Liu Cheng, Liu Qingcai, Mou Zhonglin
Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL 32611, USA.
J Exp Bot. 2024 Aug 12;75(15):4535-4548. doi: 10.1093/jxb/erae193.
Plants fully depend on their immune systems to defend against pathogens. Upon pathogen attack, plants not only activate immune responses at the infection site but also trigger a defense mechanism known as systemic acquired resistance (SAR) in distal systemic tissues to prevent subsequent infections by a broad-spectrum of pathogens. SAR is induced by mobile signals produced at the infection site. Accumulating evidence suggests that reactive oxygen species (ROS) play a central role in SAR signaling. ROS burst at the infection site is one of the earliest cellular responses following pathogen infection and can spread to systemic tissues through membrane-associated NADPH oxidase-dependent relay production of ROS. It is well known that ROS ignite redox signaling and, when in excess, cause oxidative stress, damaging cellular components. In this review, we summarize current knowledge on redox regulation of several SAR signaling components. We discuss the ROS amplification loop in systemic tissues involving multiple SAR mobile signals. Moreover, we highlight the essential role of oxidative stress in generating SAR signals including azelaic acid and extracellular NAD(P) [eNAD(P)]. Finally, we propose that eNAD(P) is a damage-associated molecular pattern serving as a converging point of SAR mobile signals in systemic tissues.
植物完全依靠自身的免疫系统来抵御病原体。受到病原体攻击时，植物不仅会在感染部位激活免疫反应，还会在远端的系统组织中触发一种称为系统获得性抗性（SAR）的防御机制，以防止广谱病原体的后续感染。SAR由感染部位产生的移动信号诱导。越来越多的证据表明，活性氧（ROS）在SAR信号传导中起核心作用。感染部位的ROS爆发是病原体感染后最早的细胞反应之一，并且可以通过膜相关的NADPH氧化酶依赖性ROS中继产生扩散到系统组织。众所周知，ROS引发氧化还原信号传导，过量时会导致氧化应激，损害细胞成分。在这篇综述中，我们总结了目前关于几种SAR信号成分氧化还原调节的知识。我们讨论了涉及多种SAR移动信号的系统组织中的ROS放大环。此外，我们强调氧化应激在产生包括壬二酸和细胞外NAD(P) [eNAD(P)]在内的SAR信号中的重要作用。最后，我们提出eNAD(P)是一种损伤相关分子模式，作为系统组织中SAR移动信号的汇聚点。
