Bioengineering Department, Biological and Pharmaceutical College, Guangdong University of Technology, Guangzhou, Guangdong, P.R. China, 510006.
BMC Plant Biol. 2021 Jan 29;21(1):66. doi: 10.1186/s12870-021-02832-x.
Glutamine synthetase (GS) acts as a key enzyme in plant nitrogen (N) metabolism. It is important to understand the regulation of GS expression in plant. Promoters can initiate the transcription of its downstream gene. Eichhornia crassipes is a most prominent aquatic invasive plant, which has negative effects on environment and economic development. It also can be used in the bioremediation of pollutants present in water and the production of feeding and energy fuel. So identification and characterization of GS promoter in E. crassipes can help to elucidate its regulation mechanism of GS expression and further to control its N metabolism.
A 1232 bp genomic fragment upstream of EcGS1b sequence from E. crassipes (EcGS1b-P) has been cloned, analyzed and functionally characterized. TSSP-TCM software and PlantCARE analysis showed a TATA-box core element, a CAAT-box, root specific expression element, light regulation elements including chs-CMA1a, Box I, and Sp1 and other cis-acting elements in the sequence. Three 5'-deletion fragments of EcGS1b upstream sequence with 400 bp, 600 bp and 900 bp length and the 1232 bp fragment were used to drive the expression of β-glucuronidase (GUS) in tobacco. The quantitative test revealed that GUS activity decreased with the decreasing of the promoter length, which indicated that there were no negative regulated elements in the EcGS1-P. The GUS expressions of EcGS1b-P in roots were significantly higher than those in leaves and stems, indicating EcGS1b-P to be a root-preferential promoter. Real-time Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) analysis of EcGS1b gene also showed higher expression in the roots of E.crassipes than in stems and leaves.
EcGS1b-P is a root-preferential promoter sequence. It can specifically drive the transcription of its downstream gene in root. This study will help to elucidate the regulatory mechanisms of EcGS1b tissue-specific expression and further study its other regulatory mechanisms in order to utilize E.crassipes in remediation of eutrophic water and control its overgrowth from the point of nutrient metabolism.
谷氨酰胺合成酶（GS）是植物氮代谢中的关键酶。了解植物中 GS 表达的调控机制非常重要。启动子可以启动其下游基因的转录。水葫芦是一种最突出的水生入侵植物，对环境和经济发展有负面影响。它也可以用于水污染物的生物修复以及饲料和能源燃料的生产。因此，鉴定和表征水葫芦中的 GS 启动子有助于阐明其 GS 表达的调控机制，并进一步控制其氮代谢。
从水葫芦中克隆、分析并功能表征了 EcGS1b 序列上游的 1232bp 基因组片段（EcGS1b-P）。TSSP-TCM 软件和 PlantCARE 分析表明，该序列中存在 TATA 盒核心元件、CAAT 盒、根特异表达元件、光调控元件，包括 chs-CMA1a、Box I 和 Sp1 等顺式作用元件。用 400bp、600bp 和 900bp 长度的 EcGS1b 上游序列的三个 5'缺失片段和 1232bp 片段驱动β-葡萄糖醛酸酶（GUS）在烟草中的表达。定量检测表明，随着启动子长度的减小，GUS 活性降低，这表明 EcGS1-P 中没有负调控元件。EcGS1b-P 在根中的 GUS 表达明显高于叶和茎，表明 EcGS1b-P 是根特异启动子。水葫芦 EcGS1b 基因的实时定量反转录-聚合酶链反应（qRT-PCR）分析也表明，该基因在根中的表达高于茎和叶。
EcGS1b-P 是一个根特异启动子序列。它可以特异性地在根中驱动其下游基因的转录。本研究将有助于阐明 EcGS1b 组织特异性表达的调控机制，并进一步研究其其他调控机制，以便从营养代谢的角度利用水葫芦修复富营养化水并控制其过度生长。
