Ministry of Education Engineering Research Center of Bioreactor and Pharmaceutical Development, Jilin Agricultural University, Changchun, Jilin 130118, China.
Planta. 2011 Feb;233(2):219-29. doi: 10.1007/s00425-010-1279-6. Epub 2010 Oct 22.
In higher plants, DREB1/CBF-type transcription factors play an important role in tolerance to low temperatures, drought, and high-salt stress. These transcription factors bind to CRT/DRE elements in promoter regions of target genes, regulating their expression. In this study, we cloned and characterized a novel gene encoding a DREB1 transcription factor from dwarf apple, Malus baccata (GenBank accession number: EF582842). Expression of MbDREB1 was induced by cold, drought, and salt stress, and also in response to exogenous ABA. Subcellular localization analyses revealed that MbDREB1 localizes in the nucleus. A yeast activity assay demonstrated that the MbDREB1 gene encodes a transcription activator, which specifically binds to DRE/CRT elements. Compared with wild-type plants, transgenic Arabidopsis overexpressing MbDREB1 showed increased tolerance to low temperature, drought, and salt stresses. Analysis of the MbDREB1 promoter revealed an ABA-responsive element (ABRE), an inducer of CBF expression 1 (ICE1)-like binding site, two MYB recognition sites, and three stress-inducible GT-1 boxes. GUS activities driven by the MbDREB1 promoter in transgenic Arabidopsis increased in response to ABA, cold temperature, drought, and salt treatments. Interestingly, the expression of both ABA-independent and ABA-dependent stress-induced genes (COR15a and rd29B, respectively) was activated under normal growth conditions in Arabidopsis overexpressing MbDREB1. These results suggest that MbDREB1 functions as a transcription factor and increases plant tolerance to low temperature, drought, and salt stress via both ABA-dependent and ABA-independent pathways.
在高等植物中，DREB1/CBF 型转录因子在耐低温、干旱和高盐胁迫方面发挥着重要作用。这些转录因子结合到靶基因启动子区域的 CRT/DRE 元件上，调节它们的表达。在本研究中，我们从小苹果（Malus baccata）中克隆并鉴定了一个新的 DREB1 转录因子基因（GenBank 登录号：EF582842）。MbDREB1 的表达受低温、干旱和盐胁迫诱导，也对外源 ABA 有响应。亚细胞定位分析表明 MbDREB1 定位于细胞核内。酵母活性测定表明 MbDREB1 基因编码一个转录激活因子，它特异性地结合 DRE/CRT 元件。与野生型植物相比，过表达 MbDREB1 的转基因拟南芥对低温、干旱和盐胁迫的耐受性增强。对 MbDREB1 启动子的分析揭示了一个 ABA 响应元件（ABRE）、CBF 表达诱导因子 1（ICE1）样结合位点、两个 MYB 识别位点和三个应激诱导的 GT-1 盒。在转基因拟南芥中，由 MbDREB1 启动子驱动的 GUS 活性在 ABA、低温、干旱和盐处理下增加。有趣的是，在过表达 MbDREB1 的拟南芥中，ABA 非依赖和 ABA 依赖的应激诱导基因（分别为 COR15a 和 rd29B）的表达在正常生长条件下也被激活。这些结果表明，MbDREB1 作为一个转录因子，通过 ABA 依赖和非依赖途径增强植物对低温、干旱和盐胁迫的耐受性。
