Functional Characterization of GhAKT1, a Novel Shaker K+ Channel Gene Involved in K+ Uptake from Cotton

Shaker-like potassium channels in plants play an important role in potassium absorption and transport. In this study, we characterized a shaker-like channel gene GhAKT1 (accession no. KF294166) from the cotton of Liaomian 17. A phylogenetic analysis showed that GhAKT1 belongs to the AKT1-subfamily in the Shaker K⁺ channel family. Confocal imaging of a GhAKT1–green fluorescent protein fusion protein in transgenic Arabidopsis plants indicated that GhAKT1 is localized in the plasma membrane. Transcript analysis located GhAKT1 predominantly in leaves with low abundance in roots, and the expression of GhAKT1 was not induced by K⁺-starvation stress in the root and leaves. Analysis of pGhAKT1::GUS transgenic Arabidopsis plants revealed GhAKT1 is expressed in many tissues of the adult plant, suggesting that it may play important roles in both nutrition and other important physiological processes. Using both akt1 mutants and overexpression lines, we observed that, GhAKT1 affected Arabidopsis seed germination and plant biomass. Moreover, under low-K⁺ stress, the overexpression line of GhAKT1 increased K⁺ influx, whereas the akt1 mutant and WT had lower flux rate in the roots by the noninvasive micro-test technique. Taken together, these results provide information for the functional analysis of GhAKT1, and suggest that GhAKT1 plays a role in K⁺ uptake.