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.

Item Type:	Refereed Article
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant physiology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Grains and seeds
Objective Field:	Wheat
UTAS Author:	Cuin, TA (Dr Tracey Cuin)
UTAS Author:	Shabala, SN (Professor Sergey Shabala)
ID Code:	60260
Year Published:	2009
Web of Science® Times Cited:	97
Deposited By:	Agricultural Science
Deposited On:	2010-01-27
Last Modified:	2012-12-12
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