The HaDREB2 transcription factor enhances basal thermotolerance and longevity of seeds through functional interaction with HaHSFA9.
The HaDREB2 transcription factor enhances basal thermotolerance and longevity of seeds through functional interaction with HaHSFA9.
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DOI：
10.1186/1471-2229-9-75
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发表时间：
2009-06-19
影响因子：
5.3
通讯作者：
Jordano J
中科院分区：
文献类型：
--
作者：
Almoguera C;Prieto-Dapena P;Díaz-Martín J;Espinosa JM;Carranco R;Jordano J
从向日葵（Helianthus annuus L.）干旱响应元件结合因子2（DREB 2）。HaDREB2和向日葵热休克因子A9（HaHSFA9）共激活向日葵胚中的Hahsp17.6G1启动子。这两个因子可能参与额外的小热应激蛋白（sHSP）启动子的转录共激活，从而有助于HaHSFA9介导的寿命和种子的基础耐热性的增强。我们发现，种子中HaDREB2的过表达并没有增加寿命。这是从用转基因烟草进行的基础耐热性和受控种子劣变的测定中推断出来的。此外，HaDREB2的组成型过表达并没有增加幼苗的耐热性，也没有导致在正常生长温度下热休克蛋白的积累。相反，当HaDREB2和HaHSFA9在种子中联合过表达时，我们观察到对种子寿命的积极影响，超出了单独过表达HaHSFA9所观察到的影响。这种额外的作用伴随着属于CI和CII胞质类的sHSP亚群的积累的微妙增强。我们的结果揭示了HaDREB 2和HaHSFA 9在种子中的功能相互依赖性。HaDREB2不同于其他先前表征的DREB2因子在植物中与种子特异性HaHSFA9因子的独特功能相互作用。HaDREB2和HaHSFA9之间没有功能相互作用时，观察到这两个因素联合过表达的营养组织。因此，我们认为，额外的，种子特异性的因素，或蛋白质修饰，可能需要HaDREB2和HaHSFA9之间的功能相互作用。
Transcription factor HaDREB2 was identified in sunflower (Helianthus annuus L.) as a drought-responsive element-binding factor 2 (DREB2) with unique properties. HaDREB2 and the sunflower Heat Shock Factor A9 (HaHSFA9) co-activated the Hahsp17.6G1 promoter in sunflower embryos. Both factors could be involved in transcriptional co-activation of additional small heat stress protein (sHSP) promoters, and thus contribute to the HaHSFA9-mediated enhancement of longevity and basal thermotolerance of seeds. We found that overexpression of HaDREB2 in seeds did not enhance longevity. This was deduced from assays of basal thermotolerance and controlled seed-deterioration, which were performed with transgenic tobacco. Furthermore, the constitutive overexpression of HaDREB2 did not increase thermotolerance in seedlings or result in the accumulation of HSPs at normal growth temperatures. In contrast, when HaDREB2 and HaHSFA9 were conjointly overexpressed in seeds, we observed positive effects on seed longevity, beyond those observed with overexpression of HaHSFA9 alone. Such additional effects are accompanied by a subtle enhancement of the accumulation of subsets of sHSPs belonging to the CI and CII cytosolic classes. Our results reveal the functional interdependency of HaDREB2 and HaHSFA9 in seeds. HaDREB2 differs from other previously characterized DREB2 factors in plants in terms of its unique functional interaction with the seed-specific HaHSFA9 factor. No functional interaction between HaDREB2 and HaHSFA9 was observed when both factors were conjointly overexpressed in vegetative tissues. We therefore suggest that additional, seed-specific factors, or protein modifications, could be required for the functional interaction between HaDREB2 and HaHSFA9.
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