GmAKT1 is involved in K uptake and Na/K homeostasis in Arabidopsis and soybean plants.

Plant roots absorb K from soil via K channels and transporters, which are important for stress responses. In this research, GmAKT1, an AKT1-type K channel, was isolated and characterized. The expression of GmAKT1 was induced by K-starvation and salinity stresses, and it was preferentially expressed in the soybean roots. And GmAKT1 was located in the plasma membrane. As an inward K channel, GmAKT1 participated in K uptake, as well as rescued the low-K-sensitive phenotype of the yeast mutant and Arabidopsis akt1 mutant. Overexpression of GmAKT1 significantly improved the growth of plants and increased K concentration, leading to lower Na/K ratios in transgenic Arabidopsis and chimeric soybean plants with transgenic hairy roots. In addition, GmAKT1 overexpression resulted in significant upregulation of these ion uptake-related genes, including GmSKOR, GmsSOS1, GmHKT1, and GmNHX1. Our findings suggested that GmAKT1 plays an important part in K uptake under low-K condition, and could maintain Na/K homeostasis under salt stress in Arabidopsis and soybean plants.