CEBAS-CSIC, Department of Stress Biology and Plant Pathology, Campus de Espinardo, P.O. Box 164, 30100 Espinardo-Murcia, Spain.
J Plant Physiol. 2012 Mar 15;169(5):459-68. doi: 10.1016/j.jplph.2011.11.018. Epub 2012 Jan 9.
One strategy to increase the level of drought and salinity tolerance is the transfer of genes codifying different types of proteins functionally related to macromolecules protection, such as group 2 of late embryogenesis abundant (LEA) proteins or dehydrins. The TAS14 dehydrin was isolated and characterized in tomato and its expression was induced by osmotic stress (NaCl and mannitol) and abscisic acid (ABA) [Godoy et al., Plant Mol Biol 1994;26:1921-1934], yet its function in drought and salinity tolerance of tomato remains elusive. In this study, transgenic tomato plants overexpressing tas14 gene under the control of the 35SCaMV promoter were generated to assess the function of tas14 gene in drought and salinity tolerance. The plants overexpressing tas14 gene achieved improved long-term drought and salinity tolerance without affecting plant growth under non-stress conditions. A mechanism of osmotic stress tolerance via osmotic potential reduction and solutes accumulation, such as sugars and K(+) is operating in tas14 overexpressing plants in drought conditions. A similar mechanism of osmotic stress tolerance was observed under salinity. Moreover, the overexpression of tas14 gene increased Na(+) accumulation only in adult leaves, whereas in young leaves, the accumulated solutes were K(+) and sugars, suggesting that plants overexpressing tas14 gene are able to distribute the Na(+) accumulation between young and adult leaves over a prolonged period in stressful conditions. Measurement of ABA showed that the action mechanism of tas14 gene is associated with an earlier and greater accumulation of ABA in leaves during short-term periods. A good feature for the application of this gene in improving drought and salt stress tolerance is the fact that its constitutive expression does not affect plant growth under non-stress conditions, and tolerance induced by overexpression of tas14 gene was observed at the different stress degrees applied to the long term.
提高干旱和盐度耐受性的一种策略是转移编码与大分子保护功能相关的不同类型蛋白质的基因，如晚期胚胎丰富蛋白（LEA）蛋白或脱水蛋白的第 2 组。TAS14 脱水蛋白在番茄中被分离和鉴定，其表达受渗透胁迫（NaCl 和甘露醇）和脱落酸（ABA）的诱导[Godoy 等人，植物分子生物学 1994；26:1921-1934]，但其在番茄干旱和盐度耐受性中的功能仍不清楚。在这项研究中，生成了在 35SCaMV 启动子控制下过表达 tas14 基因的转基因番茄植物，以评估 tas14 基因在干旱和盐度耐受性中的功能。过表达 tas14 基因的植物在不影响非胁迫条件下植物生长的情况下，实现了对干旱和盐度的长期耐受性的提高。在干旱条件下，通过渗透势降低和溶质积累（如糖和 K+）来实现渗透胁迫耐受性的机制在 tas14 过表达植物中起作用。在盐胁迫下也观察到类似的渗透胁迫耐受机制。此外，tas14 基因的过表达仅在成年叶片中增加 Na+积累，而在幼叶中，积累的溶质是 K+和糖，这表明过表达 tas14 基因的植物能够在长期胁迫条件下将 Na+积累分配到幼叶和成年叶片之间。ABA 的测量表明，tas14 基因的作用机制与短期叶片中 ABA 的早期和大量积累有关。该基因在提高干旱和盐胁迫耐受性方面的一个很好的特点是，其组成型表达不会影响非胁迫条件下的植物生长，并且在长期施加不同程度的胁迫时，观察到 tas14 基因过表达诱导的耐受性。
