Salinity is a major constraint to crop productivity and mechanisms of plant responses to salinity stress are extremely complex. Plants are able to respond to environmental stresses by activating adaptive mechanisms and reacting to environmental factors by changing their gene expression. In this regard, proteomics technique was applied to identify the responsible proteins for salinity stress in a wild salt-tolerant barley called "Hordeum marinum". Proteomics is a powerful technique to identify proteins involved in plant adaptation to stresses. At the 4-leaf stage, plants were exposed to 0 (control treatment) or 300 mM NaCl (salt treatment) in glasshouse. Salt treatment was maintained for 3 weeks. Total proteins of leaf 4 were extracted and separated by two-dimensional gel electrophoresis. More than 290 protein spots were reproducibly detected. Of these, 20 spots showed significant changes to salt treatment compared to the control: 19 spots were upregulated and 1 spot was absent. Using MALDI-TOF/TOF MS, we identified 20 cellular proteins which represented 11 different proteins and were classified into five categories. These proteins were involved in various cellular functions. Upregulation of proteins which involved in protein processing (ribosomal protein, cullin family, cp31AHv protein and RNA recognition motif (RRM) superfamily), photosynthesis (Ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) and Ribulose bisphosphate carboxylase/oxygenase activase (rubisco activase)), energy metabolism (cytosolic malate dehydrogenase (cyMDH) and fructokinase), oxygen species scavenging and defense (cystatin and thioredoxin) may increase plant adaptation to salt stress.

Keywords: Barley, Hordeum marinum, Proteomics, Salinity, Two-dimensional gel electrophoresis

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