Ectopic expression of potato ARP1 encoding auxin-repressed protein confers salinity stress tolerance in Arabidopsis thaliana.

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 (ARP1), in transgenic Arabidopsis plants. ARP1 transgenic lines were subjected to salinity stress and compared with wild-type (WT) plants. Compared to WT plants, transgenic ARP1 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 ARP1 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 ARP1 lines had increased photosynthetic capacity compared to WT plants, as indicated by various biochemical parameters and pigment indicators. Transgenic ARP1 lines also showed improved photosystem (PSII) efficiency compared to WT plants, as demonstrated by detailed chlorophyll fluorescence analyses. Moreover, both ARP1 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 ARP1 lines. We conclude that potato ARP1 is a promising candidate gene for the future development of salt-tolerant crops.