Department of Plant Ecophysiology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland.
Plant Sci. 2011 Nov;181(5):612-20. doi: 10.1016/j.plantsci.2011.03.019. Epub 2011 Apr 6.
During the last decade it has been found that cadmium (Cd), one of the most toxic elements occurring in polluted environments, interferes with nitric oxide (NO), a multifunctional signaling molecule in living organisms. The formation of NO has been demonstrated in vivo in various plant tissues exposed to Cd stress, but unfortunately, the time and intensity of NO generation, relatively frequently shows conflicting data. What is more, there is still limited information regarding the functional role of endogenously produced NO in plants challenged with heavy metals. The first pharmacological approaches revealed that exogenously applied NO can alleviate cadmium toxicity in plants, promoting the direct scavenging of reactive oxygen species (ROS) or activating antioxidant enzymes. However, recent reports have indicated that NO even contributes to Cd toxicity by promoting Cd uptake and participates in metal-induced reduction of root growth. In view of this heterogeneous knowledge, much more puzzling if we consider results first obtained using exogenous NO sources, this review is focused mainly on the implication of endogenous NO in plant response to Cd exposure. Furthermore, a basic draft for NO mode of action during cadmium stress is proposed.
在过去的十年中，人们发现镉（Cd）是污染环境中存在的最具毒性的元素之一，它会干扰一氧化氮（NO），这是一种在生物体内具有多功能信号分子的物质。已经在体内各种暴露于 Cd 胁迫的植物组织中证明了 NO 的形成，但不幸的是，NO 的生成时间和强度相对频繁地显示出相互矛盾的数据。更重要的是，关于在重金属胁迫下植物中内源性产生的 NO 的功能作用的信息仍然有限。最初的药理学方法表明，外源施加的 NO 可以减轻植物的 Cd 毒性，促进对活性氧（ROS）的直接清除或激活抗氧化酶。然而，最近的报告表明，NO 甚至通过促进 Cd 摄取并参与金属诱导的根生长减少而加剧 Cd 毒性。鉴于这种异质的知识，如果我们首先考虑使用外源 NO 源获得的结果，这篇综述主要集中在内源性 NO 在植物对 Cd 暴露的反应中的作用。此外，还提出了一个在 Cd 胁迫期间 NO 作用模式的基本草案。
