Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, 3-1-1 Koyadai, Tsukuba 305-0074, Japan.
DNA Res. 2013 Aug;20(4):315-24. doi: 10.1093/dnares/dst012. Epub 2013 Apr 19.
Plants respond to dehydration stress and tolerate water-deficit status through complex physiological and cellular processes. Many genes are induced by water deficit. Abscisic acid (ABA) plays important roles in tolerance to dehydration stress by inducing many stress genes. ABA is synthesized de novo in response to dehydration. Most of the genes involved in ABA biosynthesis have been identified, and they are expressed mainly in leaf vascular tissues. Of the products of such genes, 9-cis-epoxycarotenoid dioxygenase (NCED) is a key enzyme in ABA biosynthesis. One of the five NCED genes in Arabidopsis, AtNCED3, is significantly induced by dehydration. To understand the regulatory mechanism of the early stages of the dehydration stress response, it is important to analyse the transcriptional regulatory systems of AtNCED3. In the present study, we found that an overlapping G-box recognition sequence (5'-CACGTG-3') at -2248 bp from the transcriptional start site of AtNCED3 is an important cis-acting element in the induction of the dehydration response. We discuss the possible transcriptional regulatory system of dehydration-responsive AtNCED3 expression, and how this may control the level of ABA under water-deficit conditions.
植物通过复杂的生理和细胞过程对干旱胁迫做出响应，并耐受水分亏缺状态。许多基因受水分亏缺诱导。脱落酸（ABA）通过诱导许多胁迫基因在耐受脱水胁迫中发挥重要作用。ABA 是响应脱水而从头合成的。参与 ABA 生物合成的大多数基因已被鉴定，它们主要在叶片维管束组织中表达。在这些基因的产物中，9-顺式-环氧类胡萝卜素双加氧酶（NCED）是 ABA 生物合成的关键酶。拟南芥中的五个 NCED 基因之一，AtNCED3，受脱水显著诱导。为了理解脱水胁迫响应早期阶段的调控机制，分析 AtNCED3 的转录调控系统非常重要。在本研究中，我们发现 AtNCED3 转录起始位点上游-2248bp 处的重叠 G 框识别序列（5'-CACGTG-3'）是诱导脱水响应的一个重要顺式作用元件。我们讨论了脱水响应型 AtNCED3 表达的可能转录调控系统，以及它如何在水分亏缺条件下控制 ABA 的水平。
