Overexpression of DWF1 Enhances Low-Nitrogen Stress Tolerance in Potato Plants

Nitrogen is an important nutrient required for plant growth and development, but most of the time plants face nitrogen deficiency, all it is important to study the mechanism of low nitrogen tolerance in plants. This study addresses this gap by investigating the role of the <i>StDWF1</i> gene through the generation and analysis of transgenic potato lines overexpressing <i>StDWF1</i> (OE1, OE2, OE3). Exogenous BL treatment showed that the <i>StDWF1</i> gene responded to oleuropein lactone. Phenotypic assessments under normal nitrogen (NN) and low nitrogen (LN) conditions demonstrated that OE2 consistently outperformed WT, showing a 43% increase in root vitality and a 23% retention of chlorophyll under LN. Additionally, OE2 transgenics accumulated significantly higher levels of nitrate nitrogen (64.1% increase) and ammonium nitrogen (53% increase) compared to WT. Enzymatic assays further confirmed elevated activities of glutamine synthetase and nitrate reductase in both OE1 and OE2 lines. Hormone analyses showed that BL content of <i>StDWF1</i> overexpression lines was significantly increased under LN conditions, higher Oleandrin lactone (BL) content of OE2 improved plant stress tolerance, and WT was more affected by low nitrogen stress than OE2, resulting in higher levels of stress hormones than OE2. Temporal gene expression analysis showed significant upregulation of key nitrogen metabolism-related genes (<i>NR</i>, <i>NiR</i>, <i>AT</i>, <i>NRT2.1</i>) in OE2, with <i>StDWF1</i> expression reaching 79% higher than WT at 3 h. Protein-protein interaction assays, including yeast two-hybrid and BiLC assays, verified the interaction between <i>StDWF1</i> and <i>StGRP1</i>, suggesting the existence of a functional network to enhance low-nitrogen tolerance in potato plants. In conclusion, these findings suggest that overexpression of <i>StDWF1</i> significantly enhances low-nitrogen tolerance in transgenic potato lines, providing a promising strategy for improving crop performance under nitrogen-limited conditions.