Osmotic stress on genetically transformed tobacco plant seeds

Abstract: Salinity and water deficit limit the productivity of several crops; thus, studies related to the genetic transformation of seeds in a model plant, such as tobacco, can be an alternative to minimize negative impacts caused by environmental conditions. The purpose of this work was to evaluate the tolerance to osmotic stress of seeds from genetically transformed tobacco plants, with the introduction of the proline-synthesizer gene (p5csf129a), under salinity and water deficit conditions. To do so, five events with differences in proline content were selected, ranging from 0.70 to 10.47 µmoles.g-1 of fresh mass. The used saline concentrations were: zero (distilled water); 50; 100; 150 and 200 mmol.L-1 of NaCl, whereas for the water deficit, simulated with PEG 6000, the following osmotic potentials were used: zero (distilled water); -0.2; -0.4; -0.6 and -0.8 MPa. Each tested treatment was evaluated through germination, first germination count and germination speed index tests. It is possible to conclude that seeds from genetically transformed tobacco plants with overexpression of the gene p5csf129a, a proline synthesizer, are more tolerant to osmotic stresses. Tabacco seeds with a proline content of 10.47 µmol.g-1 showed a better perfomance, revealing higher physiological potential.

摘要：盐分与水分亏缺胁迫会限制多种作物的生产力，因此针对烟草这类模式植物开展种子遗传转化相关研究，可作为减轻环境胁迫负面影响的可行方案。本研究旨在评估转入脯氨酸合成基因（p5csf129a）的转基因烟草植株种子，在盐分胁迫与水分亏缺条件下的渗透胁迫耐受性。为此，研究选取了5个脯氨酸含量存在差异的转基因事件，其脯氨酸含量区间为0.70~10.47 µmol·g⁻¹鲜重。盐分胁迫处理采用的NaCl浓度分别为0（蒸馏水）、50、100、150及200 mmol·L⁻¹；而采用PEG 6000模拟水分亏缺时，设置的渗透势梯度为0（蒸馏水）、-0.2、-0.4、-0.6及-0.8 MPa。各处理组均通过发芽率、初次发芽计数以及发芽速率指数三项指标进行评价。研究表明，过量表达脯氨酸合成基因p5csf129a的转基因烟草植株种子，对渗透胁迫具备更强的耐受性。其中脯氨酸含量达10.47 µmol·g⁻¹的烟草种子表现最优，展现出更高的生理活性潜力。