Overexpression of BvKUP13 from sugar beet increased salt tolerance in transgenic Arabidopsis thaliana

Introduction The KUP/HAK/KT family is the largest group of potassium ion transporters in plants and plays a central role in K + uptake, transport, and abiotic stress responses. However, the function of individual KUP genes in salt-tolerant crops remains under explored. In this study, BvKUP13 was isolated from the salt-tolerant beet variety AK3018. Methods We cloned and analyzed the sequence, subcellular localization, and expression profile of BvKUP13 under salt stress. Transgenic Arabidopsis thaliana plants overexpressing BvKUP13 were generated to evaluate its role in salt stress tolerance. Results BvKUP13 encodes a protein of 732 amino acids, shows striking sequence similarity to KUP proteins from Chenopodium quinoa and Spinacia oleracea , and is localized to the endoplasmic reticulum membrane. The gene is predominantly expressed in leaves and is upregulated by NaCl treatment. Overexpression in Arabidopsis significantly improved salt tolerance, as indicated by enhanced photosynthetic efficiency, maintained Na + /K + balance, elevated antioxidant enzyme activity, and higher osmolyte levels. Reduced MDA and ROS accumulation further supported the protective role of BvKUP13 under salt stress. Discussion These findings demonstrate that BvKUP13 enhances salt tolerance by regulating ion homeostasis and strengthening physiological and biochemical stress responses. BvKUP13 is a potential candidate gene for engineering salt-tolerant sugar beet varieties.