Once plant endogenous nitric oxide (NO) production had been proved, NO research was directed toward both the source and the targets of this extremely bioactive molecule. As in mammals, plant NO was first thought to be generated mainly by a NO synthase-like enzymatic activity. However, nitrate reductase (NR)-dependent NO production is now receiving much of the attention because of the ubiquity of this enzyme in higher plant tissues and the precise regulation of its NO-production activity. NO has been reported to be a signal in many and diverse physiological processes, such as growth and biotic and abiotic stresses. Recently, NO has been shown to affect stomatal closure and interact with abscisic acid signaling pathways. We propose NR as a putative component in the signaling cascade of ABA-induced stomatal closure.

中文翻译：

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脱落酸，一氧化氮和气孔关闭-硝酸还原酶是否是缺失的环节之一？

一旦证明了植物内源性一氧化氮（NO）的产生，就没有研究针对这种具有极高生物活性的分子的来源和目标。与哺乳动物一样，最初认为植物一氧化氮主要由类似NO合酶的酶活性产生。然而，由于这种酶在高等植物组织中的普遍存在及其对NO产生活性的精确调节，因此硝酸盐还原酶（NR）依赖性NO的产生现在受到了广泛的关注。据报道，NO是许多不同生理过程中的信号，例如生长，生物和非生物胁迫。近来，已显示NO影响气孔关闭并与脱落酸信号传导途径相互作用。我们建议NR作为ABA诱导的气孔关闭信号级联中的假定成分。