Ionic relations and osmotic adjustment in durum and bread wheat under saline conditions
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Cuin, TA and Tian, Y and Betts, S and Chalmandrier, R and Shabala, SN, Ionic relations and osmotic adjustment in durum and bread wheat under saline conditions, Functional Plant Biology: An International Journal of Plant Function, 36, (12) pp. 1110-1119. ISSN 1445-4408 (2009) [Refereed Article]
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 150mM 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. © CSIRO 2009.
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