Hummel Irène, Bourdais Gildas, Gouesbet Gwenola, Couée Ivan, Malmberg Russell L, El Amrani Abdelhak
Centre National de la Recherche Scientifique, Université de Rennes 1, UMR 6553 ECOBIO, Campus de Beaulieu, bâtiment 14A, F-35042 Rennes Cedex, France.
Plant Biology Department, University of Georgia, Athens, GA 30602-7271, USA.
New Phytol. 2004 Sep;163(3):519-531. doi: 10.1111/j.1469-8137.2004.01128.x.
• In plants, polyamines can generally be synthesized by the ornithine decarboxylase and arginine decarboxylase pathways. However, the model plant Arabidopsis thaliana appears to possess only the arginine decarboxylase pathway. As two paralogous ARGININE DECARBOXYLASE (ADC) genes are present in Arabidopsis, we investigated differential expression and potential differences of promoter activity during seedling development and under specific stress conditions. • Promoter activities were studied in stable homozygotic transformants harbouring promoter::reporter gene fusions. • Under temperate conditions, ADC2 promoter activity was strongly associated with seed germination, root and leaf development, whereas ADC1 promoter activity was low during vegetative development. Light, sucrose and ethylene were shown to be important regulators of ADC2 promoter activity. By contrast, in roots and leaves of plantlets subjected to chilling treatment the ADC1 paralogue showed high promoter activity whereas ADC2 promoter activity was considerably decreased. • In situations of seed germination, root development and response to chilling, the modifications of promoter activities were associated with changes in mRNA levels, emphasizing the involvement of transcriptional regulation in ARGININE DECARBOXYLASE gene expression.
• 在植物中，多胺通常可通过鸟氨酸脱羧酶途径和精氨酸脱羧酶途径合成。然而，模式植物拟南芥似乎仅拥有精氨酸脱羧酶途径。由于拟南芥中存在两个旁系精氨酸脱羧酶（ADC）基因，我们研究了它们在幼苗发育过程中和特定胁迫条件下的差异表达及启动子活性的潜在差异。
• 在携带启动子::报告基因融合体的稳定纯合转化体中研究启动子活性。
• 在温和条件下，ADC2启动子活性与种子萌发、根和叶的发育密切相关，而在营养发育阶段ADC1启动子活性较低。光照、蔗糖和乙烯被证明是ADC2启动子活性的重要调节因子。相比之下，在经过冷处理的幼苗的根和叶中，ADC1旁系同源物显示出高启动子活性，而ADC2启动子活性则大幅下降。
• 在种子萌发、根发育和对冷胁迫的响应过程中，启动子活性的改变与mRNA水平的变化相关，这强调了转录调控在精氨酸脱羧酶基因表达中的作用。
