Plant salinity tolerance is a physiologically complex trait, with numerous mechanisms contributing to it. In this work we show that the ability of leaf mesophyll to retain K⁺ represents an important and essentially overlooked component of a salinity tolerance mechanism. The strong positive correlation between mesophyll K⁺ retention ability under saline conditions (quantified by the magnitude of NaCl-induced K⁺ efflux from mesophyll) and the overall salinity tolerance (relative fresh weight and/or survival or damage under salinity stress) was found while screening 46 barley (Hordeum vulgare L.) genotypes contrasting in their salinity tolerance. Genotypes with intrinsically higher leaf K⁺ content under control conditions were found to possess better K⁺ retention ability under salinity and, hence, overall higher tolerance. Contrary to previous reports for barley roots, K⁺ retention in mesophyll was not associated with an increased H⁺-pumping in tolerant varieties but instead correlated negatively with this trait. These findings are explained by the fact that increased H⁺ extrusion may be needed to charge balance the activity and provide the driving force for the high affinity HAK/KUP K⁺ transporters required to restore cytosolic K⁺ homeostasis in salt-sensitive genotypes.

Item Type:	Refereed Article
Keywords:	potassium retention, barley, salinity tolerance
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant physiology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the biological sciences
UTAS Author:	Wu, H (Mr Honghong Wu)
UTAS Author:	Zhu, M (Ms Min Zhu)
UTAS Author:	Shabala, L (Associate Professor Lana Shabala)
UTAS Author:	Zhou, M (Professor Meixue Zhou)
UTAS Author:	Shabala, S (Professor Sergey Shabala)
ID Code:	93410
Year Published:	2015
Web of Science® Times Cited:	82
Deposited By:	Tasmanian Institute of Agriculture
Deposited On:	2014-07-31
Last Modified:	2017-11-02
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