Abstract
Potassium plays important roles for plant growth and development, affecting nutrition, membrane potential, enzyme function and the homeostasis of many other ions. Recent studies have reported the important roles of K+ transporters and their functions in plants under abiotic stresses. However, several of putative transporter proteins still remained unclear how they function. To understand function of K+ transporters that play a major role in drought stress, we focused on a putative K+/H+ antitransporter AtKEA5, which showed the increased expression under drought stress. AtKEA family belongs to CPA (Cation Proton Antiporters) family, and consists of six members (AtKEA1-6). AtKEA5 exhibited higher homology to AtKEA4 and AtKEA6 than the other members. Among AtKEA family members, the expression levels of AtKEA2 and AtKEA5 were increased under abiotic stress, and particularly expression of AtKEA5 was highly induced in the root under drought stress. GFP-AtKEA5 protein was localized to the plasma membrane and endomembrane. Phenotypic analysis of the knockout mutants and transgenic plants of AtKEAs, and the functional analysis of AtKEA2, AtKEA4 and AtKEA6 are also being characterized.
