Transcriptomic and Physiological Insights into Auxin-Mediated Root Growth and Potassium Uptake in Tobacco Under Low- Potassium Stress

Abstract Background Improving plant potassium uptake efficiency is of great significance for agricultural production. Auxin, as a key plant hormone, promotes root growth activity and enhances the plant's ability to absorb and accumulate mineral nutrients. To investigate the role of auxin in root growth and potassium uptake mechanisms under low-potassium stress, this study utilized tobacco as a model plant and conducted hydroponic experiments. Results Low-potassium stress significantly impaired root development and potassium uptake in tobacco plants. Under these conditions, exogenous IAA enhanced root development and increased potassium uptake, while NPA inhibited root growth and adversely affected potassium absorption and retention. Transcriptome sequencing under low-potassium conditions identified 8,381 differentially expressed genes (DEGs) between the two treatment groups, which were primarily enriched in pathways related to photosynthesis-antenna proteins, photosynthesis, plant hormone signal transduction, and the MAPK signaling pathway. Analysis of DEGs associated with auxin signaling, potassium ion channels, transporters, and transcription factors revealed several key genes involved in the response to low-potassium stress, including KUP6, IAA14, ARF16, PIN1, SKOR, NPF7.3, and AP2/ERF. Notably, KUP6 was upregulated following IAA treatment and downregulated with NPA, indicating that this potassium ion transporter gene plays a crucial role in the auxin-mediated alleviation of low-potassium stress in tobacco, likely linked to endogenous auxin levels Conclusions Our research reveals that potassium deficiency impairs root development and uptake in tobacco, and auxin plays a critical role in mitigating this stress. This study highlights auxin’s regulatory function in enhancing root growth and potassium absorption under low-potassium conditions, offering insights into the molecular mechanisms of potassium stress response