The Sweet Potato K(+) Transporter IbHAK11 Regulates K(+) Deficiency and High Salinity Stress Tolerance by Maintaining Positive Ion Homeostasis

The K(+) transporter KT/HAK/KUP (K(+) transporter/high-affinity K(+)/K(+) uptake) family has a critical effect on K(+) uptake and translocation in plants under different environmental conditions. However, the functional analysis of KT/HAK/KUP members in sweet potatoes is still limited. The present work reported the physiological activity of a new gene, IbHAK11, in the KT/HAK/KUP family in sweet potatoes. IbHAK11 expression increased significantly in the low K(+)-tolerant line compared with the low K(+)-sensitive line following treatment with low K(+) concentrations. IbHAK11 upregulation promoted root growth in Arabidopsis under low K(+) conditions. Under high saline stress, transgenic lines had superior growth and photosynthetic characteristics compared with the wild-type (WT). As for IbHAK11-overexpressing plants, activation of both the non-enzymatic and enzymatic reactive oxygen species (ROS) scavenging systems was observed. Therefore, IbHAK11-overexpressing plants had lower malondialdehyde (MDA) and ROS levels (including H(2)O(2) and O(2−)) compared with WT under salt-induced stress. We also found that under both low K(+) and high salinity conditions, overexpression of IbHAK11 enhanced K(+) translocation from the root to the shoot and decreased Na(+) absorption in Arabidopsis. Consequently, IbHAK11 positively regulated K(+) deficiency and high salinity stresses by regulating K(+) translocation and Na(+) uptake, thus maintaining K(+)/Na(+) homeostasis in plants.