Nitric oxide signals ROS scavenger-mediated enhancement of PAL activity in nitrogen-deficient Matricaria chamomilla roots: side effects of scavengers
Nitric oxide signals ROS scavenger-mediated enhancement of PAL activity in nitrogen-deficient Matricaria chamomilla roots: side effects of scavengers
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DOI：
10.1016/j.freeradbiomed.2009.03.020
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发表时间：
2009-06-15
影响因子：
7.4
通讯作者：
Backor, Martin
中科院分区：
文献类型：
--
作者：
Kovacik, Jozef;Klejdus, Borivoj;Backor, Martin
由于植物组织中含有丰富的酚类代谢物，它们的积累是胁迫保护的重要工具。然而，酚类代谢的调节仍然知之甚少。使用三种 ROS 清除剂 [二硫苏糖醇 (DTT)、水杨基异羟肟酸和苯甲酸钠] 研究了处理 24 小时的氮 (N) 缺乏的洋甘菊根中活性氧 (ROS) 对苯丙氨酸解氨酶 (PAL) 活性的调节作用。清除剂降低了过氧化氢和/或超氧化物的水平（并上调了抗坏血酸/愈创木酚过氧化物酶和谷胱甘肽还原酶），但令人惊讶的是。刺激 PAL 活性。这种上调与一氧化氮 (NO) 含量、总可溶性酚、选定的酚酸和部分木质素（在 DTT 暴露的根中表达最多）的增加相关。因此，我们检验了 NO 可能参与这些变化的假设。在所有处理中，施用 2-苯基-4,4,5,5-四甲基咪唑啉-1-氧基-3-氧化物 (PTIO) 均降低了 PAL 活性和可溶性酚的积累。外源性 H2O2 和 NO 也刺激 PAL 活性和酚类物质的积累。我们得出的结论是，除了过氧化氢之外，NO 还可以在缺氮期间调节 PAL 活性。根据现有知识，还讨论了 PTIO 对 NO 含量的异常影响以及 ROS 清除剂引起的 NO 增加的可能机制。 (C) 2009 Elsevier Inc. 保留所有权利。
Owing to the abundance of phenolic metabolites in plant tissue, their accumulation represents an important tool for stress protection. However, the regulation of phenolic metabolism is still poorly known. The regulatory role of reactive oxygen species (ROS) in the activity of phenylalanine ammonia-lyase (PAL) in nitrogen (N)-deficient chamomile roots treated for 24 h was studied using three ROS scavengers [dithiothreitol (DTT), salicylhydroxamic acid, and sodium benzoate]. Scavengers decreased the level of hydrogen peroxide and/or superoxide (and up-regulated ascorbate/guaiacol peroxidase and glutathione reductase), but, surprisingly. stimulated PAL activity. This up-regulation was correlated with increases in nitric oxide (NO) content, total soluble phenols, selected phenolic acids, and, partially, lignin (being expressed the most in DTT-exposed roots). We therefore tested the hypothesis that NO may be involved in these changes. Application of 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) decreased PAL activity and the accumulation of soluble phenols in all treatments. Exogenous H2O2 and NO also stimulated PAL activity and the accumulation of phenols. We conclude that NO, in addition to hydrogen peroxide, may regulate PAL activity during N deficiency. The anomalous effect of PTIO on NO content and possible mechanism of ROS scavenger-evoked NO increases in light of the current knowledge are also discussed. (C) 2009 Elsevier Inc. All rights reserved.