An updated mechanistic overview of nitric oxide in drought tolerance of plants

Drought stress, an inevitable global issue due to climate change, hinders plant growth and yield. Nitric oxide (NO), a tiny gaseous signaling compound is now gaining massive attention from the plant science community due to its unparalleled array of mechanisms for ameliorating various abiotic stresses, including drought. Supplementation of NO has shown its astounding effect in improving drought tolerance by prominently influencing its tendency to modulate stomatal movement and reduce oxidative stress; it can enormously affect the various other physio-biochemical processes such as root structure, photosynthesis, osmolyte cumulation, and seed establishment of plants due to its amalgamation with a wide range of molecules during drought conditions. The production and inhibition of root development majorly depend on NO concentration and/or experimental conditions. As a lipophilic free gasotransmitter, NO readily reacts with free metals and oxygen species and has been shown to enhance or reduce the redox homeostasis of plants, depending on whether acting in a chronic or acute mode. NO can easily alter the enzymes, protein activities, and genomic transcriptional and post-translational modifications that assist functional retrieval from water stress. Although progress is ongoing, much work remains to be done to describe the proper target site and mechanistic approach of this vibrant molecule in plant drought tolerance. This detailed review navigates through the comprehensive and clear picture of the mechanistic potential of NO in drought stress following molecular approaches and suggests effective physiological and biochemical strategies to overcome the negative impacts of drought. We explore its potential to increase crop production, thereby ensuring global food security in drought-prone areas. In an era marked by unrelenting climatic conditions, the implications of NO show a promising approach to sustainable farming, providing a beacon of hope for future crop productivity.