Lasserre E, Godard F, Bouquin T, Hernandez J A, Pech J C, Roby D, Balagué C
Laboratoire Ethylène et Mécanismes Moléculaires de la Maturation des Fruits UA-INRA, Ecole Nationale Supérieure Agronomique de Toulouse, France.
Mol Gen Genet. 1997 Oct;256(3):211-22. doi: 10.1007/s004380050563.
ACC (1-aminocyclopropane-1-carboxylate) oxidase genes are differentially expressed in melon during development and in response to various stresses. We investigated the molecular basis of their transcription by analyzing the 5' untranslated regions of the ACC oxidase genes CM-ACO1 and CM-ACO3. In order to determine how their temporal and spatial expression patterns were established, we fused the promoter regions of CM-ACO1 (726 bp) and CM-ACO3 (2260 bp) to the beta-glucuronidase (GUS) reporter gene and examined their regulation in transgenic tobacco plants. The CM-ACO1 promoter was able to drive GUS expression in response to wounding, and to treatment with ethylene or copper sulfate. It was also rapidly induced (8-12 h postinoculation) in tobacco leaves inoculated with the hypersensitive response (HR)-inducing bacterium Ralstonia solanacearum. Expression was also observed during compatible interactions but was delayed. In contrast, the CM-ACO3 promoter was not expressed in response to infection, but was up-regulated during flower development. Both promoters were regulated during leaf senescence but in different patterns. The CM-ACO1-driven GUS activity increased sharply concomitantly with the onset of chlorophyll breakdown, while the CM-ACO3 promoter drove strong GUS expression in green, fully expanded leaves and this declined at the onset of senescence. This result is consistent with the expression patterns of these two genes in senescent melon leaves. These data suggest that the regulation of expression of CM-ACO1 is related preferentially to stress responses, whereas CM-ACO3 seems to be associated with developmental processes. The possible role of ethylene is discussed, particularly in the regulation of the CM-ACO1 gene in response to stress and during senescence.
1-氨基环丙烷-1-羧酸（ACC）氧化酶基因在甜瓜发育过程中以及对各种胁迫的响应中存在差异表达。我们通过分析ACC氧化酶基因CM-ACO1和CM-ACO3的5'非翻译区来研究其转录的分子基础。为了确定它们的时空表达模式是如何建立的，我们将CM-ACO1（726 bp）和CM-ACO3（2260 bp）的启动子区域与β-葡萄糖醛酸酶（GUS）报告基因融合，并在转基因烟草植株中检测它们的调控情况。CM-ACO1启动子能够驱动GUS表达以响应创伤、乙烯或硫酸铜处理。在用诱导过敏反应（HR）的青枯雷尔氏菌接种的烟草叶片中，它也能被快速诱导（接种后8 - 12小时）。在亲和互作过程中也观察到表达，但有所延迟。相比之下，CM-ACO3启动子在感染时不表达，但在花发育过程中上调。两个启动子在叶片衰老过程中均受到调控，但模式不同。CM-ACO1驱动的GUS活性随着叶绿素降解的开始而急剧增加，而CM-ACO3启动子在绿色、完全展开的叶片中驱动强烈的GUS表达，并且在衰老开始时下降。这一结果与这两个基因在衰老甜瓜叶片中的表达模式一致。这些数据表明，CM-ACO1表达的调控优先与胁迫反应相关，而CM-ACO3似乎与发育过程相关。文中讨论了乙烯的可能作用，特别是在响应胁迫和衰老过程中对CM-ACO1基因的调控作用。
