Uncoupling of sodium and chloride to assist breeding for salinity tolerance in crops
Date
2016
Authors
Genc, Y.
Oldach, K.
Taylor, J.
Lyons, G.
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Journal article
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New Phytologist, 2016; 210(1):145-156
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Yusuf Genc, Klaus Oldach, Julian Taylor and Graham H. Lyons
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Abstract
The separation of toxic effects of sodium (Na+) and chloride (Cl−) by the current methods of mixed salts and subsequent determination of their relevance to breeding has been problematic. We report a novel method (Na+ humate) to study the ionic effects of Na+ toxicity without interference from Cl−, and ionic and osmotic effects when combined with salinity (NaCl). Three cereal species (Hordeum vulgare, Triticum aestivum and Triticum turgidum ssp. durum with and without the Na+ exclusion gene Nax2) differing in Na+ exclusion were grown in a potting mix under sodicity (Na+ humate) and salinity (NaCl), and water use, leaf nutrient profiles and yield were determined. Under sodicity, Na+-excluding bread wheat and durum wheat with the Nax2 gene had higher yield than Na+-accumulating barley and durum wheat without the Nax2 gene. However, under salinity, despite a 100-fold difference in leaf Na+, all species yielded similarly, indicating that osmotic stress negated the benefits of Na+ exclusion. In conclusion, Na+ exclusion can be an effective mechanism for sodicity tolerance, while osmoregulation and tissue tolerance to Na+ and/or Cl− should be the main foci for further improvement of salinity tolerance in cereals. This represents a paradigm shift for breeding cereals with salinity tolerance.
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© 2015 Commonwealth of Australia, New Phytologist © 2015 New Phytologist Trust