A Host-Selective Toxin of Pyrenophora tritici-repentis, Ptr ToxA, Induces Photosystem Changes and Reactive Oxygen Species Accumulation in Sensitive Wheat
A Host-Selective Toxin of Pyrenophora tritici-repentis, Ptr ToxA, Induces Photosystem Changes and Reactive Oxygen Species Accumulation in Sensitive Wheat
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DOI：
10.1094/mpmi-22-6-0665
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发表时间：
2009-06-01
影响因子：
3.5
通讯作者：
Ciuffetti, Lynda M.
中科院分区：
文献类型：
--
作者：
Manning, Viola A.;Chu, Ashley L.;Ciuffetti, Lynda M.
Ptr ToxA（ToxA）是由小麦核腔菌（Pyrenophora tritici-repentis）产生的一种蛋白质性质的坏死性寄主选择性毒素。在这项研究中，我们已经发现，ToxA敏感的小麦叶片与ToxA的治疗导致光依赖性的活性氧（ROS）的积累，与坏死的发生相关。此外，ROS和坏死的积累可以被抗氧化剂N-乙酰半胱氨酸抑制，进一步证明ROS的产生是坏死所必需的。ToxA处理的全叶组织的显微镜评价表明，ROS积累发生在叶绿体中。从毒素A处理的叶片的总蛋白提取物的分析表明，光依赖性的叶绿体蛋白RuBisCo的减少。此外，蓝色天然凝胶电泳，然后十二烷基硫酸钠聚丙烯酰胺凝胶电泳分析表明，ToxA诱导光系统I（PSI）和光系统II（PSII）在没有光的情况下，因此，没有ROS的变化。当ToxA处理的叶片暴露于光下，所有的蛋白质在PSI和PSII都大大减少。我们建议，ToxA诱导PSI和PSII的改变，影响光合电子传递，随后导致ROS积累和细胞死亡时，植物暴露于光。
Ptr ToxA (ToxA) is a proteinaceous necrotizing host-selective toxin produced by Pyrenophora tritici-repentis, a fungal pathogen of wheat (Triticum aestivum). In this study, we have found that treatment of ToxA-sensitive wheat leaves with ToxA leads to a light-dependent accumulation of reactive oxygen species (ROS) that correlates with the onset of necrosis. Furthermore, the accumulation of ROS and necrosis could be inhibited by the antioxidant N-acetyl cysteine, providing further evidence that ROS production is required for necrosis. Microscopic evaluation of ToxA-treated whole-leaf tissue indicated that ROS accumulation occurs in the chloroplasts. Analysis of total protein extracts from ToxA-treated leaves showed a light-dependent reduction of the chloroplast protein RuBisCo. In addition, Blue native-gel electrophoresis followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis revealed that ToxA induces changes in photosystem I (PSI) and photosystem II (PSII) in the absence of light, and therefore, the absence of ROS. When ToxA-treated leaves were exposed to light, all proteins in both PSI and PSII were extremely reduced. We propose that ToxA induces alterations in PSI and PSII affecting photosynthetic electron transport, which subsequently leads to ROS accumulation and cell death when plants are exposed to light.