A high-affinity potassium transporter (MeHKT1) from cassava (Manihot esculenta) negatively regulates the response of transgenic Arabidopsis to salt stress

Abstract Background High-affinity potassium transporters (HKTs) are crucial in facilitating potassium uptake by plants. Many types of HKTs confer salt tolerance to plants through regulating K + and Na + homeostasis under salinity stress. However, their specific functions in cassava ( Manihot esculenta ) remain unclear. Results Herein, an HKT gene ( MeHKT1 ) was cloned from cassava, and its expression is triggered by exposure to salt stress. The expression of a plasma membrane-bound protein functions as transporter to rescue a low potassium (K + ) sensitivity of yeast mutant strain, but the complementation of MeHKT1 is inhibited by NaCl treatment. Under low K + stress, transgenic Arabidopsis with MeHKT1 exhibits improved growth due to increasing shoot K + content. In contrast, transgenic Arabidopsis accumulates more Na + under salt stress than wild-type (WT) plants. Nevertheless, the differences in K + content between transgenic and WT plants are not significant. Additionally, Arabidopsis expressing MeHKT1 displayed a stronger salt-sensitive phenotype. Conclusion These results suggest that under low K + condition, MeHKT1 functions as a potassium transporter. In contrast, MeHKT1 mainly transports Na + into cells under salt stress condition and negatively regulates the response of transgenic Arabidopsis to salt stress. Our results provide a reference for further research on the function of MeHKT1 , and provide a basis for further application of MeHKT1 in cassava by molecular biological means.