Nitric oxide, energy, and redox-dependent responses to hypoxia.

This article focuses on the role of nitric oxide (NO) and redox regulation in plant adaptive responses to hypoxia, a condition of low oxygen availability that challenges aerobic metabolism. It details how NO, reactive oxygen species (ROS), and reactive nitrogen species (RNS) coordinate signaling pathways that trigger anatomical adaptations such as aerenchyma formation, adventitious root development, and hyponastic growth, as well as biochemical and molecular changes including modulation of glycolysis, fermentation, and amino acid metabolism. The phytoglobin–NO (Pgb–NO) cycle is highlighted as central to maintaining cellular redox and energy homeostasis under hypoxia by regulating mitochondrial function and stabilizing hypoxia-responsive transcription factors via the oxygen-sensing N-degron pathway. Understanding these mechanisms is presented as crucial for improving plant resilience to environmental stresses like flooding, which are increasing due to climate change and threaten agricultural productivity and food security.