Expression of the Suaeda salsa SsNLP7 Transcription Factor in Solanum lycopersicum Enhances Its Salt Tolerance

The nitrate signaling core regulator <i>NLP7</i> is known to negatively regulate salt tolerance in <i>Arabidopsis thaliana</i>, but the function of the (<i>SsNLP7A</i>) gene in the halophyte <i>Suaeda salsa</i> remains unclear. To investigate whether <i>SsNLP7A</i> participates in salt stress responses, this study heterologously overexpressed the gene in tomato (<i>Solanum lycopersicum</i>) and systematically evaluated its function under salt stress through phenotypic, physiological, and transcriptomic analyses. The results indicate that <i>SsNLP7A</i> overexpression significantly promotes tomato root development and alleviates growth inhibition caused by salt stress. Under salt treatment, transgenic plants exhibited significantly higher chlorophyll content, accumulation of osmotic regulators (proline and soluble sugars), and antioxidant enzyme (POD, CAT, SOD) activity compared to wild-type plants. Transcriptome analysis further revealed that <i>SsNLP7A</i> enhances salt tolerance by regulating carbon metabolism, phytohormone signaling pathway, photosynthesis, and antioxidant pathways. Collectively, this study elucidates the positive regulatory role of <i>SsNLP7A</i> in salt stress response, providing new insights into its molecular mechanisms.