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Wheat grain yield on saline soils is improved by an ancestral Na+ transporter gene


The ability of wheat to maintain a low sodium concentration ([Na+]) in leaves correlates with improved growth under saline conditions1,2. This trait, termed Na+ exclusion, contributes to the greater salt tolerance of bread wheat relative to durum wheat3,4. To improve the salt tolerance of durum wheat, we explored natural diversity in shoot Na+ exclusion within ancestral wheat germplasm. Previously, we showed that crossing of Nax2, a gene locus in the wheat relative Triticum monococcum into a commercial durum wheat (Triticum turgidum ssp. durum var. Tamaroi) reduced its leaf [Na+] (ref. 5). Here we show that a gene in the Nax2 locus, TmHKT1;5-A, encodes a Na+-selective transporter located on the plasma membrane of root cells surrounding xylem vessels, which is therefore ideally localized to withdraw Na+ from the xylem and reduce transport of Na+ to leaves. Field trials on saline soils demonstrate that the presence of TmHKT1;5-A significantly reduces leaf [Na+] and increases durum wheat grain yield by 25% compared to near-isogenic lines without the Nax2 locus.

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Figure 1: TmHKT1;5-A expression in yeast (S. cerevisiae) and X. laevis oocytes.
Figure 2: Localization of TmHKT1;5-A and its encoded protein, and its transcriptional regulation by salt.
Figure 3: Variation in salinity across a commercially farmed field, and the relative increase in grain yield due to the presence of TmHKT1:5-A.

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The authors thank grain growers A. and J. Crowe for hosting our field trials on their property at Moree. We acknowledge the assistance of C. Blake (CSIRO), B. Collard, D. Gulliford (NSW DPI) and A. Smart (PCT); J. Dubcovsky, University of California, Davis, for kindly providing the BAC sequence used to design cslinkNax2; D. Cooper, T. Rathjen, A. Webster and J. Able for additional field data on Nax2. We thank S. Ramesh for extracting Xenopus oocytes, Adelaide Microscopy for facilities and training, G. Mayo for assistance with in situ PCR, S. Roy for assistance with confocal microscopy and flame photometry and O. Cotsaftis for the clone of OsHKT1;5. This research was supported by the Grains Research and Development Corporation (GRDC) of Australia and the Australian Research Council (ARC).

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R.M., R.A.J., R.A.H., M.T., D.P. and M.G. conceived the project and planned experiments. R.M. and M.G. supervised the research. B.X. performed all Xenopus, yeast and protoplast experiments and R.A.J. performed field research. C.S.B. performed wheat genotyping. S.D.T. assisted with electrophysiology experiments. S.J.C., A.A. and C.J. performed in situ PCR and qPCR. M.G., D.P., R.A.J. and R.M. wrote the manuscript. All authors commented on the manuscript.

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Correspondence to Matthew Gilliham.

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Munns, R., James, R., Xu, B. et al. Wheat grain yield on saline soils is improved by an ancestral Na+ transporter gene. Nat Biotechnol 30, 360–364 (2012).

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