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植物活性氧的产生及其作用和危害   总被引:3,自引:0,他引:3       下载免费PDF全文
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。  相似文献
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Ionol (BHT), a compound having antioxidant activity, at concentrations in the range 1-50 mg/liter (0.45·10-5-2.27·10-4 M), inhibits growth of etiolated wheat seedlings, changes the morphology of their organs, prolongs the coleoptile life span, and prevents the appearance of specific features of aging and apoptosis in plants. In particular, BHT prevents the age-dependent decrease in total DNA content, apoptotic internucleosomal fragmentation of nuclear DNA, appearance in the cell vac-uole of specific vesicles with active mitochondria intensively producing mtDNA, and formation of heavy mitochondrial DNA ( = 1.718 g/cm3) in coleoptiles of etiolated wheat seedlings. BHT induces large structural changes in the organization of all cellular organelles (nucleus, mitochondria, plastids, Golgi apparatus, endocytoplasmic reticulum) and the formation of new unusual membrane structures in the cytoplasm. BHT distorts the division of nuclei and cells, and this results in the appearance of multi-bladed polyploid nuclei and multinuclear cells. In roots of etiolated wheat seedlings, BHT induces intensive synthesis of pigments, presumably carotenoids, and the differentiation of plastids with formation of chloro- or chromoplasts. The observed multiple effects of BHT are due to its antioxidative properties (the structural BHT analog 3,5-di-tert-butyltoluene is physiologically inert; it has no effect similar to that of BHT). Therefore, the reactive oxygen species (ROS) controlled by BHT seem to trigger apoptosis and the structural reorganization of the cytoplasm in the apoptotic cell with formation of specific vac-uolar vesicles that contain active mitochondria intensively producing mtDNA. Thus, the inactivation of ROS by BHT may be responsible for the observed changes in the structure of all the mentioned cellular organelles. This corresponds to the idea that ROS control apoptosis and mitosis including formation of cell wall, and they are powerful secondary messengers that regulate dif-ferentiation of plastids and the Golgi apparatus in plants.  相似文献
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