Many important agronomic traits in crop plants, including stress tolerance, are complex traits controlled by quantitative trait loci (QTLs). Isolation of these QTLs holds great promise to improve world agriculture but is a challenging task. We previously mapped a rice QTL, SKC1, that maintained K+ homeostasis in the salt-tolerant variety under salt stress1, consistent with the earlier finding that K+ homeostasis is important in salt tolerance2,3. To understand the molecular basis of this QTL, we isolated the SKC1 gene by map-based cloning and found that it encoded a member of HKT-type transporters. SKC1 is preferentially expressed in the parenchyma cells surrounding the xylem vessels. Voltage-clamp analysis showed that SKC1 protein functions as a Na+-selective transporter. Physiological analysis suggested that SKC1 is involved in regulating K+/Na+ homeostasis under salt stress, providing a potential tool for improving salt tolerance in crops.
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We thank H.-Q. Yang for providing pHB vector, J. Yang, X.-Y. Huang and J.-J. Zhang for technical assistance and E.Y. Isacoff for providing X. laevis oocytes. This work was supported by grants from the Ministry of Science and Technology of China, the National Natural Science Foundation of China and the Shanghai Science and Technology Development Fund to H.-X.L. and a grant from the US Department of Agriculture to S.L.
The authors declare no competing financial interests.
Shoots Na+ contents (means±SE, n=5) in T1 rice transformants under normal or salt stress condition (120 mM NaCl for 7 days). (PDF 32 kb)
Sequence alignments of SKC1. (PDF 56 kb)
K+ and Na+ contents in the phloem sap were not significantly different between NIL(SKC1) and Koshihikari under normal or stress condition (25 mM NaCl). (PDF 34 kb)
NIL(SKC1) seedlings are more tolerant to salt then Koshihikari under salt stress (125 mM NaCl for 32 days). (PDF 158 kb)
The molecular marker primers developed in this study and primers for SKC1 analysis. (PDF 10 kb)
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