Research Center of Plant Molecular and Developmental Biology, Key Laboratory of Photosynthesis and Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, People's Republic of China.
Planta. 2009 Nov;230(6):1155-66. doi: 10.1007/s00425-009-1014-3. Epub 2009 Sep 17.
Accumulation of compatible osmolytes, such as soluble sugars, in plants is an important osmoprotective mechanism. Sugars play a role in osmotic adjustment and are associated with stabilization of proteins and cell structures, reactive oxygen species scavenging, signaling functions or induction of adaptive pathways. Galactinol is the galactosyl donor for the synthesis of raffinose family oligosaccharides (RFOs) and its synthesis by galactinol synthase (GolS) is the first committed step of the RFOs biosynthetic pathway. GolS genes are induced by a variety of stresses in both stress-sensitive and tolerant-plant species; however, the mechanism of transcriptional regulation is not fully established. In this paper, we characterized a GolS gene (BhGolS1) that was dehydration and ABA-inducible in the resurrection plant Boea hygrometrica and conferred dehydration tolerance in a transgenic tobacco system. Four W-box cis-elements were identified in the BhGolS1 promoter and shown to be bound by an early dehydration and ABA-inducible WRKY gene (BhWRKY1). These data suggest a mechanism where BhWRKY1 is likely to function in an ABA-dependent signal pathway to regulate BhGolS1 expression, which leads to the accumulation of RFOs in desiccation-tolerant B. hygrometrica leaves.
在植物中，积累相容性渗透物（如可溶性糖）是一种重要的渗透保护机制。糖在渗透调节中起作用，并与蛋白质和细胞结构的稳定、活性氧物种的清除、信号功能或诱导适应性途径有关。半乳糖醇是合成棉子糖家族低聚糖（RFOs）的半乳糖基供体，其合成由半乳糖醇合酶（GolS）催化，这是 RFOs 生物合成途径的第一步。GolS 基因在敏感和耐受植物物种的多种胁迫下被诱导；然而，转录调控的机制尚未完全建立。在本文中，我们对一种在复苏植物 Boea hygrometrica 中受脱水和 ABA 诱导的 GolS 基因（BhGolS1）进行了表征，并在转基因烟草系统中赋予了其对脱水的耐受性。在 BhGolS1 启动子中鉴定出四个 W-框顺式元件，并证明其与一个早期脱水和 ABA 诱导的 WRKY 基因（BhWRKY1）结合。这些数据表明，BhWRKY1 可能在依赖 ABA 的信号途径中发挥作用，以调节 BhGolS1 的表达，从而导致耐旱性 B. hygrometrica 叶片中 RFOs 的积累。
