Mittler R, Lam E, Shulaev V, Cohen M
Department of Plant Sciences, The Hebrew University of Jerusalem, Israel.
Plant Mol Biol. 1999 Mar;39(5):1025-35. doi: 10.1023/a:1006110223774.
In plants ascorbate peroxidase (APX) is an important H2O2-detoxifying enzyme. The expression of APX is rapidly induced in response to stresses that result in the accumulation of reactive oxygen species (ROS). We have recently reported that the steady-state level of transcripts encoding cytosolic APX (cAPX) is dramatically induced during the hypersensitive response (HR) of tobacco plants infected with tobacco mosaic virus (TMV). Because cAPX expression is closely linked to the production of ROS in plant cells, studying the regulation cAPX mRNA can reveal some of the signal transduction events associated with ROS metabolism during the HR. Analysis of cAPX mRNA induction during the HR suggested that the expression of cAPX is under the control of the HR signal transduction pathway. The activation of cAPX expression followed signaling events such as changes in protein phosphorylation and induction of ion fluxes. Expression of cAPX was suppressed under conditions of low oxygen pressure, and could only be mimicked by enhancing the intracellular generation of ROS. Interestingly, salicylic acid (SA), which is thought to be involved in ROS metabolism during the HR, did not affect the induction of cAPX mRNA during TMV-induced HR. Using cAPX expression as a marker for the production of ROS, it is suggested that SA may not be involved in the formation of ROS during the HR of tobacco to TMV, and that ROS may not be involved in the induction of the pathogenesis-related protein, PR-1, during this process.
在植物中，抗坏血酸过氧化物酶（APX）是一种重要的H2O2解毒酶。APX的表达会因导致活性氧（ROS）积累的胁迫而迅速被诱导。我们最近报道，在感染烟草花叶病毒（TMV）的烟草植株过敏反应（HR）期间，编码胞质APX（cAPX）的转录本稳态水平会显著上调。由于cAPX的表达与植物细胞中ROS的产生密切相关，研究cAPX mRNA的调控可以揭示HR期间一些与ROS代谢相关的信号转导事件。对HR期间cAPX mRNA诱导的分析表明，cAPX的表达受HR信号转导途径的控制。cAPX表达的激活伴随着诸如蛋白质磷酸化变化和离子通量诱导等信号事件。在低氧压力条件下，cAPX的表达受到抑制，并且只有通过增强细胞内ROS的产生才能模拟这种抑制。有趣的是，水杨酸（SA）被认为在HR期间参与ROS代谢，但在TMV诱导的HR期间并不影响cAPX mRNA的诱导。以cAPX表达作为ROS产生的标志物，表明SA可能不参与烟草对TMV的HR期间ROS的形成，并且在此过程中ROS可能不参与病程相关蛋白PR-1的诱导。
