A BASIC-TYPE PR-1 PROMOTER DIRECTS ETHYLENE RESPONSIVENESS, VASCULAR AND ABSCISSION ZONE-SPECIFIC EXPRESSION
A BASIC-TYPE PR-1 PROMOTER DIRECTS ETHYLENE RESPONSIVENESS, VASCULAR AND ABSCISSION ZONE-SPECIFIC EXPRESSION
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DOI：
10.1046/j.1365-313x.1993.04020225.x
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发表时间：
1993-08-01
期刊：
影响因子：
7.2
通讯作者：
FLUHR, R
中科院分区：
文献类型：
--
作者：
EYAL, Y;MELLER, Y;FLUHR, R
发病机制相关 (PR) 蛋白形成一组异质的宿主编码的低分子量蛋白，通过胞吐途径分泌。它们是植物响应各种刺激而合成的，包括病原体攻击或接触某些化学物质。烟草的PRB-1b基因编码碱性型PR-1蛋白，其转录受乙烯调节。通过转基因烟草植物中的缺失分析定义了最小乙烯响应启动子元件。含有213bp或更多的启动子序列足以增强暴露于20μl-1乙烯的转基因烟叶中β-葡萄糖醛酸酶报告基因表达的20倍增加，而67bp则不足以触发乙烯反应性。所有保留乙烯诱导能力的构建体均表现出韧皮部特异性活性，其在叶柄和花梗脱落区中是组成型的。该功能研究与启动子上主要核蛋白结合位点的体外筛选相关。使用乙烯处理和未处理植物的核提取物进行凝胶位移分析，发现启动子序列上有五个序列特异性蛋白质-DNA 复合物，跨度为 -863 至 -142 bp。基本型 PR-1 基因在叶和叶柄或花和花梗界面处的组成型表达可能代表植物对潜在病原体的防御先发制人，这表明与叶片中病原体诱导的表达具有功能相似性。
Pathogenesis-related (PR) proteins form a heterogeneous group of host-encoded, low-molecular-mass proteins that are secreted through the exocytic pathway. They are synthesized by the plant in response to various stimuli, including pathogen attack or exposure to certain chemicals. The PRB-1b gene of Nicotiana tabacum codes for a basic-type PR-1 protein whose transcription is regulated by ethylene. A minimal ethylene-responsive promoter element was defined by deletion analysis in transgenic tobacco plants. Promoter sequences containing 213 bp or more were sufficient to enhance a 20-fold increase of beta-glucuronidase reporter gene expression in transgenic tobacco leaves exposed to 20 mul l-1 of ethylene, while 67 bp were not sufficient to trigger ethylene responsiveness. All the constructs that retained ethylene inducibility exhibited phloem-specific activity, which was constitutive in petiole and pedicel abscission zones. This functional study was correlated to an in vitro screening of the major nuclear proteins' binding sites present on the promoter. Gel-shift analysis using nuclear extracts from ethylene-treated and non-treated plants revealed five sequence-specific protein-DNA complexes on promoter sequences spanning -863 to -142 bp. Constitutive expression of the basic-type PR-1 genes at the leaf and petiole or flower and pedicel interfaces may represent pre-emption of plant defenses against potential pathogens, suggesting a functional similarity to pathogen-induced expression in the leaf.