Knockout of NtARF2 enhances salt tolerance in tobacco by modulating K/Na ratio and ABA content

• NtARF2 is significantly downregulated under salt stress and exogenous ABA treatment. • Knockout of NtARF2 markedly enhances tobacco salt tolerance. • Loss of N tARF2 increases the K/Na ratio and ABA content in tobacco. • NtARF2 interacts with NtABI3, indicating a potential key role in the crosstalk between salt stress and ABA signaling pathways. Salt stress severely inhibits plant growth and negatively impacts crop yield. Auxin response factors (ARFs) play crucial roles in plant growth and development and are involved in multiple signaling pathways as well as responses to abiotic stresses. However, the molecular mechanisms by which ARFs mediate plant responses to salt stress and ABA signaling remain largely unclear. In this study, we cloned a novel tobacco ARF family gene, NtARF2 , which is significantly downregulated under salt stress and exogenous ABA treatment. NtARF2 is localized in the nucleus, and its knockout increases the K/Na ratio and ABA content in tobacco, thereby markedly enhancing salt tolerance. Furthermore, NtARF2 knockout affects stomatal size, photosynthetic performance, and antioxidant capacity. Yeast two-hybrid (Y2H) and luciferase complementation imaging (LCI) assays indicate that NtARF2 interacts with NtABI3, suggesting that it may play a key role in the crosstalk between salt stress and ABA signaling pathways. This study provides new insights into the functional role of ARF2 in tobacco salt tolerance and offers a theoretical foundation for the development of salt-tolerant crop varieties.