Cai Meng, Wei Jun, Li Xianghua, Xu Caiguo, Wang Shiping
National Key Laboratory of Crop Genetic Improvement, National Centre of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
Plant Biotechnol J. 2007 Sep;5(5):664-74. doi: 10.1111/j.1467-7652.2007.00271.x. Epub 2007 Jun 26.
The tissue-specific expression of transgenes is essential in plant breeding programmes to avoid the fitness costs caused by constitutive expression of a target gene. However, knowledge on the molecular mechanisms of tissue-specific gene expression and practicable tissue-specific promoters is limited. In this study, we identified the cis-acting elements of a tissue-specific promoter from rice, P(D54O), and tested the application of original and modified P(D54O) and its cis-elements in the regulation of gene expression. P(D54O) is a green tissue-specific promoter. Five novel tissue-specific cis-elements (LPSE1, LPSE2, LPSRE1, LPSRE2, PSE1) were characterized from P(D54O). LPSE1 activated gene expression in leaf and young panicle. LPSRE2 suppressed gene expression in leaf, root, young panicle and stem, and PSE1 suppressed gene expression in young panicle and stem. LPSRE1 and LPSE2 had dual roles in the regulation of tissue-specific gene expression; both functioned as activators in leaf, but LPSRE1 acted as a repressor in stem and LPSE2 as a repressor in young panicle and root. Transgenic rice plants carrying cry1Ac encoding Bacillus thuringiensis endotoxin, regulated by P(D54O), were resistant to leaf-folders, with no Cry1Ac protein found in endosperm or embryo. A reporter gene regulated by a series of truncated P(D54O) showed various tissue-specific expression patterns. Different fragments of P(D54O) fused with the constitutive cauliflower mosaic virus 35S promoter suppressed 35S-regulated gene expression in various tissues. P(D54O), truncated P(D54O) and the tissue-specific cis-elements provide useful tools for the regulation of tissue-specific gene expression in rice breeding programmes.
在植物育种计划中，转基因的组织特异性表达至关重要，可避免因目标基因组成型表达而导致的适应性代价。然而，关于组织特异性基因表达的分子机制以及实用的组织特异性启动子的知识却很有限。在本研究中，我们鉴定了来自水稻的组织特异性启动子P(D54O)的顺式作用元件，并测试了原始和修饰后的P(D54O)及其顺式元件在基因表达调控中的应用。P(D54O)是一种绿色组织特异性启动子。从P(D54O)中鉴定出了五个新的组织特异性顺式元件（LPSE1、LPSE2、LPSRE1、LPSRE2、PSE1）。LPSE1在叶片和幼穗中激活基因表达。LPSRE2在叶片、根、幼穗和茎中抑制基因表达，而PSE1在幼穗和茎中抑制基因表达。LPSRE1和LPSE2在组织特异性基因表达调控中具有双重作用；它们在叶片中均起激活剂作用，但LPSRE1在茎中起阻遏作用，LPSE2在幼穗和根中起阻遏作用。携带由P(D54O)调控的编码苏云金芽孢杆菌内毒素的cry1Ac基因的转基因水稻植株对卷叶螟具有抗性，在胚乳或胚中未发现Cry1Ac蛋白。由一系列截短的P(D54O)调控的报告基因表现出各种组织特异性表达模式。与组成型花椰菜花叶病毒35S启动子融合的P(D54O)不同片段在不同组织中抑制了35S调控的基因表达。P(D54O)、截短的P(D54O)和组织特异性顺式元件为水稻育种计划中组织特异性基因表达的调控提供了有用的工具。
