PtHAK5, a candidate for mediating high-affinity K + uptake in the halophytic grass, Puccinellia tenuiflora

Puccinellia tenuiflora is a typical salt-excluding halophytic grass with strong salt-tolerance, which enhances tolerance by restricting Na+ influx as well as having a strong selectivity for K+ over Na+. The HAK5 K+ transporters generally modulate effective K+ acquisition in plants, especially under low K+ condition. In this study, PtHAKS from P. tenuiflora was isolated by RT-PCR and characterized using yeast complementation. The results showed PtHAK5 consisted of 784 amino acids and shared over 80% homology with the identified high-affinity K+ transporter HAK5 from other higher plants. The expression of PtHAKS rescued the K+-uptake-defective phenotype of yeast strain CY162. In conclusion, PtHAKS is a candidate for mediating high-affinity K+ uptake under low K+ conditions.