 hours after conditioning).The proteomic profile revealed the presence of around 415 protein spots into gels stained using Coomassie brilliant blue, from which 21 spots differentially expressed were selected. Such proteins may be associated with reserve proteins or breaking of these proteins, with the repair or defense of cellular damages, involved in cell cycle, among others.