The ectopic overexpression of a seed-specific transcription factor, HaHSFA9, confers tolerance to severe dehydration in vegetative organs
The ectopic overexpression of a seed-specific transcription factor, HaHSFA9, confers tolerance to severe dehydration in vegetative organs
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DOI：
10.1111/j.1365-313x.2008.03465.x
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发表时间：
2008-06-01
期刊：
影响因子：
7.2
通讯作者：
Jordano, Juan
中科院分区：
文献类型：
--
作者：
Prieto-Dapena, Pilar;Castano, Raul;Jordano, Juan
大多数植物种子耐受干燥，但营养组织不耐受剧烈脱水，复活植物除外。因此，通常在种子中表达的基因的调节的变化被认为是负责复活植物的脱水耐受性的进化起源。在这里，我们表明向日葵种子特异性HSFA 9转录因子的组成性过表达足以赋予转基因烟草营养组织在发育种子环境之外对严重脱水的耐受性。整个3周龄的幼苗可以存活严重脱水。这被量化为初始水含量的1.96 +/-0.05%的水损失，其对应于约-40MPa的水势。存活率取决于水势，从约-20 MPa时的40%存活率到约-40 MPa时的6.5%存活率。全苗存活受到根系脱水敏感性的限制。生存与异位表达的遗传程序，涉及种子特异性，小的热休克蛋白，但不晚胚胎发生丰富的蛋白质。HSFA 9不改变蔗糖或棉子糖家族寡糖的积累。观察到的耐受性在没有降低生长和发育的情况下实现。我们的研究结果有力地支持了先前提出的小热激蛋白对种子脱水耐性的贡献。我们提供了一个成功的系统，分析严重脱水在所有营养器官的幼苗。我们建议HSFA 9是一个潜在的基因开关参与植物干燥耐受性的进化。
Most plant seeds tolerate desiccation, but vegetative tissues are intolerant to drastic dehydration, except in the case of resurrection plants. Therefore, changes in the regulation of genes normally expressed in seeds are thought to be responsible for the evolutionary origin of desiccation tolerance in resurrection plants. Here, we show that constitutive overexpression of the seed-specific HSFA9 transcription factor from sunflower is sufficient to confer tolerance to severe dehydration, outside of the developing seed context, to vegetative tissues of transgenic tobacco. Whole 3-week-old seedlings could survive severe dehydration. This was quantified as a water loss to 1.96 +/- 0.05% of the initial water content, which corresponds to a water potential of approximate to -40 MPa. Survival depended on the water potential, from 40% survival at approximate to -20 MPa to 6.5% survival at approximate to -40 MPa. Whole-seedling survival was limited by the dehydration sensitivity of the roots. Survival correlated with the ectopic expression of a genetic program involving seed-specific, small heat-shock proteins, but not late embryogenesis abundant proteins. The accumulation of sucrose or raffinose family oligosaccharides was not altered by HSFA9. The observed tolerance was achieved without a reduction of growth and development. Our results strongly support the previously suggested contribution of small heat-shock proteins to the desiccation tolerance of seeds. We provide a successful system for analyzing tolerance to severe dehydration in all vegetative organs of seedlings. We propose that HSFA9 is a potential genetic switch involved in the evolution of tolerance to vegetative desiccation.