| Biotechnology |
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| Functional characterization of a potassium transporter gene NrHAK1 in Nicotiana rustica |
| Zhao-kui GUO, Qian YANG, Xiu-qing WAN, Pei-qiang YAN |
| Department of Life Sciences and Engineering, Harbin Institute of Technology, Harbin 150001, China; Mudanjiang Tobacco Research Institute, Mudanjiang 157011, China |
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Abstract The purpose of this study is to investigate the function of a novel potassium transporter gene (NrHAK1) isolated from Nicotiana rustica roots using yeast complement and real-time PCR technique. The complementary DNA (cDNA) of NrHAK1, 2 488 bp long, contains an open reading frame (ORF) of 2 334 bp encoding a protein of 777 amino acids (87.6 kDa) with 12 predicted transmembrane domains. The NrHAK1 protein shows a high sequence similarity to those of high-affinity potassium transporters in Mesembryanthemum, Phytolacca acinosa, Arabidopsis thaliana, and so on. We found that the NrHAK1 gene could complement the yeast-mutant defect in K+ uptake. Among several tissues surveyed, the expression level of NrHAK1 was most abundant in the root tip and was up-regulated when exposed to potassium starvation. Moreover, the transcript accumulation was significantly reduced by adding 5 mmol/L NH4+ to the solution. These results suggest that NrHAK1 plays an important role in potassium absorption in N. rustica.
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Received: 05 July 2008
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