Podgórska Anna, Burian Maria, Szal Bożena
Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of WarsawWarsaw, Poland.
Front Plant Sci. 2017 Aug 22;8:1353. doi: 10.3389/fpls.2017.01353. eCollection 2017.
Reactive oxygen species (ROS), by their very nature, are highly reactive, and it is no surprise that they can cause damage to organic molecules. In cells, ROS are produced as byproducts of many metabolic reactions, but plants are prepared for this ROS output. Even though extracellular ROS generation constitutes only a minor part of a cell's total ROS level, this fraction is of extraordinary importance. In an active apoplastic ROS burst, it is mainly the respiratory burst oxidases and peroxidases that are engaged, and defects of these enzymes can affect plant development and stress responses. It must be highlighted that there are also other less well-known enzymatic or non-enzymatic ROS sources. There is a need for ROS detoxification in the apoplast, and almost all cellular antioxidants are present in this space, but the activity of antioxidant enzymes and the concentration of low-mass antioxidants is very low. The low antioxidant efficiency in the apoplast allows ROS to accumulate easily, which is a condition for ROS signaling. Therefore, the apoplastic ROS/antioxidant homeostasis is actively engaged in the reception and reaction to many biotic and abiotic stresses.
活性氧（ROS）因其本质特性而具有高度反应性，它们会对有机分子造成损害也就不足为奇了。在细胞中，ROS是许多代谢反应的副产物，但植物已为此种ROS产出做好了准备。尽管细胞外ROS的产生仅占细胞总ROS水平的一小部分，但这一部分却极为重要。在活跃的质外体ROS爆发中，主要涉及呼吸爆发氧化酶和过氧化物酶，这些酶的缺陷会影响植物发育和应激反应。必须强调的是，还存在其他不太知名的酶促或非酶促ROS来源。质外体中需要进行ROS解毒，几乎所有细胞抗氧化剂都存在于这个空间中，但抗氧化酶的活性和低分子量抗氧化剂的浓度非常低。质外体中较低的抗氧化效率使得ROS易于积累，这是ROS信号传导的一个条件。因此，质外体ROS/抗氧化剂稳态积极参与对许多生物和非生物胁迫的感知和反应。
