Departamento de BiologíaVegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, Apartado 13034, 50080, Zaragoza, Spain.
State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
New Phytol. 2022 Nov;236(3):815-832. doi: 10.1111/nph.18434. Epub 2022 Sep 6.
Legume nodules are symbiotic structures formed as a result of the interaction with rhizobia. Nodules fix atmospheric nitrogen into ammonia that is assimilated by the plant and this process requires strict metabolic regulation and signaling. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are involved as signal molecules at all stages of symbiosis, from rhizobial infection to nodule senescence. Also, reactive sulfur species (RSS) are emerging as important signals for an efficient symbiosis. Homeostasis of reactive molecules is mainly accomplished by antioxidant enzymes and metabolites and is essential to allow redox signaling while preventing oxidative damage. Here, we examine the metabolic pathways of reactive molecules and antioxidants with an emphasis on their functions in signaling and protection of symbiosis. In addition to providing an update of recent findings while paying tribute to original studies, we identify several key questions. These include the need of new methodologies to detect and quantify ROS, RNS, and RSS, avoiding potential artifacts due to their short lifetimes and tissue manipulation; the regulation of redox-active proteins by post-translational modification; the production and exchange of reactive molecules in plastids, peroxisomes, nuclei, and bacteroids; and the unknown but expected crosstalk between ROS, RNS, and RSS in nodules.
豆科植物根瘤是与根瘤菌相互作用形成的共生结构。根瘤将大气中的氮固定为氨，被植物同化，这个过程需要严格的代谢调控和信号转导。活性氧（ROS）和活性氮（RNS）作为信号分子参与共生的各个阶段，从根瘤菌感染到根瘤衰老。此外，活性硫（RSS）作为有效的共生信号分子正在出现。活性分子的动态平衡主要通过抗氧化酶和代谢物来实现，这对于允许氧化还原信号转导同时防止氧化损伤是必不可少的。在这里，我们检查了活性分子和抗氧化剂的代谢途径，重点关注它们在信号转导和共生保护中的功能。除了提供最新发现的更新并向原始研究致敬外，我们还确定了几个关键问题。这些问题包括需要新的方法来检测和定量 ROS、RNS 和 RSS，避免由于其短寿命和组织处理而产生潜在的假象；氧化还原活性蛋白的翻译后修饰调节；质体、过氧化物酶体、核和类菌体中活性分子的产生和交换；以及在根瘤中尚未可知但预期的 ROS、RNS 和 RSS 之间的串扰。
