Department of Bioenergy Science and Technology, Chonnam National University, Gwangju 61186, Republic of Korea.
Plant Cell Physiol. 2018 May 1;59(5):966-977. doi: 10.1093/pcp/pcy033.
The aerial parts of terrestrial plants are covered with hydrophobic wax layers, which represent the primary barrier between plant cells and the environment and act to protect plants from abiotic and biotic stresses. Although total wax loads are precisely regulated in an environmental- or organ-specific manner, regulatory mechanisms underlying cuticular wax biosynthesis remain largely unknown. In this study, we characterized DEWAX2 (DECREASE WAX BIOSYNTHESIS2) which encodes an APETALA 2 (AP2)/ethylene response element-binding factor (ERF)-type transcription factor and is predominantly expressed in young seedlings, and rosette and cauline leaves. Total wax loads increased by approximately 12% and 16% in rosette and cauline leaves of dewax2, respectively, but were not significantly altered in the stems of dewax2 relative to the wild type (WT). The excess wax phenotype of dewax2 leaves was rescued upon expression of DEWAX2 driven by its own promoter. Overexpression of DEWAX2 decreased total wax loads by approximately 15% and 26% in the stems and rosette leaves compared with those of the WT, respectively. DEWAX2:eYFP (enhanced yellow fluorescent protein) was localized to the nucleus in Arabidopsis roots and hypocotyls. DEWAX2 possessed transcriptional repression activity in tobacco protoplasts. Transcriptome and quantitative real-time PCR analyses showed that the transcript levels of CER1, ACLA2, LACS1, LACS2 and KCS12 were down-regulated in DEWAX2 overexpression lines compared with the WT. Transient transcriptional assays showed that DEWAX2 represses the expression of its putative target genes. Quantitative chromatin immunoprecipitation-PCR revealed that DEWAX2 binds directly to the GCC motifs of the LACS1, LACS2, KCS12 and CER1 promoters. These results suggest that DEWAX2-mediated transcriptional repression may contribute to the total wax load in Arabidopsis leaves.
陆生植物的地上部分被疏水性蜡层覆盖,这是植物细胞与环境之间的主要屏障,有助于植物抵御非生物和生物胁迫。尽管总蜡负荷以环境或器官特异性的方式精确调节,但角质层蜡生物合成的调节机制在很大程度上仍然未知。在这项研究中,我们对 DEWAX2(减少蜡生物合成 2)进行了表征,该基因编码一个 APETALA 2(AP2)/乙烯反应元件结合因子(ERF)-型转录因子,主要在幼苗、莲座叶和茎中表达。与野生型(WT)相比,dewax2 的莲座叶和茎中的总蜡负荷分别增加了约 12%和 16%,但茎中的总蜡负荷没有明显改变。dewax2 叶片的多余蜡表型在由其自身启动子驱动的 DEWAX2 表达时得到挽救。与 WT 相比,DEWAX2 的过表达使茎和莲座叶中的总蜡负荷分别减少了约 15%和 26%。DEWAX2:eYFP(增强型黄色荧光蛋白)在拟南芥根和下胚轴中定位于细胞核。DEWAX2 在烟草原生质体中具有转录抑制活性。转录组和定量实时 PCR 分析表明,与 WT 相比,DEWAX2 过表达系中 CER1、ACLA2、LACS1、LACS2 和 KCS12 的转录水平下调。瞬时转录分析表明,DEWAX2 抑制其假定靶基因的表达。定量染色质免疫沉淀-PCR 显示,DEWAX2 直接结合到 LACS1、LACS2、KCS12 和 CER1 启动子的 GCC 基序上。这些结果表明,DEWAX2 介导的转录抑制可能有助于拟南芥叶片中的总蜡负荷。