A novel High-affinity potassium transporter gene NrHAK 1 was isolated from Nicotiana rustica roots. The cDNA of NrHAK 1 contains 2488 nucleotides and an ORF of 2331 nucleotides that encodes a protein of 777 amino acids (Mr 87.6 kdaltons) with 12 predicted transmembrane domains. The amino acid sequence encoded by the NrHAK 1 cDNA shows high homology to that of High-affinity potassium transporter in Mesembryanthemum , Phytolacca acinosa and Arabidopsis thaliana etc. The NrHAK 1 gene can also complement yeast mutants defective in K⁺ uptake. Transcript levels of NrHAK 1 increased by K⁺ starvation and by salt stress of 200 mM NaCl in leaves and roots. These results suggest that NrHAK 1 plays an important role in potassium transportation in Nicotiana .