KDC1, a novel carrot root hair K+ channel - Cloning, characterization, andexpression in mammalian cells

Potassium is an essential nutrient which plays an important role in many as pects of plant growth and development. Plants have developed a number of hi ghly specific mechanisms to take up potassium from the soil; these include the expression of K+ transporters and potassium channels in root cells. Des pite the fact that root epidermal and hair cells are in direct contact with the soil, the role of these tissues in K+ uptake is not well understood. H ere we report the molecular cloning and functional characterization of a no vel potassium channel KDC1 which forms part of a new subfamily of plant K-i n channels. Kdc1 was isolated from carrot root RNA and in situ hybridizatio n experiments show Kdc1 to be highly expressed in root hair cells. Expressi ng the KDC1 protein in Chinese hamster ovary cells identified it as a volta ge and pH-dependent inwardly rectifying potassium channel. An electrophysio logical analysis of carrot root hair protoplasts confirmed the biophysical properties of the Kdc1 gene product (KDC1) in the heterologous expression s ystem. KDC1 thus represents a major K+ uptake channel in carrot root hair c ells.