拟南芥bZIP1转录因子通过与ABRE元件结合调节ABA信号传导

Arabidopsis bZIP1 Transcription Factor Binding to the ABRE Cis-Element Regulates Abscisic Acid Signal Transduction

ABA作为一种重要的植物激素和生长调节剂,介导了高等植物在营养生长阶段对各种外界环境的响应和适应。bZIP类转录因子可以通过ABA依赖途径和ABA非依赖途径调节植物的生长发育和对非生物胁迫的耐性。本研究通过AtbZIP1T-DNA插入突变的拟南芥植株ko-1(SALK_059343)和ko-2(SALK_069489C)在ABA处理后的表型实验,验证了AtbZIP1参与ABA依赖的信号传导通路。采用"三引物法",分别在DNA水平和RNA水平通过PCR和RT-PCR验证了AtbZIP1基因在拟南芥突变体中的沉默效果。定量分析数据表明,在种子萌发阶段,经过0.6μmolL–1ABA和0.8μmolL–1ABA处理后,AtbZIP1缺失突变体拟南芥植株萌发率和叶片展开/绿色率比野生型植株高,在幼苗生长阶段,经过50μmolL–1ABA处理后,AtbZIP1缺失突变体拟南芥植株根长比野生型植株长。为了确定AtbZIP1基因参与ABA信号传导是否依赖于ABRE元件,在大肠杆菌中表达了AtbZIP1HIS6融合蛋白,并设计了核心序列为CACGTG的ABRE元件。凝胶阻滞电泳结果表明AtbZIP1融合蛋白可以与ABRE元件特异性结合。半定量RT-PCR分析表明,AtbZIP1基因的缺失改变了下游的ABA响应基因的表达。该结果表明,AtbZIP1可以通过与ABRE元件结合调节植物对ABA处理的敏感性和下游ABA响应基因的表达,从而参与植物的ABA信号传导通路。

Abscisic acid （ABA） is a phytohormone and mediates the response and adaptation of higher plants to various environmental stresses during vegetative growth. The basic leucine zipper （bZIP） transcription factors are also important regulators of plant development and abiotic resistance, acting through either ABA-dependent or ABA-independent pathways. In this study, we investigated and characterized the involvement of the AtbZIP1 gene in plant responsiveness to ABA. As confirmed by PCR and RT-PCR, AtbZIP1 has been silenced in mutant Arabidopsis ko-1 （SALK_059343） and ko-2 （SALK_069489C）. The AtbZIP1 knockout plants demonstrated reduced sensitivity to ABA both at the seed germination and seedling stage with improvements in rates of germination, leaf opening/greening, and primary root length. In order to investigate whether the regulation of AtbZIP1 mediated ABA responsiveness depended on the ABA-responsive elements （ABRE）, we expressed the AtbZIP1 HIS6 fusion protein in E. coli and found that the AtbZIP1 HIS6 specifically bound to the ABRE cis-elements. Semi-quantitive RT PCR showed that AtbZIP1 disruption altered expressions of some ABA responsive genes, such as NCED3, RD22, KIN1, and RD29A. Our results indicated that AtbZIP1 regulates abscisic acid signal transduction by binding to the ABREs and altered the expressions of the ABA responsive genes.