Hong Eunji, Lim Chae Woo, Han Sang-Wook, Lee Sung Chul
Department of Life Science (BK21 Program), Chung-Ang UniversitySeoul, South Korea.
Department of Integrative Plant Science, Chung-Ang UniversityAnseong, South Korea.
Front Plant Sci. 2017 Aug 22;8:1407. doi: 10.3389/fpls.2017.01407. eCollection 2017.
Abscisic acid (ABA) is a plant hormone that plays a critical role in the response to environmental stress conditions, especially regulation of the stomatal aperture under water-deficit conditions. The signal transduction occurring during the stress response is initiated by transcription of defense-related genes. Here, we isolated the pepper ethylene-responsive transcription factor CaAIEF1 ( ABA Induced ERF 1). The gene was significantly induced after exposure to ABA, drought, and high salinity. Fusion of the acidic domain in the C-terminal region of CaAIEF1 to the GAL4 DNA-binding domain had a transactivation effect on the reporter gene in yeast. Further, the CaAIEF1-GFP fusion constructs localized in the nucleus. We used -silenced plants and -overexpressing (OX) plants to elucidate the biological function of CaAIEF1 in response to ABA and drought stress. -silenced pepper plants and -OX Arabidopsis plants displayed drought-sensitive and -tolerant phenotypes, respectively, which were characterized by regulation of transpirational water loss and stomatal aperture. In drought stress condition, quantitative RT-PCR analyses revealed that the expression levels of pepper stress-related genes were higher in -silenced pepper plants than control plants. Moreover, expression levels of Arabidopsis stress-related genes were significantly reduced in -OX plants compared with control plants in drought stress condition. Our findings suggest that CaAIEF1 positively regulates the drought stress response and the ABA signaling.
脱落酸（ABA）是一种植物激素，在植物对环境胁迫条件的响应中起着关键作用，尤其是在水分亏缺条件下对气孔孔径的调节。胁迫响应过程中发生的信号转导是由防御相关基因的转录启动的。在此，我们分离出了辣椒乙烯响应转录因子CaAIEF1（ABA诱导的ERF 1）。该基因在暴露于ABA、干旱和高盐环境后被显著诱导。将CaAIEF1 C端区域的酸性结构域与GAL4 DNA结合结构域融合，对酵母中的报告基因具有反式激活作用。此外，CaAIEF1-GFP融合构建体定位于细胞核。我们使用基因沉默植株和过表达（OX）植株来阐明CaAIEF1在响应ABA和干旱胁迫中的生物学功能。基因沉默的辣椒植株和过表达的拟南芥植株分别表现出对干旱敏感和耐受的表型，其特征在于对蒸腾失水和气孔孔径的调节。在干旱胁迫条件下，定量RT-PCR分析表明，基因沉默的辣椒植株中辣椒胁迫相关基因的表达水平高于对照植株。此外，在干旱胁迫条件下，与对照植株相比，过表达植株中拟南芥胁迫相关基因的表达水平显著降低。我们的研究结果表明，CaAIEF1正向调节干旱胁迫响应和ABA信号传导。
