Understanding how plants use nitrogen is crucial for improving crop yields and reducing environmental impact. Key enzymes like nitrate reductase and glutamine synthetase play a vital role in converting inorganic nitrogen into organic forms that plants can use. By studying these enzymes in major crops like rice, maize, and wheat, as well as in Arabidopsis, researchers are working towards developing crops with higher nitrogen use efficiency. This research aims to address the challenges of excessive nitrogen use in agriculture and pave the way for more sustainable farming practices.