The apoplastic oxidative burst in response to biotic stress in plants: a three-component system
The apoplastic oxidative burst in response to biotic stress in plants: a three-component system
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DOI：
10.1093/jexbot/53.372.1367
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发表时间：
2002-05-01
影响因子：
6.9
通讯作者：
Minibayeva, F
中科院分区：
文献类型：
--
作者：
Bolwell, GP;Bindschedler, LV;Minibayeva, F
氧化猝发是植物细胞抗性机制中普遍存在的早期部分，是植物细胞对病原体攻击作出反应时产生的活性氧物种。通过对一些植物-病原菌相互作用的研究，以及通过对培养细胞的激发子处理所模拟的那些，也变得明显的是，可能有不止一种机制在运作。然而，一种机制可能在任何给定的物种中占主导地位。NADPH氧化酶参与了许多系统的研究，并已被克隆和鉴定。然而，在用来自Colletotrichum lindemuthianum的细胞壁激发子处理的菜豆(Phaseolus Ual Garis)细胞中，酶系统是ROS的主要来源，似乎依赖于细胞外过氧化物酶。第二个成分，细胞外碱化，是大多数诱导系统共同的最早反应之一，由于钙和质子的内流和K+的外流而发生的。第三种成分，即实际的还原剂/底物，仍然难以捉摸。比较了诱导前后质外体液体的低分子化合物组成。底物只有在诱导几分钟后才可用，并可被提取，因此通过LC-MS比较图谱，可以识别可能的底物。其机理已被证明是复杂的，可能涉及许多低分子量组分。饱和脂肪酸如棕榈酸和硬脂酸可以刺激过氧化氢的产生，而不伴随氧脂的产生。这一生化证据得到了细菌感染部位乳头形成的免疫定位研究的支持，这些研究表明，在氯化铈染色显示的过氧化氢产生部位存在过氧化物酶同工酶，以及交联壁蛋白、胼胝质和胼胝质合成酶。该过氧化物酶已被克隆并在巴斯德毕赤酵母中表达，其催化氧化反应的动力学与纯化的酶相同。此外，用四季豆过氧化物酶反义定向转化的拟南芥植株已被证明对细菌和真菌病原体高度敏感。因此，拟南芥可能是另一个有可能引发质外体氧化爆发的物种，这些转化的植物株系可能有助于鉴定与之相关的过氧化物酶。
The oxidative burst, the generation of reactive oxygen species (ROS) in response to microbial pathogen attack, is a ubiquitous early part of the resistance mechanisms of plant cells. It has also become apparent from the study of a number of plant-pathogen interactions and those modelled by elicitor treatment of cultured cells that there may be more than one mechanism operating. However, one mechanism may be dominant in any given species. NADPH oxidases have been implicated in a number of systems and have been cloned and characterized. However, the enzyme system which is the major source of ROS in French bean (Phaseolus vulgaris) cells treated with a cell wall elicitor from Colletotrichum lindemuthianum, appears to be dependent on an exocellular peroxidase. The second component, the extracellular alkalinization, occurs as a result of the Ca2+ and proton influxes and the K+ efflux common to most elicitation systems as one of the earliest responses. The third component, the actual reductant/substrate, has remained elusive. The low molecular weight compound composition of apoplastic fluid was compared before and after elicitation. The substrate only becomes available some min after elicitation and can be extracted, so that by comparing the profiles by LC-MS it has been possible to identify possible substrates. The mechanism has proved to be complex and may involve a number of low molecular weight components. Stimulation of H2O2 production was observed with saturated fatty acids such as palmitate and stearate without concomitant oxylipin production. This biochemical evidence is supported by immunolocalization studies on papillae forming at bacterial infection sites that show the peroxidase isoform present at sites of H2O2 production revealed by cerium chloride staining together with the cross-linked wall proteins and callose and callose synthase. The peroxidase has been cloned and expressed in Pichia pastoris and has been shown to catalyse the oxidation reaction with the same kinetics as the purified enzyme. Furthermore, Arabidopsis plants transformed heterologously using the French bean peroxidase in antisense orientation have proved to be highly susceptible to bacterial and fungal pathogens. Thus it is possible that Arabidopsis is another species with the potential to mount an apoplastic oxidative burst and these transformed plant lines may be useful to identify the peroxidase that is responsible.