title: Uncoupling of sodium and chloride to assist breeding for salinity tolerance in crops.
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.
authors.affiliation: South Australian Research and Development Institute, Plant Genomics Centre, Waite Campus, Glen Osmond, SA, 5064, Australia.|School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA, 5064, Australia.
authors.forename: Yusuf
authors.identifier: http://orcid.org/0000-0002-6302-6692
authors.initials: Y
authors.lastname: Genc
authors.affiliation: South Australian Research and Development Institute, Plant Genomics Centre, Waite Campus, Glen Osmond, SA, 5064, Australia.|School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA, 5064, Australia.
authors.forename: Klaus
authors.initials: K
authors.lastname: Oldach
authors.affiliation: School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA, 5064, Australia.
authors.forename: Julian
authors.initials: J
authors.lastname: Taylor
authors.affiliation: South Australian Research and Development Institute, Plant Genomics Centre, Waite Campus, Glen Osmond, SA, 5064, Australia.|School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA, 5064, Australia.
authors.forename: Graham H
authors.initials: GH
authors.lastname: Lyons
mesh_terms: D001947:Breeding; D002712:Chlorides / Q000378:metabolism / Q000494:pharmacology*; D018556:Crops, Agricultural / Q000187:drug effects / Q000254:growth & development*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D054712:Salinity; D055049:Salt Tolerance / Q000187:drug effects*; D012639:Seeds / Q000187:drug effects / Q000254:growth & development; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D002712:Chlorides; D012964:Sodium
keywords: chloride (Cl−); ionic; osmotic; salinity; sodicity; sodium (Na+); sodium humate; tolerance