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Xylem ionic relations and salinity tolerance in barley

journal contribution
posted on 2023-05-17, 04:59 authored by Sergey ShabalaSergey Shabala, Svetlana ShabalaSvetlana Shabala, Tracey Cuin, Pang, J, Percey, WJ, Chen, Z, Conn, S, Eing, C, Wegner, LH
Control of ion loading into the xylem has been repeatedly named as a crucial factor determining plant salt tolerance. In this study we further investigate this issue by applying a range of biophysical [the microelectrode ion flux measurement (MIFE) technique for non-invasive ion flux measurements, the patch clamp technique, membrane potential measurements] and physiological (xylem sap and tissue nutrient analysis, photosynthetic characteristics, stomatal conductance) techniques to barley varieties contrasting in their salt tolerance. We report that restricting Na+ loading into the xylem is not essential for conferring salinity tolerance in barley, with tolerant varieties showing xylem Na+ concentrations at least as high as those of sensitive ones. At the same time, tolerant genotypes are capable of maintaining higher xylem K+/Na+ ratios and efficiently sequester the accumulated Na+ in leaves. The former is achieved by more efficient loading of K+ into the xylem. We argue that the observed increases in xylem K+ and Na+ concentrations in tolerant genotypes are required for efficient osmotic adjustment, needed to support leaf expansion growth. We also provide evidence that K+-permeable voltage-sensitive channels are involved in xylem loading and operate in a feedback manner to maintain a constant K+/Na+ ratio in the xylem sap.


Publication title

The Plant Journal










Tasmanian Institute of Agriculture (TIA)


Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

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