植物活性氧的产生及其作用和危害

活性氧(ROS)是一类由O2转化而来的自由基或具有高反应活性的离子或分子。植物消耗的O2约有1%在叶绿体、线粒体、过氧化物酶体等多种亚细胞单位中被转化成了ROS。ROS有益或有害取决于它在植物体内的浓度。低浓度的ROS作为第二信使能在植物细胞信号转导途径中介导多种应答反应,高浓度的ROS则引起生物大分子的氧化损伤甚至细胞死亡。植物体内ROS产生和清除之间的平衡十分重要,并由一套有效的酶促和非酶促抗氧化系统来监控。该文主要系统介绍了植物ROS的种类、产生部位、在信号转导中的作用及其对植物细胞造成的主要伤害等方面的研究进展,为利用基因工程手段来提高植物对环境胁迫的抗性提供信息和思路。

Generation of Reactive Oxygen Species and Their Functions and Deleterious Effects in Plants

Reactive oxygen species (ROS) are a group of free radicals,reactive molecules and ions that are derived from O₂.It is estimated that about 1% of plants-consumed O₂ is converted to ROS in various subcellular compartments such as chloroplast,mitochondria,and peroxisome.ROS are well recognized for playing a dual role as both deleterious and beneficial factors,depending on their concentration in plants.At low concentration ROS acts as second messenger in signaling cascades that mediate several responses in plant cells,whereas at high concentration it triggers oxidative damages to biomolecules and even cell death.Equilibrium between ROS production and scavenging is crucial for plants,and monitored by an efficient antioxidative system consisting of both nonenzymic and enzymic antioxidants.This review thoroughly introduced the current proceedings of studies on plant ROS mainly in terms of their types,production sites,roles in signaling and major damages to plant cells,aiming to provide an insight for improving plant resistance to environmental stress through genetic engineering.