Identification of proteins associated with ion homeostasis and salt tolerance in barley

Identification and characterization of proteins involved in salt tolerance are imperative for revealing its genetic mechanisms. In this study, ionic and proteomic responses of a Tibetan wild barley XZ16 and a well-known salt-tolerant barley cv. CM72 were analyzed using inductively coupled plasma-optical emission spectrometer, 2DE, and MALDI-TOF/TOF MS techniques to determine salt-induced differences in element and protein profiles between the two genotypes. In total, 41 differentially expressed proteins were identified in roots and leaves, and they were associated with ion homeostasis, cell redox homeostasis, metabolic process, and photosynthesis. Under salinity stress, calmodulin, Na/K transporters, and H⁺-ATPases were involved in establishment of ion homeostasis for barley plants. Moreover, ribulose-1,5-bisphosphate carboxylase/oxygenase activase and oxygen-evolving enhancer proteins were significantly upregulated under salinity stress, indicating the great impact of salinity on photosynthesis. In comparison with CM72, XZ16 had greater relative dry weight and lower Na accumulation in the shoots under salinity stress. A higher expression of HvNHX1 in the roots, and some specific proteins responsible for ion homeostasis and cell redox homeostasis, was also found in XZ16 exposed to salt stress. The current results showed that Tibetan wild barley XZ16 and cultivated barley cultivar CM72 differ in the mechanism of salt tolerance.