List of the primers used in the study.

<div><p>Salinity stress is one of the most detrimental factors affecting crop production worldwide. Genetic engineering offers a promising approach for improving agronomic traits and enhancing stress tolerance. In a previous work, several potential candidate genes were identified in potato using large-scale functional yeast screening. In this work, we characterized one of the identified genes, an auxin-repressed protein 1 (<i>ARP1)</i>, in transgenic <i>Arabidopsis</i> plants. <i>ARP1</i> transgenic lines were subjected to salinity stress and compared with wild-type (WT) plants. Compared to WT plants, transgenic <i>ARP1</i> lines showed significant improvements in morphological parameters, such as plant height, leaves per plant, root length, and fresh weight. Additionally, biochemical and physiological analyses revealed that the transgenic <i>ARP1</i> lines exhibited improved stomatal conductance, reduced electrolyte leakage, increased proline and chlorophyll accumulation, significantly enhanced malondialdehyde accumulation, and antioxidant enzyme activity. Additionally, spectral analysis revealed that transgenic <i>ARP1</i> lines had increased photosynthetic capacity compared to WT plants, as indicated by various biochemical parameters and pigment indicators. Transgenic <i>ARP1</i> lines also showed improved photosystem (PSII) efficiency compared to WT plants, as demonstrated by detailed chlorophyll fluorescence analyses. Moreover, both <i>ARP1</i> lines showed significantly higher expression levels of SOD, CAT, and APX than the WT plants under salt stress. The highest increase in relative expression was observed with SOD (3-fold increase) as compared to their respective WT in both <i>ARP1</i> lines. We conclude that potato <i>ARP1</i> is a promising candidate gene for the future development of salt-tolerant crops.</p></div>