The Shaker Type Potassium Channel, GORK, Regulates Abscisic Acid Signaling in Arabidopsis

Evolution of adaptive mechanisms to abiotic stress is essential for plant growth and development. Plants adapt to stress conditions by activating the abscisic acid (ABA) signaling pathway. It has been suggested that the ABA receptor, clade A protein phosphatase, SnRK2 type kinase, and SLAC1 anion channel are important components of the ABA signaling pathway. In this study, we report that the shaker type potassium (K(+)) channel, GORK, modulates plant responses to ABA and abiotic stresses. Our results indicate that the full length of PP2CA is needed to interact with the GORK C-terminal region. We identified a loss of function allele in gork that displayed ABA-hyposensitive phenotype. gork and pp2ca mutants showed opposite responses to ABA in seed germination and seedling growth. Additionally, gork mutant was tolerant to the NaCl and mannitol treatments, whereas pp2ca mutant was sensitive to the NaCl and mannitol treatments. Thus, our results indicate that GORK enhances the sensitivity to ABA and negatively regulates the mechanisms involved in high salinity and osmotic stresses via PP2CA-mediated signals.