Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea.
J Pineal Res. 2017 Mar;62(2). doi: 10.1111/jpi.12379. Epub 2016 Dec 31.
Melatonin influences plant innate immunity through the mitogen-activated protein kinase (MAPK) pathway. However, the most upstream MAPK component in melatonin signaling and the dependence of generation of a reactive oxygen species (ROS) burst on melatonin synthesis and signaling remain unclear. In this study, treatment of several mekk (alias mapkkk)-knockout Arabidopsis mutants with melatonin revealed that the MAPKKK3 and OXI1 (oxidative signal-inducible1) kinases are responsible for triggering melatonin-induced defense signaling pathways. In addition, melatonin induction upon infection with the avirulent pathogen Pseudomonas syringae DC3000 (avrRpt2) was independent of H O and NO individually, but dependent on the combination of H O and NO. Moreover, melatonin-mediated induction of the expression of defense-related genes, such as PR1 and ICS1, was not altered in the H O -deficient rbohD/F-knockout mutant cotreated with an NO scavenger, indicating that melatonin functions downstream of the ROS and NO burst. Collectively, the data indicate that melatonin-mediated induction of an innate immune response requires multiple signaling molecules and activation of MAPKKK3 and OXI1, followed by triggering of downstream MAPK cascades, such as MAPK3 and MAPK6.
褪黑素通过丝裂原活化蛋白激酶（MAPK）途径影响植物固有免疫。然而，褪黑素信号转导中最上游的 MAPK 成分以及活性氧（ROS）爆发的产生对褪黑素合成和信号转导的依赖性仍不清楚。在这项研究中，用褪黑素处理几种 Mekk（别名 Mapkkk）敲除拟南芥突变体后发现，MAPKKK3 和 OXI1（氧化信号诱导 1）激酶负责触发褪黑素诱导的防御信号通路。此外，感染无毒性病原体丁香假单胞菌 DC3000（avrRpt2）后诱导褪黑素的产生不依赖于 H 2 O 2 和 NO 单独作用，但依赖于 H 2 O 2 和 NO 的组合。此外，在用 H 2 O 2 缺陷型 rbohD/F 敲除突变体共处理 NO 清除剂时，褪黑素介导的防御相关基因如 PR1 和 ICS1 的表达诱导并未改变，表明褪黑素在 ROS 和 NO 爆发的下游发挥作用。总之，数据表明，褪黑素介导的先天免疫反应的诱导需要多种信号分子以及 MAPKKK3 和 OXI1 的激活，随后触发 MAPK 级联反应，如 MAPK3 和 MAPK6。
