Ionic relations and osmotic adjustment in durum and bread wheat under saline conditions
Tracey Ann Cuin A , Yu Tian B , Stewart A. Betts A C , Rémi Chalmandrier A D and Sergey Shabala A EA School of Agricultural Science, University of Tasmania, Private Bag 54, Hobart, Tas. 7001, Australia.
B Institute of Grassland Science, Department of Life Science, Northeast Normal University, ChangChun City, Jilin Province 130024, P.R. China.
C Present address: Department of Agriculture, Fisheries and Forestry, 18 Marcus Clarke Street, Canberra City, ACT 2601, Australia.
D Present address: Institut Polytechnique, LaSalle Beauvais, BP 30313, 60026 Beauvais, France.
E Corresponding author. Email: sergey.shabala@utas.edu.au
Functional Plant Biology 36(12) 1110-1119 https://doi.org/10.1071/FP09051
Submitted: 4 March 2009 Accepted: 10 September 2009 Published: 3 December 2009
Abstract
Wheat breeding for salinity tolerance has traditionally focussed on Na+ exclusion from the shoot, but its association with salinity tolerance remains tenuous. Accordingly, the physiological significance of shoot Na+ exclusion and maintenance of an optimal K+ : Na+ ratio was re-evaluated by studying NaCl-induced responses in 50 genotypes of bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. ssp. durum) treated with 150 mM NaCl. Overall, Na+ exclusion from the shoot correlated with salinity tolerance in both species and this exclusion was more efficient in bread compared with durum wheat. Interestingly, shoot sap K+ increased significantly in nearly all durum and bread wheat genotypes. Conversely, the total shoot K+ content declined. We argue that this increase in shoot sap K+ is needed to provide efficient osmotic adjustment under saline conditions. Durum wheat was able to completely adjust shoot sap osmolality using K+, Na+ and Cl–; it had intrinsically higher levels of these solutes. In bread wheat, organic osmolytes must contribute ~13% of the total shoot osmolality. In contrast to barley (Hordeum vulgare L.), NaCl-induced K+ efflux from seedling roots did not predict salinity tolerance in wheat, implying that shoot, not root K+ retention is important in this species.
Additional keywords: salinity tolerance, screening, shoot sap ion content, Triticum aestivum, Triticum turgidum ssp. durum.
Acknowledgements
This work was supported by a GDRC grant UT00013 to Associate Professor S. Shabala. We thank Mr Phil Andrews and Mrs Valentina Jacobs for their technical assistance and Michael Mackay, David Gulliford and Michael Manvell (Tamworth Agricultural Institute, NSW, Australia) for kindly supplying the seeds for this study.
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