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

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.