Department of Grassland Science, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Engineering Research Center for Grassland Science, Tianhe, Wushan Road, Guangzhou, 510642, China.
Department of Grassland Science, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China; College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, 650201, China.
Plant Physiol Biochem. 2018 Aug;129:357-367. doi: 10.1016/j.plaphy.2018.04.010. Epub 2018 Apr 11.
Little is known about the cross talk between the lignin biosynthesis gene promoters and the regulatory proteins that modulate molecular signaling and respond to various stresses. In this study, we characterized the promoter region of the lignin biosynthesis pathway cinnamyl alcohol dehydrogenase (CAD) gene in elephant grass, Pennisetum purpureum. Quantification of the transcript levels of the PpCAD promoter revealed it is preferentially expressed in vascular tissue, especially xylem. Histochemical and fluorometric assays confirmed the vascular-preferential expression of the PpCAD promoter, as the highest β-glucuronidase (GUS) activity was found in the basal stem in transgenic tobacco plants expressing a 1154-bp PpCAD promoter-GUS fusion construct. Moreover, 5'-deleted PpCAD promoter analyses showed that the 1154-bp PpCAD promoter fragment had the highest transcriptional activity, whereas the 2054-bp fragment had multifarious inducible activity responding to gibberellin (GA), methyl jasmonate (MeJA), abscisic acid (ABA), and wounding. The regions from -248 to -243 bp and -1416 to -1411 bp contained W-box cis-elements, which were detected by electrophoretic mobility shift assay (EMSA). The binding effects of the GA-responsive elements (from -561 to -555 bp and -1077 to -1071 bp), MeJA-responsive element (from -1146 to -1142 bp), and the ABA-responsive cis-element (from -1879 to -1874 bp) were also validated by EMSA. Based on our results, we suggest that lignin deposition associated with PpCAD promoter activity adapts to the environment through molecular signaling involving GA, MeJA, and ABA.
关于木质素生物合成基因启动子与调节分子信号转导并响应各种胁迫的调节蛋白之间的串扰知之甚少。在这项研究中，我们对象草（Pennisetum purpureum）木质素生物合成途径肉桂醇脱氢酶（CAD）基因的启动子区进行了表征。PpCAD 启动子转录本水平的定量分析表明，它在血管组织中优先表达，特别是木质部。组织化学和荧光测定证实了 PpCAD 启动子的血管优先表达，因为在表达 1154bp PpCAD 启动子-GUS 融合构建体的转基因烟草植物的基部茎中发现了最高的β-葡糖苷酸酶（GUS）活性。此外，5'缺失的 PpCAD 启动子分析表明，1154bp PpCAD 启动子片段具有最高的转录活性，而 2054bp 片段具有多种诱导活性，可响应赤霉素（GA）、茉莉酸甲酯（MeJA）、脱落酸（ABA）和创伤。-248 到-243bp 和-1416 到-1411bp 区域包含 W-box 顺式元件，通过电泳迁移率变动分析（EMSA）检测到这些元件。GA 反应元件（-561 到-555bp 和-1077 到-1071bp）、MeJA 反应元件（-1146 到-1142bp）和 ABA 反应顺式元件（-1879 到-1874bp）的结合效应也通过 EMSA 得到验证。基于我们的结果，我们认为与 PpCAD 启动子活性相关的木质素沉积通过涉及 GA、MeJA 和 ABA 的分子信号适应环境。
