Nitric Oxide Dynamics in High-Altitude Medicinal Plants: Role in Stress Adaptation, Signaling, and Phytohormonal Interactions.

Nitric oxide (NO) is a pivotal signaling molecule that plays a crucial role in the high-altitude adaptation and stress tolerance of medicinal plants. Under hypoxic conditions prevalent in high-altitude environments, NO facilitates oxygen sensing, regulates mitochondrial function, and influences ethylene biosynthesis, thereby enhancing plant resilience. This review elucidates NO's modulation of oxidative stress responses through interactions with reactive oxygen species (ROS) to maintain redox homeostasis. Additionally, NO's interaction with key phytohormones, including abscisic acid, ethylene, and gibberellins, is examined, highlighting its role in hormone-mediated stress adaptation. Numerous medicinal plants adapted to high altitudes demonstrate NO's influence on secondary metabolite production, growth, and reproductive processes. The intricate crosstalk between NO and other signaling molecules, such as gasotransmitters and secondary messengers, reveals a complex network of integrative signaling pathways facilitating adaptive responses. Furthermore, advancements in NO detection and quantification techniques, along with existing challenges, are reviewed to provide insights into enhancing the understanding and application of NO dynamics in plant stress tolerance. In conclusion, this synthesis of current knowledge proposes potential biotechnological applications and future research directions to further explore NO-mediated adaptation mechanisms in medicinal plants thriving in high-altitude environments.